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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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Zhekova HR, Ramirez Echemendía DP, Sejdiu BI, Pushkin A, Tieleman DP, Kurtz I. Molecular dynamics simulations of lipid-protein interactions in SLC4 proteins. Biophys J 2024; 123:1705-1721. [PMID: 38760929 PMCID: PMC11214021 DOI: 10.1016/j.bpj.2024.05.013] [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: 07/31/2023] [Revised: 04/09/2024] [Accepted: 05/14/2024] [Indexed: 05/20/2024] Open
Abstract
The SLC4 family of secondary bicarbonate transporters is responsible for the transport of HCO3-, CO32-, Cl-, Na+, K+, NH3, and H+, which are necessary for regulation of pH and ion homeostasis. They are widely expressed in numerous tissues throughout the body and function in different cell types with different membrane properties. Potential lipid roles in SLC4 function have been reported in experimental studies, focusing mostly on two members of the family: AE1 (Cl-/HCO3- exchanger) and NBCe1 (Na+-CO32-cotransporter). Previous computational studies of the outward-facing state of AE1 with model lipid membranes revealed enhanced protein-lipid interactions between cholesterol (CHOL) and phosphatidylinositol bisphosphate (PIP2). However, the protein-lipid interactions in other members of the family and other conformation states are still poorly understood and this precludes the detailed studies of a potential regulatory role for lipids in the SLC4 family. In this work, we performed coarse-grained and atomistic molecular dynamics simulations on three members of the SLC4 family with different transport modes: AE1, NBCe1, and NDCBE (an Na+-CO32-/Cl- exchanger), in model HEK293 membranes consisting of CHOL, PIP2, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and sphingomyelin. The recently resolved inward-facing state of AE1 was also included in the simulations. Lipid-protein contact analysis of the simulated trajectories was performed with the ProLint server, which provides a multitude of visualization tools for illustration of areas of enhanced lipid-protein contact and identification of putative lipid binding sites within the protein matrix. We observed enrichment of CHOL and PIP2 around all proteins with subtle differences in their distribution depending on the protein type and conformation state. Putative binding sites were identified for CHOL, PIP2, phosphatidylcholine, and sphingomyelin in the three studied proteins, and their potential roles in the SLC4 transport function, conformational transition, and protein dimerization are discussed.
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Affiliation(s)
- Hristina R Zhekova
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Daniel P Ramirez Echemendía
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Besian I Sejdiu
- Department of Structural Biology and Center of Excellence for Data Driven Discovery, St Jude Children's Research Hospital, Memphis, Tennessee
| | - Alexander Pushkin
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - D Peter Tieleman
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
| | - Ira Kurtz
- Department of Medicine, Division of Nephrology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California; Brain Research Institute, University of California, Los Angeles, Los Angeles, California.
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3
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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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4
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Abstract
Understanding how cells sense gases or gaseous solutes is a fundamental question in biology and is pivotal for the evolution of molecular and organismal life. In numerous organisms, gases can diffuse into cells, be transported, generated, and sensed. Controlling gases in the cellular environment is essential to prevent cellular and molecular damage due to interactions with gas-dependent free radicals. Consequently, the mechanisms governing acute gas sensing are evolutionarily conserved and have been experimentally elucidated in various organisms. However, the scientific literature on direct gas sensing is largely based on hemoprotein-based gasoreceptors (or sensors). As RNA-based G-quadruplex (G4) structures can also bind to heme, I propose that some ribozymes can act as gas-sensing riboceptors (ribonucleic acid receptors). Additionally, I present a few other ideas for non-heme metal ion- or metal cluster-based gas-sensing riboceptors. Studying riboceptors can help understand the evolutionary origins of cellular and gasocrine signaling.
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Affiliation(s)
- Savani Anbalagan
- Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznań, Poland
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5
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Zhang G, Odenkirk MT, Janczak CM, Lee R, Richardson K, Wang Z, Aspinwall CA, Marty MT. Identifying Membrane Protein-Lipid Interactions with Lipidomic Lipid Exchange-Mass Spectrometry. J Am Chem Soc 2023; 145:20859-20867. [PMID: 37700579 PMCID: PMC10540470 DOI: 10.1021/jacs.3c05883] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
Lipids can play important roles in modulating membrane protein structure and function. However, it is challenging to identify natural lipids bound to membrane proteins in complex bilayers. Here, we developed lipidomic lipid exchange-mass spectrometry (LX-MS) to study the lipid affinity for membrane proteins on a lipidomic scale. We first mix membrane protein nanodiscs with empty nanodiscs that have no embedded membrane proteins. After allowing lipids to passively exchange between the two populations, we separate the two types of nanodiscs and perform lipidomic analysis on each with liquid chromatography and MS. Enrichment of lipids in the membrane protein nanodiscs reveals the affinity of individual lipids for binding the target membrane protein. We apply this approach to study three membrane proteins. With the Escherichia coli ammonium transporter AmtB and aquaporin AqpZ in nanodiscs with E. coli polar lipid extracts, we detected binding of cardiolipin and phosphatidyl-glycerol lipids to the proteins. With the acetylcholine receptor in nanodiscs with brain polar lipid extracts, we discovered a complex set of lipid interactions that depended on the head group and tail composition. Overall, lipidomic LX-MS provides a detailed understanding of the lipid-binding affinity and thermodynamics for membrane proteins in complex bilayers and provides a unique perspective on the chemical environment surrounding membrane proteins.
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Affiliation(s)
- Guozhi Zhang
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
| | - Melanie T. Odenkirk
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
- Bio5 Institute, University of Arizona, Tucson, AZ, 85721, USA
| | | | - Ray Lee
- Scintillation Nanotechnologies, Inc., Tucson, AZ, 85721, USA
| | | | - Zhihan Wang
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
| | - Craig A. Aspinwall
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
- Bio5 Institute, University of Arizona, Tucson, AZ, 85721, USA
| | - Michael T. Marty
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
- Bio5 Institute, University of Arizona, Tucson, AZ, 85721, USA
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6
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Zhekova HR, Ramirez-Echemendía DP, Sejdiu BI, Pushkin A, Tieleman DP, Kurtz I. Coarse-grained molecular dynamics simulations of lipid-protein interactions in SLC4 proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.26.546592. [PMID: 37425774 PMCID: PMC10327080 DOI: 10.1101/2023.06.26.546592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
The SLC4 family of secondary bicarbonate transporters is responsible for the transport of HCO 3 -, CO 3 2- , Cl - , Na + , K + , NH 3 and H + necessary for regulation of pH and ion homeostasis. They are widely expressed in numerous tissues throughout the body and function in different cell types with different membrane properties. Potential lipid roles in SLC4 function have been reported in experimental studies, focusing mostly on two members of the family: AE1 (Cl - /HCO 3 - exchanger) and NBCe1 (Na + -CO 3 2- cotransporter). Previous computational studies of the outward facing (OF) state of AE1 with model lipid membranes revealed enhanced protein-lipid interactions between cholesterol (CHOL) and phosphatidylinositol bisphosphate (PIP2). However, the protein-lipid interactions in other members of the family and other conformation states are still poorly understood and this precludes the detailed studies of a potential regulatory role for lipids in the SLC4 family. In this work, we performed multiple 50 µs coarse-grained molecular dynamics simulations on three members of the SLC4 family with different transport modes: AE1, NBCe1 and NDCBE (a Na + -CO 3 2- /Cl - exchanger), in model HEK293 membranes consisting of CHOL, PIP2, phosphatidylcholine (POPC), phosphatidylethanolamine (POPE), phosphatidylserine (POPS), and sphingomyelin (POSM). The recently resolved inward-facing (IF) state of AE1 was also included in the simulations. Lipid-protein contact analysis of the simulated trajectories was performed with the ProLint server, which provides a multitude of visualization tools for illustration of areas of enhanced lipid-protein contact and identification of putative lipid binding sites within the protein matrix. We observed enrichment of CHOL and PIP2 around all proteins with subtle differences in their distribution depending on the protein type and conformation state. Putative binding sites were identified for CHOL, PIP2, POPC, and POSM in the three studied proteins and their potential roles in the SLC4 transport function, conformational transition and protein dimerization were discussed. Statement of significance The SLC4 protein family is involved in critical physiological processes like pH and blood pressure regulation and maintenance of ion homeostasis. Its members can be found in various tissues. A number of studies suggest possible lipid regulation of the SLC4 function. However, the protein-lipid interactions in the SLC4 family are still poorly understood. Here we make use of long coarse-grained molecular dynamics simulations to assess the protein-lipid interactions in three SLC4 proteins with different transport modes, AE1, NBCe1, and NDCBE. We identify putative lipid binding sites for several lipid types of potential mechanistic importance, discuss them in the framework of the known experimental data and provide a necessary basis for further studies on lipid regulation of SLC4 function.
