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Tsujii M, Tanudjaja E, Zhang H, Shimizukawa H, Konishi A, Furuta T, Ishimaru Y, Uozumi N. Dissecting structure and function of the monovalent cation/H + antiporters Mdm38 and Ylh47 in Saccharomyces cerevisiae. J Bacteriol 2024; 206:e0018224. [PMID: 39082862 PMCID: PMC11340316 DOI: 10.1128/jb.00182-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Accepted: 07/09/2024] [Indexed: 08/23/2024] Open
Abstract
Saccharomyces cerevisiae Mdm38 and Ylh47 are homologs of the Ca2+/H+ antiporter Letm1, a candidate gene for seizures associated with Wolf-Hirschhorn syndrome in humans. Mdm38 is important for K+/H+ exchange across the inner mitochondrial membrane and contributes to membrane potential formation and mitochondrial protein translation. Ylh47 also localizes to the inner mitochondrial membrane. However, knowledge of the structures and detailed transport activities of Mdm38 and Ylh47 is limited. In this study, we conducted characterization of the ion transport activities and related structural properties of Mdm38 and Ylh47. Growth tests using Na+/H+ antiporter-deficient Escherichia coli strain TO114 showed that Mdm38 and Ylh47 had Na+ efflux activity. Measurement of transport activity across E. coli-inverted membranes showed that Mdm38 and Ylh47 had K+/H+, Na+/H+, and Li+/H+ antiport activity, but unlike Letm1, they lacked Ca2+/H+ antiport activity. Deletion of the ribosome-binding domain resulted in decreased Na+ efflux activity in Mdm38. Structural models of Mdm38 and Ylh47 identified a highly conserved glutamic acid in the pore-forming membrane-spanning region. Replacement of this glutamic acid with alanine, a non-polar amino acid, significantly impaired the ability of Mdm38 and Ylh47 to complement the salt sensitivity of E. coli TO114. These findings not only provide important insights into the structure and function of the Letm1-Mdm38-Ylh47 antiporter family but by revealing their distinctive properties also shed light on the physiological roles of these transporters in yeast and animals. IMPORTANCE The inner membrane of mitochondria contains numerous ion transporters, including those facilitating H+ transport by the electron transport chain and ATP synthase to maintain membrane potential. Letm1 in the inner membrane of mitochondria in animals functions as a Ca2+/H+ antiporter. However, this study reveals that homologous antiporters in mitochondria of yeast, Mdm38 and Ylh47, do not transport Ca2+ but instead are selective for K+ and Na+. Additionally, the identification of conserved amino acids crucial for antiporter activity further expanded our understanding of the structure and function of the Letm1-Mdm38-Ylh47 antiporter family.
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Affiliation(s)
- Masaru Tsujii
- Graduate School of Engineering, Tohoku University, Aobayama, Sendai, Japan
| | - Ellen Tanudjaja
- Graduate School of Engineering, Tohoku University, Aobayama, Sendai, Japan
| | - Haoyu Zhang
- Graduate School of Engineering, Tohoku University, Aobayama, Sendai, Japan
| | - Haruto Shimizukawa
- Graduate School of Engineering, Tohoku University, Aobayama, Sendai, Japan
| | - Ayumi Konishi
- Graduate School of Engineering, Tohoku University, Aobayama, Sendai, Japan
| | - Tadaomi Furuta
- School of Life Science and Technology, Tokyo Institute of Technology, Nagatsuta-cho, Yokohama, Japan
| | - Yasuhiro Ishimaru
- Graduate School of Engineering, Tohoku University, Aobayama, Sendai, Japan
| | - Nobuyuki Uozumi
- Graduate School of Engineering, Tohoku University, Aobayama, Sendai, Japan
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2
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Qu H, Zhen Y, Xu M, Huang Y, Wang Y, Ji G, Zhang Y, Li H, Dong Z, Zheng X. Structures of a sperm-specific sodium-hydrogen exchanger. CELL INSIGHT 2024; 3:100177. [PMID: 38957574 PMCID: PMC11214986 DOI: 10.1016/j.cellin.2024.100177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 05/21/2024] [Accepted: 05/21/2024] [Indexed: 07/04/2024]
Affiliation(s)
- Hongyuan Qu
- Academy of Medical Sciences, Tianjian Laboratory of Advanced Biomedical Sciences, State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, 450001, China
- State Key Laboratory of Molecular Oncology, MOE Key Laboratory of Protein Sciences, SXMU-Tsinghua Collaborative Innovation Center for Frontier Medicine, School of Medicine, Tsinghua University, Beijing, 100084, China
- Beijing Frontier Research Center for Biological Structure and Beijing Advanced Innovation Center for Structural Biology, Beijing, 100084, China
| | - Yi Zhen
- Academy of Medical Sciences, Tianjian Laboratory of Advanced Biomedical Sciences, State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, 450001, China
| | - Mohan Xu
- Academy of Medical Sciences, Tianjian Laboratory of Advanced Biomedical Sciences, State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, 450001, China
| | - Yan Huang
- Academy of Medical Sciences, Tianjian Laboratory of Advanced Biomedical Sciences, State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, 450001, China
- Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University, Beijing, 100048, China
| | - Yashu Wang
- Academy of Medical Sciences, Tianjian Laboratory of Advanced Biomedical Sciences, State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, 450001, China
| | - Gaoyuan Ji
- State Key Laboratory of Molecular Oncology, MOE Key Laboratory of Protein Sciences, SXMU-Tsinghua Collaborative Innovation Center for Frontier Medicine, School of Medicine, Tsinghua University, Beijing, 100084, China
- Beijing Frontier Research Center for Biological Structure and Beijing Advanced Innovation Center for Structural Biology, Beijing, 100084, China
| | - Yuyu Zhang
- Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University, Beijing, 100048, China
| | - Haitao Li
- State Key Laboratory of Molecular Oncology, MOE Key Laboratory of Protein Sciences, SXMU-Tsinghua Collaborative Innovation Center for Frontier Medicine, School of Medicine, Tsinghua University, Beijing, 100084, China
- Beijing Frontier Research Center for Biological Structure and Beijing Advanced Innovation Center for Structural Biology, Beijing, 100084, China
| | - Zigang Dong
- Academy of Medical Sciences, Tianjian Laboratory of Advanced Biomedical Sciences, State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, 450001, China
| | - Xiangdong Zheng
- Academy of Medical Sciences, Tianjian Laboratory of Advanced Biomedical Sciences, State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, 450001, China
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3
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Hammes UZ, Pedersen BP. Structure and Function of Auxin Transporters. ANNUAL REVIEW OF PLANT BIOLOGY 2024; 75:185-209. [PMID: 38211951 DOI: 10.1146/annurev-arplant-070523-034109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
Auxins, a group of central hormones in plant growth and development, are transported by a diverse range of transporters with distinct biochemical and structural properties. This review summarizes the current knowledge on all known auxin transporters with respect to their biochemical and biophysical properties and the methods used to characterize them. In particular, we focus on the recent advances that were made concerning the PIN-FORMED family of auxin exporters. Insights derived from solving their structures have improved our understanding of the auxin export process, and we discuss the current state of the art on PIN-mediated auxin transport, including the use of biophysical methods to examine their properties. Understanding the mechanisms of auxin transport is crucial for understanding plant growth and development, as well as for the development of more effective strategies for crop production and plant biotechnology.
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Affiliation(s)
- Ulrich Z Hammes
- School of Life Sciences, Plant Systems Biology, Technical University of Munich, Freising, Germany;
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4
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Gulati A, Kokane S, Perez-Boerema A, Alleva C, Meier PF, Matsuoka R, Drew D. Structure and mechanism of the K +/H + exchanger KefC. Nat Commun 2024; 15:4751. [PMID: 38834573 PMCID: PMC11150392 DOI: 10.1038/s41467-024-49082-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 05/23/2024] [Indexed: 06/06/2024] Open
Abstract
Intracellular potassium (K+) homeostasis is fundamental to cell viability. In addition to channels, K+ levels are maintained by various ion transporters. One major family is the proton-driven K+ efflux transporters, which in gram-negative bacteria is important for detoxification and in plants is critical for efficient photosynthesis and growth. Despite their importance, the structure and molecular basis for K+-selectivity is poorly understood. Here, we report ~3.1 Å resolution cryo-EM structures of the Escherichia coli glutathione (GSH)-gated K+ efflux transporter KefC in complex with AMP, AMP/GSH and an ion-binding variant. KefC forms a homodimer similar to the inward-facing conformation of Na+/H+ antiporter NapA. By structural assignment of a coordinated K+ ion, MD simulations, and SSM-based electrophysiology, we demonstrate how ion-binding in KefC is adapted for binding a dehydrated K+ ion. KefC harbors C-terminal regulator of K+ conductance (RCK) domains, as present in some bacterial K+-ion channels. The domain-swapped helices in the RCK domains bind AMP and GSH and they inhibit transport by directly interacting with the ion-transporter module. Taken together, we propose that KefC is activated by detachment of the RCK domains and that ion selectivity exploits the biophysical properties likewise adapted by K+-ion-channels.
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Affiliation(s)
- Ashutosh Gulati
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Surabhi Kokane
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Annemarie Perez-Boerema
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Claudia Alleva
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Pascal F Meier
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Rei Matsuoka
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
| | - David Drew
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden.
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5
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Chávez JC, Carrasquel-Martínez G, Hernández-Garduño S, Matamoros Volante A, Treviño CL, Nishigaki T, Darszon A. Cytosolic and Acrosomal pH Regulation in Mammalian Sperm. Cells 2024; 13:865. [PMID: 38786087 PMCID: PMC11120249 DOI: 10.3390/cells13100865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 05/07/2024] [Accepted: 05/09/2024] [Indexed: 05/25/2024] Open
Abstract
As in most cells, intracellular pH regulation is fundamental for sperm physiology. Key sperm functions like swimming, maturation, and a unique exocytotic process, the acrosome reaction, necessary for gamete fusion, are deeply influenced by pH. Sperm pH regulation, both intracellularly and within organelles such as the acrosome, requires a coordinated interplay of various transporters and channels, ensuring that this cell is primed for fertilization. Consistent with the pivotal importance of pH regulation in mammalian sperm physiology, several of its unique transporters are dependent on cytosolic pH. Examples include the Ca2+ channel CatSper and the K+ channel Slo3. The absence of these channels leads to male infertility. This review outlines the main transport elements involved in pH regulation, including cytosolic and acrosomal pH, that participate in these complex functions. We present a glimpse of how these transporters are regulated and how distinct sets of them are orchestrated to allow sperm to fertilize the egg. Much research is needed to begin to envision the complete set of players and the choreography of how cytosolic and organellar pH are regulated in each sperm function.
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Affiliation(s)
- Julio C. Chávez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología (IBT), Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Morelos, Mexico; (J.C.C.); (G.C.-M.)
| | - Gabriela Carrasquel-Martínez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología (IBT), Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Morelos, Mexico; (J.C.C.); (G.C.-M.)
- CITMER, Medicina Reproductiva, México City 11520, Mexico
| | - Sandra Hernández-Garduño
- Departamento de Morfología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México (UNAM), México City 04510, Mexico;
| | - Arturo Matamoros Volante
- Department of Electrical and Computer Engineering and School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA;
| | - Claudia L. Treviño
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología (IBT), Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Morelos, Mexico; (J.C.C.); (G.C.-M.)
| | - Takuya Nishigaki
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología (IBT), Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Morelos, Mexico; (J.C.C.); (G.C.-M.)
| | - Alberto Darszon
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología (IBT), Universidad Nacional Autónoma de México (UNAM), Cuernavaca 62210, Morelos, Mexico; (J.C.C.); (G.C.-M.)
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6
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Yadav A, Kumar D, Dwivedi M. Site-directed mutagenesis at the Glu78 in Ec-NhaA transporter impacting ion exchange: a biophysical study. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2024; 53:193-203. [PMID: 38647543 DOI: 10.1007/s00249-024-01709-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 03/24/2024] [Accepted: 03/27/2024] [Indexed: 04/25/2024]
Abstract
Na+/H+ antiporters facilitate the exchange of Na+ for H+ across the cytoplasmic membrane in prokaryotic and eukaryotic cells. These transporters are crucial to maintain the homeostasis of sodium ions, consequently pH, and volume of the cells. Therefore, sodium/proton antiporters are considered promising therapeutic targets in humans. The Na+/H+ antiporter in Escherichia coli (Ec-NhaA), a prototype of cation-proton antiporter (CPA) family, transports two protons and one sodium (or Li+) in opposite direction. Previous mutagenesis experiments on Ec-NhaA have proposed Asp164, Asp163, and Asp133 amino acids with the significant implication in functional and structural integrity and create site for ion-binding. However, the mechanism and the sites for the binding of the two protons remain unknown and controversial which could be critical for pH regulation. In this study, we have explored the role of Glu78 in the regulation of pH by Ec-NhaA. Although we have created various mutants, E78C has shown a considerable effect on the stoichiometry of NhaA and presented comparable phenotypes. The ITC experiment has shown the binding of ~ 5 protons in response to the transport of one lithium ion. The phenotype analysis on selective medium showed a significant expression compared to WT Ec-NhaA. This represents the importance of Glu78 in transporting the H+ across the membrane where a single mutation with Cys amino acid alters the number of H+ significantly maintaining the activity of the protein.
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Affiliation(s)
- Anuradha Yadav
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India
| | - Dinesh Kumar
- Center of Biomedical Research, SGPGIMS Campus, Lucknow, 226014, India
| | - Manish Dwivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, 226028, India.
- Research Cell, Amity University Uttar Pradesh, Lucknow, 226028, India.
