1
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Kobayashi TA, Shimada H, Sano FK, Itoh Y, Enoki S, Okada Y, Kusakizako T, Nureki O. Dimeric transport mechanism of human vitamin C transporter SVCT1. Nat Commun 2024; 15:5569. [PMID: 38956111 PMCID: PMC11219872 DOI: 10.1038/s41467-024-49899-2] [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: 05/31/2023] [Accepted: 06/20/2024] [Indexed: 07/04/2024] Open
Abstract
Vitamin C plays important roles as a cofactor in many enzymatic reactions and as an antioxidant against oxidative stress. As some mammals including humans cannot synthesize vitamin C de novo from glucose, its uptake from dietary sources is essential, and is mediated by the sodium-dependent vitamin C transporter 1 (SVCT1). Despite its physiological significance in maintaining vitamin C homeostasis, the structural basis of the substrate transport mechanism remained unclear. Here, we report the cryo-EM structures of human SVCT1 in different states at 2.5-3.5 Å resolutions. The binding manner of vitamin C together with two sodium ions reveals the counter ion-dependent substrate recognition mechanism. Furthermore, comparisons of the inward-open and occluded structures support a transport mechanism combining elevator and distinct rotational motions. Our results demonstrate the molecular mechanism of vitamin C transport with its underlying conformational cycle, potentially leading to future industrial and medical applications.
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Affiliation(s)
- Takaaki A Kobayashi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Hiroto Shimada
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
- Research Division, Chugai Pharmaceutical Co., Ltd., Kanagawa, Japan
| | - Fumiya K Sano
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Yuzuru Itoh
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Sawako Enoki
- Department of Physics, and Universal Biology Institute (UBI), Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Yasushi Okada
- Department of Physics, and Universal Biology Institute (UBI), Graduate School of Science, The University of Tokyo, Tokyo, Japan
- Department of Cell Biology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Laboratory for Cell Polarity Regulation, RIKEN Center for Biosystems Dynamics Research (BDR), Osaka, Japan
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, Tokyo, Japan
| | - Tsukasa Kusakizako
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
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2
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Cimadamore-Werthein C, King MS, Lacabanne D, Pyrihová E, Jaiquel Baron S, Kunji ER. Human mitochondrial carriers of the SLC25 family function as monomers exchanging substrates with a ping-pong kinetic mechanism. EMBO J 2024:10.1038/s44318-024-00150-0. [PMID: 38937634 DOI: 10.1038/s44318-024-00150-0] [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: 03/14/2024] [Revised: 05/30/2024] [Accepted: 05/31/2024] [Indexed: 06/29/2024] Open
Abstract
Members of the SLC25 mitochondrial carrier family link cytosolic and mitochondrial metabolism and support cellular maintenance and growth by transporting compounds across the mitochondrial inner membrane. Their monomeric or dimeric state and kinetic mechanism have been a matter of long-standing debate. It is believed by some that they exist as homodimers and transport substrates with a sequential kinetic mechanism, forming a ternary complex where both exchanged substrates are bound simultaneously. Some studies, in contrast, have provided evidence indicating that the mitochondrial ADP/ATP carrier (SLC25A4) functions as a monomer, has a single substrate binding site, and operates with a ping-pong kinetic mechanism, whereby ADP is imported before ATP is exported. Here we reanalyze the oligomeric state and kinetic properties of the human mitochondrial citrate carrier (SLC25A1), dicarboxylate carrier (SLC25A10), oxoglutarate carrier (SLC25A11), and aspartate/glutamate carrier (SLC25A13), all previously reported to be dimers with a sequential kinetic mechanism. We demonstrate that they are monomers, except for dimeric SLC25A13, and operate with a ping-pong kinetic mechanism in which the substrate import and export steps occur consecutively. These observations are consistent with a common transport mechanism, based on a functional monomer, in which a single central substrate-binding site is alternately accessible.
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Affiliation(s)
- Camila Cimadamore-Werthein
- Medical Research Council Mitochondrial Biology Unit, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
| | - Martin S King
- Medical Research Council Mitochondrial Biology Unit, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
| | - Denis Lacabanne
- Medical Research Council Mitochondrial Biology Unit, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
| | - Eva Pyrihová
- Medical Research Council Mitochondrial Biology Unit, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
| | - Stephany Jaiquel Baron
- Medical Research Council Mitochondrial Biology Unit, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom
| | - Edmund Rs Kunji
- Medical Research Council Mitochondrial Biology Unit, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, United Kingdom.
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3
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Zhao B, Cao Z, Zheng Y, Nguyen P, Bowen A, Edwards RH, Stroud RM, Zhou Y, Van Lookeren Campagne M, Li F. Structural and mechanistic insights into a lysosomal membrane enzyme HGSNAT involved in Sanfilippo syndrome. Nat Commun 2024; 15:5388. [PMID: 38918376 PMCID: PMC11199644 DOI: 10.1038/s41467-024-49614-1] [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: 02/19/2024] [Accepted: 06/11/2024] [Indexed: 06/27/2024] Open
Abstract
Heparan sulfate (HS) is degraded in lysosome by a series of glycosidases. Before the glycosidases can act, the terminal glucosamine of HS must be acetylated by the integral lysosomal membrane enzyme heparan-α-glucosaminide N-acetyltransferase (HGSNAT). Mutations of HGSNAT cause HS accumulation and consequently mucopolysaccharidosis IIIC, a devastating lysosomal storage disease characterized by progressive neurological deterioration and early death where no treatment is available. HGSNAT catalyzes a unique transmembrane acetylation reaction where the acetyl group of cytosolic acetyl-CoA is transported across the lysosomal membrane and attached to HS in one reaction. However, the reaction mechanism remains elusive. Here we report six cryo-EM structures of HGSNAT along the reaction pathway. These structures reveal a dimer arrangement and a unique structural fold, which enables the elucidation of the reaction mechanism. We find that a central pore within each monomer traverses the membrane and controls access of cytosolic acetyl-CoA to the active site at its luminal mouth where glucosamine binds. A histidine-aspartic acid catalytic dyad catalyzes the transfer reaction via a ternary complex mechanism. Furthermore, the structures allow the mapping of disease-causing variants and reveal their potential impact on the function, thus creating a framework to guide structure-based drug discovery efforts.
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Affiliation(s)
- Boyang Zhao
- Amgen Research, Department of Structural biology, South San Francisco, CA, USA
| | - Zhongzheng Cao
- Amgen Research, Department of Inflammation, South San Francisco, CA, USA
| | - Yi Zheng
- Amgen Research, Department of Discovery Protein Science, South San Francisco, CA, USA
| | - Phuong Nguyen
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
- Laboratory for Genomics Research, UCSF School of Medicine, San Francisco, CA, USA
| | - Alisa Bowen
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
- Adanate, Alameda, CA, USA
| | - Robert H Edwards
- Departments of Neurology and Physiology, UCSF School of Medicine, San Francisco, CA, USA
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California San Francisco (UCSF) School of Medicine, San Francisco, CA, USA
| | - Yi Zhou
- Amgen Research, Department of Inflammation, South San Francisco, CA, USA
| | | | - Fei Li
- Amgen Research, Department of Structural biology, South San Francisco, CA, USA.
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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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Huang SH, Amemiya S. Transient theory for scanning electrochemical microscopy of biological membrane transport: uncovering membrane-permeant interactions. Analyst 2024; 149:3115-3122. [PMID: 38647017 PMCID: PMC11131039 DOI: 10.1039/d4an00411f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Accepted: 04/15/2024] [Indexed: 04/25/2024]
Abstract
Scanning electrochemical microscopy (SECM) has emerged as a powerful method to quantitatively investigate the transport of molecules and ions across various biological membranes as represented by living cells. Advantageously, SECM allows for the in situ and non-destructive imaging and measurement of high membrane permeability under simple steady-state conditions, thereby facilitating quantitative data analysis. The SECM method, however, has not provided any information about the interactions of a transported species, i.e., a permeant, with a membrane through its components, e.g., lipids, channels, and carriers. Herein, we propose theoretically that SECM enables the quantitative investigation of membrane-permeant interactions by employing transient conditions. Specifically, we model the membrane-permeant interactions based on a Langmuir-type isotherm to define the strength and kinetics of the interactions as well as the concentration of interaction sites. Finite element simulation predicts that each of the three parameters uniquely affects the chronoamperometric current response of an SECM tip to a permeant. Significantly, this prediction implies that all three parameters are determinable from an experimental chronoamperometric response of the SECM tip. Complimentarily, the steady-state current response of the SECM tip yields the overall membrane permeability based on the combination of the three parameters. Interestingly, our simulation also reveals the optimum strength of membrane-permeant interactions to maximize the transient flux of the permeant from the membrane to the tip.
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Affiliation(s)
- Siao-Han Huang
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
| | - Shigeru Amemiya
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
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6
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Lu X, Huang J. Molecular mechanisms of Na +-driven bile acid transport in human NTCP. Biophys J 2024; 123:1195-1210. [PMID: 38544409 PMCID: PMC11140467 DOI: 10.1016/j.bpj.2024.03.033] [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: 01/01/2024] [Revised: 02/17/2024] [Accepted: 03/25/2024] [Indexed: 04/12/2024] Open
Abstract
Human Na+ taurocholate co-transporting protein (hNTCP) is a key bile salt transporter to maintain enterohepatic circulation and is responsible for the recognition of hepatitis B and D viruses. Despite landmark cryoelectron microscopy studies revealing open-pore and inward-facing states of hNTCP stabilized by antibodies, the transport mechanism remains largely unknown. To address this knowledge gap, we used molecular dynamics and enhanced sampling metadynamics simulations to elucidate the intrinsic mechanism of hNTCP-mediated taurocholate acid (TCA) transport driven by Na+ binding. We uncovered three TCA-binding modes, including one that closely matched the limited cryoelectron microscopy density observed in the open-pore hNTCP. We also captured several key hNTCP conformations in the substrate transport cycle, particularly including an outward-facing, substrate-bound state. Furthermore, we provided thermodynamic evidence supporting that changes in the Na+-binding state drive the TCA transport by exploiting the amphiphilic nature of the substrate and modulating the protein environment, thereby enabling the TCA molecule to flip through. Understanding these mechanistic details of Na+-driven bile acid transport may aid in the development of hNTCP-targeted therapies for liver diseases.
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Affiliation(s)
- Xiaoli Lu
- Westlake AI Therapeutics Laboratory, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China; Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
| | - Jing Huang
- Westlake AI Therapeutics Laboratory, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China; Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China.