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7
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Tzortzini E, Kolocouris A. Molecular Biophysics of Class A G Protein Coupled Receptors-Lipids Interactome at a Glance-Highlights from the A 2A Adenosine Receptor. Biomolecules 2023; 13:957. [PMID: 37371538 DOI: 10.3390/biom13060957] [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: 05/04/2023] [Revised: 05/25/2023] [Accepted: 05/28/2023] [Indexed: 06/29/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are embedded in phospholipid membrane bilayers with cholesterol representing 34% of the total lipid content in mammalian plasma membranes. Membrane lipids interact with GPCRs structures and modulate their function and drug-stimulated signaling through conformational selection. It has been shown that anionic phospholipids form strong interactions between positively charged residues in the G protein and the TM5-TM6-TM 7 cytoplasmic interface of class A GPCRs stabilizing the signaling GPCR-G complex. Cholesterol with a high content in plasma membranes can be identified in more specific sites in the transmembrane region of GPCRs, such as the Cholesterol Consensus Motif (CCM) and Cholesterol Recognition Amino Acid Consensus (CRAC) motifs and other receptor dependent and receptor state dependent sites. Experimental biophysical methods, atomistic (AA) MD simulations and coarse-grained (CG) molecular dynamics simulations have been applied to investigate these interactions. We emphasized here the impact of phosphatidyl inositol-4,5-bisphosphate (PtdIns(4,5)P2 or PIP2), a minor phospholipid component and of cholesterol on the function-related conformational equilibria of the human A2A adenosine receptor (A2AR), a representative receptor in class A GPCR. Several GPCRs of class A interacted with PIP2 and cholesterol and in many cases the mechanism of the modulation of their function remains unknown. This review provides a helpful comprehensive overview for biophysics that enter the field of GPCRs-lipid systems.
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Affiliation(s)
- Efpraxia Tzortzini
- Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, 15771 Athens, Greece
| | - Antonios Kolocouris
- Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, 15771 Athens, Greece
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8
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Du Z, Zhou X, Lai Y, Xu J, Zhang Y, Zhou S, Feng Z, Yu L, Tang Y, Wang W, Yu L, Tian C, Ran T, Chen H, Guddat LW, Liu F, Gao Y, Rao Z, Gong H. Structure of the human respiratory complex II. Proc Natl Acad Sci U S A 2023; 120:e2216713120. [PMID: 37098072 PMCID: PMC10161127 DOI: 10.1073/pnas.2216713120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 03/10/2023] [Indexed: 04/26/2023] Open
Abstract
Human complex II is a key protein complex that links two essential energy-producing processes: the tricarboxylic acid cycle and oxidative phosphorylation. Deficiencies due to mutagenesis have been shown to cause mitochondrial disease and some types of cancers. However, the structure of this complex is yet to be resolved, hindering a comprehensive understanding of the functional aspects of this molecular machine. Here, we have determined the structure of human complex II in the presence of ubiquinone at 2.86 Å resolution by cryoelectron microscopy, showing it comprises two water-soluble subunits, SDHA and SDHB, and two membrane-spanning subunits, SDHC and SDHD. This structure allows us to propose a route for electron transfer. In addition, clinically relevant mutations are mapped onto the structure. This mapping provides a molecular understanding to explain why these variants have the potential to produce disease.
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Affiliation(s)
- Zhanqiang Du
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Xiaoting Zhou
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot 010070, China
| | - Yuezheng Lai
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Jinxu Xu
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Yuying Zhang
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Shan Zhou
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Ziyan Feng
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Long Yu
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Yanting Tang
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
| | - Weiwei Wang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Lu Yu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Changlin Tian
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Ting Ran
- Innovative Center For Pathogen Research, Guangzhou Laboratory, Guangzhou 510005, China
| | - Hongming Chen
- Innovative Center For Pathogen Research, Guangzhou Laboratory, Guangzhou 510005, China
| | - Luke W Guddat
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Fengjiang Liu
- Innovative Center For Pathogen Research, Guangzhou Laboratory, Guangzhou 510005, China
| | - Yan Gao
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Zihe Rao
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- Laboratory of Structural Biology, Tsinghua University, Beijing 100084, China
| | - Hongri Gong
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Responses, College of Life Sciences, Nankai University, Tianjin 300353, China
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Wang M, He J, Li S, Cai Q, Zhang K, She J. Structural basis of vitamin C recognition and transport by mammalian SVCT1 transporter. Nat Commun 2023; 14:1361. [PMID: 36914666 PMCID: PMC10011568 DOI: 10.1038/s41467-023-37037-3] [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: 09/06/2022] [Accepted: 02/28/2023] [Indexed: 03/15/2023] Open
Abstract
Vitamin C (L-ascorbic acid) is an essential nutrient for human health, and its deficiency has long been known to cause scurvy. Sodium-dependent vitamin C transporters (SVCTs) are responsible for vitamin C uptake and tissue distribution in mammals. Here, we present cryogenic electron microscopy structures of mouse SVCT1 in both the apo and substrate-bound states. Mouse SVCT1 forms a homodimer with each protomer containing a core domain and a gate domain. The tightly packed extracellular interfaces between the core domain and gate domain stabilize the protein in an inward-open conformation for both the apo and substrate-bound structures. Vitamin C binds at the core domain of each subunit, and two potential sodium ions are identified near the binding site. The coordination of sodium ions by vitamin C explains their coupling transport. SVCTs probably deliver substrate through an elevator mechanism in combination with local structural arrangements. Altogether, our results reveal the molecular mechanism by which SVCTs recognize vitamin C and lay a foundation for further mechanistic studies on SVCT substrate transport.
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Affiliation(s)
- Mingxing Wang
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230026, China
| | - Jin He
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230026, China
| | - Shanshan Li
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230026, China
| | - Qianwen Cai
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China
| | - Kaiming Zhang
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230026, China.
| | - Ji She
- MOE Key Laboratory for Cellular Dynamics, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230026, China.
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10
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Hydrogen/deuterium exchange-mass spectrometry of integral membrane proteins in native-like environments: current scenario and the way forward. Essays Biochem 2023; 67:187-200. [PMID: 36876893 PMCID: PMC10070480 DOI: 10.1042/ebc20220173] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/09/2023] [Accepted: 01/13/2023] [Indexed: 03/07/2023]
Abstract
Integral membrane proteins (IMPs) perform a range of diverse functions and their dysfunction underlies numerous pathological conditions. Consequently, IMPs constitute most drug targets, and the elucidation of their mechanism of action has become an intense field of research. Historically, IMP studies have relied on their extraction from membranes using detergents, which have the potential to perturbate their structure and dynamics. To circumnavigate this issue, an array of membrane mimetics has been developed that aim to reconstitute IMPs into native-like lipid environments that more accurately represent the biological membrane. Hydrogen/deuterium exchange-mass spectrometry (HDX-MS) has emerged as a versatile tool for probing protein dynamics in solution. The continued development of HDX-MS methodology has allowed practitioners to investigate IMPs using increasingly native-like membrane mimetics, and even pushing the study of IMPs into the in vivo cellular environment. Consequently, HDX-MS has come of age and is playing an ever-increasingly important role in the IMP structural biologist toolkit. In the present mini-review, we discuss the evolution of membrane mimetics in the HDX-MS context, focusing on seminal publications and recent innovations that have led to this point. We also discuss state-of-the-art methodological and instrumental advancements that are likely to play a significant role in the generation of high-quality HDX-MS data of IMPs in the future.