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7
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Cai Z, Peng H, Sun S, He J, Luo F, Huang Y. DeepKa Web Server: High-Throughput Protein p Ka Prediction. J Chem Inf Model 2024; 64:2933-2940. [PMID: 38530291 DOI: 10.1021/acs.jcim.3c02013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
DeepKa is a deep-learning-based protein pKa predictor proposed in our previous work. In this study, a web server was developed that enables online protein pKa prediction driven by DeepKa. The web server provides a user-friendly interface where a single step of entering a valid PDB code or uploading a PDB format file is required to submit a job. Two case studies have been attached in order to explain how pKa's calculated by the web server could be utilized by users. Finally, combining the web server with post processing as described in case studies, this work suggests a quick workflow of investigating the relationship between protein structure and function that are pH dependent. The web server of DeepKa is freely available at http://www.computbiophys.com/DeepKa/main.
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Affiliation(s)
- Zhitao Cai
- College of Computer Engineering, Jimei University, Xiamen 361021, China
| | - Hao Peng
- National Pilot School of Software, Yunnan University, Kunming 650504, China
| | - Shuo Sun
- College of Computer Engineering, Jimei University, Xiamen 361021, China
| | - Jiahao He
- College of Computer Engineering, Jimei University, Xiamen 361021, China
| | - Fangfang Luo
- College of Computer Engineering, Jimei University, Xiamen 361021, China
| | - Yandong Huang
- College of Computer Engineering, Jimei University, Xiamen 361021, China
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8
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Rimon A, Amartely H, Padan E. The crossing of two unwound transmembrane regions that is the hallmark of the NhaA structural fold is critical for antiporter activity. Sci Rep 2024; 14:5915. [PMID: 38467695 PMCID: PMC10928194 DOI: 10.1038/s41598-024-56425-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 03/06/2024] [Indexed: 03/13/2024] Open
Abstract
Cell pH and Na+ homeostasis requires Na+/H+ antiporters. The crystal structure of NhaA, the main Escherichia coli Na+/H+ antiporter, revealed a unique NhaA structural fold shared by prokaryotic and eukaryotic membrane proteins. Out of the 12 NhaA transmembrane segments (TMs), TMs III-V and X-XII are topologically inverted repeats with unwound TMs IV and XI forming the X shape characterizing the NhaA fold. We show that intramolecular cross-linking under oxidizing conditions of a NhaA mutant with two Cys replacements across the crossing (D133C-T340C) inhibits antiporter activity and impairs NhaA-dependent cell growth in high-salts. The affinity purified D133C-T340C protein binds Li+ (the Na+ surrogate substrate of NhaA) under reducing conditions. The cross-linking traps the antiporter in an outward-facing conformation, blocking the antiport cycle. As many secondary transporters are found to share the NhaA fold, including some involved in human diseases, our data have importance for both basic and clinical research.
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Affiliation(s)
- Abraham Rimon
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Jerusalem, Israel
- The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 91904, Jerusalem, Israel
| | - Hadar Amartely
- Wolfson Center for Applied Structural Biology, Jerusalem, Israel
- The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 91904, Jerusalem, Israel
| | - Etana Padan
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Jerusalem, Israel.
- The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 91904, Jerusalem, Israel.
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9
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Hariharan P, Shi Y, Katsube S, Willibal K, Burrows ND, Mitchell P, Bakhtiiari A, Stanfield S, Pardon E, Kaback HR, Liang R, Steyaert J, Viner R, Guan L. Mobile barrier mechanisms for Na +-coupled symport in an MFS sugar transporter. eLife 2024; 12:RP92462. [PMID: 38381130 PMCID: PMC10942615 DOI: 10.7554/elife.92462] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024] Open
Abstract
While many 3D structures of cation-coupled transporters have been determined, the mechanistic details governing the obligatory coupling and functional regulations still remain elusive. The bacterial melibiose transporter (MelB) is a prototype of major facilitator superfamily transporters. With a conformation-selective nanobody, we determined a low-sugar affinity inward-facing Na+-bound cryoEM structure. The available outward-facing sugar-bound structures showed that the N- and C-terminal residues of the inner barrier contribute to the sugar selectivity. The inward-open conformation shows that the sugar selectivity pocket is also broken when the inner barrier is broken. Isothermal titration calorimetry measurements revealed that this inward-facing conformation trapped by this nanobody exhibited a greatly decreased sugar-binding affinity, suggesting the mechanisms for substrate intracellular release and accumulation. While the inner/outer barrier shift directly regulates the sugar-binding affinity, it has little or no effect on the cation binding, which is supported by molecular dynamics simulations. Furthermore, the hydron/deuterium exchange mass spectrometry analyses allowed us to identify dynamic regions; some regions are involved in the functionally important inner barrier-specific salt-bridge network, which indicates their critical roles in the barrier switching mechanisms for transport. These complementary results provided structural and dynamic insights into the mobile barrier mechanism for cation-coupled symport.
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Affiliation(s)
- Parameswaran Hariharan
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, School of MedicineLubbockUnited States
| | - Yuqi Shi
- Thermo Fisher ScientificSan JoseUnited States
| | - Satoshi Katsube
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, School of MedicineLubbockUnited States
| | - Katleen Willibal
- VIB-VUB Center for Structural Biology, VIB, Pleinlaan 2BrusselsBelgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2BrusselsBelgium
| | - Nathan D Burrows
- Division of CryoEM and Bioimaging, Stanford Synchrotron Radiation Light Source, SLAC National Accelerator LaboratoryMenlo ParkUnited States
| | - Patrick Mitchell
- Division of CryoEM and Bioimaging, Stanford Synchrotron Radiation Light Source, SLAC National Accelerator LaboratoryMenlo ParkUnited States
| | | | - Samantha Stanfield
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, School of MedicineLubbockUnited States
| | - Els Pardon
- VIB-VUB Center for Structural Biology, VIB, Pleinlaan 2BrusselsBelgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2BrusselsBelgium
| | - H Ronald Kaback
- Department of Physiology, University of California, Los AngelesLos AngelesUnited States
| | - Ruibin Liang
- Department of Chemistry and Biochemistry, Texas Tech UniversityLubbockUnited States
| | - Jan Steyaert
- VIB-VUB Center for Structural Biology, VIB, Pleinlaan 2BrusselsBelgium
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2BrusselsBelgium
| | - Rosa Viner
- Thermo Fisher ScientificSan JoseUnited States
| | - Lan Guan
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, School of MedicineLubbockUnited States
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10
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Zimmermannová O, Velázquez D, Papoušková K, Průša V, Radová V, Falson P, Sychrová H. The Hydrophilic C-terminus of Yeast Plasma-membrane Na +/H + Antiporters Impacts Their Ability to Transport K . J Mol Biol 2024; 436:168443. [PMID: 38211892 DOI: 10.1016/j.jmb.2024.168443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/18/2023] [Accepted: 01/06/2024] [Indexed: 01/13/2024]
Abstract
Yeast plasma-membrane Na+/H+ antiporters (Nha/Sod) ensure the optimal intracellular level of alkali-metal cations and protons in cells. They are predicted to consist of 13 transmembrane segments (TMSs) and a large hydrophilic C-terminal cytoplasmic part with seven conserved domains. The substrate specificity, specifically the ability to recognize and transport K+ cations in addition to Na+ and Li+, differs among homologs. In this work, we reveal that the composition of the C-terminus impacts the ability of antiporters to transport particular cations. In the osmotolerant yeast Zygosaccharomyces rouxii, the Sod2-22 antiporter only efficiently exports Na+ and Li+, but not K+. The introduction of a negative charge or removal of a positive charge in one of the C-terminal conserved regions (C3) enabled ZrSod2-22 to transport K+. The same mutations rescued the low level of activity and purely Li+ specificity of ZrSod2-22 with the A179T mutation in TMS6, suggesting a possible interaction between this TMS and the C-terminus. The truncation or replacement of the C-terminal part of ZrSod2-22 with the C-terminus of a K+-transporting Nha/Sod antiporter (Saccharomyces cerevisiae Nha1 or Z. rouxii Nha1) also resulted in an antiporter with the capacity to export K+. In addition, in ScNha1, the replacement of three positively charged arginine residues 539-541 in the C3 region with alanine caused its inability to provide cells with tolerance to Li+. All our results demonstrate that the physiological functions of yeast Nha/Sod antiporters, either in salt tolerance or in K+ homeostasis, depend on the composition of their C-terminal parts.
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Affiliation(s)
- Olga Zimmermannová
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Diego Velázquez
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Klára Papoušková
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Vojtěch Průša
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Viktorie Radová
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
| | - Pierre Falson
- Drug Resistance Membrane Proteins Group, National Centre for Scientific Research and Lyon I University Laboratory n°5086, Institute of Biology and Chemistry of Proteins, Lyon, France.
| | - Hana Sychrová
- Laboratory of Membrane Transport, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic.
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11
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Drew D, Boudker O. Ion and lipid orchestration of secondary active transport. Nature 2024; 626:963-974. [PMID: 38418916 DOI: 10.1038/s41586-024-07062-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 01/12/2024] [Indexed: 03/02/2024]
Abstract
Transporting small molecules across cell membranes is an essential process in cell physiology. Many structurally diverse, secondary active transporters harness transmembrane electrochemical gradients of ions to power the uptake or efflux of nutrients, signalling molecules, drugs and other ions across cell membranes. Transporters reside in lipid bilayers on the interface between two aqueous compartments, where they are energized and regulated by symported, antiported and allosteric ions on both sides of the membrane and the membrane bilayer itself. Here we outline the mechanisms by which transporters couple ion and solute fluxes and discuss how structural and mechanistic variations enable them to meet specific physiological needs and adapt to environmental conditions. We then consider how general bilayer properties and specific lipid binding modulate transporter activity. Together, ion gradients and lipid properties ensure the effective transport, regulation and distribution of small molecules across cell membranes.
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Affiliation(s)
- David Drew
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
| | - Olga Boudker
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA.
- Howard Hughes Medical Institute, Weill Cornell Medicine, New York, NY, USA.
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12
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El Salamouni NS, Buckley BJ, Lee R, Ranson M, Kelso MJ, Yu H. Ion Transport and Inhibitor Binding by Human NHE1: Insights from Molecular Dynamics Simulations and Free Energy Calculations. J Phys Chem B 2024; 128:440-450. [PMID: 38185879 DOI: 10.1021/acs.jpcb.3c05863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
The human Na+/H+ exchanger (NHE1) plays a crucial role in maintaining intracellular pH by regulating the electroneutral exchange of a single intracellular H+ for one extracellular Na+ across the plasma membrane. Understanding the molecular mechanisms governing ion transport and the binding of inhibitors is of importance in the development of anticancer therapeutics targeting NHE1. In this context, we performed molecular dynamics (MD) simulations based on the recent cryo-electron microscopy (cryo-EM) structures of outward- and inward-facing conformations of NHE1. These simulations allowed us to explore the dynamics of the protein, examine the ion-translocation pore, and confirm that Asp267 is the ion-binding residue. Our free energy calculations did not show a significant difference between Na+ and K+ binding at the ion-binding site. Consequently, Na+ over K+ selectivity cannot be solely explained by differences in ion binding. Our MD simulations involving NHE1 inhibitors (cariporide and amiloride analogues) maintained stable interactions with Asp267 and Glu346. Our study highlights the importance of the salt bridge between the positively charged acylguanidine moiety and Asp267, which appears to play a role in the competitive inhibitory mechanism for this class of inhibitors. Our computational study provides a detailed mechanistic interpretation of experimental data and serves the basis of future structure-based inhibitor design.
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Affiliation(s)
- Nehad S El Salamouni
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Benjamin J Buckley
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Richmond Lee
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Marie Ranson
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Michael J Kelso
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Haibo Yu
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Molecular Horizons, University of Wollongong, Wollongong, NSW 2522, Australia
- ARC Centre of Excellence in Quantum Biotechnology, University of Wollongong, Wollongong, NSW 2522, Australia
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13
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Bei Q, Reitz T, Schädler M, Hodgskiss LH, Peng J, Schnabel B, Buscot F, Eisenhauer N, Schleper C, Heintz-Buschart A. Metabolic potential of Nitrososphaera-associated clades. THE ISME JOURNAL 2024; 18:wrae086. [PMID: 38742714 PMCID: PMC11131427 DOI: 10.1093/ismejo/wrae086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/13/2024] [Accepted: 05/11/2024] [Indexed: 05/16/2024]
Abstract
Soil ammonia-oxidizing archaea (AOA) play a crucial role in converting ammonia to nitrite, thereby mobilizing reactive nitrogen species into their soluble form, with a significant impact on nitrogen losses from terrestrial soils. Yet, our knowledge regarding their diversity and functions remains limited. In this study, we reconstructed 97 high-quality AOA metagenome-assembled genomes (MAGs) from 180 soil samples collected in Central Germany during 2014-2019 summers. These MAGs were affiliated with the order Nitrososphaerales and clustered into four family-level clades (NS-α/γ/δ/ε). Among these MAGs, 75 belonged to the most abundant but least understood δ-clade. Within the δ-clade, the amoA genes in three MAGs from neutral soils showed a 99.5% similarity to the fosmid clone 54d9, which has served as representative of the δ-clade for the past two decades since even today no cultivated representatives are available. Seventy-two MAGs constituted a distinct δ sub-clade, and their abundance and expression activity were more than twice that of other MAGs in slightly acidic soils. Unlike the less abundant clades (α, γ, and ε), the δ-MAGs possessed multiple highly expressed intracellular and extracellular carbohydrate-active enzymes responsible for carbohydrate binding (CBM32) and degradation (GH5), along with highly expressed genes involved in ammonia oxidation. Together, these results suggest metabolic versatility of uncultured soil AOA and a potential mixotrophic or chemolithoheterotrophic lifestyle among 54d9-like AOA.