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7
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Yuan G, Nong T, Hunpatin OS, Shi C, Su X, Wang Q, Liu H, Dai P, Ning Y. Research Progress on Plant Shaker K + Channels. PLANTS (BASEL, SWITZERLAND) 2024; 13:1423. [PMID: 38794493 PMCID: PMC11125005 DOI: 10.3390/plants13101423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 05/16/2024] [Accepted: 05/16/2024] [Indexed: 05/26/2024]
Abstract
Plant growth and development are driven by intricate processes, with the cell membrane serving as a crucial interface between cells and their external environment. Maintaining balance and signal transduction across the cell membrane is essential for cellular stability and a host of life processes. Ion channels play a critical role in regulating intracellular ion concentrations and potentials. Among these, K+ channels on plant cell membranes are of paramount importance. The research of Shaker K+ channels has become a paradigm in the study of plant ion channels. This study offers a comprehensive overview of advancements in Shaker K+ channels, including insights into protein structure, function, regulatory mechanisms, and research techniques. Investigating Shaker K+ channels has enhanced our understanding of the regulatory mechanisms governing ion absorption and transport in plant cells. This knowledge offers invaluable guidance for enhancing crop yields and improving resistance to environmental stressors. Moreover, an extensive review of research methodologies in Shaker K+ channel studies provides essential reference solutions for researchers, promoting further advancements in ion channel research.
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Affiliation(s)
- Guang Yuan
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Tongjia Nong
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Oluwaseyi Setonji Hunpatin
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Chuhan Shi
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Xiaoqing Su
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Qian Wang
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
| | - Haobao Liu
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
| | - Peigang Dai
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
| | - Yang Ning
- Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, China
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8
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Takeuchi K, Ueda T, Imai M, Fujisaki M, Shimura M, Tokunaga Y, Kofuku Y, Shimada I. Affinity-directed substrate/H +-antiport by a MATE transporter. Structure 2024:S0969-2126(24)00181-3. [PMID: 38815577 DOI: 10.1016/j.str.2024.05.004] [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: 11/06/2023] [Revised: 03/16/2024] [Accepted: 05/03/2024] [Indexed: 06/01/2024]
Abstract
Multidrug and toxin extrusion (MATE) family transporters excrete toxic compounds coupled to Na+/H+ influx. Although structures of MATE transporters are available, the mechanism by which substrate export is coupled to ion influx remains unknown. To address this issue, we conducted a structural analysis of Pyrococcus furiosus MATE (PfMATE) using solution nuclear magnetic resonance (NMR). The NMR analysis, along with thorough substitutions of all non-exposed acidic residues, confirmed that PfMATE is under an equilibrium between inward-facing (IF) and outward-facing (OF) conformations, dictated by the Glu163 protonation. Importantly, we found that only the IF conformation exhibits a mid-μM affinity for substrate recognition. In contrast, the OF conformation exhibited only weak mM substrate affinity, suitable for releasing substrate to the extracellular side. These results indicate that PfMATE is an affinity-directed H+ antiporter where substrates selectively bind to the protonated IF conformation in the equilibrium, and subsequent proton release mechanistically ensures H+-coupled substrate excretion by the transporter.
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Affiliation(s)
- Koh Takeuchi
- Graduate School of Pharmacological Sciences, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan; Molecular Profiling Research Center for Drug Discovery and Cellular Molecular Biotechnology Research Institute, National Institute of Advanced Science and Technology, Aomi, Koto, Tokyo 135-0063, Japan.
| | - Takumi Ueda
- Graduate School of Pharmacological Sciences, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan
| | - Misaki Imai
- Graduate School of Pharmacological Sciences, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan; Research and Development Department, Japan Biological Informatics Consortium, Aomi 2-3-26, Koto-ku, Tokyo 135-0064, Japan
| | - Miwa Fujisaki
- Graduate School of Pharmacological Sciences, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan; Research and Development Department, Japan Biological Informatics Consortium, Aomi 2-3-26, Koto-ku, Tokyo 135-0064, Japan
| | - Mie Shimura
- Graduate School of Pharmacological Sciences, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan
| | - Yuji Tokunaga
- Graduate School of Pharmacological Sciences, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan; Molecular Profiling Research Center for Drug Discovery and Cellular Molecular Biotechnology Research Institute, National Institute of Advanced Science and Technology, Aomi, Koto, Tokyo 135-0063, Japan
| | - Yutaka Kofuku
- Graduate School of Pharmacological Sciences, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan
| | - Ichio Shimada
- Graduate School of Pharmacological Sciences, The University of Tokyo, Hongo, Bunkyo, Tokyo 113-0033, Japan; Center for Biosystems Dynamics Research, RIKEN, Kanagawa 230-0045, Japan; Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima City, Hiroshima 739-8528, Japan.
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9
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Hu W, Song A, Zheng H. Substrate binding plasticity revealed by Cryo-EM structures of SLC26A2. Nat Commun 2024; 15:3616. [PMID: 38684689 PMCID: PMC11059360 DOI: 10.1038/s41467-024-48028-3] [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: 09/28/2023] [Accepted: 04/17/2024] [Indexed: 05/02/2024] Open
Abstract
SLC26A2 is a vital solute carrier responsible for transporting essential nutritional ions, including sulfate, within the human body. Pathogenic mutations within SLC26A2 give rise to a spectrum of human diseases, ranging from lethal to mild symptoms. The molecular details regarding the versatile substrate-transporter interactions and the impact of pathogenic mutations on SLC26A2 transporter function remain unclear. Here, using cryo-electron microscopy, we determine three high-resolution structures of SLC26A2 in complexes with different substrates. These structures unveil valuable insights, including the distinct features of the homodimer assembly, the dynamic nature of substrate binding, and the potential ramifications of pathogenic mutations. This structural-functional information regarding SLC26A2 will advance our understanding of cellular sulfate transport mechanisms and provide foundations for future therapeutic development against various human diseases.
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Affiliation(s)
- Wenxin Hu
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, School of Medicine, Aurora, US
| | - Alex Song
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, School of Medicine, Aurora, US
| | - Hongjin Zheng
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, School of Medicine, Aurora, US.
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10
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Marinelli F, Faraldo-Gómez JD. Conformational free-energy landscapes of a Na +/Ca 2+ exchanger explain its alternating-access mechanism and functional specificity. Proc Natl Acad Sci U S A 2024; 121:e2318009121. [PMID: 38588414 PMCID: PMC11032461 DOI: 10.1073/pnas.2318009121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 02/20/2024] [Indexed: 04/10/2024] Open
Abstract
Secondary-active transporters catalyze the movement of myriad substances across all cellular membranes, typically against opposing concentration gradients, and without consuming any ATP. To do so, these proteins employ an intriguing structural mechanism evolved to be activated only upon recognition or release of the transported species. We examine this self-regulated mechanism using a homolog of the cardiac Na+/Ca2+ exchanger as a model system. Using advanced computer simulations, we map out the complete functional cycle of this transporter, including unknown conformations that we validate against existing experimental data. Calculated free-energy landscapes reveal why this transporter functions as an antiporter rather than a symporter, why it specifically exchanges Na+ and Ca2+, and why the stoichiometry of this exchange is exactly 3:1. We also rationalize why the protein does not exchange H+ for either Ca2+ or Na+, despite being able to bind H+ and its high similarity with H+/Ca2+ exchangers. Interestingly, the nature of this transporter is not explained by its primary structural states, known as inward- and outward-open conformations; instead, the defining factor is the feasibility of conformational intermediates between those states, wherein access pathways leading to the substrate binding sites become simultaneously occluded from both sides of the membrane. This analysis offers a physically coherent, broadly transferable route to understand the emergence of function from structure among secondary-active membrane transporters.
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Affiliation(s)
- Fabrizio Marinelli
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, NIH, Bethesda, MD20814
| | - José D. Faraldo-Gómez
- Theoretical Molecular Biophysics Laboratory, National Heart, Lung and Blood Institute, NIH, Bethesda, MD20814
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11
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Birkemeier M, Swindle A, Bowman J, Lynch VJ. Pervasive loss of regulated necrotic cell death genes in elephants, hyraxes, and sea cows ( Paenungualta). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.04.588129. [PMID: 38617256 PMCID: PMC11014510 DOI: 10.1101/2024.04.04.588129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Gene loss can promote phenotypic differences between species, for example, if a gene constrains phenotypic variation in a trait, its loss allows for the evolution of a greater range of variation or even new phenotypes. Here, we explore the contribution of gene loss to the evolution of large bodies and augmented cancer resistance in elephants. We used genomes from 17 Afrotherian and Xenarthran species to identify lost genes, i.e., genes that have pseudogenized or been completely lost, and Dollo parsimony to reconstruct the evolutionary history of gene loss across species. We unexpectedly discovered a burst of gene losses in the Afrotherian stem lineage and found that the loss of genes with functions in regulated necrotic cell death modes was pervasive in elephants, hyraxes, and sea cows (Paenungulata). Among the lost genes are MLKL and RIPK3, which mediate necroptosis, and sensors that activate inflammasomes to induce pyroptosis, including AIM2, MEFV, NLRC4, NLRP1, and NLRP6. These data suggest that the mechanisms that regulate necrosis and pyroptosis are either extremely derived or potentially lost in these lineages, which may contribute to the repeated evolution of large bodies and cancer resistance in Paenungulates as well as susceptibility to pathogen infection.
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Affiliation(s)
- Meaghan Birkemeier
- Department of Biological Sciences, University at Buffalo, SUNY, 551 Cooke Hall, Buffalo, NY, USA
| | - Arianna Swindle
- Department of Biological Sciences, University at Buffalo, SUNY, 551 Cooke Hall, Buffalo, NY, USA
| | - Jacob Bowman
- Department of Biological Sciences, University at Buffalo, SUNY, 551 Cooke Hall, Buffalo, NY, USA
| | - Vincent J. Lynch
- Department of Biological Sciences, University at Buffalo, SUNY, 551 Cooke Hall, Buffalo, NY, USA
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12
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Aziz I, Kayastha K, Kaltwasser S, Vonck J, Welsch S, Murphy BJ, Kahnt J, Wu D, Wagner T, Shima S, Ermler U. Structural and mechanistic basis of the central energy-converting methyltransferase complex of methanogenesis. Proc Natl Acad Sci U S A 2024; 121:e2315568121. [PMID: 38530900 PMCID: PMC10998594 DOI: 10.1073/pnas.2315568121] [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: 09/13/2023] [Accepted: 02/24/2024] [Indexed: 03/28/2024] Open
Abstract
Methanogenic archaea inhabiting anaerobic environments play a crucial role in the global biogeochemical material cycle. The most universal electrogenic reaction of their methane-producing energy metabolism is catalyzed by N 5-methyl-tetrahydromethanopterin: coenzyme M methyltransferase (MtrABCDEFGH), which couples the vectorial Na+ transport with a methyl transfer between the one-carbon carriers tetrahydromethanopterin and coenzyme M via a vitamin B12 derivative (cobamide) as prosthetic group. We present the 2.08 Å cryo-EM structure of Mtr(ABCDEFG)3 composed of the central Mtr(ABFG)3 stalk symmetrically flanked by three membrane-spanning MtrCDE globes. Tetraether glycolipids visible in the map fill gaps inside the multisubunit complex. Putative coenzyme M and Na+ were identified inside or in a side-pocket of a cytoplasmic cavity formed within MtrCDE. Its bottom marks the gate of the transmembrane pore occluded in the cryo-EM map. By integrating Alphafold2 information, functionally competent MtrA-MtrH and MtrA-MtrCDE subcomplexes could be modeled and thus the methyl-tetrahydromethanopterin demethylation and coenzyme M methylation half-reactions structurally described. Methyl-transfer-driven Na+ transport is proposed to be based on a strong and weak complex between MtrCDE and MtrA carrying vitamin B12, the latter being placed at the entrance of the cytoplasmic MtrCDE cavity. Hypothetically, strongly attached methyl-cob(III)amide (His-on) carrying MtrA induces an inward-facing conformation, Na+ flux into the membrane protein center and finally coenzyme M methylation while the generated loosely attached (or detached) MtrA carrying cob(I)amide (His-off) induces an outward-facing conformation and an extracellular Na+ outflux. Methyl-cob(III)amide (His-on) is regenerated in the distant active site of the methyl-tetrahydromethanopterin binding MtrH implicating a large-scale shuttling movement of the vitamin B12-carrying domain.