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11
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Mass spectrometry of intact membrane proteins: shifting towards a more native-like context. Essays Biochem 2023; 67:201-213. [PMID: 36807530 PMCID: PMC10070488 DOI: 10.1042/ebc20220169] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/20/2023] [Accepted: 01/23/2023] [Indexed: 02/23/2023]
Abstract
Integral membrane proteins are involved in a plethora of biological processes including cellular signalling, molecular transport, and catalysis. Many of these functions are mediated by non-covalent interactions with other proteins, substrates, metabolites, and surrounding lipids. Uncovering such interactions and deciphering their effect on protein activity is essential for understanding the regulatory mechanisms underlying integral membrane protein function. However, the detection of such dynamic complexes has proven to be challenging using traditional approaches in structural biology. Native mass spectrometry has emerged as a powerful technique for the structural characterisation of membrane proteins and their complexes, enabling the detection and identification of protein-binding partners. In this review, we discuss recent native mass spectrometry-based studies that have characterised non-covalent interactions of membrane proteins in the presence of detergents or membrane mimetics. We additionally highlight recent progress towards the study of membrane proteins within native membranes and provide our perspective on how these could be combined with recent developments in instrumentation to investigate increasingly complex biomolecular systems.
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12
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Beltran JL, McGrath LG, Caruso S, Bain RK, Hendrix CE, Kamran H, Johnston HG, Collings RM, Henry MCN, Abera TAL, Donoso VA, Carriker EC, Thurtle-Schmidt BH. Borate Transporters and SLC4 Bicarbonate Transporters Share Key Functional Properties. MEMBRANES 2023; 13:membranes13020235. [PMID: 36837738 PMCID: PMC9959716 DOI: 10.3390/membranes13020235] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 06/03/2023]
Abstract
Borate transporters are membrane transport proteins that regulate intracellular borate levels. In plants, borate is a micronutrient essential for growth but is toxic in excess, while in yeast, borate is unnecessary for growth and borate export confers tolerance. Borate transporters share structural homology with human bicarbonate transporters in the SLC4 family despite low sequence identity and differences in transported solutes. Here, we characterize the S. cerevisiae borate transporter Bor1p and examine whether key biochemical features of SLC4 transporters extend to borate transporters. We show that borate transporters and SLC4 transporters share multiple properties, including lipid-promoted dimerization, sensitivity to stilbene disulfonate-derived inhibitors, and a requirement for an acidic residue at the solute binding site. We also identify several amino acids critical for Bor1p function and show that disease-causing mutations in human SLC4A1 will eliminate in vivo function when their homologous mutations are introduced in Bor1p. Our data help elucidate mechanistic features of Bor1p and reveal significant functional properties shared between borate transporters and SLC4 transporters.
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13
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Holmes AOM, Goldman A, Kalli AC. mPPases create a conserved anionic membrane fingerprint as identified via multi-scale simulations. PLoS Comput Biol 2022; 18:e1010578. [PMID: 36191052 PMCID: PMC9560603 DOI: 10.1371/journal.pcbi.1010578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 10/13/2022] [Accepted: 09/16/2022] [Indexed: 11/06/2022] Open
Abstract
Membrane-integral pyrophosphatases (mPPases) are membrane-bound enzymes responsible for hydrolysing inorganic pyrophosphate and translocating a cation across the membrane. Their function is essential for the infectivity of clinically relevant protozoan parasites and plant maturation. Recent developments have indicated that their mechanism is more complicated than previously thought and that the membrane environment may be important for their function. In this work, we use multiscale molecular dynamics simulations to demonstrate for the first time that mPPases form specific anionic lipid interactions at 4 sites at the distal and interfacial regions of the protein. These interactions are conserved in simulations of the mPPases from Thermotoga maritima, Vigna radiata and Clostridium leptum and characterised by interactions with positive residues on helices 1, 2, 3 and 4 for the distal site, or 9, 10, 13 and 14 for the interfacial site. Due to the importance of these helices in protein stability and function, these lipid interactions may play a crucial role in the mPPase mechanism and enable future structural and functional studies.
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Affiliation(s)
- Alexandra O. M. Holmes
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Adrian Goldman
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
- Research Program in Molecular and Integrative Biosciences, University of Helsinki, Helsinki, Finland
| | - Antreas C. Kalli
- Leeds Institute of Cardiovascular and Metabolic Medicine and Astbury Centre for Structural Biology, University of Leeds, Leeds, United Kingdom
- * E-mail:
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14
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Dimakis D, Pyrris Y, Diallinas G. Transmembrane helices 5 and 12 control transport dynamics, substrate affinity, and specificity in the elevator-type UapA transporter. Genetics 2022; 222:6650625. [PMID: 35894659 PMCID: PMC9434233 DOI: 10.1093/genetics/iyac107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 07/11/2022] [Indexed: 01/17/2023] Open
Abstract
An increasing number of solute transporters have been shown to function with the so-called sliding-elevator mechanism. Despite structural and functional differences, all elevator-type transporters use a common mechanism of substrate translocation via reversible movements of a mobile core domain (the elevator) hosting the substrate binding site along a rigid scaffold domain stably anchored in the plasma membrane via homodimerization. One of the best-studied elevator transporters is the UapA uric acid-xanthine/H+ symporter of the filamentous fungus Aspergillus nidulans. Here, we present a genetic analysis for deciphering the role of transmembrane segments (TMS) 5 and 12 in UapA transport function. We show that specific residues in both TMS5 and TMS12 control, negatively or positively, the dynamics of transport, but also substrate binding affinity and specificity. More specifically, mutations in TMS5 can lead not only to increased rate of transport but also to an inactive transporter due to high-affinity substrate-trapping, whereas mutations in TMS12 lead to apparently uncontrolled sliding and broadened specificity, leading in specific cases to UapA-mediated purine toxicity. Our findings shed new light on how elevator transporters function and how this knowledge can be applied to genetically modify their transport characteristics.
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Affiliation(s)
- Dimitris Dimakis
- Department of Biology, National and Kapodistrian University of Athens, 15784 Athens, Greece
| | - Yiannis Pyrris
- Department of Biology, National and Kapodistrian University of Athens, 15784 Athens, Greece
| | - George Diallinas
- Corresponding author: Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15784 Athens, Greece.
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15
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Sarkar K, Joedicke L, Westwood M, Burnley R, Wright M, McMillan D, Byrne B. Modulation of PTH1R signaling by an extracellular binding antibody. VITAMINS AND HORMONES 2022; 120:109-132. [PMID: 35953107 DOI: 10.1016/bs.vh.2022.04.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Parathyroid hormone receptor 1 (PTH1R) is a class B G-protein coupled receptor with key roles in bone development. The receptor signals through both the Gs and Gq G-proteins as well as through β-arrestin in a G-protein independent manner. Current treatments for bone disorders, such as osteoporosis, target the PTH1R but are suboptimal in their efficacy. Monoclonal antibodies represent a major growth area in therapeutics as a result of their superior specificity and long serum half-life. Here, we discovered antibodies against the extracellular domain (ECD) of PTH1R from a phage display library. One of these antibodies, ECD-ScFvhFc, binds PTH1R with high affinity and although it has little or no effect on G-protein dependent receptor signaling, it does reduce PTH1R mediated β-arrestin signaling. Hydrogen-deuterium exchange mass spectrometry (HDX-MS) demonstrated that the ECD-ScFvhFc binding site overlapped partially with that of the cognate ligand, PTH. The results of this study demonstrate the suitability of PTH1R as a target for therapeutic antibody development.
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Affiliation(s)
- Kaushik Sarkar
- Department of Life Sciences, Imperial College, London, United Kingdom; UCB Pharma, Slough, United Kingdom
| | | | | | | | | | | | - Bernadette Byrne
- Department of Life Sciences, Imperial College, London, United Kingdom.
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16
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Keener JE, Jayasekera HS, Marty MT. Investigating the Lipid Selectivity of Membrane Proteins in Heterogeneous Nanodiscs. Anal Chem 2022; 94:8497-8505. [PMID: 35621361 DOI: 10.1021/acs.analchem.2c01488] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structure and function of membrane proteins can be significantly impacted by the surrounding lipid environment, but membrane protein-lipid interactions in lipid bilayers are often difficult to study due to their transient and polydisperse nature. Here, we used two native mass spectrometry (MS) approaches to investigate how the Escherichia coli ammonium transporter trimer (AmtB) and aquaporin Z (AqpZ) selectively remodel their local lipid environment in heterogeneous lipoprotein nanodiscs. First, we used gas-phase ejection to isolate the membrane protein with bound lipids from heterogeneous nanodiscs with different combinations of lipids. Second, we used solution-phase detergent extraction as an orthogonal approach to study membrane protein remodeling of lipids in the nanodisc with native MS. Our results showed that Triton X-100 and lauryldimethylamine oxide retain lipid selectivity that agrees with gas-phase ejection, but C8E4 distorts some preferential lipid interactions. Both approaches reveal that AmtB has a few selective binding sites for phosphatidylcholine (PC) lipids, is selective for binding phosphatidylglycerols (PG) overall, and is nonselective for phosphatidylethanolamines (PE). In contrast, AqpZ prefers either PC or PG over PE and prefers PC over PG. Overall, these experiments provide a picture of how membrane proteins bind different lipid head groups in the context of mixed lipid bilayers.