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Affiliation(s)
- Qicheng Bei
- Department of Soil Ecology, Helmholtz Centre for Environmental Research – UFZ, 06120 Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, United States
| | - Thomas Reitz
- Department of Soil Ecology, Helmholtz Centre for Environmental Research – UFZ, 06120 Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany
| | - Martin Schädler
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany
- Department of Community Ecology, Helmholtz Centre for Environmental Research – UFZ, 06120 Halle (Saale), Germany
| | - Logan H Hodgskiss
- Archaea Biology and Ecogenomics Unit, Department of Functional and Evolutionary Ecology, University of Vienna, 1030 Vienna, Austria
| | - Jingjing Peng
- College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China
| | - Beatrix Schnabel
- Department of Soil Ecology, Helmholtz Centre for Environmental Research – UFZ, 06120 Halle (Saale), Germany
| | - François Buscot
- Department of Soil Ecology, Helmholtz Centre for Environmental Research – UFZ, 06120 Halle (Saale), Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany
| | - Nico Eisenhauer
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany
- Institute of Biology, Leipzig University, 04103 Leipzig, Germany
| | - Christa Schleper
- Archaea Biology and Ecogenomics Unit, Department of Functional and Evolutionary Ecology, University of Vienna, 1030 Vienna, Austria
| | - Anna Heintz-Buschart
- Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, the Netherlands
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14
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Xu L, Jia W, Tao X, Ye F, Zhang Y, Ding ZJ, Zheng SJ, Qiao S, Su N, Zhang Y, Wu S, Guo J. Structures and mechanisms of the Arabidopsis cytokinin transporter AZG1. NATURE PLANTS 2024; 10:180-191. [PMID: 38172575 DOI: 10.1038/s41477-023-01590-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 11/10/2023] [Indexed: 01/05/2024]
Abstract
Cytokinins are essential for plant growth and development, and their tissue distributions are regulated by transmembrane transport. Recent studies have revealed that members of the 'Aza-Guanine Resistant' (AZG) protein family from Arabidopsis thaliana can mediate cytokinin uptake in roots. Here we present 2.7 to 3.3 Å cryo-electron microscopy structures of Arabidopsis AZG1 in the apo state and in complex with its substrates trans-zeatin (tZ), 6-benzyleaminopurine (6-BAP) or kinetin. AZG1 forms a homodimer and each subunit shares a similar topology and domain arrangement with the proteins of the nucleobase/ascorbate transporter (NAT) family. These structures, along with functional analyses, reveal the molecular basis for cytokinin recognition. Comparison of the AZG1 structures determined in inward-facing conformations and predicted by AlphaFold2 in the occluded conformation allowed us to propose that AZG1 may carry cytokinins across the membrane through an elevator mechanism.
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Affiliation(s)
- Lingyi Xu
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
- Nanhu Brain-computer Interface Institute, Hangzhou, China.
| | - Wei Jia
- National Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, Zhejiang, China
- Calibra Lab at DIAN Diagnostics, Key Laboratory of Digital Technology in Medical Diagnostics of Zhejiang Provinces, Hangzhou, Zhejiang, China
| | - Xin Tao
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, Hubei, China
| | - Fan Ye
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Nanhu Brain-computer Interface Institute, Hangzhou, China
| | - Yan Zhang
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- Nanhu Brain-computer Interface Institute, Hangzhou, China
| | - Zhong Jie Ding
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Shao Jian Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Shuai Qiao
- International Institutes of Medicine, the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang, China
| | - Nannan Su
- International Institutes of Medicine, the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang, China
| | - Yu Zhang
- National Engineering Laboratory of Intelligent Food Technology and Equipment, Zhejiang Key Laboratory for Agro-Food Processing, College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, Zhejiang, China.
| | - Shan Wu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, Hubei, China.
| | - Jiangtao Guo
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
- Nanhu Brain-computer Interface Institute, Hangzhou, China.
- NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Science and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
- Department of Cardiology, Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
- Cancer Center, Zhejiang University, Hangzhou, Zhejiang, China.
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, Zhejiang, China.
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15
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Ung KL, Schulz L, Kleine-Vehn J, Pedersen BP, Hammes UZ. Auxin transport at the endoplasmic reticulum: roles and structural similarity of PIN-FORMED and PIN-LIKES. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:6893-6903. [PMID: 37279330 DOI: 10.1093/jxb/erad192] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 06/02/2023] [Indexed: 06/08/2023]
Abstract
Auxin is a crucial plant hormone that controls a multitude of developmental processes. The directional movement of auxin between cells is largely facilitated by canonical PIN-FORMED proteins in the plasma membrane. In contrast, non-canonical PIN-FORMED proteins and PIN-LIKES proteins appear to reside mainly in the endoplasmic reticulum. Despite recent progress in identifying the roles of the endoplasmic reticulum in cellular auxin responses, the transport dynamics of auxin at the endoplasmic reticulum are not well understood. PIN-LIKES are structurally related to PIN-FORMED proteins, and recently published structures of these transporters have provided new insights into PIN-FORMED proteins and PIN-LIKES function. In this review, we summarize current knowledge on PIN-FORMED proteins and PIN-LIKES in intracellular auxin transport. We discuss the physiological properties of the endoplasmic reticulum and the consequences for transport processes across the ER membrane. Finally, we highlight the emerging role of the endoplasmic reticulum in the dynamics of cellular auxin signalling and its impact on plant development.
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Affiliation(s)
- Kien Lam Ung
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark
| | - Lukas Schulz
- Plant Systems Biology, School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
| | - Jürgen Kleine-Vehn
- Institute of Biology II, Department of Molecular Plant Physiology (MoPP), University of Freiburg, 79104 Freiburg, Germany
- Center for Integrative Biological Signalling Studies (CIBSS), University of Freiburg, 79104 Freiburg, Germany
| | | | - Ulrich Z Hammes
- Plant Systems Biology, School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
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16
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Hariharan P, Shi Y, Katsube S, Willibal K, Burrows ND, Mitchell P, Bakhtiiari A, Stanfield S, Pardon E, Kaback HR, Liang R, Steyaert J, Viner R, Guan L. Mobile barrier mechanisms for Na +-coupled symport in an MFS sugar transporter. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.18.558283. [PMID: 37790566 PMCID: PMC10542114 DOI: 10.1101/2023.09.18.558283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
While many 3D structures of cation-coupled transporters have been determined, the mechanistic details governing the obligatory coupling and functional regulations still remain elusive. The bacterial melibiose transporter (MelB) is a prototype of the Na+-coupled major facilitator superfamily transporters. With a conformational nanobody (Nb), we determined a low-sugar affinity inward-facing Na+-bound cryoEM structure. Collectively with the available outward-facing sugar-bound structures, both the outer and inner barriers were localized. The N- and C-terminal residues of the inner barrier contribute to the sugar selectivity pocket. When the inner barrier is broken as shown in the inward-open conformation, the sugar selectivity pocket is also broken. The binding assays by isothermal titration calorimetry revealed that this inward-facing conformation trapped by the conformation-selective Nb exhibited a greatly decreased sugar-binding affinity, suggesting the mechanisms for the substrate intracellular release and accumulation. While the inner/outer barrier shift directly regulates the sugar-binding affinity, it has little or no effect on the cation binding, which is also supported by molecular dynamics simulations. Furthermore, the use of this Nb in combination with the hydron/deuterium exchange mass spectrometry allowed us to identify dynamic regions; some regions are involved in the functionally important inner barrier-specific salt-bridge network, which indicates their critical roles in the barrier switching mechanisms for transport. These complementary results provided structural and dynamic insights into the mobile barrier mechanism for cation-coupled symport.
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Affiliation(s)
- Parameswaran Hariharan
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX 79424, USA
| | - Yuqi Shi
- Thermo Fisher Scientific, San Jose, CA 95134, USA
| | - Satoshi Katsube
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX 79424, USA
| | | | - Nathan D. Burrows
- Division of CryoEM and Bioimaging, Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Patrick Mitchell
- Division of CryoEM and Bioimaging, Stanford Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | | | - Samantha Stanfield
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX 79424, USA
| | - Els Pardon
- VIB-VUB Center for Structural Biology, 1050 Brussel, Belgium
| | - H. Ronald Kaback
- Department of Physiology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Ruibin Liang
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Jan Steyaert
- VIB-VUB Center for Structural Biology, 1050 Brussel, Belgium
| | - Rosa Viner
- Thermo Fisher Scientific, San Jose, CA 95134, USA
| | - Lan Guan
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX 79424, USA
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17
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Yeo H, Mehta V, Gulati A, Drew D. Structure and electromechanical coupling of a voltage-gated Na +/H + exchanger. Nature 2023; 623:193-201. [PMID: 37880360 PMCID: PMC10620092 DOI: 10.1038/s41586-023-06518-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 08/04/2023] [Indexed: 10/27/2023]
Abstract
Voltage-sensing domains control the activation of voltage-gated ion channels, with a few exceptions1. One such exception is the sperm-specific Na+/H+ exchanger SLC9C1, which is the only known transporter to be regulated by voltage-sensing domains2-5. After hyperpolarization of sperm flagella, SLC9C1 becomes active, causing pH alkalinization and CatSper Ca2+ channel activation, which drives chemotaxis2,6. SLC9C1 activation is further regulated by cAMP2,7, which is produced by soluble adenyl cyclase (sAC). SLC9C1 is therefore an essential component of the pH-sAC-cAMP signalling pathway in metazoa8,9, required for sperm motility and fertilization4. Despite its importance, the molecular basis of SLC9C1 voltage activation is unclear. Here we report cryo-electron microscopy (cryo-EM) structures of sea urchin SLC9C1 in detergent and nanodiscs. We show that the voltage-sensing domains are positioned in an unusual configuration, sandwiching each side of the SLC9C1 homodimer. The S4 segment is very long, 90 Å in length, and connects the voltage-sensing domains to the cytoplasmic cyclic-nucleotide-binding domains. The S4 segment is in the up configuration-the inactive state of SLC9C1. Consistently, although a negatively charged cavity is accessible for Na+ to bind to the ion-transporting domains of SLC9C1, an intracellular helix connected to S4 restricts their movement. On the basis of the differences in the cryo-EM structure of SLC9C1 in the presence of cAMP, we propose that, upon hyperpolarization, the S4 segment moves down, removing this constriction and enabling Na+/H+ exchange.
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Affiliation(s)
- Hyunku Yeo
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Ved Mehta
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - Ashutosh Gulati
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden
| | - David Drew
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, Stockholm, Sweden.
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18
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Ung KL, Schulz L, Stokes DL, Hammes UZ, Pedersen BP. Substrate recognition and transport mechanism of the PIN-FORMED auxin exporters. Trends Biochem Sci 2023; 48:937-948. [PMID: 37574372 PMCID: PMC10592131 DOI: 10.1016/j.tibs.2023.07.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 06/30/2023] [Accepted: 07/17/2023] [Indexed: 08/15/2023]
Abstract
Auxins are pivotal plant hormones that regulate plant growth and transmembrane polar auxin transport (PAT) direct patterns of development. The PIN-FORMED (PIN) family of membrane transporters mediate auxin export from the plant cell and play crucial roles in PAT. Here we describe the recently solved structures of PIN transporters, PIN1, PIN3, and PIN8, and also their mechanisms of substrate recognition and transport of auxin. We compare structures of PINs in both inward- and outward-facing conformations, as well as PINs with different binding configurations for auxin. By this comparative analysis, a model emerges for an elevator transport mechanism. Central structural elements necessary for function are identified, and we show that these are shared with other distantly related protein families.
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Affiliation(s)
- Kien Lam Ung
- Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus C, Denmark
| | - Lukas Schulz
- Plant Systems Biology, School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
| | - David L Stokes
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, NY 10016, USA
| | - Ulrich Z Hammes
- Plant Systems Biology, School of Life Sciences Weihenstephan, Technical University of Munich, 85354 Freising, Germany
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19
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Zhang XY, Tang LH, Nie JW, Zhang CR, Han X, Li QY, Qin L, Wang MH, Huang X, Yu F, Su M, Wang Y, Xu RM, Guo Y, Xie Q, Chen YH. Structure and activation mechanism of the rice Salt Overly Sensitive 1 (SOS1) Na +/H + antiporter. NATURE PLANTS 2023; 9:1924-1936. [PMID: 37884653 DOI: 10.1038/s41477-023-01551-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 09/27/2023] [Indexed: 10/28/2023]
Abstract
Salinity is one of the most severe abiotic stresses that adversely affect plant growth and agricultural productivity. The plant Na+/H+ antiporter Salt Overly Sensitive 1 (SOS1) located in the plasma membrane extrudes excess Na+ out of cells in response to salt stress and confers salt tolerance. However, the molecular mechanism underlying SOS1 activation remains largely elusive. Here we elucidate two cryo-electron microscopy structures of rice (Oryza sativa) SOS1, a full-length protein in an auto-inhibited state and a truncated version in an active state. The SOS1 forms a dimeric architecture, with an NhaA-folded transmembrane domain portion in the membrane and an elongated cytosolic portion of multiple regulatory domains in the cytoplasm. The structural comparison shows that SOS1 adopts an elevator transport mechanism accompanied by a conformational transition of the highly conserved Pro148 in the unwound transmembrane helix 5 (TM5), switching from an occluded conformation in the auto-inhibited state to a conducting conformation in the active state. These findings allow us to propose an inhibition-release mechanism for SOS1 activation and elucidate how SOS1 controls Na+ homeostasis in response to salt stress.