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Affiliation(s)
- Iram Aziz
- Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt am MainD-60438, Germany
| | - Kanwal Kayastha
- Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt am MainD-60438, Germany
| | - Susann Kaltwasser
- Central Electron Microscopy Facility, Max Planck Institute of Biophysics, Frankfurt am MainD-60438, Germany
| | - Janet Vonck
- Structural Biology, Max Planck Institute of Biophysics, Frankfurt am MainD-60438, Germany
| | - Sonja Welsch
- Central Electron Microscopy Facility, Max Planck Institute of Biophysics, Frankfurt am MainD-60438, Germany
| | - Bonnie J. Murphy
- Redox and Metalloprotein Research Group, Max Planck Institute of Biophysics, Frankfurt am MainD-60438, Germany
| | - Jörg Kahnt
- Max Planck Institute for Terrestrial Microbiology, MarburgD-35043, Germany
| | - Di Wu
- Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt am MainD-60438, Germany
| | - Tristan Wagner
- Max Planck Institute for Marine Microbiology, BremenD-28359, Germany
| | - Seigo Shima
- Max Planck Institute for Terrestrial Microbiology, MarburgD-35043, Germany
| | - Ulrich Ermler
- Molecular Membrane Biology, Max Planck Institute of Biophysics, Frankfurt am MainD-60438, Germany
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13
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Holmberg SR, Sakamoto Y, Kato A, Romero MF. The role of Na +-coupled bicarbonate transporters (NCBT) in health and disease. Pflugers Arch 2024; 476:479-503. [PMID: 38536494 DOI: 10.1007/s00424-024-02937-w] [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: 12/15/2023] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 04/11/2024]
Abstract
Cellular and organism survival depends upon the regulation of pH, which is regulated by highly specialized cell membrane transporters, the solute carriers (SLC) (For a comprehensive list of the solute carrier family members, see: https://www.bioparadigms.org/slc/ ). The SLC4 family of bicarbonate (HCO3-) transporters consists of ten members, sorted by their coupling to either sodium (NBCe1, NBCe2, NBCn1, NBCn2, NDCBE), chloride (AE1, AE2, AE3), or borate (BTR1). The ionic coupling of SLC4A9 (AE4) remains controversial. These SLC4 bicarbonate transporters may be controlled by cellular ionic gradients, cellular membrane voltage, and signaling molecules to maintain critical cellular and systemic pH (acid-base) balance. There are profound consequences when blood pH deviates even a small amount outside the normal range (7.35-7.45). Chiefly, Na+-coupled bicarbonate transporters (NCBT) control intracellular pH in nearly every living cell, maintaining the biological pH required for life. Additionally, NCBTs have important roles to regulate cell volume and maintain salt balance as well as absorption and secretion of acid-base equivalents. Due to their varied tissue expression, NCBTs have roles in pathophysiology, which become apparent in physiologic responses when their expression is reduced or genetically deleted. Variations in physiological pH are seen in a wide variety of conditions, from canonically acid-base related conditions to pathologies not necessarily associated with acid-base dysfunction such as cancer, glaucoma, or various neurological diseases. The membranous location of the SLC4 transporters as well as recent advances in discovering their structural biology makes them accessible and attractive as a druggable target in a disease context. The role of sodium-coupled bicarbonate transporters in such a large array of conditions illustrates the potential of treating a wide range of disease states by modifying function of these transporters, whether that be through inhibition or enhancement.
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Affiliation(s)
- Shannon R Holmberg
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN 55905, USA
- Biochemistry & Molecular Biology, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN, USA
| | - Yohei Sakamoto
- School of Life Science and Technology, Tokyo Institute of Technology, Midori-Ku, Yokohama, 226-8501, Japan
| | - Akira Kato
- School of Life Science and Technology, Tokyo Institute of Technology, Midori-Ku, Yokohama, 226-8501, Japan
| | - Michael F Romero
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN 55905, USA.
- Nephrology & Hypertension, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN, USA.
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14
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Newstead S. Future opportunities in solute carrier structural biology. Nat Struct Mol Biol 2024; 31:587-590. [PMID: 38637662 DOI: 10.1038/s41594-024-01271-0] [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: 03/03/2024] [Accepted: 03/07/2024] [Indexed: 04/20/2024]
Abstract
Solute carriers (SLCs) control the flow of small molecules and ions across biological membranes. Over the last 20 years, the pace of research in SLC biology has accelerated markedly, opening new opportunities to treat metabolic diseases, cancer and neurological disorders. Recently, new families of atypical SLCs, with roles in organelle biology, metabolite signaling and trafficking, have expanded their roles in the cell. This Perspective discusses work leading to current advances and the emerging opportunities to target and modulate SLCs to uncover new biology and treat human disease.
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Affiliation(s)
- Simon Newstead
- Department of Biochemistry, University of Oxford, Oxford, UK.
- The Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK.
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15
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Raza S, Sarkar D, Chan LJG, Mae J, Sutter M, Petzold CJ, Kerfeld CA, Ralston CY, Gupta S, Vermaas JV. Comparative Pore Structure and Dynamics for Bacterial Microcompartment Shell Protein Assemblies in Sheets or Shells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.12.584231. [PMID: 38559214 PMCID: PMC10980050 DOI: 10.1101/2024.03.12.584231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Bacterial microcompartments (BMCs) are protein-bound organelles found in some bacteria which encapsulate enzymes for enhanced catalytic activity. These compartments spatially sequester enzymes within semi-permeable shell proteins, analogous to many membrane-bound organelles. The shell proteins assemble into multimeric tiles; hexamers, trimers, and pentamers, and these tiles self-assemble into larger assemblies with icosahedral symmetry. While icosahedral shells are the predominant form in vivo, the tiles can also form nanoscale cylinders or sheets. The individual multimeric tiles feature central pores that are key to regulating transport across the protein shell. Our primary interest is to quantify pore shape changes in response to alternative component morphologies at the nanoscale. We use molecular modeling tools to develop atomically detailed models for both planar sheets of tiles and curved structures representative of the complete shells found in vivo. Subsequently, these models were animated using classical molecular dynamics simulations. From the resulting trajectories, we analyzed overall structural stability, water accessibility to individual residues, water residence time, and pore geometry for the hexameric and trimeric protein tiles from the Haliangium ochraceum model BMC shell. These exhaustive analyses suggest no substantial variation in pore structure or solvent accessibility between the flat and curved shell geometries. We additionally compare our analysis to hydroxyl radical footprinting data to serve as a check against our simulation results, highlighting specific residues where water molecules are bound for a long time. Although with little variation in morphology or water interaction, we propose that the planar and capsular morphology can be used interchangeably when studying permeability through BMC pores.
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Affiliation(s)
- Saad Raza
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing MI 48824
| | - Daipayan Sarkar
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing MI 48824
| | - Leanne Jade G Chan
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
- Current address: Calico Life Sciences LLC, South San Francisco, CA 94080
| | - Joshua Mae
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing MI 48824
| | - Markus Sutter
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing MI 48824
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720
| | - Christopher J Petzold
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Cheryl A Kerfeld
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing MI 48824
- Department Of Biochemistry and Molecular Biology, Michigan State University, East Lansing MI 48824
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720
| | - Corie Y Ralston
- Molecular Foundry Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720
| | - Sayan Gupta
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720
| | - Josh V Vermaas
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing MI 48824
- Department Of Biochemistry and Molecular Biology, Michigan State University, East Lansing MI 48824
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16
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Wang J, Luo Y, Ye F, Ding ZJ, Zheng SJ, Qiao S, Wang Y, Guo J, Yang W, Su N. Structures and ion transport mechanisms of plant high-affinity potassium transporters. MOLECULAR PLANT 2024; 17:409-422. [PMID: 38335958 DOI: 10.1016/j.molp.2024.01.007] [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: 12/01/2023] [Revised: 01/11/2024] [Accepted: 01/19/2024] [Indexed: 02/12/2024]
Abstract
Plant high-affinity K+ transporters (HKTs) mediate Na+ and K+ uptake, maintain Na+/K+ homeostasis, and therefore play crucial roles in plant salt tolerance. In this study, we present cryoelectron microscopy structures of HKTs from two classes, class I HKT1;1 from Arabidopsis thaliana (AtHKT1;1) and class II HKT2;1 from Triticum aestivum (TaHKT2;1), in both Na+- and K+-bound states at 2.6- to 3.0-Å resolutions. Both AtHKT1;1 and TaHKT2;1 function as homodimers. Each HKT subunit consists of four tandem domain units (D1-D4) with a repeated K+-channel-like M-P-M topology. In each subunit, D1-D4 assemble into an ion conduction pore with a pseudo-four-fold symmetry. Although both TaHKT2;1 and AtHKT1;1 have only one putative Na+ ion bound in the selectivity filter with a similar coordination pattern, the two HKTs display different K+ binding modes in the filter. TaHKT2;1 has three K+ ions bound in the selectivity filter, but AtHKT1;1 has only two K+ ions bound in the filter, which has a narrowed external entrance due to the presence of a Ser residue in the first filter motif. These structures, along with computational, mutational, and electrophysiological analyses, enable us to pinpoint key residues that are critical for the ion selectivity of HKTs. The findings provide new insights into the ion selectivity and ion transport mechanisms of plant HKTs and improve our understanding about how HKTs mediate plant salt tolerance and enhance crop growth.
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Affiliation(s)
- Jiangqin Wang
- International Institutes of Medicine, the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang 322000, China
| | - Yanping Luo
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Fan Ye
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Zhong Jie Ding
- State Key Laboratory of Plant Environmental Resilience, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Shao Jian Zheng
- State Key Laboratory of Plant Environmental Resilience, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Shuai Qiao
- International Institutes of Medicine, the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang 322000, China
| | - Yong Wang
- College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Jiangtao Guo
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; State Key Laboratory of Plant Environmental Resilience, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, 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 310058, China; Nanhu Brain-computer Interface Institute, Hangzhou, Zhejiang 311100, China.
| | - Wei Yang
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, 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 310058, China.
| | - Nannan Su
- International Institutes of Medicine, the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Yiwu, Zhejiang 322000, China.