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Affiliation(s)
- James E Keener
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Hiruni S Jayasekera
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Michael T Marty
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States.,Bio5 Institute, University of Arizona, Tucson, Arizona 85721, United States
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17
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Oluwole AO, Corey RA, Brown CM, Hernández-Rocamora VM, Stansfeld PJ, Vollmer W, Bolla JR, Robinson CV. Peptidoglycan biosynthesis is driven by lipid transfer along enzyme-substrate affinity gradients. Nat Commun 2022; 13:2278. [PMID: 35477938 PMCID: PMC9046198 DOI: 10.1038/s41467-022-29836-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 03/31/2022] [Indexed: 01/02/2023] Open
Abstract
Maintenance of bacterial cell shape and resistance to osmotic stress by the peptidoglycan (PG) renders PG biosynthetic enzymes and precursors attractive targets for combating bacterial infections. Here, by applying native mass spectrometry, we elucidate the effects of lipid substrates on the PG membrane enzymes MraY, MurG, and MurJ. We show that dimerization of MraY is coupled with binding of the carrier lipid substrate undecaprenyl phosphate (C55-P). Further, we demonstrate the use of native MS for biosynthetic reaction monitoring and find that the passage of substrates and products is controlled by the relative binding affinities of the different membrane enzymes. Overall, we provide a molecular view of how PG membrane enzymes convey lipid precursors through favourable binding events and highlight possible opportunities for intervention. Bacterial cell wall enzymes and their precursors are critical targets for antibiotic development. Here, the authors investigate several biosynthetic enzymes with their substrates and show that the passage of substrates and products in the pathway is controlled by their relative binding affinities.
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Affiliation(s)
- Abraham O Oluwole
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK.,The Kavli Institute for Nanoscience Discovery, South Parks Road, Oxford, OX1 3QU, UK
| | - Robin A Corey
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Chelsea M Brown
- School of Life Sciences and Department of Chemistry, University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK
| | - Victor M Hernández-Rocamora
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.,School of Life Sciences and Department of Chemistry, University of Warwick, Gibbet Hill Campus, Coventry, CV4 7AL, UK
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Jani R Bolla
- The Kavli Institute for Nanoscience Discovery, South Parks Road, Oxford, OX1 3QU, UK. .,Department of Plant Sciences/Biology, University of Oxford, Oxford, OX1 3RB, UK.
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK. .,The Kavli Institute for Nanoscience Discovery, South Parks Road, Oxford, OX1 3QU, UK.
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18
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Yen HY, Abramsson ML, Agasid MT, Lama D, Gault J, Liko I, Kaldmäe M, Saluri M, Qureshi AA, Suades A, Drew D, Degiacomi MT, Marklund EG, Allison TM, Robinson CV, Landreh M. Electrospray ionization of native membrane proteins proceeds via a charge equilibration step. RSC Adv 2022; 12:9671-9680. [PMID: 35424940 PMCID: PMC8972943 DOI: 10.1039/d2ra01282k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 03/21/2022] [Indexed: 11/21/2022] Open
Abstract
Electrospray ionization mass spectrometry is increasingly applied to study the structures and interactions of membrane protein complexes. However, the charging mechanism is complicated by the presence of detergent micelles during ionization. Here, we show that the final charge of membrane proteins can be predicted by their molecular weight when released from the non-charge reducing saccharide detergents. Our data indicate that PEG detergents lower the charge depending on the number of detergent molecules in the surrounding micelle, whereas fos-choline detergents may additionally participate in ion–ion reactions after desolvation. The supercharging reagent sulfolane, on the other hand, has no discernible effect on the charge of detergent-free membrane proteins. Taking our observations into the context of protein-detergent interactions in the gas phase, we propose a charge equilibration model for the generation of native-like membrane protein ions. During ionization of the protein-detergent complex, the ESI charges are distributed between detergent and protein according to proton affinity of the detergent, number of detergent molecules, and surface area of the protein. Charge equilibration influenced by detergents determines the final charge state of membrane proteins. This process likely contributes to maintaining a native-like fold after detergent release and can be harnessed to stabilize particularly labile membrane protein complexes in the gas phase. The electrospray ionization mechanism contributes to preserving the structures and interactions of membrane protein complexes in native mass spectrometry.![]()
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Affiliation(s)
- Hsin-Yung Yen
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK .,Institute of Biological Chemistry, Academia Sinica 128, Academia Road Sec. 2, Nankang Taipei 115 Taiwan
| | - Mia L Abramsson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Tomtebodavägen 23A 17165 Stockholm Sweden
| | - Mark T Agasid
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Dilraj Lama
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Tomtebodavägen 23A 17165 Stockholm Sweden
| | - Joseph Gault
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Idlir Liko
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Margit Kaldmäe
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Tomtebodavägen 23A 17165 Stockholm Sweden
| | - Mihkel Saluri
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Tomtebodavägen 23A 17165 Stockholm Sweden
| | - Abdul Aziz Qureshi
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK .,Department of Biochemistry and Biophysics, Stockholm University 10691 Stockholm Sweden
| | - Albert Suades
- Department of Biochemistry and Biophysics, Stockholm University 10691 Stockholm Sweden
| | - David Drew
- Department of Biochemistry and Biophysics, Stockholm University 10691 Stockholm Sweden
| | | | - Erik G Marklund
- Department of Chemistry - BMC, Uppsala University Box 576 75123 Uppsala Sweden
| | - Timothy M Allison
- Biomolecular Interaction Centre, School of Physical and Chemical Sciences, University of Canterbury Christchurch 8140 New Zealand
| | - Carol V Robinson
- Department of Chemistry, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Michael Landreh
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet Tomtebodavägen 23A 17165 Stockholm Sweden
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19
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Zhang B, Peng Y, Wang Y, Wang X. Exploring the trimerization process of a transmembrane helix with an ionizable residue by molecular dynamics simulations: a case study of transmembrane domain 5 of LMP-1. Phys Chem Chem Phys 2022; 24:7084-7092. [PMID: 35262149 DOI: 10.1039/d2cp00102k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The oligomerization of membrane proteins is an important biological process that plays a critical role in the initialization of membrane protein receptor signaling. Unveiling how transmembrane segments oligomerize is critical for understanding the mechanism of membrane receptor signaling activation. Owing to the complicated membrane environment and the extraordinary dynamic properties of the ionizable residues in the transmembrane segment, it is extremely challenging to thoroughly understand the oligomerization process of the transmembrane domain. In this study, transmembrane domain 5 (TMD5) of latent membrane protein-1 from Epstein-Barr virus was used as a prototype model to investigate the trimerization process of the transmembrane segment with ionizable residues. The trimerization process of TMD5 was rebuilt and investigated via conventional molecular dynamics simulations and constant-pH molecular dynamics simulations. When TMD5s approached each other, the tilting angles of the TMD5 monomer decreased. TMD5s formed stable trimers until two interacting sites (D150s and Q139s) along each transmembrane helix were created to lock the TMD5s. The pKa values of D150 shifted toward neutral states in the membrane environment. When TMD5s were monomers, the pKa shift of D150 was mainly influenced by its microenvironment in the lipid bilayer. When TMD5s were moving close to each other, protein-protein interactions became the main contributing factor for the pKa shift of D150s. Overall, this work elucidates the behavior of the TMD5 helix and the pKa shift of ionizable residue D150 in the process of TMD5 oligomerization. This study may provide insight into the development of agents for targeting the oligomerization of membrane proteins.