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Affiliation(s)
- Xiang-Yun Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Ling-Hui Tang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jia-Wei Nie
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chun-Rui Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiaonan Han
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Qi-Yu Li
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Li Qin
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Mei-Hua Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiahe Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Feifei Yu
- College of Grassland Science and Technology, China Agricultural University, Beijing, China
| | - Min Su
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Yingchun Wang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Rui-Ming Xu
- University of Chinese Academy of Sciences, Beijing, China
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yan Guo
- State Key Laboratory of Plant Environmental Resilience, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Qi Xie
- University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
- National Center of Technology Innovation for Maize, State Key Laboratory of Crop Germplasm Innovation and Molecular Breeding, Syngenta Group China, Beijing, China
| | - Yu-Hang Chen
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
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20
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Zhang Y, Zhou J, Ni X, Wang Q, Jia Y, Xu X, Wu H, Fu P, Wen H, Guo Y, Yang G. Structural basis for the activity regulation of Salt Overly Sensitive 1 in Arabidopsis salt tolerance. NATURE PLANTS 2023; 9:1915-1923. [PMID: 37884652 DOI: 10.1038/s41477-023-01550-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 09/27/2023] [Indexed: 10/28/2023]
Abstract
The plasma membrane Na+/H+ exchanger Salt Overly Sensitive 1 (SOS1) is crucial for plant salt tolerance. Unlike typical sodium/proton exchangers, SOS1 contains a large cytoplasmic domain (CPD) that regulates Na+/H+ exchange activity. However, the underlying modulation mechanism remains unclear. Here we report the structures of SOS1 from Arabidopsis thaliana in two conformations, primarily differing in CPD flexibility. The CPD comprises an interfacial domain, a cyclic nucleotide-binding domain-like domain (CNBD-like domain) and an autoinhibition domain. Through yeast cell-based Na+ tolerance test, we reveal the regulatory role of the interfacial domain and the activation role of the CNBD-like domain. The CPD forms a negatively charged cavity that is connected to the ion binding site. The transport of Na+ may be coupled with the conformational change of CPD. These findings provide structural and functional insight into SOS1 activity regulation.
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Affiliation(s)
- Yanming Zhang
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jiaqi Zhou
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xuping Ni
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | | | - Yutian Jia
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xia Xu
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Haoyang Wu
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Peng Fu
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Han Wen
- DP Technology, Beijing, China
| | - Yan Guo
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Guanghui Yang
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, China.
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21
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Kalienkova V, Peter MF, Rheinberger J, Paulino C. Structures of a sperm-specific solute carrier gated by voltage and cAMP. Nature 2023; 623:202-209. [PMID: 37880361 PMCID: PMC10620091 DOI: 10.1038/s41586-023-06629-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 09/08/2023] [Indexed: 10/27/2023]
Abstract
The newly characterized sperm-specific Na+/H+ exchanger stands out by its unique tripartite domain composition1,2. It unites a classical solute carrier unit with regulatory domains usually found in ion channels, namely, a voltage-sensing domain and a cyclic-nucleotide binding domain1,3, which makes it a mechanistic chimera and a secondary-active transporter activated strictly by membrane voltage. Our structures of the sea urchin SpSLC9C1 in the absence and presence of ligands reveal the overall domain arrangement and new structural coupling elements. They allow us to propose a gating model, where movements in the voltage sensor indirectly cause the release of the exchanging unit from a locked state through long-distance allosteric effects transmitted by the newly characterized coupling helices. We further propose that modulation by its ligand cyclic AMP occurs by means of disruption of the cytosolic dimer interface, which lowers the energy barrier for S4 movements in the voltage-sensing domain. As SLC9C1 members have been shown to be essential for male fertility, including in mammals2,4,5, our structure represents a potential new platform for the development of new on-demand contraceptives.
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Affiliation(s)
- Valeria Kalienkova
- Groningen Biomolecular Sciences and Biotechnology, University of Groningen, Groningen, The Netherlands
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Martin F Peter
- Groningen Biomolecular Sciences and Biotechnology, University of Groningen, Groningen, The Netherlands
- Biochemistry Center, Heidelberg University, Heidelberg, Germany
| | - Jan Rheinberger
- Biochemistry Center, Heidelberg University, Heidelberg, Germany
| | - Cristina Paulino
- Groningen Biomolecular Sciences and Biotechnology, University of Groningen, Groningen, The Netherlands.
- Biochemistry Center, Heidelberg University, Heidelberg, Germany.
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22
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Holling T, Brylka L, Scholz T, Bierhals T, Herget T, Meinecke P, Schinke T, Oheim R, Kutsche K. TMCO3, a Putative K + :Proton Antiporter at the Golgi Apparatus, Is Important for Longitudinal Growth in Mice and Humans. J Bone Miner Res 2023; 38:1334-1349. [PMID: 37554015 DOI: 10.1002/jbmr.4827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 04/27/2023] [Accepted: 05/07/2023] [Indexed: 08/10/2023]
Abstract
Isolated short stature, defined as short stature without any other abnormalities, is a common heterogeneous condition in children. Exome sequencing identified the homozygous nonsense variant c.1832G>A/p.(Trp611*) in TMCO3 in two sisters with isolated short stature. Radiological studies, biochemical measurements, assessment of the skeletal status, and three-dimensional bone microarchitecture revealed no relevant skeletal and bone abnormalities in both sisters. The homozygous TMCO3 variant segregated with short stature in the family. TMCO3 transcript levels were reduced by ~50% in leukocyte-derived RNA of both sisters compared with controls, likely due to nonsense-mediated mRNA decay. In primary urinary cells of heterozygous family members, we detected significantly reduced TMCO3 protein levels. TMCO3 is functionally uncharacterized. We ectopically expressed wild-type TMCO3 in HeLa and ATDC5 chondrogenic cells and detected TMCO3 predominantly at the Golgi apparatus, whereas the TMCO3W611* mutant did not reach the Golgi. Coordinated co-expression of TMCO3W611* -HA and EGFP in HeLa cells confirmed intrinsic instability and/or degradation of the mutant. Tmco3 is expressed in all relevant mouse skeletal cell types. Highest abundance of Tmco3 was found in chondrocytes of the prehypertrophic zone in mouse and minipig growth plates where it co-localizes with a Golgi marker. Knockdown of Tmco3 in differentiated ATDC5 cells caused reduced and increased expression of Pthlh and Ihh, respectively. Measurement of long bones in Tmco3tm1b(KOMP)Wtsi knockout mice revealed significant shortening of forelimbs and hindlimbs. TMCO3 is a potential member of the monovalent cation:proton antiporter 2 (CPA2) family. By in silico tools and homology modeling, TMCO3 is predicted to have an N-terminal secretory signal peptide, forms a dimer localized to the membrane, and is organized in a dimerization and a core domain. The core domain contains the CPA2 motif essential for K+ binding and selectivity. Collectively, our data demonstrate that loss of TMCO3 causes growth defects in both humans and mice. © 2023 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Tess Holling
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Laura Brylka
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tasja Scholz
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tatjana Bierhals
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Theresia Herget
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Peter Meinecke
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ralf Oheim
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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23
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Wang Y, Pan C, Chen Q, Xie Q, Gao Y, He L, Li Y, Dong Y, Jiang X, Zhao Y. Architecture and autoinhibitory mechanism of the plasma membrane Na +/H + antiporter SOS1 in Arabidopsis. Nat Commun 2023; 14:4487. [PMID: 37495621 PMCID: PMC10372031 DOI: 10.1038/s41467-023-40215-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 07/13/2023] [Indexed: 07/28/2023] Open
Abstract
Salt-overly-sensitive 1 (SOS1) is a unique electroneutral Na+/H+ antiporter at the plasma membrane of higher plants and plays a central role in resisting salt stress. SOS1 is kept in a resting state with basal activity and activated upon phosphorylation. Here, we report the structures of SOS1. SOS1 forms a homodimer, with each monomer composed of transmembrane and intracellular domains. We find that SOS1 is locked in an occluded state by shifting of the lateral-gate TM5b toward the dimerization domain, thus shielding the Na+/H+ binding site. We speculate that the dimerization of the intracellular domain is crucial to stabilize the transporter in this specific conformation. Moreover, two discrete fragments and a residue W1013 are important to prevent the transition of SOS1 to an alternative conformational state, as validated by functional complementation assays. Our study enriches understanding of the alternate access model of eukaryotic Na+/H+ exchangers.
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Affiliation(s)
- Yuhang Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, 100101, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Chengcai Pan
- National Center for Technology Innovation of Saline-Alkali tolerant Rice/College of Coastal Agricultural Sciences, Guangdong Ocean University, 524088, Zhanjiang, China
| | - Qihao Chen
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, 100101, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Qing Xie
- National Center for Technology Innovation of Saline-Alkali tolerant Rice/College of Coastal Agricultural Sciences, Guangdong Ocean University, 524088, Zhanjiang, China
| | - Yiwei Gao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, 100101, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Lingli He
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, 100101, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Yue Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, 100101, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Yanli Dong
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, 100101, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Xingyu Jiang
- National Center for Technology Innovation of Saline-Alkali tolerant Rice/College of Coastal Agricultural Sciences, Guangdong Ocean University, 524088, Zhanjiang, China.
| | - Yan Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 100101, Beijing, China.
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, 100101, Beijing, China.
- College of Life Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China.
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24
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Rombolá-Caldentey B, Mendoza I, Quintero FJ, Pardo JM. Structure-Guided Identification of Critical Residues in the Vacuolar Cation/Proton Antiporter NHX1 from Arabidopsis thaliana. PLANTS (BASEL, SWITZERLAND) 2023; 12:2778. [PMID: 37570932 PMCID: PMC10421325 DOI: 10.3390/plants12152778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/24/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023]
Abstract
Cation/Proton Antiporters (CPA) acting in all biological membranes regulate the volume and pH of cells and of intracellular organelles. A key issue with these proteins is their structure-function relationships since they present intrinsic regulatory features that rely on structural determinants, including pH sensitivity and the stoichiometry of ion exchange. Crystal structures are only available for prokaryotic CPA, whereas the eukaryotic ones have been modeled using the former as templates. Here, we present an updated and improved structural model of the tonoplast-localized K+, Na+/H+ antiporter NHX1 of Arabidopsis as a representative of the vacuolar NHX family that is essential for the accumulation of K+ into plant vacuoles. Conserved residues that were judged as functionally important were mutated, and the resulting protein variants were tested for activity in the yeast Saccharomyces cerevisiae. The results indicate that residue N184 in the ND-motif characteristic of CPA1 could be replaced by the DD-motif of CPA2 family members with minimal consequences for their activity. Attempts to alter the electroneutrality of AtNHX1 by different combinations of amino acid replacements at N184, R353 and R390 residues resulted in inactive or partly active proteins with a differential ability to control the vacuolar pH of the yeast.
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Affiliation(s)
| | | | | | - José M. Pardo
- Instituto de Bioquimica Vegetal y Fotosintesis, cicCartuja, Consejo Superior de Investigaciones Cientificas, Universidad de Sevilla, 41092 Sevilla, Spain; (B.R.-C.); (I.M.); (F.J.Q.)
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25
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Li J, Cai L, Lu H, Ma B, Chen G, Kong D, Hu Y, Ye Z, Ruan Y. Effects of Ion Combinations and Their Concentrations on Denitrification Performance and Gene Expressions of an Aerobic Strain Marinobacter Hydrocarbonoclasticus RAD-2. Microorganisms 2023; 11:1867. [PMID: 37630427 PMCID: PMC10456938 DOI: 10.3390/microorganisms11081867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/17/2023] [Accepted: 07/18/2023] [Indexed: 08/27/2023] Open
Abstract
Salinity is one of the most important factors affecting the nitrogen-removal efficiency of denitrifying bacteria. A series of different ion combinations and salinity gradients were carried out to clarify the effects of ion types and concentrations on nitrogen removal by halophilic aerobic denitrifying bacteria RAD-2. Nitrate concentrations, nitrite concentrations, TAN concentrations, and OD600 were monitored to investigate their effects on denitrification in each group. The results showed that Na+, K+, and Cl- accelerated the denitrification process and improved nitrogen-removal efficiency at moderate additions, while Ca2+ and Mg2+ showed no significant effect. Na+ was effective alone, while K+ or Cl- needed to be combined with at least one of Na+, K+, or Cl- to achieve similar efficiency. The batch tests of salinity confirmed that the addition of a moderate concentration of NaCl/Na2SO4 could effectively improve nitrogen-removal efficiency, while excessive salinity might hinder denitrification metabolism. In the salinity range of 5~40‱, a 5‱ dosage might be the most economical method for strain RAD-2. Real-time PCR experiments on 17 key nitrogen metabolism-related genes revealed that chloride was widely involved in the nitrogen and carbon metabolism of microorganisms by altering cell osmotic pressure and opening ion channel proteins, thereby affecting the efficiency of denitrification. The results of this study may contribute to a better understanding of the different roles of various ions in aerobic denitrification and highlight the importance of salinity control in highly salted wastewater treatment.
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Affiliation(s)
- Junchi Li
- Institute of Agricultural Bio-Environmental Engineering, College of Bio-Systems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China; (J.L.); (Y.H.)
- The Rural Development Academy, Zhejiang University, Hangzhou 310058, China;
| | - Lei Cai
- Laboratory of Microbial Resources, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310035, China;
| | - Huifeng Lu
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China;
| | - Bin Ma
- Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China;
| | - Guangsuo Chen
- The Rural Development Academy, Zhejiang University, Hangzhou 310058, China;
| | - Dedong Kong
- Institute of Digital Agriculture, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; (D.K.); (Z.Y.)
| | - Yiming Hu
- Institute of Agricultural Bio-Environmental Engineering, College of Bio-Systems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China; (J.L.); (Y.H.)