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17
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Monterroso B, Margolin W, Boersma AJ, Rivas G, Poolman B, Zorrilla S. Macromolecular Crowding, Phase Separation, and Homeostasis in the Orchestration of Bacterial Cellular Functions. Chem Rev 2024; 124:1899-1949. [PMID: 38331392 PMCID: PMC10906006 DOI: 10.1021/acs.chemrev.3c00622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 12/01/2023] [Accepted: 01/10/2024] [Indexed: 02/10/2024]
Abstract
Macromolecular crowding affects the activity of proteins and functional macromolecular complexes in all cells, including bacteria. Crowding, together with physicochemical parameters such as pH, ionic strength, and the energy status, influences the structure of the cytoplasm and thereby indirectly macromolecular function. Notably, crowding also promotes the formation of biomolecular condensates by phase separation, initially identified in eukaryotic cells but more recently discovered to play key functions in bacteria. Bacterial cells require a variety of mechanisms to maintain physicochemical homeostasis, in particular in environments with fluctuating conditions, and the formation of biomolecular condensates is emerging as one such mechanism. In this work, we connect physicochemical homeostasis and macromolecular crowding with the formation and function of biomolecular condensates in the bacterial cell and compare the supramolecular structures found in bacteria with those of eukaryotic cells. We focus on the effects of crowding and phase separation on the control of bacterial chromosome replication, segregation, and cell division, and we discuss the contribution of biomolecular condensates to bacterial cell fitness and adaptation to environmental stress.
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Affiliation(s)
- Begoña Monterroso
- Department
of Structural and Chemical Biology, Centro de Investigaciones Biológicas
Margarita Salas, Consejo Superior de Investigaciones
Científicas (CSIC), 28040 Madrid, Spain
| | - William Margolin
- Department
of Microbiology and Molecular Genetics, McGovern Medical School, UTHealth-Houston, Houston, Texas 77030, United States
| | - Arnold J. Boersma
- Cellular
Protein Chemistry, Bijvoet Centre for Biomolecular Research, Faculty
of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Germán Rivas
- Department
of Structural and Chemical Biology, Centro de Investigaciones Biológicas
Margarita Salas, Consejo Superior de Investigaciones
Científicas (CSIC), 28040 Madrid, Spain
| | - Bert Poolman
- Department
of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Silvia Zorrilla
- Department
of Structural and Chemical Biology, Centro de Investigaciones Biológicas
Margarita Salas, Consejo Superior de Investigaciones
Científicas (CSIC), 28040 Madrid, Spain
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18
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Kim JH, Mailloux L, Bloor D, Tae H, Nguyen H, McDowell M, Padilla J, DeWaard A. Multiple roles for the cytoplasmic C-terminal domains of the yeast cell surface receptors Rgt2 and Snf3 in glucose sensing and signaling. Sci Rep 2024; 14:4055. [PMID: 38374219 PMCID: PMC10876965 DOI: 10.1038/s41598-024-54628-2] [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: 01/11/2024] [Accepted: 02/14/2024] [Indexed: 02/21/2024] Open
Abstract
The plasma membrane proteins Rgt2 and Snf3 are glucose sensing receptors (GSRs) that generate an intracellular signal for the induction of gene expression in response to high and low extracellular glucose concentrations, respectively. The GSRs consist of a 12-transmembrane glucose recognition domain and a cytoplasmic C-terminal signaling tail. The GSR tails are dissimilar in length and sequence, but their distinct roles in glucose signal transduction are poorly understood. Here, we show that swapping the tails between Rgt2 and Snf3 does not alter the signaling activity of the GSRs, so long as their tails are phosphorylated in a Yck-dependent manner. Attachment of the GSR tails to Hxt1 converts the transporter into a glucose receptor; however, the tails attached to Hxt1 are not phosphorylated by the Ycks, resulting in only partial signaling. Moreover, in response to non-fermentable carbon substrates, Rgt2 and Hxt1-RT (RT, Rgt2-tail) are efficiently endocytosed, whereas Snf3 and Hxt1-ST (ST, Snf3-tail) are endocytosis-impaired. Thus, the tails are important regulatory domains required for the endocytosis of the Rgt2 and Snf3 glucose sensing receptors triggered by different cellular stimuli. Taken together, these results suggest multiple roles for the tail domains in GSR-mediated glucose sensing and signaling.
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Affiliation(s)
- Jeong-Ho Kim
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA.
| | - Levi Mailloux
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Daniel Bloor
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Haeun Tae
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Han Nguyen
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Morgan McDowell
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Jaqueline Padilla
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
| | - Anna DeWaard
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA, 24502, USA
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19
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Chaves JCS, Dando SJ, White AR, Oikari LE. Blood-brain barrier transporters: An overview of function, dysfunction in Alzheimer's disease and strategies for treatment. Biochim Biophys Acta Mol Basis Dis 2024; 1870:166967. [PMID: 38008230 DOI: 10.1016/j.bbadis.2023.166967] [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: 07/21/2023] [Revised: 11/15/2023] [Accepted: 11/17/2023] [Indexed: 11/28/2023]
Abstract
The blood-brain-barrier (BBB) has a major function in maintaining brain homeostasis by regulating the entry of molecules from the blood to the brain. Key players in BBB function are BBB transporters which are highly expressed in brain endothelial cells (BECs) and critical in mediating the exchange of nutrients and waste products. BBB transporters can also influence drug delivery into the brain by inhibiting or facilitating the entry of brain targeting therapeutics for the treatment of brain disorders, such as Alzheimer's disease (AD). Recent studies have shown that AD is associated with a disrupted BBB and transporter dysfunction, although their roles in the development in AD are not fully understand. Modulation of BBB transporter activity may pose a novel approach to enhance the delivery of drugs to the brain for enhanced treatment of AD. In this review, we will give an overview of key functions of BBB transporters and known changes in AD. In addition, we will discuss current strategies for transporter modulation for enhanced drug delivery into the brain.
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Affiliation(s)
- Juliana C S Chaves
- Mental Health and Neuroscience Program, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia; School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, QUT, Brisbane, QLD, Australia
| | - Samantha J Dando
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, Brisbane, Australia
| | - Anthony R White
- Mental Health and Neuroscience Program, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia; School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, QUT, Brisbane, QLD, Australia
| | - Lotta E Oikari
- Mental Health and Neuroscience Program, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia; School of Biomedical Sciences, Faculty of Health, Queensland University of Technology, QUT, Brisbane, QLD, Australia.
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20
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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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21
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Ohnuki J, Jaunet-Lahary T, Yamashita A, Okazaki KI. Accelerated Molecular Dynamics and AlphaFold Uncover a Missing Conformational State of Transporter Protein OxlT. J Phys Chem Lett 2024; 15:725-732. [PMID: 38215403 DOI: 10.1021/acs.jpclett.3c03052] [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: 01/14/2024]
Abstract
Transporter proteins change their conformations to carry their substrate across the cell membrane. The conformational dynamics is vital to understanding the transport function. We have studied the oxalate transporter (OxlT), an oxalate:formate antiporter from Oxalobacter formigenes, significant in avoiding kidney stone formation. The atomic structure of OxlT has been recently solved in the outward-open and occluded states. However, the inward-open conformation is still missing, hindering a complete understanding of the transporter. Here, we performed a Gaussian accelerated molecular dynamics simulation to sample the extensive conformational space of OxlT and successfully predicted the inward-open conformation where cytoplasmic substrate formate binding was preferred over oxalate binding. We also identified critical interactions for the inward-open conformation. The results were complemented by an AlphaFold2 structure prediction. Although AlphaFold2 solely predicted OxlT in the outward-open conformation, mutation of the identified critical residues made it partly predict the inward-open conformation, identifying possible state-shifting mutations.
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Affiliation(s)
- Jun Ohnuki
- Research Center for Computational Science, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Okazaki, Aichi 444-8585, Japan
| | - Titouan Jaunet-Lahary
- Research Center for Computational Science, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan
| | - Atsuko Yamashita
- Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan
| | - Kei-Ichi Okazaki
- Research Center for Computational Science, Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki 444-8585, Japan
- Graduate Institute for Advanced Studies, SOKENDAI, Okazaki, Aichi 444-8585, Japan
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22
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Pyrris Y, Papadaki GF, Mikros E, Diallinas G. The last two transmembrane helices in the APC-type FurE transporter act as an intramolecular chaperone essential for concentrative ER-exit. MICROBIAL CELL (GRAZ, AUSTRIA) 2024; 11:1-15. [PMID: 38225947 PMCID: PMC10788122 DOI: 10.15698/mic2024.01.811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 10/31/2023] [Accepted: 11/13/2023] [Indexed: 01/17/2024]
Abstract
FurE is a H+ symporter specific for the cellular uptake of uric acid, allantoin, uracil, and toxic nucleobase analogues in the fungus Aspergillus nidulans. Being member of the NCS1 protein family, FurE is structurally related to the APC-superfamily of transporters. APC-type transporters are characterised by a 5+5 inverted repeat fold made of ten transmembrane segments (TMS1-10) and function through the rocking-bundle mechanism. Most APC-type transporters possess two extra C-terminal TMS segments (TMS11-12), the function of which remains elusive. Here we present a systematic mutational analysis of TMS11-12 of FurE and show that two specific aromatic residues in TMS12, Trp473 and Tyr484, are essential for ER-exit and trafficking to the plasma membrane (PM). Molecular modeling shows that Trp473 and Tyr484 might be essential through dynamic interactions with residues in TMS2 (Leu91), TMS3 (Phe111), TMS10 (Val404, Asp406) and other aromatic residues in TMS12. Genetic analysis confirms the essential role of Phe111, Asp406 and TMS12 aromatic residues in FurE ER-exit. We further show that co-expression of FurE-Y484F or FurE-W473A with wild-type FurE leads to a dominant negative phenotype, compatible with the concept that FurE molecules oligomerize or partition in specific microdomains to achieve concentrative ER-exit and traffic to the PM. Importantly, truncated FurE versions lacking TMS11-12 are unable to reproduce a negative effect on the trafficking of co-expressed wild-type FurE. Overall, we show that TMS11-12 acts as an intramolecular chaperone for proper FurE folding, which seems to provide a structural code for FurE partitioning in ER-exit sites.
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Affiliation(s)
- Yiannis Pyrris
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, Athens, 15784, Greece
| | - Georgia F. Papadaki
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, Athens, 15784, Greece
| | - Emmanuel Mikros
- Department of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis, Athens, 15771, Greece
| | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, Athens, 15784, Greece
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, 70013, Greece
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23
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Geertsma ER, Oliver D. SLC26 Anion Transporters. Handb Exp Pharmacol 2024; 283:319-360. [PMID: 37947907 DOI: 10.1007/164_2023_698] [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] [Indexed: 11/12/2023]
Abstract
Solute carrier family 26 (SLC26) is a family of functionally diverse anion transporters found in all kingdoms of life. Anions transported by SLC26 proteins include chloride, bicarbonate, and sulfate, but also small organic dicarboxylates such as fumarate and oxalate. The human genome encodes ten functional homologs, several of which are causally associated with severe human diseases, highlighting their physiological importance. Here, we review novel insights into the structure and function of SLC26 proteins and summarize the physiological relevance of human members.