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Affiliation(s)
- Bo Zhang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, China. .,Department of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Yinghua Peng
- State Key Laboratory for Molecular Biology of Special Economic Animal, Institute of Special Animal and Plant Sciences, Chinese Academy of Agricultural Sciences, Changchun, Jilin, 130112, China
| | - Yibo Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, China.
| | - Xiaohui Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, China. .,Department of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China.,Beijing National Laboratory for Molecular Sciences, Beijing, 100190, China
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20
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Kalli AC, Reithmeier RAF. Organization and Dynamics of the Red Blood Cell Band 3 Anion Exchanger SLC4A1: Insights From Molecular Dynamics Simulations. Front Physiol 2022; 13:817945. [PMID: 35283786 PMCID: PMC8914234 DOI: 10.3389/fphys.2022.817945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 01/27/2022] [Indexed: 01/16/2023] Open
Abstract
Molecular dynamics (MD) simulations have provided new insights into the organization and dynamics of the red blood cell Band 3 anion exchanger (AE1, SLC4A1). Band 3, like many solute carriers, works by an alternating access mode of transport where the protein rapidly (104/s) changes its conformation between outward and inward-facing states via a transient occluded anion-bound intermediate. While structural studies of membrane proteins usually reveal valuable structural information, these studies provide a static view often in the presence of detergents. Membrane transporters are embedded in a lipid bilayer and associated lipids play a role in their folding and function. In this review, we highlight MD simulations of Band 3 in realistic lipid bilayers that revealed specific lipid and protein interactions and were used to re-create a model of the Wright (Wr) blood group antigen complex of Band 3 and Glycophorin A. Current MD studies of Band 3 and related transporters are focused on describing the trajectory of substrate binding and translocation in real time. A structure of the intact Band 3 protein has yet to be achieved experimentally, but cryo-electron microscopy in combination with MD simulations holds promise to capture the conformational changes associated with anion transport in exquisite molecular detail.
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Affiliation(s)
- Antreas C. Kalli
- Leeds Institute of Cardiovascular and Metabolic Medicine and Astbury Center for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Reinhart A. F. Reithmeier
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
- *Correspondence: Reinhart A. F. Reithmeier,
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21
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Thermostability-based binding assays reveal complex interplay of cation, substrate and lipid binding in the bacterial DASS transporter, VcINDY. Biochem J 2021; 478:3847-3867. [PMID: 34643224 PMCID: PMC8652582 DOI: 10.1042/bcj20210061] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 10/08/2021] [Accepted: 10/13/2021] [Indexed: 12/04/2022]
Abstract
The divalent anion sodium symporter (DASS) family of transporters (SLC13 family in humans) are key regulators of metabolic homeostasis, disruption of which results in protection from diabetes and obesity, and inhibition of liver cancer cell proliferation. Thus, DASS transporter inhibitors are attractive targets in the treatment of chronic, age-related metabolic diseases. The characterisation of several DASS transporters has revealed variation in the substrate selectivity and flexibility in the coupling ion used to power transport. Here, using the model DASS co-transporter, VcINDY from Vibrio cholerae, we have examined the interplay of the three major interactions that occur during transport: the coupling ion, the substrate, and the lipid environment. Using a series of high-throughput thermostability-based interaction assays, we have shown that substrate binding is Na+-dependent; a requirement that is orchestrated through a combination of electrostatic attraction and Na+-induced priming of the binding site architecture. We have identified novel DASS ligands and revealed that ligand binding is dominated by the requirement of two carboxylate groups in the ligand that are precisely distanced to satisfy carboxylate interaction regions of the substrate-binding site. We have also identified a complex relationship between substrate and lipid interactions, which suggests a dynamic, regulatory role for lipids in VcINDY's transport cycle.
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22
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Diallinas G. Transporter Specificity: A Tale of Loosened Elevator-Sliding. Trends Biochem Sci 2021; 46:708-717. [PMID: 33903007 DOI: 10.1016/j.tibs.2021.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 03/13/2021] [Accepted: 03/26/2021] [Indexed: 12/14/2022]
Abstract
Elevator-type transporters are a group of proteins translocating nutrients and metabolites across cell membranes. Despite structural and functional differences, elevator-type transporters use a common mechanism of substrate translocation via reversible movements of a mobile core domain (the elevator), which includes the substrate binding site, along a rigid scaffold domain, stably anchored in the plasma membrane. How substrate specificity is determined in elevator transporters remains elusive. Here, I discuss how a recent report on the sliding elevator mechanism, seen under the context of genetic analysis of a prototype fungal transporter, sheds light on how specificity might be genetically modified. I propose that flexible specificity alterations might occur by 'loosening' of the sliding mechanism from tight coupling to substrate binding.
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Affiliation(s)
- George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15784, Athens, Greece; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, Greece.
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23
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Insights into the Role of Membrane Lipids in the Structure, Function and Regulation of Integral Membrane Proteins. Int J Mol Sci 2021; 22:ijms22169026. [PMID: 34445730 PMCID: PMC8396450 DOI: 10.3390/ijms22169026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/15/2021] [Accepted: 08/17/2021] [Indexed: 02/07/2023] Open
Abstract
Membrane proteins exist within the highly hydrophobic membranes surrounding cells and organelles, playing key roles in cellular function. It is becoming increasingly clear that the membrane does not just act as an appropriate environment for these proteins, but that the lipids that make up these membranes are essential for membrane protein structure and function. Recent technological advances in cryogenic electron microscopy and in advanced mass spectrometry methods, as well as the development of alternative membrane mimetic systems, have allowed experimental study of membrane protein–lipid complexes. These have been complemented by computational approaches, exploiting the ability of Molecular Dynamics simulations to allow exploration of membrane protein conformational changes in membranes with a defined lipid content. These studies have revealed the importance of lipids in stabilising the oligomeric forms of membrane proteins, mediating protein–protein interactions, maintaining a specific conformational state of a membrane protein and activity. Here we review some of the key recent advances in the field of membrane protein–lipid studies, with major emphasis on respiratory complexes, transporters, channels and G-protein coupled receptors.
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24
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Ernst M, Robertson JL. The Role of the Membrane in Transporter Folding and Activity. J Mol Biol 2021; 433:167103. [PMID: 34139219 PMCID: PMC8756397 DOI: 10.1016/j.jmb.2021.167103] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 06/07/2021] [Accepted: 06/08/2021] [Indexed: 12/23/2022]
Abstract
The synthesis, folding, and function of membrane transport proteins are critical factors for defining cellular physiology. Since the stability of these proteins evolved amidst the lipid bilayer, it is no surprise that we are finding that many of these membrane proteins demonstrate coupling of their structure or activity in some way to the membrane. More and more transporter structures are being determined with some information about the surrounding membrane, and computational modeling is providing further molecular details about these solvation structures. Thus, the field is moving towards identifying which molecular mechanisms - lipid interactions, membrane perturbations, differential solvation, and bulk membrane effects - are involved in linking membrane energetics to transporter stability and function. In this review, we present an overview of these mechanisms and the growing evidence that the lipid bilayer is a major determinant of the fold, form, and function of membrane transport proteins in membranes.
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Affiliation(s)
- Melanie Ernst
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine in St. Louis, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Janice L Robertson
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine in St. Louis, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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25
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Cecchetti C, Strauss J, Stohrer C, Naylor C, Pryor E, Hobbs J, Tanley S, Goldman A, Byrne B. A novel high-throughput screen for identifying lipids that stabilise membrane proteins in detergent based solution. PLoS One 2021; 16:e0254118. [PMID: 34252116 PMCID: PMC8274869 DOI: 10.1371/journal.pone.0254118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 06/20/2021] [Indexed: 12/29/2022] Open
Abstract
Membrane proteins have a range of crucial biological functions and are the target of about 60% of all prescribed drugs. For most studies, they need to be extracted out of the lipid-bilayer, e.g. by detergent solubilisation, leading to the loss of native lipids, which may disturb important protein-lipid/bilayer interactions and thus functional and structural integrity. Relipidation of membrane proteins has proven extremely successful for studying challenging targets, but the identification of suitable lipids can be expensive and laborious. Therefore, we developed a screen to aid the high-throughput identification of beneficial lipids. The screen covers a large lipid space and was designed to be suitable for a range of stability assessment methods. Here, we demonstrate its use as a tool for identifying stabilising lipids for three membrane proteins: a bacterial pyrophosphatase (Tm-PPase), a fungal purine transporter (UapA) and a human GPCR (A2AR). A2AR is stabilised by cholesteryl hemisuccinate, a lipid well known to stabilise GPCRs, validating the approach. Additionally, our screen also identified a range of new lipids which stabilised our test proteins, providing a starting point for further investigation and demonstrating its value as a novel tool for membrane protein research. The pre-dispensed screen will be made commercially available to the scientific community in future and has a number of potential applications in the field.