- The Rural Development Academy, Zhejiang University, Hangzhou 310058, China;
| | - Ziran Ye
- Institute of Digital Agriculture, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China; (D.K.); (Z.Y.)
| | - Yunjie Ruan
- Institute of Agricultural Bio-Environmental Engineering, College of Bio-Systems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China; (J.L.); (Y.H.)
- The Rural Development Academy, Zhejiang University, Hangzhou 310058, China;
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26
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Wijesinghe WCB, Min D. Single-Molecule Force Spectroscopy of Membrane Protein Folding. J Mol Biol 2023; 435:167975. [PMID: 37330286 DOI: 10.1016/j.jmb.2023.167975] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 01/13/2023] [Accepted: 01/17/2023] [Indexed: 06/19/2023]
Abstract
Single-molecule force spectroscopy is a unique method that can probe the structural changes of single proteins at a high spatiotemporal resolution while mechanically manipulating them over a wide force range. Here, we review the current understanding of membrane protein folding learned by using the force spectroscopy approach. Membrane protein folding in lipid bilayers is one of the most complex biological processes in which diverse lipid molecules and chaperone proteins are intricately involved. The approach of single protein forced unfolding in lipid bilayers has produced important findings and insights into membrane protein folding. This review provides an overview of the forced unfolding approach, including recent achievements and technical advances. Progress in the methods can reveal more interesting cases of membrane protein folding and clarify general mechanisms and principles.
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Affiliation(s)
- W C Bhashini Wijesinghe
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Duyoung Min
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea; Center for Wave Energy Materials, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
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27
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Mizio K, Wawrzycka D, Staszewski J, Wysocki R, Maciaszczyk-Dziubinska E. Identification of amino acid substitutions that toggle substrate selectivity of the yeast arsenite transporter Acr3. JOURNAL OF HAZARDOUS MATERIALS 2023; 456:131653. [PMID: 37224717 DOI: 10.1016/j.jhazmat.2023.131653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/03/2023] [Accepted: 05/15/2023] [Indexed: 05/26/2023]
Abstract
The Acr3 protein family plays a crucial role in metalloid detoxification and includes members from bacteria to higher plants. Most of the Acr3 transporters studied so far are specific for arsenite, whereas Acr3 from budding yeast also shows some capacity to transport antimonite. However, the molecular basis of Acr3 substrate specificity remains poorly understood. By analyzing randomly generated and rationally designed yeast Acr3 variants, critical residues determining substrate specificity were identified for the first time. Replacement of Val173 with Ala abolished antimonite transport without affecting arsenite extrusion. In contrast, substitution of Glu353 with Asp resulted in a loss of arsenite transport activity and a concomitant increase in antimonite translocation capacity. Importantly, Val173 is located close to the hypothetical substrate binding site, whereas Glu353 has been proposed to participate in substrate binding. Identification of key residues conferring substrate selectivity provides a valuable starting point for further studies of the Acr3 family and may have implications for the development of biotechnological applications in metalloid remediation. Moreover, our data contribute to understanding why members of the Acr3 family evolved as arsenite-specific transporters in an environment of ubiquitously present arsenic and trace amounts of antimony.
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Affiliation(s)
- Katarzyna Mizio
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Donata Wawrzycka
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Jacek Staszewski
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Robert Wysocki
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Ewa Maciaszczyk-Dziubinska
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland.
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28
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Sharma R, Mishanina TV. A riboswitch-controlled manganese exporter (Alx) tunes intracellular Mn 2+ concentration in E. coli at alkaline pH. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.07.539761. [PMID: 37214827 PMCID: PMC10197570 DOI: 10.1101/2023.05.07.539761] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Cells use transition metal ions as structural components of biomolecules and cofactors in enzymatic reactions, making transition metals vital cellular components. The buildup of a particular metal ion in certain stress conditions becomes harmful to the organism due to the misincorporation of the excess ion into biomolecules, resulting in perturbed enzymatic activity or metal-catalyzed formation of reactive oxygen species. Organisms optimize metal concentration by regulating the expression of proteins that import and export that metal, often in a metal concentration-dependent manner. One such regulation mechanism is via riboswitches, which are 5'-untranslated regions (UTR) of an mRNA that undergo conformational changes to promote or inhibit the expression of the downstream gene, commonly in response to a ligand. The yybP-ykoY family of bacterial riboswitches shares a conserved aptamer domain that binds manganese (Mn2+). In E. coli, the yybP-ykoY riboswitch precedes and regulates the expression of two genes: mntP, which based on extensive genetic evidence encodes an Mn2+ exporter, and alx, which encodes a putative metal ion transporter whose cognate ligand is currently in question. Expression of alx is upregulated by both elevated intracellular concentrations of Mn2+ and alkaline pH. With metal ion measurements and gene expression studies, we demonstrate that the alkalinization of media increases cytoplasmic Mn2+ content, which in turn enhances alx expression. Alx then exports excess Mn2+ to prevent toxic buildup of the metal inside the cell, with the export activity maximal at alkaline pH. Using mutational and complementation experiments, we pinpoint a set of acidic residues in the predicted transmembrane segments of Alx that play a crucial role in its Mn2+ export. We propose that Alx-mediated Mn2+ export provides a primary protective layer that fine-tunes the cytoplasmic Mn2+ levels, especially during alkaline stress.
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Affiliation(s)
- Ravish Sharma
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093
| | - Tatiana V. Mishanina
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Dr, La Jolla, CA 92093
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29
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Andersen CG, Bavnhøj L, Pedersen BP. May the proton motive force be with you: A plant transporter review. Curr Opin Struct Biol 2023; 79:102535. [PMID: 36796226 DOI: 10.1016/j.sbi.2023.102535] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/28/2022] [Accepted: 01/03/2023] [Indexed: 02/16/2023]
Abstract
As our ecosystems experience challenges associated with climate change, an improved understanding of the fundamental biochemical processes governing plant physiology is needed. Strikingly, current structural information on plant membrane transporters is severely limited compared to other kingdoms of life, with only 18 unique structures in total. To advance future breakthroughs and insight in plant cell molecular biology, structural knowledge of membrane transporters is indispensable. This review summarizes the current status of structural knowledge in the plant membrane transporter field. Plants utilize the proton motive force (PMF) to drive secondary active transport. We discuss the PMF, how it relates to secondary active transport and provide a classification of PMF driven secondary active transport, discussing recently published structures of symporters, antiporters, and uniporters from plants.
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Affiliation(s)
| | - Laust Bavnhøj
- Department of Molecular Biology and Genetics, Aarhus University, 8000, Aarhus C, Denmark. https://twitter.com/laustbavnhoej
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30
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Li Y, Li H, Gao J, Niu B, Wang H, Wang W. Visualizing the Intermittent Gating of Na + /H + Antiporters in Single Native Bioluminescent Bacteria. Angew Chem Int Ed Engl 2023; 62:e202215800. [PMID: 36562656 DOI: 10.1002/anie.202215800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/22/2022] [Accepted: 12/23/2022] [Indexed: 12/24/2022]
Abstract
While the intermittent gating of ion channels has been well studied for decades, dynamics of the action of secondary transporters, another major pathway for ion transmembrane transports, remains largely unexplored in living cells. Herein, intermittent blinking of the spontaneous bioluminescence (BL) from single native bacteria, P. phosphoreum, was reported, investigated and attributed to the intermittent gating of sodium/proton antiporters (NhaA) between the active and inactive conformations. Each gating event caused the rapid depolarization and recovery of membrane potential within several seconds, accompanying with the apparent BL blinking due to the transient inhibitions on the activity of the respiratory chain. Temperature-dependent measurements further obtained an activation energy barrier of the conformational change of 20.3 kJ mol-1 .
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Affiliation(s)
- Yaohua Li
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, ChemBIC (Chemistry and Biomedicine Innovation Center), Nanjing University, Nanjing, 210023, China
| | - Haoran Li
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, ChemBIC (Chemistry and Biomedicine Innovation Center), Nanjing University, Nanjing, 210023, China
| | - Jia Gao
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, ChemBIC (Chemistry and Biomedicine Innovation Center), Nanjing University, Nanjing, 210023, China
| | - Ben Niu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, ChemBIC (Chemistry and Biomedicine Innovation Center), Nanjing University, Nanjing, 210023, China
| | - Huan Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, ChemBIC (Chemistry and Biomedicine Innovation Center), Nanjing University, Nanjing, 210023, China
| | - Wei Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, ChemBIC (Chemistry and Biomedicine Innovation Center), Nanjing University, Nanjing, 210023, China
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31
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Singh PK, Cecchini G, Nakagawa T, Iverson TM. CryoEM structure of a post-assembly MS-ring reveals plasticity in stoichiometry and conformation. PLoS One 2023; 18:e0285343. [PMID: 37205674 DOI: 10.1371/journal.pone.0285343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 04/20/2023] [Indexed: 05/21/2023] Open
Abstract
The flagellar motor supports bacterial chemotaxis, a process that allows bacteria to move in response to their environment. A central feature of this motor is the MS-ring, which is composed entirely of repeats of the FliF subunit. This MS-ring is critical for the assembly and stability of the flagellar switch and the entire flagellum. Despite multiple independent cryoEM structures of the MS-ring, there remains a debate about the stoichiometry and organization of the ring-building motifs (RBMs). Here, we report the cryoEM structure of a Salmonella MS-ring that was purified from the assembled flagellar switch complex (MSC-ring). We term this the 'post-assembly' state. Using 2D class averages, we show that under these conditions, the post-assembly MS-ring can contain 32, 33, or 34 FliF subunits, with 33 being the most common. RBM3 has a single location with C32, C33, or C34 symmetry. RBM2 is found in two locations with RBM2inner having C21 or C22 symmetry and an RBM2outer-RBM1 having C11 symmetry. Comparison to previously reported structures identifies several differences. Most strikingly, we find that the membrane domain forms 11 regions of discrete density at the base of the structure rather than a contiguous ring, although density could not be unambiguously interpreted. We further find density in some previously unresolved areas, and we assigned amino acids to those regions. Finally, we find differences in interdomain angles in RBM3 that affect the diameter of the ring. Together, these investigations support a model of the flagellum with structural plasticity, which may be important for flagellar assembly and function.
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Affiliation(s)
- Prashant K Singh
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States of America
| | - Gary Cecchini
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, CA, United States of America
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, United States of America
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, TN, United States of America
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States of America
| | - T M Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States of America
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States of America
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States of America
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, United States of America
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32
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Lv P, Shang Y, Zhang Y, Wang W, Liu Y, Su D, Wang W, Li C, Ma C, Yang C. Structural basis for the arsenite binding and translocation of Acr3 antiporter with NhaA folding pattern. FASEB J 2022; 36:e22659. [PMID: 36394534 DOI: 10.1096/fj.202201280r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 10/05/2022] [Accepted: 11/07/2022] [Indexed: 11/18/2022]
Abstract
The arsenical resistance-3 (ACR3) family constitutes the most common pathway that confers high-level resistance to toxic metalloids in various microorganisms and lower plants. Based on the structural model constructed by AlphaFold2, the Acr3 antiporter from Bacillus subtilis (Acr3Bs ) exhibits a typical NhaA structure fold, with two discontinuous helices of transmembrane (TM) segments, TM4 and TM9, interacting with each other and forming an X-shaped structure. As the structural information available for these important arsenite-efflux pumps is limited, we investigated the evolutionary conservation among 300 homolog sequences and identified three conserved motifs in both the discontinuous helices and TM5. Through site-directed mutagenesis, microscale thermophoresis (MST), and fluorescence resonance energy transfer (FRET) analyses, the identified Motif C in TM9 was found to be a critical element for substrate binding, in which N292 and E295 are involved in substrate coordination, while R118 in TM4 and E322 in TM10 is responsible for structural stabilization. In addition, the highly conserved residues on Motif B of TM5 are potentially key factors in the protonation/deprotonation process. These consensus motifs and residues are essential for metalloid compound translocation of Acr3 antiporters, by framing the core domain and the typical X-shaped of NhaA fold.
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Affiliation(s)
- Peiwen Lv
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, P.R. China
| | - Yan Shang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, P.R. China
| | - Ye Zhang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, P.R. China
| | - Wenkai Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, P.R. China
| | - Yuanxiang Liu
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, P.R. China
| | - Dandan Su
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, P.R. China
| | - Wei Wang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, P.R. China
| | - Chunfang Li
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, P.R. China
| | - Cuiqing Ma
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, P.R. China
| | - Chunyu Yang
- State Key Laboratory of Microbial Technology, Institute of Microbial Technology, Shandong University, Qingdao, P.R. China
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33
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Velázquez D, Průša V, Masrati G, Yariv E, Sychrova H, Ben‐Tal N, Zimmermannova O. Allosteric links between the hydrophilic N-terminus and transmembrane core of human Na + /H + antiporter NHA2. Protein Sci 2022; 31:e4460. [PMID: 36177733 PMCID: PMC9667825 DOI: 10.1002/pro.4460] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 09/16/2022] [Accepted: 09/25/2022] [Indexed: 12/13/2022]
Abstract
The human Na+ /H+ antiporter NHA2 (SLC9B2) transports Na+ or Li+ across the plasma membrane in exchange for protons, and is implicated in various pathologies. It is a 537 amino acids protein with an 82 residues long hydrophilic cytoplasmic N-terminus followed by a transmembrane part comprising 14 transmembrane helices. We optimized the functional expression of HsNHA2 in the plasma membrane of a salt-sensitive Saccharomyces cerevisiae strain and characterized in vivo a set of mutated or truncated versions of HsNHA2 in terms of their substrate specificity, transport activity, localization, and protein stability. We identified a highly conserved proline 246, located in the core of the protein, as being crucial for ion selectivity. The replacement of P246 with serine or threonine resulted in antiporters with altered substrate specificity that were not only highly active at acidic pH 4.0 (like the native antiporter), but also at neutral pH. P246T/S versions also exhibited increased resistance to the HsNHA2-specific inhibitor phloretin. We experimentally proved that a putative salt bridge between E215 and R432 is important for antiporter function, but also structural integrity. Truncations of the first 50-70 residues of the N-terminus doubled the transport activity of HsNHA2, while changes in the charge at positions E47, E56, K57, or K58 decreased the antiporter's transport activity. Thus, the hydrophilic N-terminal part of the protein appears to allosterically auto-inhibit cation transport of HsNHA2. Our data also show this in vivo approach to be useful for a rapid screening of SNP's effect on HsNHA2 activity.