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Affiliation(s)
- Eric R Geertsma
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, Marburg, Germany.
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Marburg, Giessen, Germany.
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24
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Clarke A, Farr CV, El-Kasaby A, Szöllősi D, Freissmuth M, Sucic S, Stockner T. Probing binding and occlusion of substrate in the human creatine transporter-1 by computation and mutagenesis. Protein Sci 2024; 33:e4842. [PMID: 38032325 PMCID: PMC10751730 DOI: 10.1002/pro.4842] [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: 07/24/2023] [Revised: 11/16/2023] [Accepted: 11/18/2023] [Indexed: 12/01/2023]
Abstract
In chordates, energy buffering is achieved in part through phosphocreatine, which requires cellular uptake of creatine by the membrane-embedded creatine transporter (CRT1/SLC6A8). Mutations in human slc6a8 lead to creatine transporter deficiency syndrome, for which there is only limited treatment. Here, we used a combined homology modeling, molecular dynamics, and experimental approach to generate a structural model of CRT1. Our observations support the following conclusions: contrary to previous proposals, C144, a key residue in the substrate binding site, is not present in a charged state. Similarly, the side chain D458 must be present in a protonated form to maintain the structural integrity of CRT1. Finally, we identified that the interaction chain Y148-creatine-Na+ is essential to the process of occlusion, which occurs via a "hold-and-pull" mechanism. The model should be useful to study the impact of disease-associated point mutations on the folding of CRT1 and identify approaches which correct folding-deficient mutants.
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Affiliation(s)
- Amy Clarke
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Clemens V Farr
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Ali El-Kasaby
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Daniel Szöllősi
- Department of Theoretical and Computational Biophysics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Thomas Stockner
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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25
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Paul A, Shukla D. Oligomerization of Monoamine Transporters. Subcell Biochem 2024; 104:119-137. [PMID: 38963486 DOI: 10.1007/978-3-031-58843-3_7] [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] [Indexed: 07/05/2024]
Abstract
Transporters of the monoamine transporter (MAT) family regulate the uptake of important neurotransmitters like dopamine, serotonin, and norepinephrine. The MAT family functions using the electrochemical gradient of ions across the membrane and comprises three transporters, dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET). MAT transporters have been observed to exist in monomeric states to higher-order oligomeric states. Structural features, allosteric modulation, and lipid environment regulate the oligomerization of MAT transporters. NET and SERT oligomerization are regulated by levels of PIP2 present in the membrane. The kink present in TM12 in the MAT family is crucial for dimer interface formation. Allosteric modulation in the dimer interface hinders dimer formation. Oligomerization also influences the transporters' function, trafficking, and regulation. This chapter will focus on recent studies on monoamine transporters and discuss the factors affecting their oligomerization and its impact on their function.
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Affiliation(s)
- Arnav Paul
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Diwakar Shukla
- Department of Chemical and Biomolecular Engineering, Department of Bioengineering, Center for Biophysics and Quantitative Biology, Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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26
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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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27
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Kukułowicz J, Pietrzak-Lichwa K, Klimończyk K, Idlin N, Bajda M. The SLC6A15-SLC6A20 Neutral Amino Acid Transporter Subfamily: Functions, Diseases, and Their Therapeutic Relevance. Pharmacol Rev 2023; 76:142-193. [PMID: 37940347 DOI: 10.1124/pharmrev.123.000886] [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: 03/23/2023] [Revised: 09/07/2023] [Accepted: 11/02/2023] [Indexed: 11/10/2023] Open
Abstract
The neutral amino acid transporter subfamily that consists of six members, consecutively SLC6A15-SLC620, also called orphan transporters, represents membrane, sodium-dependent symporter proteins that belong to the family of solute carrier 6 (SLC6). Primarily, they mediate the transport of neutral amino acids from the extracellular milieu toward cell or storage vesicles utilizing an electric membrane potential as the driving force. Orphan transporters are widely distributed throughout the body, covering many systems; for instance, the central nervous, renal, or intestinal system, supplying cells into molecules used in biochemical, signaling, and building pathways afterward. They are responsible for intestinal absorption and renal reabsorption of amino acids. In the central nervous system, orphan transporters constitute a significant medium for the provision of neurotransmitter precursors. Diseases related with aforementioned transporters highlight their significance; SLC6A19 mutations are associated with metabolic Hartnup disorder, whereas altered expression of SLC6A15 has been associated with a depression/stress-related disorders. Mutations of SLC6A18-SLCA20 cause iminoglycinuria and/or hyperglycinuria. SLC6A18-SLC6A20 to reach the cellular membrane require an ancillary unit ACE2 that is a molecular target for the spike protein of the SARS-CoV-2 virus. SLC6A19 has been proposed as a molecular target for the treatment of metabolic disorders resembling gastric surgery bypass. Inhibition of SLC6A15 appears to have a promising outcome in the treatment of psychiatric disorders. SLC6A19 and SLC6A20 have been suggested as potential targets in the treatment of COVID-19. In this review, we gathered recent advances on orphan transporters, their structure, functions, related disorders, and diseases, and in particular their relevance as therapeutic targets. SIGNIFICANCE STATEMENT: The following review systematizes current knowledge about the SLC6A15-SLCA20 neutral amino acid transporter subfamily and their therapeutic relevance in the treatment of different diseases.
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Affiliation(s)
- Jędrzej Kukułowicz
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Krzysztof Pietrzak-Lichwa
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Klaudia Klimończyk
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Nathalie Idlin
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Marek Bajda
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
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28
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Kim JH, Mailloux L, Bloor D, Maddox B, Humble J. The role of salt bridge networks in the stability of the yeast hexose transporter 1. Biochim Biophys Acta Gen Subj 2023; 1867:130490. [PMID: 37844739 DOI: 10.1016/j.bbagen.2023.130490] [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: 08/31/2023] [Revised: 10/06/2023] [Accepted: 10/12/2023] [Indexed: 10/18/2023]
Abstract
BACKGROUND The yeast S. cerevisiae preferably metabolizes glucose through aerobic glycolysis. Glucose transport is facilitated by multiple hexose transporters (Hxts), and their expression and activity are tightly regulated by multiple mechanisms. However, detailed structural and functional analyses of Hxts remain limited, largely due to the lack of crystal structure. METHODS Homology modeling was used to build a 3D structural model for the yeast glucose transporter Hxt1 and investigate the effects of site directed mutations on Hxt1 stability and glucose transport activity. RESULTS The conserved salt bridge-forming residues observed in the human Glut4 and the yeast glucose receptor Rgt2 were identified within and between the two 6-transmembrane spanning segments of Hxt1. Most of the RGT2 mutations that disrupt the salt bridge networks were known to cause constitutive signal generation, whereas the corresponding substitutions in HXT1 were shown to decrease Hxt1 stability. While substitutions of the two residues in the salt bridge 2 in Glut4-E329Q and E393D-were reported to abolish glucose transport, the equivalent substitutions in Hxt1 (D382Q and E454D) did not affect Hxt1 glucose transport activity. CONCLUSIONS Substitutions of equivalent salt bridge-forming residues in Hxt1, Rgt2, and Glut4 are predicted to lock them in an inward-facing conformation but lead to different functional consequences. GENERAL SIGNIFICANCE The salt bridge networks in yeast and human glucose transporters and yeast glucose receptors may play different roles in maintaining their structural and functional integrity.
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Affiliation(s)
- Jeong-Ho Kim
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA 24502, USA.
| | - Levi Mailloux
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA 24502, USA
| | - Daniel Bloor
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA 24502, USA
| | - Bradley Maddox
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA 24502, USA
| | - Julia Humble
- Department of Biology and Chemistry, Liberty University, 1971 University Blvd, Lynchburg, VA 24502, USA
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29
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Becker P, Naughton F, Brotherton D, Pacheco-Gomez R, Beckstein O, Cameron AD. Mechanism of substrate binding and transport in BASS transporters. eLife 2023; 12:RP89167. [PMID: 37963091 PMCID: PMC10645422 DOI: 10.7554/elife.89167] [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] [Indexed: 11/16/2023] Open
Abstract
The bile acid sodium symporter (BASS) family transports a wide array of molecules across membranes, including bile acids in humans, and small metabolites in plants. These transporters, many of which are sodium-coupled, have been shown to use an elevator mechanism of transport, but exactly how substrate binding is coupled to sodium ion binding and transport is not clear. Here, we solve the crystal structure at 2.3 Å of a transporter from Neisseria meningitidis (ASBTNM) in complex with pantoate, a potential substrate of ASBTNM. The BASS family is characterised by two helices that cross-over in the centre of the protein in an arrangement that is intricately held together by two sodium ions. We observe that the pantoate binds, specifically, between the N-termini of two of the opposing helices in this cross-over region. During molecular dynamics simulations the pantoate remains in this position when sodium ions are present but is more mobile in their absence. Comparison of structures in the presence and absence of pantoate demonstrates that pantoate elicits a conformational change in one of the cross-over helices. This modifies the interface between the two domains that move relative to one another to elicit the elevator mechanism. These results have implications, not only for ASBTNM but for the BASS family as a whole and indeed other transporters that work through the elevator mechanism.
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Affiliation(s)
- Patrick Becker
- School of Life Sciences, University of WarwickCoventryUnited Kingdom
| | - Fiona Naughton
- Department of Physics, Arizona State UniversityTempeUnited States
| | | | | | - Oliver Beckstein
- Department of Physics, Arizona State UniversityTempeUnited States
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30
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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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31
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Parker JL, Kato T, Kuteyi G, Sitsel O, Newstead S. Molecular basis for selective uptake and elimination of organic anions in the kidney by OAT1. Nat Struct Mol Biol 2023; 30:1786-1793. [PMID: 37482561 PMCID: PMC10643130 DOI: 10.1038/s41594-023-01039-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 06/20/2023] [Indexed: 07/25/2023]
Abstract
In mammals, the kidney plays an essential role in maintaining blood homeostasis through the selective uptake, retention or elimination of toxins, drugs and metabolites. Organic anion transporters (OATs) are responsible for the recognition of metabolites and toxins in the nephron and their eventual urinary excretion. Inhibition of OATs is used therapeutically to improve drug efficacy and reduce nephrotoxicity. The founding member of the renal organic anion transporter family, OAT1 (also known as SLC22A6), uses the export of α-ketoglutarate (α-KG), a key intermediate in the Krebs cycle, to drive selective transport and is allosterically regulated by intracellular chloride. However, the mechanisms linking metabolite cycling, drug transport and intracellular chloride remain obscure. Here, we present cryogenic-electron microscopy structures of OAT1 bound to α-KG, the antiviral tenofovir and clinical inhibitor probenecid, used in the treatment of Gout. Complementary in vivo cellular assays explain the molecular basis for α-KG driven drug elimination and the allosteric regulation of organic anion transport in the kidney by chloride.
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Affiliation(s)
- Joanne L Parker
- Department of Biochemistry, University of Oxford, Oxford, UK.
- The Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK.
| | - Takafumi Kato
- Department of Biochemistry, University of Oxford, Oxford, UK.