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Affiliation(s)
- Cristina Cecchetti
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Jannik Strauss
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Claudia Stohrer
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | | | - Edward Pryor
- Anatrace, Maumee, Ohio, United States of America
| | | | | | - Adrian Goldman
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
- MIBS, Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- * E-mail: (AG); (BB)
| | - Bernadette Byrne
- Department of Life Sciences, Imperial College London, London, United Kingdom
- * E-mail: (AG); (BB)
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Jodaitis L, van Oene T, Martens C. Assessing the Role of Lipids in the Molecular Mechanism of Membrane Proteins. Int J Mol Sci 2021; 22:7267. [PMID: 34298884 PMCID: PMC8306737 DOI: 10.3390/ijms22147267] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/30/2021] [Accepted: 07/01/2021] [Indexed: 02/06/2023] Open
Abstract
Membrane proteins have evolved to work optimally within the complex environment of the biological membrane. Consequently, interactions with surrounding lipids are part of their molecular mechanism. Yet, the identification of lipid-protein interactions and the assessment of their molecular role is an experimental challenge. Recently, biophysical approaches have emerged that are compatible with the study of membrane proteins in an environment closer to the biological membrane. These novel approaches revealed specific mechanisms of regulation of membrane protein function. Lipids have been shown to play a role in oligomerization, conformational transitions or allosteric coupling. In this review, we summarize the recent biophysical approaches, or combination thereof, that allow to decipher the role of lipid-protein interactions in the mechanism of membrane proteins.
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Affiliation(s)
| | | | - Chloé Martens
- Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, 1050 Brussels, Belgium; (L.J.); (T.v.O.)
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Impact of Membrane Lipids on UapA and AzgA Transporter Subcellular Localization and Activity in Aspergillus nidulans. J Fungi (Basel) 2021; 7:jof7070514. [PMID: 34203131 PMCID: PMC8304608 DOI: 10.3390/jof7070514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/24/2021] [Accepted: 06/24/2021] [Indexed: 12/21/2022] Open
Abstract
Recent biochemical and biophysical evidence have established that membrane lipids, namely phospholipids, sphingolipids and sterols, are critical for the function of eukaryotic plasma membrane transporters. Here, we study the effect of selected membrane lipid biosynthesis mutations and of the ergosterol-related antifungal itraconazole on the subcellular localization, stability and transport kinetics of two well-studied purine transporters, UapA and AzgA, in Aspergillus nidulans. We show that genetic reduction in biosynthesis of ergosterol, sphingolipids or phosphoinositides arrest A. nidulans growth after germling formation, but solely blocks in early steps of ergosterol (Erg11) or sphingolipid (BasA) synthesis have a negative effect on plasma membrane (PM) localization and stability of transporters before growth arrest. Surprisingly, the fraction of UapA or AzgA that reaches the PM in lipid biosynthesis mutants is shown to conserve normal apparent transport kinetics. We further show that turnover of UapA, which is the transporter mostly sensitive to membrane lipid content modification, occurs during its trafficking and by enhanced endocytosis, and is partly dependent on autophagy and Hect-type HulARsp5 ubiquitination. Our results point out that the role of specific membrane lipids on transporter biogenesis and function in vivo is complex, combinatorial and transporter-dependent.
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28
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Agasid MT, Robinson CV. Probing membrane protein-lipid interactions. Curr Opin Struct Biol 2021; 69:78-85. [PMID: 33930613 DOI: 10.1016/j.sbi.2021.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 03/08/2021] [Accepted: 03/21/2021] [Indexed: 12/15/2022]
Abstract
Structure determination of membrane proteins has highlighted the many roles played by lipids in influencing overall protein architecture. It is now widely accepted that lipids surrounding membrane proteins play crucial roles by modulating their conformational, structural, and functional properties. Capturing often transient lipid interactions and defining their chemical identity, however, remains challenging. Recent advances in mass spectrometry have resolved questions concerning lipid interactions by providing the molecular composition of intact complexes in association with lipids. Together with other biophysical tools, a picture is emerging of the dynamic nature of lipid-mediated interactions and their effects on conformation, interactions, and signaling.
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Affiliation(s)
- Mark T Agasid
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
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29
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Endocytosis of nutrient transporters in fungi: The ART of connecting signaling and trafficking. Comput Struct Biotechnol J 2021; 19:1713-1737. [PMID: 33897977 PMCID: PMC8050425 DOI: 10.1016/j.csbj.2021.03.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 03/14/2021] [Accepted: 03/14/2021] [Indexed: 12/11/2022] Open
Abstract
Plasma membrane transporters play pivotal roles in the import of nutrients, including sugars, amino acids, nucleobases, carboxylic acids, and metal ions, that surround fungal cells. The selective removal of these transporters by endocytosis is one of the most important regulatory mechanisms that ensures a rapid adaptation of cells to the changing environment (e.g., nutrient fluctuations or different stresses). At the heart of this mechanism lies a network of proteins that includes the arrestin‐related trafficking adaptors (ARTs) which link the ubiquitin ligase Rsp5 to nutrient transporters and endocytic factors. Transporter conformational changes, as well as dynamic interactions between its cytosolic termini/loops and with lipids of the plasma membrane, are also critical during the endocytic process. Here, we review the current knowledge and recent findings on the molecular mechanisms involved in nutrient transporter endocytosis, both in the budding yeast Saccharomyces cerevisiae and in some species of the filamentous fungus Aspergillus. We elaborate on the physiological importance of tightly regulated endocytosis for cellular fitness under dynamic conditions found in nature and highlight how further understanding and engineering of this process is essential to maximize titer, rate and yield (TRY)-values of engineered cell factories in industrial biotechnological processes.
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Key Words
- AAs, amino acids
- ACT, amino Acid/Choline Transporter
- AP, adaptor protein
- APC, amino acid-polyamine-organocation
- Arg, arginine
- Arrestins
- Arts, arrestin‐related trafficking adaptors
- Asp, aspartic acid
- Aspergilli
- Biotechnology
- C, carbon
- C-terminus, carboxyl-terminus
- Cell factories
- Conformational changes
- Cu, copper
- DUBs, deubiquitinating enzymes
- EMCs, eisosome membrane compartments
- ER, endoplasmic reticulum
- ESCRT, endosomal sorting complex required for transport
- Endocytic signals
- Endocytosis
- Fe, iron
- Fungi
- GAAC, general amino acid control
- Glu, glutamic acid
- H+, proton
- IF, inward-facing
- LAT, L-type Amino acid Transporter
- LID, loop Interaction Domain
- Lys, lysine
- MCCs, membrane compartments containing the arginine permease Can1
- MCCs/eisosomes
- MCPs, membrane compartments of Pma1
- MFS, major facilitator superfamily
- MVB, multi vesicular bodies
- Met, methionine
- Metabolism
- Mn, manganese
- N, nitrogen
- N-terminus, amino-terminus
- NAT, nucleobase Ascorbate Transporter
- NCS1, nucleobase/Cation Symporter 1
- NCS2, nucleobase cation symporter family 2
- NH4+, ammonium
- Nutrient transporters
- OF, outward-facing
- PEST, proline (P), glutamic acid (E), serine (S), and threonine (T)
- PM, plasma membrane
- PVE, prevacuolar endosome
- Saccharomyces cerevisiae
- Signaling pathways
- Structure-function
- TGN, trans-Golgi network
- TMSs, transmembrane segments
- TORC1, target of rapamycin complex 1
- TRY, titer, rate and yield
- Trp, tryptophan
- Tyr, tyrosine
- Ub, ubiquitin
- Ubiquitylation
- VPS, vacuolar protein sorting
- W/V, weight per volume
- YAT, yeast Amino acid Transporter
- Zn, Zinc
- fAATs, fungal AA transporters
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Affiliation(s)
- James E. Keener
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Guozhi Zhang
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Michael T. Marty
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
- Bio5 Institute, University of Arizona, Tucson, AZ 85721, USA
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31
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Bagheri Y, Ali AA, You M. Current Methods for Detecting Cell Membrane Transient Interactions. Front Chem 2020; 8:603259. [PMID: 33365301 PMCID: PMC7750205 DOI: 10.3389/fchem.2020.603259] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 10/16/2020] [Indexed: 12/28/2022] Open
Abstract
Short-lived cell membrane complexes play a key role in regulating cell signaling and communication. Many of these complexes are formed based on low-affinity and transient interactions among various lipids and proteins. New techniques have emerged to study these previously overlooked membrane transient interactions. Exciting functions of these transient interactions have been discovered in cellular events such as immune signaling, host-pathogen interactions, and diseases such as cancer. In this review, we have summarized current experimental methods that allow us to detect and analyze short-lived cell membrane protein-protein, lipid-protein, and lipid-lipid interactions. These methods can provide useful information about the strengths, kinetics, and/or spatial patterns of membrane transient interactions. However, each method also has its own limitations. We hope this review can be used as a guideline to help the audience to choose proper approaches for studying membrane transient interactions in different membrane trafficking and cell signaling events.