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Affiliation(s)
- Diego Velázquez
- Laboratory of Membrane TransportInstitute of Physiology of the Czech Academy of SciencesPragueCzech Republic
| | - Vojtěch Průša
- Laboratory of Membrane TransportInstitute of Physiology of the Czech Academy of SciencesPragueCzech Republic
| | - Gal Masrati
- Department of Biochemistry and Molecular BiologyGeorge S. Wise Faculty of Life Sciences, Tel‐Aviv UniversityTel‐AvivIsrael
| | - Elon Yariv
- Department of Biochemistry and Molecular BiologyGeorge S. Wise Faculty of Life Sciences, Tel‐Aviv UniversityTel‐AvivIsrael
| | - Hana Sychrova
- Laboratory of Membrane TransportInstitute of Physiology of the Czech Academy of SciencesPragueCzech Republic
| | - Nir Ben‐Tal
- Department of Biochemistry and Molecular BiologyGeorge S. Wise Faculty of Life Sciences, Tel‐Aviv UniversityTel‐AvivIsrael
| | - Olga Zimmermannova
- Laboratory of Membrane TransportInstitute of Physiology of the Czech Academy of SciencesPragueCzech Republic
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34
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Winkelmann I, Uzdavinys P, Kenney IM, Brock J, Meier PF, Wagner LM, Gabriel F, Jung S, Matsuoka R, von Ballmoos C, Beckstein O, Drew D. Crystal structure of the Na +/H + antiporter NhaA at active pH reveals the mechanistic basis for pH sensing. Nat Commun 2022; 13:6383. [PMID: 36289233 PMCID: PMC9606361 DOI: 10.1038/s41467-022-34120-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 10/14/2022] [Indexed: 12/25/2022] Open
Abstract
The strict exchange of protons for sodium ions across cell membranes by Na+/H+ exchangers is a fundamental mechanism for cell homeostasis. At active pH, Na+/H+ exchange can be modelled as competition between H+ and Na+ to an ion-binding site, harbouring either one or two aspartic-acid residues. Nevertheless, extensive analysis on the model Na+/H+ antiporter NhaA from Escherichia coli, has shown that residues on the cytoplasmic surface, termed the pH sensor, shifts the pH at which NhaA becomes active. It was unclear how to incorporate the pH senor model into an alternating-access mechanism based on the NhaA structure at inactive pH 4. Here, we report the crystal structure of NhaA at active pH 6.5, and to an improved resolution of 2.2 Å. We show that at pH 6.5, residues in the pH sensor rearrange to form new salt-bridge interactions involving key histidine residues that widen the inward-facing cavity. What we now refer to as a pH gate, triggers a conformational change that enables water and Na+ to access the ion-binding site, as supported by molecular dynamics (MD) simulations. Our work highlights a unique, channel-like switch prior to substrate translocation in a secondary-active transporter.
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Affiliation(s)
- Iven Winkelmann
- grid.10548.380000 0004 1936 9377Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Povilas Uzdavinys
- grid.10548.380000 0004 1936 9377Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Ian M. Kenney
- grid.215654.10000 0001 2151 2636Center for Biological Physics and Department of Physics, Arizona State University, Tempe, AZ 85287 USA
| | - Joseph Brock
- grid.10548.380000 0004 1936 9377Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Pascal F. Meier
- grid.10548.380000 0004 1936 9377Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Lina-Marie Wagner
- grid.10548.380000 0004 1936 9377Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Florian Gabriel
- grid.10548.380000 0004 1936 9377Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Sukkyeong Jung
- grid.10548.380000 0004 1936 9377Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Rei Matsuoka
- grid.10548.380000 0004 1936 9377Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Christoph von Ballmoos
- grid.5734.50000 0001 0726 5157Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Oliver Beckstein
- grid.215654.10000 0001 2151 2636Center for Biological Physics and Department of Physics, Arizona State University, Tempe, AZ 85287 USA
| | - David Drew
- grid.10548.380000 0004 1936 9377Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
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35
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A structure and evolutionary-based classification of solute carriers. iScience 2022; 25:105096. [PMID: 36164651 PMCID: PMC9508557 DOI: 10.1016/j.isci.2022.105096] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/22/2022] [Accepted: 09/04/2022] [Indexed: 11/22/2022] Open
Abstract
Solute carriers are an operationally defined diverse family of membrane proteins involved in the transport of nutrients, metabolites, xenobiotics, and drugs. Here, we provide an integrative classification of solute carriers by combining evolutionary information with proteome-wide structure models recently made available through the AlphaFold resource. Analyses of orthologous relations among 455 protein-coding genes currently classified as human solute carriers, over the fully sequenced genomes of 2,100 species, suggest no more than approximately 180 independent evolutionary origins. Structural comparative analyses provided further insight revealing a total of 24 structurally distinct transmembrane folds, increasing by approximately 40% the number of previously described SLC structural folds. In addition, a structural comparative analysis identified a new human solute carrier member and revealed details of noncanonical ones. Our analyses uncover new ancestral relations between solute carrier genes, provide insights into the evolution of remote homologs and a platform to test hypotheses of functional deorphanization.
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36
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Prokaryotic Na+/H+ Exchangers—Transport Mechanism and Essential Residues. Int J Mol Sci 2022; 23:ijms23169156. [PMID: 36012428 PMCID: PMC9408914 DOI: 10.3390/ijms23169156] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/09/2022] [Accepted: 08/13/2022] [Indexed: 11/16/2022] Open
Abstract
Na+/H+ exchangers are essential for Na+ and pH homeostasis in all organisms. Human Na+/H+ exchangers are of high medical interest, and insights into their structure and function are aided by the investigation of prokaryotic homologues. Most prokaryotic Na+/H+ exchangers belong to either the Cation/Proton Antiporter (CPA) superfamily, the Ion Transport (IT) superfamily, or the Na+-translocating Mrp transporter superfamily. Several structures have been solved so far for CPA and Mrp members, but none for the IT members. NhaA from E. coli has served as the prototype of Na+/H+ exchangers due to the high amount of structural and functional data available. Recent structures from other CPA exchangers, together with diverse functional information, have allowed elucidation of some common working principles shared by Na+/H+ exchangers from different families, such as the type of residues involved in the substrate binding and even a simple mechanism sufficient to explain the pH regulation in the CPA and IT superfamilies. Here, we review several aspects of prokaryotic Na+/H+ exchanger structure and function, discussing the similarities and differences between different transporters, with a focus on the CPA and IT exchangers. We also discuss the proposed transport mechanisms for Na+/H+ exchangers that explain their highly pH-regulated activity profile.
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37
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Yang Z, Xia J, Hong J, Zhang C, Wei H, Ying W, Sun C, Sun L, Mao Y, Gao Y, Tan S, Friml J, Li D, Liu X, Sun L. Structural insights into auxin recognition and efflux by Arabidopsis PIN1. Nature 2022; 609:611-615. [PMID: 35917925 PMCID: PMC9477737 DOI: 10.1038/s41586-022-05143-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 07/25/2022] [Indexed: 11/09/2022]
Abstract
Polar auxin transport is unique to plants and coordinates their growth and development1,2. The PIN-FORMED (PIN) auxin transporters exhibit highly asymmetrical localizations at the plasma membrane and drive polar auxin transport3,4; however, their structures and transport mechanisms remain largely unknown. Here, we report three inward-facing conformation structures of Arabidopsis thaliana PIN1: the apo state, bound to the natural auxin indole-3-acetic acid (IAA), and in complex with the polar auxin transport inhibitor N-1-naphthylphthalamic acid (NPA). The transmembrane domain of PIN1 shares a conserved NhaA fold5. In the substrate-bound structure, IAA is coordinated by both hydrophobic stacking and hydrogen bonding. NPA competes with IAA for the same site at the intracellular pocket, but with a much higher affinity. These findings inform our understanding of the substrate recognition and transport mechanisms of PINs and set up a framework for future research on directional auxin transport, one of the most crucial processes underlying plant development. Structures of the Arabidopsis thaliana auxin exporter PIN1 in the apo state, bound to the natural auxin or bound to an inhibitor provide insights into the polar auxin transport mechanisms mediated by PIN family transporters.
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Affiliation(s)
- Zhisen Yang
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Jing Xia
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Jingjing Hong
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of CAS, Chinese Academy of Sciences (CAS), Shanghai, China
| | - Chenxi Zhang
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Hong Wei
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Wei Ying
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Chunqiao Sun
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Lianghanxiao Sun
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yanbo Mao
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yongxiang Gao
- Cryo-EM Center, Core Facility Center for Life Sciences, University of Science and Technology of China, Hefei, China
| | - Shutang Tan
- MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Jiří Friml
- Institute of Science and Technology Austria (IST Austria), Am Campus 1, Klosterneuburg, Austria
| | - Dianfan Li
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of CAS, Chinese Academy of Sciences (CAS), Shanghai, China
| | - Xin Liu
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China. .,Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, China.
| | - Linfeng Sun
- The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China. .,Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, China.
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38
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Su N, Zhu A, Tao X, Ding ZJ, Chang S, Ye F, Zhang Y, Zhao C, Chen Q, Wang J, Zhou CY, Guo Y, Jiao S, Zhang S, Wen H, Ma L, Ye S, Zheng SJ, Yang F, Wu S, Guo J. Structures and mechanisms of the Arabidopsis auxin transporter PIN3. Nature 2022; 609:616-621. [PMID: 35917926 DOI: 10.1038/s41586-022-05142-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 07/25/2022] [Indexed: 11/09/2022]
Abstract
The PIN-FORMED (PIN) protein family of auxin transporters mediates the polar auxin transport and plays crucial roles in plant growth and development1,2. Here we present cryo-EM structures of PIN3 from Arabidopsis thaliana (AtPIN3) in the apo state and in complex with its substrate indole-3-acetic acid (IAA) and the inhibitor N-1-naphthylphthalamic acid (NPA) at 2.6-3.0 Å resolution. AtPIN3 exists as a homodimer, with the transmembrane helices (TMs) 1, 2, and 7 in the scaffold domain involved in dimerization. The dimeric AtPIN3 forms a large, joint extracellular-facing cavity at the dimer interface while each subunit adopts an inward-facing conformation. The structural and functional analyses, along with computational studies, reveal the structural basis for the recognition of IAA and NPA and elucidate the molecular mechanism of NPA inhibition on the PIN-mediated auxin transport. The AtPIN3 structures support an elevator-like model for the transport of auxin, whereby the transport domains undergo up-down rigid-body motions and the dimerized scaffold domains remain static.
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Affiliation(s)
- Nannan Su
- Department of Biophysics, and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Aiqin Zhu
- Department of Biophysics and Kidney Disease Center, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xin Tao
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, Hubei, China
| | - Zhong Jie Ding
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Shenghai Chang
- Center of Cryo-Electron Microscopy, Zhejiang University School of Medicine, Hangzhou, China
| | - Fan Ye
- Department of Biophysics, and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yan Zhang
- Department of Biophysics, and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Cheng Zhao
- Department of Biophysics, and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Qian Chen
- Department of Biophysics, and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jiangqin Wang
- Department of Biophysics, and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Chen Yu Zhou
- Center of Cryo-Electron Microscopy, Zhejiang University School of Medicine, Hangzhou, China
| | - Yirong Guo
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, China
| | - Shasha Jiao
- Institute of Pesticide and Environmental Toxicology, Zhejiang University, Hangzhou, China
| | - Sufen Zhang
- College of agriculture and biotechnology, Zhejiang University, Hangzhou, China
| | - Han Wen
- DP Technology, Beijing, China
| | - Lixin Ma
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, Hubei, China
| | - Sheng Ye
- Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, School of Life Sciences, Tianjin University, Tianjin, China
| | - Shao Jian Zheng
- Center of Cryo-Electron Microscopy, Zhejiang University School of Medicine, Hangzhou, China
| | - Fan Yang
- Department of Biophysics and Kidney Disease Center, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China. .,Alibaba-Zhejiang University Joint Research Center of Future Digital Healthcare, Hangzhou, Zhejiang, China. .,NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Science and Brain-machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
| | - Shan Wu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan, Hubei, China.
| | - Jiangtao Guo
- Department of Biophysics, and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China. .,Center of Cryo-Electron Microscopy, Zhejiang University School of Medicine, Hangzhou, China. .,NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Science and Brain-machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, Zhejiang, China. .,Department of Cardiology, Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China. .,Cancer Center, Zhejiang University, Hangzhou, Zhejiang, China. .,Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, Zhejiang, China.