- The Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK.
| | - Gabriel Kuteyi
- Department of Biochemistry, University of Oxford, Oxford, UK
- The Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Oleg Sitsel
- Department of Biochemistry, University of Oxford, Oxford, UK
- Max Planck Institute of Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Simon Newstead
- Department of Biochemistry, University of Oxford, Oxford, UK.
- The Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK.
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32
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Stewart GW, Gibson JS, Rees DC. The cation-leaky hereditary stomatocytosis syndromes: A tale of six proteins. Br J Haematol 2023; 203:509-522. [PMID: 37679660 DOI: 10.1111/bjh.19093] [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] [Received: 06/07/2023] [Revised: 08/13/2023] [Accepted: 08/22/2023] [Indexed: 09/09/2023]
Abstract
This review concerns a series of dominantly inherited haemolytic anaemias in which the membrane of the erythrocyte 'leaks' the univalent cations, compromising the osmotic stability of the cell. The majority of the conditions are explained by mutations in one of six genes, coding for multispanning membrane proteins of different structure and function. These are: RhAG, coding for an ammonium carrier; SLC4A1, coding for the band 3 anion exchanger; PIEZO1, coding for a mechanosensitive cation channel; GLUT1, coding for a glucose transporter; KCNN4, coding for an internal-calcium-activated potassium channel; and ABCB6, coding for a porphyrin transporter. This review describes the five clinical syndromes associated with genetic defects in these genes and their variable genotype/phenotype relationships.
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Affiliation(s)
- Gordon W Stewart
- Division of Medicine, Faculty of Medical Sciences, University College London, London, UK
| | - John S Gibson
- Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - David C Rees
- Haematological Medicine, Kings College London, London, UK
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33
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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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Pidathala S, Liao S, Dai Y, Li X, Long C, Chang CL, Zhang Z, Lee CH. Mechanisms of neurotransmitter transport and drug inhibition in human VMAT2. Nature 2023; 623:1086-1092. [PMID: 37914936 DOI: 10.1038/s41586-023-06727-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 10/09/2023] [Indexed: 11/03/2023]
Abstract
Monoamine neurotransmitters such as dopamine and serotonin control important brain pathways, including movement, sleep, reward and mood1. Dysfunction of monoaminergic circuits has been implicated in various neurodegenerative and neuropsychiatric disorders2. Vesicular monoamine transporters (VMATs) pack monoamines into vesicles for synaptic release and are essential to neurotransmission3-5. VMATs are also therapeutic drug targets for a number of different conditions6-9. Despite the importance of these transporters, the mechanisms of substrate transport and drug inhibition of VMATs have remained elusive. Here we report cryo-electron microscopy structures of the human vesicular monoamine transporter VMAT2 in complex with the antichorea drug tetrabenazine, the antihypertensive drug reserpine or the substrate serotonin. Remarkably, the two drugs use completely distinct inhibition mechanisms. Tetrabenazine binds VMAT2 in a lumen-facing conformation, locking the luminal gating lid in an occluded state to arrest the transport cycle. By contrast, reserpine binds in a cytoplasm-facing conformation, expanding the vestibule and blocking substrate access. Structural analyses of VMAT2 also reveal the conformational changes following transporter isomerization that drive substrate transport into the vesicle. These findings provide a structural framework for understanding the physiology and pharmacology of neurotransmitter packaging by synaptic vesicular transporters.
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Affiliation(s)
- Shabareesh Pidathala
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Shuyun Liao
- State Key Laboratory of Membrane Biology, Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, China
| | - Yaxin Dai
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Xiao Li
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Changkun Long
- State Key Laboratory of Membrane Biology, Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, China
| | - Chi-Lun Chang
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Zhe Zhang
- State Key Laboratory of Membrane Biology, Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, School of Life Sciences, Peking University, Beijing, China.
| | - Chia-Hsueh Lee
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA.
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35
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Alam S, Doherty E, Ortega-Prieto P, Arizanova J, Fets L. Membrane transporters in cell physiology, cancer metabolism and drug response. Dis Model Mech 2023; 16:dmm050404. [PMID: 38037877 PMCID: PMC10695176 DOI: 10.1242/dmm.050404] [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] [Indexed: 12/02/2023] Open
Abstract
By controlling the passage of small molecules across lipid bilayers, membrane transporters influence not only the uptake and efflux of nutrients, but also the metabolic state of the cell. With more than 450 members, the Solute Carriers (SLCs) are the largest transporter super-family, clustering into families with different substrate specificities and regulatory properties. Cells of different types are, therefore, able to tailor their transporter expression signatures depending on their metabolic requirements, and the physiological importance of these proteins is illustrated by their mis-regulation in a number of disease states. In cancer, transporter expression is heterogeneous, and the SLC family has been shown to facilitate the accumulation of biomass, influence redox homeostasis, and also mediate metabolic crosstalk with other cell types within the tumour microenvironment. This Review explores the roles of membrane transporters in physiological and malignant settings, and how these roles can affect drug response, through either indirect modulation of sensitivity or the direct transport of small-molecule therapeutic compounds into cells.
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Affiliation(s)
- Sara Alam
- Drug Transport and Tumour Metabolism Lab, MRC Laboratory of Medical Sciences, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Emily Doherty
- Drug Transport and Tumour Metabolism Lab, MRC Laboratory of Medical Sciences, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Paula Ortega-Prieto
- Drug Transport and Tumour Metabolism Lab, MRC Laboratory of Medical Sciences, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Julia Arizanova
- Drug Transport and Tumour Metabolism Lab, MRC Laboratory of Medical Sciences, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
| | - Louise Fets
- Drug Transport and Tumour Metabolism Lab, MRC Laboratory of Medical Sciences, Hammersmith Hospital Campus, Du Cane Road, London, W12 0NN, UK
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36
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Lu Y, Zuo P, Chen H, Shan H, Wang W, Dai Z, Xu H, Chen Y, Liang L, Ding D, Jin Y, Yin Y. Structural insights into the conformational changes of BTR1/SLC4A11 in complex with PIP 2. Nat Commun 2023; 14:6157. [PMID: 37788993 PMCID: PMC10547724 DOI: 10.1038/s41467-023-41924-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 09/25/2023] [Indexed: 10/05/2023] Open
Abstract
BTR1 (SLC4A11) is a NH3 stimulated H+ (OH-) transporter belonging to the SLC4 family. Dysfunction of BTR1 leads to diseases such as congenital hereditary endothelial dystrophy (CHED) and Fuchs endothelial corneal dystrophy (FECD). However, the mechanistic basis of BTR1 activation by alkaline pH, transport activity regulation and pathogenic mutations remains elusive. Here, we present cryo-EM structures of human BTR1 in the outward-facing state in complex with its activating ligands PIP2 and the inward-facing state with the pathogenic R125H mutation. We reveal that PIP2 binds at the interface between the transmembrane domain and the N-terminal cytosolic domain of BTR1. Disruption of either the PIP2 binding site or protonation of PIP2 phosphate groups by acidic pH can transform BTR1 into an inward-facing conformation. Our results provide insights into the mechanisms of how the transport activity and conformation changes of BTR1 are regulated by PIP2 binding and interaction of TMD and NTD.
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Affiliation(s)
- Yishuo Lu
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
| | - Peng Zuo
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Hongyi Chen
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
| | - Hui Shan
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China
| | - Weize Wang
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Zonglin Dai
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | | | | | - Ling Liang
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
- Department of Biochemistry and Biophysics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Dian Ding
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Yan Jin
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Yuxin Yin
- Institute of Precision Medicine, Peking University Shenzhen Hospital, Shenzhen, 518036, China.
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China.
- Institute of Systems Biomedicine, Department of Pathology, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China.
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37
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Zantza I, Pyrris Y, Raniolo S, Papadaki GF, Lambrinidis G, Limongelli V, Diallinas G, Mikros E. Uracil/H + Symport by FurE Refines Aspects of the Rocking-bundle Mechanism of APC-type Transporters. J Mol Biol 2023; 435:168226. [PMID: 37544358 DOI: 10.1016/j.jmb.2023.168226] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 07/22/2023] [Accepted: 07/31/2023] [Indexed: 08/08/2023]
Abstract
Transporters mediate the uptake of solutes, metabolites and drugs across the cell membrane. The eukaryotic FurE nucleobase/H+ symporter of Aspergillus nidulans has been used as a model protein to address structure-function relationships in the APC transporter superfamily, members of which are characterized by the LeuT-fold and seem to operate by the so-called 'rocking-bundle' mechanism. In this study, we reveal the binding mode, translocation and release pathway of uracil/H+ by FurE using path collective variable, funnel metadynamics and rational mutational analysis. Our study reveals a stepwise, induced-fit, mechanism of ordered sequential transport of proton and uracil, which in turn suggests that FurE, functions as a multi-step gated pore, rather than employing 'rocking' of compact domains, as often proposed for APC transporters. Finally, our work supports that specific residues of the cytoplasmic N-tail are involved in substrate translocation, in line with their essentiality for FurE function.
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Affiliation(s)
- Iliana Zantza
- Department of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis, Athens 15771, Greece.
| | - Yiannis Pyrris
- Department of Biology, National and Kapodistrian University of Athens, Panepistimiopolis, Athens 15781, Greece.
| | - Stefano Raniolo
- Faculty of Biomedical Sciences, Euler Institute, Università della Svizzera italiana (USI), Lugano 6900, Switzerland.
| | - Georgia F Papadaki
- Department of Biology, National and Kapodistrian University of Athens, Panepistimiopolis, Athens 15781, Greece
| | - George Lambrinidis
- Department of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis, Athens 15771, Greece.
| | - Vittorio Limongelli
- Faculty of Biomedical Sciences, Euler Institute, Università della Svizzera italiana (USI), Lugano 6900, Switzerland; Department of Pharmacy, University of Naples "Federico II", Naples 80131, Italy.
| | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimiopolis, Athens 15781, Greece; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion 70013, Greece.
| | - Emmanuel Mikros
- Department of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis, Athens 15771, Greece; Athena Research and Innovation Center in Information Communication & Knowledge Technologies, Marousi 15125, Greece.
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38
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Schlessinger A, Zatorski N, Hutchinson K, Colas C. Targeting SLC transporters: small molecules as modulators and therapeutic opportunities. Trends Biochem Sci 2023; 48:801-814. [PMID: 37355450 PMCID: PMC10525040 DOI: 10.1016/j.tibs.2023.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/24/2023] [Accepted: 05/25/2023] [Indexed: 06/26/2023]
Abstract
Solute carrier (SLCs) transporters mediate the transport of a broad range of solutes across biological membranes. Dysregulation of SLCs has been associated with various pathologies, including metabolic and neurological disorders, as well as cancer and rare diseases. SLCs are therefore emerging as key targets for therapeutic intervention with several recently approved drugs targeting these proteins. Unlocking this large and complex group of proteins is essential to identifying unknown SLC targets and developing next-generation SLC therapeutics. Recent progress in experimental and computational techniques has significantly advanced SLC research, including drug discovery. Here, we review emerging topics in therapeutic discovery of SLCs, focusing on state-of-the-art approaches in structural, chemical, and computational biology, and discuss current challenges in transporter drug discovery.