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Affiliation(s)
| | | | - Mingxu You
- Department of Chemistry, University of Massachusetts, Amherst, MA, United States
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Maldonado-Hernández R, Quesada O, Colón-Sáez JO, Lasalde-Dominicci JA. Sequential purification and characterization of Torpedo californica nAChR-DC supplemented with CHS for high-resolution crystallization studies. Anal Biochem 2020; 610:113887. [PMID: 32763308 DOI: 10.1016/j.ab.2020.113887] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 07/14/2020] [Accepted: 07/22/2020] [Indexed: 01/26/2023]
Abstract
Over the past 10 years we have been developing a multi-attribute analytical platform that allows for the preparation of milligram amounts of functional, high-pure, and stable Torpedo (muscle-type) nAChR detergent complexes for crystallization purpose. In the present work, we have been able to significantly improve and optimize the purity and yield of nicotinic acetylcholine receptors in detergent complexes (nAChR-DC) without compromising stability and functionality. We implemented new methods in the process, such as analysis and rapid production of samples for future crystallization preparations. Native nAChR was extracted from the electric organ of Torpedo californica using the lipid-like detergent LysoFos Choline 16 (LFC-16), followed by three consecutive steps of chromatography purification. We evaluated the effect of cholesteryl hemisuccinate (CHS) supplementation during the affinity purification steps of nAChR-LFC-16 in terms of receptor secondary structure, stability and functionality. CHS produced significant changes in the degree of β-secondary structure, these changes compromise the diffusion of the nAChR-LFC-16 in lipid cubic phase. The behavior was reversed by Methyl-β-Cyclodextrin treatment. Also, CHS decreased acetylcholine evoked currents of Xenopus leavis oocyte injected with nAChR-LFC-16 in a concentration-dependent manner. Methyl-β-Cyclodextrin treatment do not reverse functionality, however column delipidation produced a functional protein similar to nAChR-LFC-16 without CHS treatment.
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Affiliation(s)
- Rafael Maldonado-Hernández
- Department of the Biology, University of Puerto Rico, Río Piedras Campus, San Juan, Puerto Rico; Molecular Sciences Research Center, University of Puerto Rico, San Juan, Puerto Rico
| | - Orestes Quesada
- Department of Physical Sciences, University of Puerto Rico, Río Piedras Campus, San Juan, Puerto Rico; Molecular Sciences Research Center, University of Puerto Rico, San Juan, Puerto Rico
| | - José O Colón-Sáez
- Pharmaceutical Sciences, University of Puerto Rico Medical Science Campus, Puerto Rico
| | - José A Lasalde-Dominicci
- Department of the Biology, University of Puerto Rico, Río Piedras Campus, San Juan, Puerto Rico; Molecular Sciences Research Center, University of Puerto Rico, San Juan, Puerto Rico; Institute of Neurobiology, University of Puerto Rico Medical Science Campus, Puerto Rico.
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Barth M, Schmidt C. Native mass spectrometry-A valuable tool in structural biology. JOURNAL OF MASS SPECTROMETRY : JMS 2020; 55:e4578. [PMID: 32662584 DOI: 10.1002/jms.4578] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/18/2020] [Accepted: 05/19/2020] [Indexed: 05/16/2023]
Abstract
Proteins and the complexes they form with their ligands are the players of cellular action. Their function is directly linked with their structure making the structural analysis of protein-ligand complexes essential. Classical techniques of structural biology include X-ray crystallography, nuclear magnetic resonance spectroscopy and recently distinguished cryo-electron microscopy. However, protein-ligand complexes are often dynamic and heterogeneous and consequently challenging for these techniques. Alternative approaches are therefore needed and gained importance during the last decades. One alternative is native mass spectrometry, which is the analysis of intact protein complexes in the gas phase. To achieve this, sample preparation and instrument conditions have to be optimised. Native mass spectrometry then reveals stoichiometry, protein interactions and topology of protein assemblies. Advanced techniques such as ion mobility and high-resolution mass spectrometry further add to the range of applications and deliver information on shape and microheterogeneity of the complexes. In this tutorial, we explain the basics of native mass spectrometry including sample requirements, instrument modifications and interpretation of native mass spectra. We further discuss the developments of native mass spectrometry and provide example spectra and applications.
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Affiliation(s)
- Marie Barth
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany
| | - Carla Schmidt
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Institute for Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany
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34
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Varadarajan V, Desikan R, Ayappa KG. Assessing the extent of the structural and dynamic modulation of membrane lipids due to pore forming toxins: insights from molecular dynamics simulations. SOFT MATTER 2020; 16:4840-4857. [PMID: 32421131 DOI: 10.1039/d0sm00086h] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Infections caused by many virulent bacterial strains are triggered by the release of pore forming toxins (PFTs), which form oligomeric transmembrane pore complexes on the target plasma membrane. The spatial extent of the perturbation to the surrounding lipids during pore formation is relatively unexplored. Using all-atom molecular dynamics simulations, we investigate the changes in the structure and dynamics of lipids in a 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid bilayer in the presence of contrasting PFTs. Cytolysin A (ClyA), an α toxin with its inserted wedge shaped bundle of inserted α helices, induces significant asymmetry across the membrane leaflets in comparison with α hemolysin (AHL), a β toxin. Despite the differences in hydrophobic mismatch and uniquely different topologies of the two oligomers, perturbations to lipid order as reflected in the tilt angle and order parameters and membrane thinning are short ranged, lying within ∼2.5 nm from the periphery of either pore complex, and commensurate with distances typically associated with van der Waals forces. In contrast, the spatial extent of perturbations to the lipid dynamics extends outward to at least 4 nm for both proteins, and the continuous survival probabilities reveal the presence of a tightly bound shell of lipids in this region. Displacement probability distributions show long tails and the distinctly non-Gaussian features reflect the induced dynamic heterogeneity. A detailed profiling of the protein-lipid contacts with tyrosine, tryptophan, lysine and arginine residues shows increased non-polar contacts in the cytoplasmic leaflet for both PFTs, with a higher number of atomic contacts in the case of AHL in the extracellular leaflet due to the mushroom-like topology of the pore complex. The short ranged nature of the perturbations observed in this simple one component membrane suggests inherent plasticity of membrane lipids enabling the recovery of the structure and membrane fluidity even in the presence of these large oligomeric transmembrane protein assemblies. This observation has implications in membrane repair processes such as budding or vesicle fusion events used to mitigate PFT virulence, where the underlying lipid dynamics and fluidity in the vicinity of the pore complex are expected to play an important role.
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Affiliation(s)
- Vadhana Varadarajan
- Department of Chemical Engineering, Indian Institute of Science, Bangalore-560012, India.