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39
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Lv P, Li Y, Wang R, Zhang Y, Wang W, Liu Y, Shang Y, Su D, Wang W, Yang C. The pH sensor and ion binding of NhaD Na
+
/H
+
antiporter from IT superfamily. Mol Microbiol 2022; 118:244-257. [DOI: 10.1111/mmi.14965] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 07/13/2022] [Accepted: 07/14/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Peiwen Lv
- State Key Laboratory of Microbial Technology Institute of Microbial Technology, Shandong University Qingdao P. R. China
| | - Yaru Li
- State Key Laboratory of Microbial Technology Institute of Microbial Technology, Shandong University Qingdao P. R. China
| | - Ruimin Wang
- State Key Laboratory of Microbial Technology Institute of Microbial Technology, Shandong University Qingdao P. R. China
| | - Ye Zhang
- State Key Laboratory of Microbial Technology Institute of Microbial Technology, Shandong University Qingdao P. R. China
| | - Wenkai Wang
- State Key Laboratory of Microbial Technology Institute of Microbial Technology, Shandong University Qingdao P. R. China
| | - Yuanxiang Liu
- State Key Laboratory of Microbial Technology Institute of Microbial Technology, Shandong University Qingdao P. R. China
| | - Yan Shang
- State Key Laboratory of Microbial Technology Institute of Microbial Technology, Shandong University Qingdao P. R. China
| | - Dandan Su
- State Key Laboratory of Microbial Technology Institute of Microbial Technology, Shandong University Qingdao P. R. China
| | - Wei Wang
- State Key Laboratory of Microbial Technology Institute of Microbial Technology, Shandong University Qingdao P. R. China
| | - Chunyu Yang
- State Key Laboratory of Microbial Technology Institute of Microbial Technology, Shandong University Qingdao P. R. China
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40
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Ung KL, Winkler M, Schulz L, Kolb M, Janacek DP, Dedic E, Stokes DL, Hammes UZ, Pedersen BP. Structures and mechanism of the plant PIN-FORMED auxin transporter. Nature 2022; 609:605-610. [PMID: 35768502 PMCID: PMC9477730 DOI: 10.1038/s41586-022-04883-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 05/19/2022] [Indexed: 11/15/2022]
Abstract
Auxins are hormones that have central roles and control nearly all aspects of growth and development in plants1–3. The proteins in the PIN-FORMED (PIN) family (also known as the auxin efflux carrier family) are key participants in this process and control auxin export from the cytosol to the extracellular space4–9. Owing to a lack of structural and biochemical data, the molecular mechanism of PIN-mediated auxin transport is not understood. Here we present biophysical analysis together with three structures of Arabidopsis thaliana PIN8: two outward-facing conformations with and without auxin, and one inward-facing conformation bound to the herbicide naphthylphthalamic acid. The structure forms a homodimer, with each monomer divided into a transport and scaffold domain with a clearly defined auxin binding site. Next to the binding site, a proline–proline crossover is a pivot point for structural changes associated with transport, which we show to be independent of proton and ion gradients and probably driven by the negative charge of the auxin. The structures and biochemical data reveal an elevator-type transport mechanism reminiscent of bile acid/sodium symporters, bicarbonate/sodium symporters and sodium/proton antiporters. Our results provide a comprehensive molecular model for auxin recognition and transport by PINs, link and expand on a well-known conceptual framework for transport, and explain a central mechanism of polar auxin transport, a core feature of plant physiology, growth and development. Structural and biophysical analysis of the Arabidopsis thaliana auxin transporter PIN8 reveal that PIN transporters export auxin using an elevator mechanism.
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Affiliation(s)
- Kien Lam Ung
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Mikael Winkler
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Lukas Schulz
- Plant Systems Biology, School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
| | - Martina Kolb
- Plant Systems Biology, School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
| | - Dorina P Janacek
- Plant Systems Biology, School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany
| | - Emil Dedic
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - David L Stokes
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Ulrich Z Hammes
- Plant Systems Biology, School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany.
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41
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Park JH, Iwamoto M, Yun JH, Uchikubo-Kamo T, Son D, Jin Z, Yoshida H, Ohki M, Ishimoto N, Mizutani K, Oshima M, Muramatsu M, Wakita T, Shirouzu M, Liu K, Uemura T, Nomura N, Iwata S, Watashi K, Tame JRH, Nishizawa T, Lee W, Park SY. Structural insights into the HBV receptor and bile acid transporter NTCP. Nature 2022; 606:1027-1031. [PMID: 35580630 PMCID: PMC9242859 DOI: 10.1038/s41586-022-04857-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 05/11/2022] [Indexed: 01/05/2023]
Abstract
Around 250 million people are infected with hepatitis B virus (HBV) worldwide1, and 15 million may also carry the satellite virus hepatitis D virus (HDV), which confers even greater risk of severe liver disease2. The HBV receptor has been identified as sodium taurocholate co-transporting polypeptide (NTCP), which interacts directly with the first 48 amino acid residues of the N-myristoylated N-terminal preS1 domain of the viral large protein3. Despite the pressing need for therapeutic agents to counter HBV, the structure of NTCP remains unsolved. This 349-residue protein is closely related to human apical sodium-dependent bile acid transporter (ASBT), another member of the solute carrier family SLC10. Crystal structures have been reported of similar bile acid transporters from bacteria4,5, and these models are believed to resemble closely both NTCP and ASBT. Here we have used cryo-electron microscopy to solve the structure of NTCP bound to an antibody, clearly showing that the transporter has no equivalent of the first transmembrane helix found in other SLC10 proteins, and that the N terminus is exposed on the extracellular face. Comparison of our structure with those of related proteins indicates a common mechanism of bile acid transport, but the NTCP structure displays an additional pocket formed by residues that are known to interact with preS1, presenting new opportunities for structure-based drug design. Cryo-electron structures of the hepatitis B virus receptor NTCP show a distinct membrane topology compared with other SLC10 proteins, but a common bile acid transport mechanism that is shared with related mammalian and bacterial proteins.
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Affiliation(s)
- Jae-Hyun Park
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Masashi Iwamoto
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Ji-Hye Yun
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea.,PCG-Biotech, Seoul, South Korea
| | - Tomomi Uchikubo-Kamo
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Japan
| | - Donghwan Son
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Zeyu Jin
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan.,Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Hisashi Yoshida
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Mio Ohki
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Naito Ishimoto
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Kenji Mizutani
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Mizuki Oshima
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan.,Department of Biological Sciences, Tokyo University of Science, Noda, Japan
| | - Masamichi Muramatsu
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Takaji Wakita
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan
| | - Mikako Shirouzu
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, Yokohama, Japan
| | - Kehong Liu
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Tomoko Uemura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Norimichi Nomura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - So Iwata
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,RIKEN SPring-8 Center, Sayo-gun, Japan
| | - Koichi Watashi
- Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan.,Department of Biological Sciences, Tokyo University of Science, Noda, Japan.,Research Center for Drug and Vaccine Development, Tokyo, Japan
| | - Jeremy R H Tame
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Tomohiro Nishizawa
- Laboratory of Biomembrane Dynamics, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan
| | - Weontae Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea. .,PCG-Biotech, Seoul, South Korea.
| | - Sam-Yong Park
- Drug Design Laboratory, Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan.
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42
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Dong Y, Li H, Ilie A, Gao Y, Boucher A, Zhang XC, Orlowski J, Zhao Y. Structural basis of autoinhibition of the human NHE3-CHP1 complex. SCIENCE ADVANCES 2022; 8:eabn3925. [PMID: 35613257 PMCID: PMC9132474 DOI: 10.1126/sciadv.abn3925] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 04/11/2022] [Indexed: 06/15/2023]
Abstract
Sodium-proton exchanger 3 (NHE3/SLC9A3) located in the apical membrane of renal and gastrointestinal epithelia mediates salt and fluid absorption and regulates pH homeostasis. As an auxiliary regulatory factor of NHE proteins, calcineurin B homologous protein 1 (CHP1) facilitates NHE3 maturation, plasmalemmal expression, and pH sensitivity. Dysfunctions of NHE3 are associated with renal and digestive system disorders. Here, we report the cryo-electron microscopy structure of the human NHE3-CHP1 complex in its inward-facing conformation. We found that a cytosolic helix-loop-helix motif in NHE3 blocks the intracellular cavity formed between the core and dimerization domains, functioning as an autoinhibitory element and hindering substrate transport. Furthermore, two phosphatidylinositol molecules are found to bind to the peripheric juxtamembrane sides of the complex, function as anchors to stabilize the complex, and may thus enhance its transport activity.
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Affiliation(s)
- Yanli Dong
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hang Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Alina Ilie
- Department of Physiology, McGill University, Montreal, Canada
| | - Yiwei Gao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Annie Boucher
- Department of Physiology, McGill University, Montreal, Canada
| | - Xuejun Cai Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - John Orlowski
- Department of Physiology, McGill University, Montreal, Canada
| | - Yan Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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43
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Anderegg MA, Gyimesi G, Ho TM, Hediger MA, Fuster DG. The Less Well-Known Little Brothers: The SLC9B/NHA Sodium Proton Exchanger Subfamily—Structure, Function, Regulation and Potential Drug-Target Approaches. Front Physiol 2022; 13:898508. [PMID: 35694410 PMCID: PMC9174904 DOI: 10.3389/fphys.2022.898508] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 05/04/2022] [Indexed: 12/15/2022] Open
Abstract
The SLC9 gene family encodes Na+/H+ exchangers (NHEs), a group of membrane transport proteins critically involved in the regulation of cytoplasmic and organellar pH, cell volume, as well as systemic acid-base and volume homeostasis. NHEs of the SLC9A subfamily (NHE 1–9) are well-known for their roles in human physiology and disease. Much less is known about the two members of the SLC9B subfamily, NHA1 and NHA2, which share higher similarity to prokaryotic NHEs than the SLC9A paralogs. NHA2 (also known as SLC9B2) is ubiquitously expressed and has recently been shown to participate in renal blood pressure and electrolyte regulation, insulin secretion and systemic glucose homeostasis. In addition, NHA2 has been proposed to contribute to the pathogenesis of polycystic kidney disease, the most common inherited kidney disease in humans. NHA1 (also known as SLC9B1) is mainly expressed in testis and is important for sperm motility and thus male fertility, but has not been associated with human disease thus far. In this review, we present a summary of the structure, function and regulation of expression of the SLC9B subfamily members, focusing primarily on the better-studied SLC9B paralog, NHA2. Furthermore, we will review the potential of the SLC9B subfamily as drug targets.
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Affiliation(s)
- Manuel A. Anderegg
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- *Correspondence: Manuel A. Anderegg,
| | - Gergely Gyimesi
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Membrane Transport Discovery Lab, Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Tin Manh Ho
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Matthias A. Hediger
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Membrane Transport Discovery Lab, Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Daniel G. Fuster
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
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44
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Chen AY, Lee J, Damjanovic A, Brooks BR. Protein p Ka Prediction by Tree-Based Machine Learning. J Chem Theory Comput 2022; 18:2673-2686. [PMID: 35289611 PMCID: PMC10510853 DOI: 10.1021/acs.jctc.1c01257] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protonation states of ionizable protein residues modulate many essential biological processes. For correct modeling and understanding of these processes, it is crucial to accurately determine their pKa values. Here, we present four tree-based machine learning models for protein pKa prediction. The four models, Random Forest, Extra Trees, eXtreme Gradient Boosting (XGBoost), and Light Gradient Boosting Machine (LightGBM), were trained on three experimental PDB and pKa datasets, two of which included a notable portion of internal residues. We observed similar performance among the four machine learning algorithms. The best model trained on the largest dataset performs 37% better than the widely used empirical pKa prediction tool PROPKA and 15% better than the published result from the pKa prediction method DelPhiPKa. The overall root-mean-square error (RMSE) for this model is 0.69, with surface and buried RMSE values being 0.56 and 0.78, respectively, considering six residue types (Asp, Glu, His, Lys, Cys, and Tyr), and 0.63 when considering Asp, Glu, His, and Lys only. We provide pKa predictions for proteins in human proteome from the AlphaFold Protein Structure Database and observed that 1% of Asp/Glu/Lys residues have highly shifted pKa values close to the physiological pH.