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Affiliation(s)
- Avner Schlessinger
- Department of Pharmacological Sciences Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
| | - Nicole Zatorski
- Department of Pharmacological Sciences Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Keino Hutchinson
- Department of Pharmacological Sciences Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Claire Colas
- University of Vienna, Department of Pharmaceutical Chemistry, Vienna, Austria.
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39
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Singh M, Ito S, Hososhima S, Abe-Yoshizumi R, Tsunoda SP, Inoue K, Kandori H. Light-Driven Chloride and Sulfate Pump with Two Different Transport Modes. J Phys Chem B 2023; 127:7123-7134. [PMID: 37552856 DOI: 10.1021/acs.jpcb.3c02116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Ion pumps are membrane proteins that actively translocate ions by using energy. All known pumps bind ions in the resting state, and external energy allows ion transport through protein structural changes. The light-driven sodium-ion pump Krokinobacter eikastus rhodopsin 2 (KR2) is an exceptional case in which ion binding follows the energy input. In this study, we report another case of this unusual transport mode. The NTQ rhodopsin from Alteribacter aurantiacus (AaClR) is a natural light-driven chloride pump, in which the chloride ion binds to the resting state. AaClR is also able to pump sulfate ions, though the pump efficiency is much lower for sulfate ions than for chloride ions. Detailed spectroscopic analysis revealed no binding of the sulfate ion to the resting state of AaClR, indicating that binding of the substrate (sulfate ion) to the resting state is not necessary for active transport. This property of the AaClR sulfate pump is similar to that of the KR2 sodium pump. Photocycle dynamics of the AaClR sulfate pump resemble a non-functional cycle in the absence of anions. Despite this, flash photolysis and difference Fourier transform infrared spectroscopy suggest transient binding of the sulfate ion to AaClR. The molecular mechanism of this unusual active transport by AaClR is discussed.
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Affiliation(s)
- Manish Singh
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Shota Ito
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Shoko Hososhima
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Rei Abe-Yoshizumi
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
| | - Satoshi P Tsunoda
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-855, Japan
| | - Keiichi Inoue
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-855, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan
- OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Nagoya 466-855, Japan
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40
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Becker P, Naughton FB, Brotherton DH, Pacheco-Gomez R, Beckstein O, Cameron AD. Mechanism of substrate binding and transport in BASS transporters. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.02.543391. [PMID: 37645971 PMCID: PMC10461908 DOI: 10.1101/2023.06.02.543391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
The Bile Acid Sodium Symporter (BASS) family transports a wide array of molecules across membranes, including bile acids in humans, and small metabolites in plants. These transporters, many of which are sodium-coupled, have been shown to use an elevator mechanism of transport, but exactly how substrate binding is coupled to sodium ion binding and transport is not clear. Here we solve the crystal structure at 2.3 Å of a transporter from Neisseria Meningitidis (ASBTNM) in complex with pantoate, a potential substrate of ASBTNM. The BASS family is characterised by two helices that cross-over in the centre of the protein in an arrangement that is intricately held together by two sodium ions. We observe that the pantoate binds, specifically, between the N-termini of two of the opposing helices in this cross-over region. During molecular dynamics simulations the pantoate remains in this position when sodium ions are present but is more mobile in their absence. Comparison of structures in the presence and absence of pantoate demonstrates that pantoate elicits a conformational change in one of the cross-over helices. This modifies the interface between the two domains that move relative to one another to elicit the elevator mechanism. These results have implications, not only for ASBTNM but for the BASS family as a whole and indeed other transporters that work through the elevator mechanism.
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Affiliation(s)
- Patrick Becker
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, U.K
| | | | - Deborah H. Brotherton
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, U.K
| | | | - Oliver Beckstein
- Department of Physics, Arizona State University, Tempe, AZ 85287
| | - Alexander D. Cameron
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, U.K
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41
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Sever M, Merzel F. Influence of SGLT1 Sugar Uptake Inhibitors on Water Transport. Molecules 2023; 28:5295. [PMID: 37513169 PMCID: PMC10385929 DOI: 10.3390/molecules28145295] [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: 05/15/2023] [Revised: 07/05/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023] Open
Abstract
Sodium glucose cotransporters (SGLTs) are cotransporters located in the cell membrane of various epithelia that uptake glucose or galactose and sodium into the cell. Its founding member, SGLT1, represents a major pharmaceutically relevant target protein for development of new antidiabetic drugs, in addition to being the target protein of the oral rehydration therapy. Previous studies focused primarily on the transport of substrates and ions, while our study focuses on the effect of water transport. SGLT1 is implicated in the absorption of water, yet the exact mechanism of how the water absorption occurs or how inhibitors of SGLT1, such as phlorizin, are able to inhibit it is still unclear. Here we present a comprehensive study based on molecular dynamics simulations with the aim of determining the influence of the energetic and dynamic properties of SGLT1, which are influenced by selected sugar uptake inhibitors on water permeation.
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Affiliation(s)
- Marko Sever
- Theory Department, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
- Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Franci Merzel
- Theory Department, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
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42
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Dvorak V, Superti-Furga G. Structural and functional annotation of solute carrier transporters: implication for drug discovery. Expert Opin Drug Discov 2023; 18:1099-1115. [PMID: 37563933 DOI: 10.1080/17460441.2023.2244760] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 08/01/2023] [Indexed: 08/12/2023]
Abstract
INTRODUCTION Solute carriers (SLCs) represent the largest group of membrane transporters in the human genome. They play a central role in controlling the compartmentalization of metabolism and most of this superfamily is linked to human disease. Despite being in general considered druggable and attractive therapeutic targets, many SLCs remain poorly annotated, both functionally and structurally. AREAS COVERED The aim of this review is to provide an overview of functional and structural parameters of SLCs that play important roles in their druggability. To do this, the authors provide an overview of experimentally solved structures of human SLCs, with emphasis on structures solved in complex with chemical modulators. From the functional annotations, the authors focus on SLC localization and SLC substrate annotations. EXPERT OPINION Recent progress in the structural and functional annotations allows to refine the SLC druggability index. Particularly the increasing number of experimentally solved structures of SLCs provides insights into mode-of-action of a significant number of chemical modulators of SLCs.
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Affiliation(s)
- Vojtech Dvorak
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Giulio Superti-Furga
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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43
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Sever M, Merzel F. Collective Domain Motion Facilitates Water Transport in SGLT1. Int J Mol Sci 2023; 24:10528. [PMID: 37445706 DOI: 10.3390/ijms241310528] [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: 05/05/2023] [Revised: 06/17/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
The human sodium-glucose cotransporter protein (SGLT1) is an important representative of the sodium solute symporters belonging to the secondary active transporters that are critical to the homeostasis of sugar, sodium, and water in the cell. The underlying transport mechanism of SGLT1 is based on switching between inward- and outward-facing conformations, known as the alternating access model, which is crucial for substrate transport, and has also been postulated for water permeation. However, the nature of water transport remains unclear and is disputed along the passive and active transport, with the latter postulating the presence of the pumping effect. To better examine the water transport in SGLT1, we performed a series of equilibrium all-atom molecular dynamics simulations, totaling over 6 μs of sample representative conformational states of SGLT1 and its complexes, with the natural substrates, ions, and inhibitors. In addition to elucidating the basic physical factors influencing water permeation, such as channel openings and energetics, we focus on dynamic flexibility and its relationship with domain motion. Our results clearly demonstrate a dependence of instantaneous water flux on the channel opening and local water diffusion in the channel, strongly supporting the existence of a passive water transport in SGLT1. In addition, a strong correlation found between the local water diffusion and protein domain motion, resembling the "rocking-bundle" motion, reveals its facilitating role in the water transport.
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Affiliation(s)
- Marko Sever
- Theory Departnemt, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
- Faculty of Pharmacy, University of Ljubljana, Aškerčeva 7, 1000 Ljubljana, Slovenia
| | - Franci Merzel
- Theory Departnemt, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
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44
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Legrand D, Herbaut M, Durin Z, Brysbaert G, Bardor M, Lensink MF, Foulquier F. New insights into the pathogenicity of TMEM165 variants using structural modeling based on AlphaFold 2 predictions. Comput Struct Biotechnol J 2023; 21:3424-3436. [PMID: 37416081 PMCID: PMC10319644 DOI: 10.1016/j.csbj.2023.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/15/2023] [Accepted: 06/15/2023] [Indexed: 07/08/2023] Open
Abstract
TMEM165 is a Golgi protein playing a crucial role in Mn2+ transport, and whose mutations in patients are known to cause Congenital Disorders of Glycosylation. Some of those mutations affect the highly-conserved consensus motifs E-φ-G-D-[KR]-[TS] characterizing the CaCA2/UPF0016 family, presumably important for the transport of Mn2+ which is essential for the function of many Golgi glycosylation enzymes. Others, like the G>R304 mutation, are far away from these motifs in the sequence. Until recently, the classical membrane protein topology prediction methods were unable to provide a clear picture of the organization of TMEM165 inside the cell membrane, or to explain in a convincing manner the impact of patient and experimentally-generated mutations on the transporter function of TMEM165. In this study, AlphaFold 2 was used to build a TMEM165 model that was then refined by molecular dynamics simulation with membrane lipids and water. This model provides a realistic picture of the 3D protein scaffold formed from a two-fold repeat of three transmembrane helices/domains where the consensus motifs face each other to form a putative acidic cation-binding site at the cytosolic side of the protein. It sheds new light on the impact of mutations on the transporter function of TMEM165, found in patients and studied experimentally in vitro, formerly and within this study. More particularly and very interestingly, this model explains the impact of the G>R304 mutation on TMEM165's function. These findings provide great confidence in the predicted TMEM165 model whose structural features are discussed in the study and compared to other structural and functional TMEM165 homologs from the CaCA2/UPF0016 family and the LysE superfamily.
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Affiliation(s)
- Dominique Legrand
- Univ. Lille, CNRS, UMR 8576 – UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
| | - Mélissandre Herbaut
- Univ. Lille, CNRS, UMR 8576 – UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
| | - Zoé Durin
- Univ. Lille, CNRS, UMR 8576 – UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
| | - Guillaume Brysbaert
- Univ. Lille, CNRS, UMR 8576 – UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
| | - Muriel Bardor
- Univ. Lille, CNRS, UMR 8576 – UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
- Université de Rouen Normandie, Laboratoire GlycoMEV UR 4358, SFR Normandie Végétal FED 4277, Innovation Chimie Carnot, F-76000 Rouen, France
| | - Marc F. Lensink
- Univ. Lille, CNRS, UMR 8576 – UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
| | - François Foulquier
- Univ. Lille, CNRS, UMR 8576 – UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
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45
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Trebesch N, Tajkhorshid E. Structure Reveals Homology in Elevator Transporters. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.14.544989. [PMID: 37398459 PMCID: PMC10312693 DOI: 10.1101/2023.06.14.544989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The elevator transport mechanism is one of the handful of canonical mechanisms by which transporters shuttle their substrates across the semi-permeable membranes that surround cells and organelles. Studies of molecular function are naturally guided by evolutionary context, but until now this context has been limited for elevator transporters because established evolutionary classification methods have organized them into several apparently unrelated families. Through comprehensive examination of the pertinent structures available in the Protein Data Bank, we show that 62 elevator transporters from 18 families share a conserved architecture in their transport domains consisting of 10 helices connected in 8 topologies. Through quantitative analysis of the structural similarity, structural complexity, and topologically-corrected sequence similarity among the transport domains, we provide compelling evidence that these elevator transporters are all homologous. Using our analysis, we have constructed a phylogenetic tree to enable quantification and visualization of the evolutionary relationships among elevator transporters and their families. We also report several examples of functional features that are shared by elevator transporters from different families. Our findings shed new light on the elevator transport mechanism and allow us to understand it in a far deeper and more nuanced manner.
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Affiliation(s)
- Noah Trebesch
- Theoretical and Computational Biophysics Group, NIH Resource for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Resource for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign
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Garrudo FFF, Linhardt RJ, Ferreira FC, Morgado J. Designing Electrical Stimulation Platforms for Neural Cell Cultivation Using Poly(aniline): Camphorsulfonic Acid. Polymers (Basel) 2023; 15:2674. [PMID: 37376320 DOI: 10.3390/polym15122674] [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: 04/19/2023] [Revised: 06/01/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Electrical stimulation is a powerful strategy to improve the differentiation of neural stem cells into neurons. Such an approach can be implemented, in association with biomaterials and nanotechnology, for the development of new therapies for neurological diseases, including direct cell transplantation and the development of platforms for drug screening and disease progression evaluation. Poly(aniline):camphorsulfonic acid (PANI:CSA) is one of the most well-studied electroconductive polymers, capable of directing an externally applied electrical field to neural cells in culture. There are several examples in the literature on the development of PANI:CSA-based scaffolds and platforms for electrical stimulation, but no review has examined the fundamentals and physico-chemical determinants of PANI:CSA for the design of platforms for electrical stimulation. This review evaluates the current literature regarding the application of electrical stimulation to neural cells, specifically reviewing: (1) the fundamentals of bioelectricity and electrical stimulation; (2) the use of PANI:CSA-based systems for electrical stimulation of cell cultures; and (3) the development of scaffolds and setups to support the electrical stimulation of cells. Throughout this work, we critically evaluate the revised literature and provide a steppingstone for the clinical application of the electrical stimulation of cells using electroconductive PANI:CSA platforms/scaffolds.
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Affiliation(s)
- Fábio F F Garrudo
- Instituto de Telecomunicações, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal
- iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Robert J Linhardt
- Department of Chemical and Biological Engineering, Biology and Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180, USA
| | - Frederico Castelo Ferreira
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal
- iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal
| | - Jorge Morgado
- Instituto de Telecomunicações, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal
- Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal
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Lichtinger SM, Biggin PC. Tackling Hysteresis in Conformational Sampling: How to Be Forgetful with MEMENTO. J Chem Theory Comput 2023. [PMID: 37285481 DOI: 10.1021/acs.jctc.3c00140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The structure of proteins has long been recognized to hold the key to understanding and engineering their function, and rapid advances in structural biology and protein structure prediction are now supplying researchers with an ever-increasing wealth of structural information. Most of the time, however, structures can only be determined in free energy minima, one at a time. While conformational flexibility may thus be inferred from static end-state structures, their interconversion mechanisms─a central ambition of structural biology─are often beyond the scope of direct experimentation. Given the dynamical nature of the processes in question, many studies have attempted to explore conformational transitions using molecular dynamics (MD). However, ensuring proper convergence and reversibility in the predicted transitions is extremely challenging. In particular, a commonly used technique to map out a path from a starting to a target conformation called steered MD (SMD) can suffer from starting-state dependence (hysteresis) when combined with techniques such as umbrella sampling (US) to compute the free energy profile of a transition. Here, we study this problem in detail on conformational changes of increasing complexity. We also present a new, history-independent approach that we term "MEMENTO" (Morphing End states by Modelling Ensembles with iNdependent TOpologies) to generate paths that alleviate hysteresis in the construction of conformational free energy profiles. MEMENTO utilizes template-based structure modelling to restore physically reasonable protein conformations based on coordinate interpolation (morphing) as an ensemble of plausible intermediates, from which a smooth path is picked. We compare SMD and MEMENTO on well-characterized test cases (the toy peptide deca-alanine and the enzyme adenylate kinase) before discussing its use in more complicated systems (the kinase P38α and the bacterial leucine transporter LeuT). Our work shows that for all but the simplest systems SMD paths should not in general be used to seed umbrella sampling or related techniques, unless the paths are validated by consistent results from biased runs in opposite directions. MEMENTO, on the other hand, performs well as a flexible tool to generate intermediate structures for umbrella sampling. We also demonstrate that extended end-state sampling combined with MEMENTO can aid the discovery of collective variables on a case-by-case basis.
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Affiliation(s)
| | - Philip C Biggin
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
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Muhammednazaar S, Yao J, Guo R, Rhee MS, Kim KH, Kang SG, Hong H. Lipid Bilayer Strengthens the Cooperative Network of a Membrane-Integral Enzyme. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.30.542905. [PMID: 37398072 PMCID: PMC10312574 DOI: 10.1101/2023.05.30.542905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Lipid bilayer provides a two-dimensional hydrophobic solvent milieu for membrane proteins in cells. Although the native bilayer is widely recognized as an optimal environment for folding and function of membrane proteins, the underlying physical basis remains elusive. Here, employing the intramembrane protease GlpG of Escherichia coli as a model, we elucidate how the bilayer stabilizes a membrane protein and engages the protein's residue interaction network compared to the nonnative hydrophobic medium, micelles. We find that the bilayer enhances GlpG stability by promoting residue burial in the protein interior compared to micelles. Strikingly, while the cooperative residue interactions cluster into multiple distinct regions in micelles, the whole packed regions of the protein act as a single cooperative unit in the bilayer. Molecular dynamics (MD) simulation indicates that lipids less efficiently solvate GlpG than detergents. Thus, the bilayerinduced enhancement of stability and cooperativity likely stems from the dominant intraprotein interactions outcompeting the weak lipid solvation. Our findings reveal a foundational mechanism in the folding, function, and quality control of membrane proteins. The enhanced cooperativity benefits function facilitating propagation of local structural perturbation across the membrane. However, the same phenomenon can render the proteins' conformational integrity vulnerable to missense mutations causing conformational diseases1,2.
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Affiliation(s)
| | - Jiaqi Yao
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Ruiqiong Guo
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - May S Rhee
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Kelly H Kim
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Seung-Gu Kang
- Computational Biology Center, IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598, USA
| | - Heedeok Hong
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
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Badiee SA, Isu UH, Khodadadi E, Moradi M. The Alternating Access Mechanism in Mammalian Multidrug Resistance Transporters and Their Bacterial Homologs. MEMBRANES 2023; 13:568. [PMID: 37367772 DOI: 10.3390/membranes13060568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 05/23/2023] [Accepted: 05/27/2023] [Indexed: 06/28/2023]
Abstract
Multidrug resistance (MDR) proteins belonging to the ATP-Binding Cassette (ABC) transporter group play a crucial role in the export of cytotoxic drugs across cell membranes. These proteins are particularly fascinating due to their ability to confer drug resistance, which subsequently leads to the failure of therapeutic interventions and hinders successful treatments. One key mechanism by which multidrug resistance (MDR) proteins carry out their transport function is through alternating access. This mechanism involves intricate conformational changes that enable the binding and transport of substrates across cellular membranes. In this extensive review, we provide an overview of ABC transporters, including their classifications and structural similarities. We focus specifically on well-known mammalian multidrug resistance proteins such as MRP1 and Pgp (MDR1), as well as bacterial counterparts such as Sav1866 and lipid flippase MsbA. By exploring the structural and functional features of these MDR proteins, we shed light on the roles of their nucleotide-binding domains (NBDs) and transmembrane domains (TMDs) in the transport process. Notably, while the structures of NBDs in prokaryotic ABC proteins, such as Sav1866, MsbA, and mammalian Pgp, are identical, MRP1 exhibits distinct characteristics in its NBDs. Our review also emphasizes the importance of two ATP molecules for the formation of an interface between the two binding sites of NBD domains across all these transporters. ATP hydrolysis occurs following substrate transport and is vital for recycling the transporters in subsequent cycles of substrate transportation. Specifically, among the studied transporters, only NBD2 in MRP1 possesses the ability to hydrolyze ATP, while both NBDs of Pgp, Sav1866, and MsbA are capable of carrying out this reaction. Furthermore, we highlight recent advancements in the study of MDR proteins and the alternating access mechanism. We discuss the experimental and computational approaches utilized to investigate the structure and dynamics of MDR proteins, providing valuable insights into their conformational changes and substrate transport. This review not only contributes to an enhanced understanding of multidrug resistance proteins but also holds immense potential for guiding future research and facilitating the development of effective strategies to overcome multidrug resistance, thus improving therapeutic interventions.
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Affiliation(s)
- Shadi A Badiee
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Ugochi H Isu
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Ehsaneh Khodadadi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
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Zakrzewicz D, Geyer J. Interactions of Na +/taurocholate cotransporting polypeptide with host cellular proteins upon hepatitis B and D virus infection: novel potential targets for antiviral therapy. Biol Chem 2023:hsz-2022-0345. [PMID: 37103224 DOI: 10.1515/hsz-2022-0345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 04/13/2023] [Indexed: 04/28/2023]
Abstract
Na+/taurocholate cotransporting polypeptide (NTCP) is a member of the solute carrier (SLC) family 10 transporters (gene symbol SLC10A1) and is responsible for the sodium-dependent uptake of bile salts across the basolateral membrane of hepatocytes. In addition to its primary transporter function, NTCP is the high-affinity hepatic receptor for hepatitis B (HBV) and hepatitis D (HDV) viruses and, therefore, is a prerequisite for HBV/HDV virus entry into hepatocytes. The inhibition of HBV/HDV binding to NTCP and internalization of the virus/NTCP receptor complex has become a major concept in the development of new antiviral drugs called HBV/HDV entry inhibitors. Hence, NTCP has emerged as a promising target for therapeutic interventions against HBV/HDV infections in the last decade. In this review, recent findings on protein-protein interactions (PPIs) between NTCP and cofactors relevant for entry of the virus/NTCP receptor complex are summarized. In addition, strategies aiming to block PPIs with NTCP to dampen virus tropism and HBV/HDV infection rates are discussed. Finally, this article suggests novel directions for future investigations evaluating the functional contribution of NTCP-mediated PPIs in the development and progression of HBV/HDV infection and subsequent chronic liver disorders.
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Affiliation(s)
- Dariusz Zakrzewicz
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus-Liebig-University Giessen, Schubertstr. 81, D-35392 Giessen, Germany
| | - Joachim Geyer
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus-Liebig-University Giessen, Schubertstr. 81, D-35392 Giessen, Germany
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