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Affiliation(s)
- Ada Y. Chen
- Department of Physics & Astronomy, Johns Hopkins
University, Baltimore, Maryland, 21218
- Laboratory of Computational Biology, National Heart, Lung
and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892
| | - Juyong Lee
- Department of Chemistry, Division of Chemistry and
Biochemistry, Kangwon National University, 1 Gangwondaehak-gil, Chuncheon, 24341,
Republic of Korea
| | - Ana Damjanovic
- Department of Biophysics, Johns Hopkins University,
Baltimore, Maryland, 21218
| | - Bernard R. Brooks
- Laboratory of Computational Biology, National Heart, Lung
and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892
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45
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Salamzade R, Manson AL, Walker BJ, Brennan-Krohn T, Worby CJ, Ma P, He LL, Shea TP, Qu J, Chapman SB, Howe W, Young SK, Wurster JI, Delaney ML, Kanjilal S, Onderdonk AB, Bittencourt CE, Gussin GM, Kim D, Peterson EM, Ferraro MJ, Hooper DC, Shenoy ES, Cuomo CA, Cosimi LA, Huang SS, Kirby JE, Pierce VM, Bhattacharyya RP, Earl AM. Inter-species geographic signatures for tracing horizontal gene transfer and long-term persistence of carbapenem resistance. Genome Med 2022; 14:37. [PMID: 35379360 PMCID: PMC8981930 DOI: 10.1186/s13073-022-01040-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 03/22/2022] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Carbapenem-resistant Enterobacterales (CRE) are an urgent global health threat. Inferring the dynamics of local CRE dissemination is currently limited by our inability to confidently trace the spread of resistance determinants to unrelated bacterial hosts. Whole-genome sequence comparison is useful for identifying CRE clonal transmission and outbreaks, but high-frequency horizontal gene transfer (HGT) of carbapenem resistance genes and subsequent genome rearrangement complicate tracing the local persistence and mobilization of these genes across organisms. METHODS To overcome this limitation, we developed a new approach to identify recent HGT of large, near-identical plasmid segments across species boundaries, which also allowed us to overcome technical challenges with genome assembly. We applied this to complete and near-complete genome assemblies to examine the local spread of CRE in a systematic, prospective collection of all CRE, as well as time- and species-matched carbapenem-susceptible Enterobacterales, isolated from patients from four US hospitals over nearly 5 years. RESULTS Our CRE collection comprised a diverse range of species, lineages, and carbapenem resistance mechanisms, many of which were encoded on a variety of promiscuous plasmid types. We found and quantified rearrangement, persistence, and repeated transfer of plasmid segments, including those harboring carbapenemases, between organisms over multiple years. Some plasmid segments were found to be strongly associated with specific locales, thus representing geographic signatures that make it possible to trace recent and localized HGT events. Functional analysis of these signatures revealed genes commonly found in plasmids of nosocomial pathogens, such as functions required for plasmid retention and spread, as well survival against a variety of antibiotic and antiseptics common to the hospital environment. CONCLUSIONS Collectively, the framework we developed provides a clearer, high-resolution picture of the epidemiology of antibiotic resistance importation, spread, and persistence in patients and healthcare networks.
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Affiliation(s)
- Rauf Salamzade
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA ,grid.14003.360000 0001 2167 3675Present Address: Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706 USA
| | - Abigail L. Manson
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
| | - Bruce J. Walker
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA ,Applied Invention, Cambridge, MA 02139 USA
| | - Thea Brennan-Krohn
- grid.239395.70000 0000 9011 8547Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215 USA
| | - Colin J. Worby
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
| | - Peijun Ma
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
| | - Lorrie L. He
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
| | - Terrance P. Shea
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
| | - James Qu
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
| | - Sinéad B. Chapman
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
| | - Whitney Howe
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
| | - Sarah K. Young
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
| | - Jenna I. Wurster
- grid.38142.3c000000041936754XDepartment of Ophthalmology, Department of Microbiology, Harvard Medical School and Massachusetts Eye and Ear Infirmary, 240 Charles St., Boston, MA 02114 USA
| | - Mary L. Delaney
- grid.38142.3c000000041936754XDivision of Infectious Disease, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 USA
| | - Sanjat Kanjilal
- grid.38142.3c000000041936754XDivision of Infectious Disease, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 USA ,grid.38142.3c000000041936754XDepartment of Population Medicine, Harvard Medical School and Harvard Pilgrim Healthcare Institute, Boston, MA 02215 USA
| | - Andrew B. Onderdonk
- grid.38142.3c000000041936754XDivision of Infectious Disease, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 USA
| | - Cassiana E. Bittencourt
- grid.266093.80000 0001 0668 7243Department of Pathology and Laboratory Medicine, University of California Irvine School of Medicine, Orange, CA 92868 USA
| | - Gabrielle M. Gussin
- grid.266093.80000 0001 0668 7243Division of Infectious Diseases, University of California Irvine School of Medicine, Irvine, CA 92617 USA
| | - Diane Kim
- grid.266093.80000 0001 0668 7243Division of Infectious Diseases, University of California Irvine School of Medicine, Irvine, CA 92617 USA
| | - Ellena M. Peterson
- grid.266093.80000 0001 0668 7243Department of Pathology and Laboratory Medicine, University of California Irvine School of Medicine, Orange, CA 92868 USA
| | - Mary Jane Ferraro
- grid.32224.350000 0004 0386 9924Massachusetts General Hospital, Boston, MA 02114 USA
| | - David C. Hooper
- grid.32224.350000 0004 0386 9924Massachusetts General Hospital, Boston, MA 02114 USA
| | - Erica S. Shenoy
- grid.32224.350000 0004 0386 9924Massachusetts General Hospital, Boston, MA 02114 USA
| | - Christina A. Cuomo
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
| | - Lisa A. Cosimi
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA ,grid.38142.3c000000041936754XDivision of Infectious Disease, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115 USA
| | - Susan S. Huang
- grid.266093.80000 0001 0668 7243Division of Infectious Diseases, University of California Irvine School of Medicine, Irvine, CA 92617 USA
| | - James E. Kirby
- grid.239395.70000 0000 9011 8547Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215 USA
| | - Virginia M. Pierce
- grid.32224.350000 0004 0386 9924Massachusetts General Hospital, Boston, MA 02114 USA
| | - Roby P. Bhattacharyya
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA ,grid.32224.350000 0004 0386 9924Massachusetts General Hospital, Boston, MA 02114 USA
| | - Ashlee M. Earl
- grid.66859.340000 0004 0546 1623Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142 USA
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46
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Abstract
Soil salinization has become a major problem for agriculture worldwide, especially because this phenomenon is continuously expanding in different regions of the world. Salinity is a complex mechanism, and in the soil ecosystem, it affects both microorganisms and plants, some of which have developed efficient strategies to alleviate salt stress conditions. Currently, various methods can be used to reduce the negative effects of this problem. However, the use of biological methods, such as plant-growth-promoting bacteria (PGPB), phytoremediation, and amendment, seems to be very advantageous and promising as a remedy for sustainable and ecological agriculture. Other approaches aim to combine different techniques, as well as the utilization of genetic engineering methods. These techniques alone or combined can effectively contribute to the development of sustainable and eco-friendly agriculture.
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47
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Xie Q, Zhou Y, Jiang X. Structure, Function, and Regulation of the Plasma Membrane Na +/H + Antiporter Salt Overly Sensitive 1 in Plants. FRONTIERS IN PLANT SCIENCE 2022; 13:866265. [PMID: 35432437 PMCID: PMC9009148 DOI: 10.3389/fpls.2022.866265] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/08/2022] [Indexed: 05/24/2023]
Abstract
Physiological studies have confirmed that export of Na+ to improve salt tolerance in plants is regulated by the combined activities of a complex transport system. In the Na+ transport system, the Na+/H+ antiporter salt overly sensitive 1 (SOS1) is the main protein that functions to excrete Na+ out of plant cells. In this paper, we review the structure and function of the Na+/H+ antiporter and the physiological process of Na+ transport in SOS signaling pathway, and discuss the regulation of SOS1 during phosphorylation activation by protein kinase and the balance mechanism of inhibiting SOS1 antiporter at molecular and protein levels. In addition, we carried out phylogenetic tree analysis of SOS1 proteins reported so far in plants, which implied the specificity of salt tolerance mechanism from model plants to higher crops under salt stress. Finally, the high complexity of the regulatory network of adaptation to salt tolerance, and the feasibility of coping strategies in the process of genetic improvement of salt tolerance quality of higher crops were reviewed.
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Affiliation(s)
- Qing Xie
- National Innovation Center for Technology of Saline-Alkaline Tolerant Rice/College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, China
- Hainan Key Laboratory for Biotechnology of Salt Tolerant Crops/School of Horticulture, Hainan University, Haikou, China
| | - Yang Zhou
- Hainan Key Laboratory for Biotechnology of Salt Tolerant Crops/School of Horticulture, Hainan University, Haikou, China
| | - Xingyu Jiang
- National Innovation Center for Technology of Saline-Alkaline Tolerant Rice/College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, China
- Hainan Key Laboratory for Biotechnology of Salt Tolerant Crops/School of Horticulture, Hainan University, Haikou, China
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48
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Beckstein O, Naughton F. General principles of secondary active transporter function. BIOPHYSICS REVIEWS 2022; 3:011307. [PMID: 35434715 PMCID: PMC8984959 DOI: 10.1063/5.0047967] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 02/23/2022] [Indexed: 04/13/2023]
Abstract
Transport of ions and small molecules across the cell membrane against electrochemical gradients is catalyzed by integral membrane proteins that use a source of free energy to drive the energetically uphill flux of the transported substrate. Secondary active transporters couple the spontaneous influx of a "driving" ion such as Na+ or H+ to the flux of the substrate. The thermodynamics of such cyclical non-equilibrium systems are well understood, and recent work has focused on the molecular mechanism of secondary active transport. The fact that these transporters change their conformation between an inward-facing and outward-facing conformation in a cyclical fashion, called the alternating access model, is broadly recognized as the molecular framework in which to describe transporter function. However, only with the advent of high resolution crystal structures and detailed computer simulations, it has become possible to recognize common molecular-level principles between disparate transporter families. Inverted repeat symmetry in secondary active transporters has shed light onto how protein structures can encode a bi-stable two-state system. Based on structural data, three broad classes of alternating access transitions have been described as rocker-switch, rocking-bundle, and elevator mechanisms. More detailed analysis indicates that transporters can be understood as gated pores with at least two coupled gates. These gates are not just a convenient cartoon element to illustrate a putative mechanism but map to distinct parts of the transporter protein. Enumerating all distinct gate states naturally includes occluded states in the alternating access picture and also suggests what kind of protein conformations might be observable. By connecting the possible conformational states and ion/substrate bound states in a kinetic model, a unified picture emerges in which the symporter, antiporter, and uniporter functions are extremes in a continuum of functionality. As usual with biological systems, few principles and rules are absolute and exceptions are discussed as well as how biological complexity may be integrated in quantitative kinetic models that may provide a bridge from the structure to function.
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Affiliation(s)
- Oliver Beckstein
- Department of Physics, Arizona State University, Tempe, Arizona 85287, USA
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49
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Matsuoka R, Fudim R, Jung S, Zhang C, Bazzone A, Chatzikyriakidou Y, Robinson CV, Nomura N, Iwata S, Landreh M, Orellana L, Beckstein O, Drew D. Structure, mechanism and lipid-mediated remodeling of the mammalian Na +/H + exchanger NHA2. Nat Struct Mol Biol 2022; 29:108-120. [PMID: 35173351 PMCID: PMC8850199 DOI: 10.1038/s41594-022-00738-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 12/14/2021] [Indexed: 11/09/2022]
Abstract
The Na+/H+ exchanger SLC9B2, also known as NHA2, correlates with the long-sought-after Na+/Li+ exchanger linked to the pathogenesis of diabetes mellitus and essential hypertension in humans. Despite the functional importance of NHA2, structural information and the molecular basis for its ion-exchange mechanism have been lacking. Here we report the cryo-EM structures of bison NHA2 in detergent and in nanodiscs, at 3.0 and 3.5 Å resolution, respectively. The bison NHA2 structure, together with solid-state membrane-based electrophysiology, establishes the molecular basis for electroneutral ion exchange. NHA2 consists of 14 transmembrane (TM) segments, rather than the 13 TMs previously observed in mammalian Na+/H+ exchangers (NHEs) and related bacterial antiporters. The additional N-terminal helix in NHA2 forms a unique homodimer interface with a large intracellular gap between the protomers, which closes in the presence of phosphoinositol lipids. We propose that the additional N-terminal helix has evolved as a lipid-mediated remodeling switch for the regulation of NHA2 activity.
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Affiliation(s)
- Rei Matsuoka
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Roman Fudim
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
| | - Sukkyeong Jung
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Chenou Zhang
- Center for Biological Physics, Department of Physics, Arizona State University, Tempe, AZ, USA
| | | | | | | | - Norimichi Nomura
- Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto, Japan
| | - So Iwata
- Graduate School of Medicine, Kyoto University, Konoe-cho, Yoshida, Sakyo-ku, Kyoto, Japan
| | - Michael Landreh
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Laura Orellana
- Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Oliver Beckstein
- Center for Biological Physics, Department of Physics, Arizona State University, Tempe, AZ, USA.
| | - David Drew
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
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Ottolia M, John S, Hazan A, Goldhaber JI. The Cardiac Na + -Ca 2+ Exchanger: From Structure to Function. Compr Physiol 2021; 12:2681-2717. [PMID: 34964124 DOI: 10.1002/cphy.c200031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Ca2+ homeostasis is essential for cell function and survival. As such, the cytosolic Ca2+ concentration is tightly controlled by a wide number of specialized Ca2+ handling proteins. One among them is the Na+ -Ca2+ exchanger (NCX), a ubiquitous plasma membrane transporter that exploits the electrochemical gradient of Na+ to drive Ca2+ out of the cell, against its concentration gradient. In this critical role, this secondary transporter guides vital physiological processes such as Ca2+ homeostasis, muscle contraction, bone formation, and memory to name a few. Herein, we review the progress made in recent years about the structure of the mammalian NCX and how it relates to function. Particular emphasis will be given to the mammalian cardiac isoform, NCX1.1, due to the extensive studies conducted on this protein. Given the degree of conservation among the eukaryotic exchangers, the information highlighted herein will provide a foundation for our understanding of this transporter family. We will discuss gene structure, alternative splicing, topology, regulatory mechanisms, and NCX's functional role on cardiac physiology. Throughout this article, we will attempt to highlight important milestones in the field and controversial topics where future studies are required. © 2021 American Physiological Society. Compr Physiol 12:1-37, 2021.
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Affiliation(s)
- Michela Ottolia
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA
| | - Scott John
- Department of Medicine (Cardiology), UCLA, Los Angeles, California, USA
| | - Adina Hazan
- Smidt Heart Institute, Cedars Sinai Medical Center, Los Angeles, California, USA
| | - Joshua I Goldhaber
- Smidt Heart Institute, Cedars Sinai Medical Center, Los Angeles, California, USA
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