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35
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Lloris-Garcerá P, Klinter S, Chen L, Skynner MJ, Löving R, Frauenfeld J. DirectMX - One-Step Reconstitution of Membrane Proteins From Crude Cell Membranes Into Salipro Nanoparticles. Front Bioeng Biotechnol 2020; 8:215. [PMID: 32266242 PMCID: PMC7096351 DOI: 10.3389/fbioe.2020.00215] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 03/03/2020] [Indexed: 01/14/2023] Open
Abstract
Integral membrane proteins (IMPs) are central to many physiological processes and represent ∼60% of current drug targets. An intricate interplay with the lipid molecules in the cell membrane is known to influence the stability, structure and function of IMPs. Detergents are commonly used to solubilize and extract IMPs from cell membranes. However, due to the loss of the lipid environment, IMPs usually tend to be unstable and lose function in the continuous presence of detergent. To overcome this problem, various technologies have been developed, including protein engineering by mutagenesis to improve IMP stability, as well as methods to reconstitute IMPs into detergent-free entities, such as nanodiscs based on apolipoprotein A or its membrane scaffold protein (MSP) derivatives, amphipols, and styrene-maleic acid copolymer-lipid particles (SMALPs). Although significant progress has been made in this field, working with inherently unstable human IMP targets (e.g., GPCRs, ion channels and transporters) remains a challenging task. Here, we present a novel methodology, termed DirectMX (for direct membrane extraction), taking advantage of the saposin-lipoprotein (Salipro) nanoparticle technology to reconstitute fragile IMPs directly from human crude cell membranes. We demonstrate the applicability of the DirectMX methodology by the reconstitution of a human solute carrier transporter and a wild-type GPCR belonging to the human chemokine receptor (CKR) family. We envision that DirectMX bears the potential to enable studies of IMPs that so far remained inaccessible to other solubilization, stabilization or reconstitution methods.
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36
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Campagnaro GD, de Koning HP. Purine and pyrimidine transporters of pathogenic protozoa - conduits for therapeutic agents. Med Res Rev 2020; 40:1679-1714. [PMID: 32144812 DOI: 10.1002/med.21667] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 02/12/2020] [Accepted: 02/18/2020] [Indexed: 02/06/2023]
Abstract
Purines and pyrimidines are essential nutrients for any cell. Most organisms are able to synthesize their own purines and pyrimidines, but this ability was lost in protozoans that adapted to parasitism, leading to a great diversification in transporter activities in these organisms, especially for the acquisition of amino acids and nucleosides from their hosts throughout their life cycles. Many of these transporters have been shown to have sufficiently different substrate affinities from mammalian transporters, making them good carriers for therapeutic agents. In this review, we summarize the knowledge obtained on purine and pyrimidine activities identified in protozoan parasites to date and discuss their importance for the survival of these parasites and as drug carriers, as well as the perspectives of developments in the field.
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Affiliation(s)
- Gustavo D Campagnaro
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 120 University Place, Glasgow, UK
| | - Harry P de Koning
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 120 University Place, Glasgow, UK
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37
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Bender J, Schmidt C. Mass spectrometry of membrane protein complexes. Biol Chem 2020; 400:813-829. [PMID: 30956223 DOI: 10.1515/hsz-2018-0443] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/25/2019] [Indexed: 12/24/2022]
Abstract
Membrane proteins are key players in the cell. Due to their hydrophobic nature they require solubilising agents such as detergents or membrane mimetics during purification and, consequently, are challenging targets in structural biology. In addition, their natural lipid environment is crucial for their structure and function further hampering their analysis. Alternative approaches are therefore required when the analysis by conventional techniques proves difficult. In this review, we highlight the broad application of mass spectrometry (MS) for the characterisation of membrane proteins and their interactions with lipids. We show that MS unambiguously identifies the protein and lipid components of membrane protein complexes, unravels their three-dimensional arrangements and further provides clues of protein-lipid interactions.
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Affiliation(s)
- Julian Bender
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Centre, Martin Luther University Halle-Wittenberg, Institute for Biochemistry and Biotechnology, Kurt-Mothes-Str. 3a, D-06120 Halle, Germany
| | - Carla Schmidt
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Centre, Martin Luther University Halle-Wittenberg, Institute for Biochemistry and Biotechnology, Kurt-Mothes-Str. 3a, D-06120 Halle, Germany
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38
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Styrene maleic-acid lipid particles (SMALPs) into detergent or amphipols: An exchange protocol for membrane protein characterisation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183192. [PMID: 31945320 PMCID: PMC7086155 DOI: 10.1016/j.bbamem.2020.183192] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 12/06/2019] [Accepted: 01/10/2020] [Indexed: 12/24/2022]
Abstract
Membrane proteins are traditionally extracted and purified in detergent for biochemical and structural characterisation. This process is often costly and laborious, and the stripping away of potentially stabilising lipids from the membrane protein of interest can have detrimental effects on protein integrity. Recently, styrene-maleic acid (SMA) co-polymers have offered a solution to this problem by extracting membrane proteins directly from their native membrane, while retaining their naturally associated lipids in the form of stable SMA lipid particles (SMALPs). However, the inherent nature and heterogeneity of the polymer renders their use challenging for some downstream applications – particularly mass spectrometry (MS). While advances in cryo-electron microscopy (cryo-EM) have enhanced our understanding of membrane protein:lipid interactions in both SMALPs and detergent, the resolution obtained with this technique is often insufficient to accurately identify closely associated lipids within the transmembrane annulus. Native-MS has the power to fill this knowledge gap, but the SMA polymer itself remains largely incompatible with this technique. To increase sample homogeneity and allow characterisation of membrane protein:lipid complexes by native-MS, we have developed a novel SMA-exchange method; whereby the membrane protein of interest is first solubilised and purified in SMA, then transferred into amphipols or detergents. This allows the membrane protein and endogenously associated lipids extracted by SMA co-polymer to be identified and examined by MS, thereby complementing results obtained by cryo-EM and creating a better understanding of how the lipid bilayer directly affects membrane protein structure and function. First reported exchange protocol for transferring membrane proteins solubilised in SMALPs, into detergent or amphipols. Purification of protein:lipid complexes without detergent for mass spectrometry and subsequent lipid identification. Cost effective membrane protein purification requiring only minimal amounts of detergents in the exchange process.
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Kourkoulou A, Grevias P, Lambrinidis G, Pyle E, Dionysopoulou M, Politis A, Mikros E, Byrne B, Diallinas G. Specific Residues in a Purine Transporter Are Critical for Dimerization, ER Exit, and Function. Genetics 2019; 213:1357-1372. [PMID: 31611232 PMCID: PMC6893392 DOI: 10.1534/genetics.119.302566] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/02/2019] [Indexed: 12/11/2022] Open
Abstract
Transporters are transmembrane proteins that mediate the selective translocation of solutes across biological membranes. Recently, we have shown that specific interactions with plasma membrane phospholipids are essential for the formation and/or stability of functional dimers of the purine transporter UapA, a prototypic eukaryotic member of the ubiquitous nucleobase ascorbate transporter (NAT) family. Here, we provide strong evidence that distinct interactions of UapA with membrane lipids are essential for ab initio formation of functional dimers in the ER, or ER exit and further subcellular trafficking. Through genetic screens, we identify mutations that restore defects in dimer formation and/or trafficking. Suppressors of defective dimerization restore ab initio formation of UapA dimers in the ER. Most of these suppressors are located in the movable core domain, but also in the core-dimerization interface and in residues of the dimerization domain exposed to lipids. Molecular dynamics suggest that the majority of suppressors stabilize interhelical interactions in the core domain and thus assist the formation of functional UapA dimers. Among suppressors restoring dimerization, a specific mutation, T401P, was also isolated independently as a suppressor restoring trafficking, suggesting that stabilization of the core domain restores function by sustaining structural defects caused by the abolishment of essential interactions with specific lipids. Importantly, the introduction of mutations topologically equivalent to T401P into a rat homolog of UapA, namely rSNBT1, permitted the functional expression of a mammalian NAT in Aspergillus nidulans Thus, our results provide a potential route for the functional expression and manipulation of mammalian transporters in the model Aspergillus system.
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Affiliation(s)
- Anezia Kourkoulou
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15784, Greece
| | - Pothos Grevias
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15784, Greece
| | - George Lambrinidis
- Department of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis, 15771, Greece
| | - Euan Pyle
- Department of Life Sciences, Imperial College London, SW7 2AZ, UK
- Department of Chemistry, King's College London, SE1 1DB, UK
| | - Mariangela Dionysopoulou
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15784, Greece
| | | | - Emmanuel Mikros
- Department of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis, 15771, Greece
| | - Bernadette Byrne
- Department of Life Sciences, Imperial College London, SW7 2AZ, UK
| | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15784, Greece
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Holmes AOM, Kalli AC, Goldman A. The Function of Membrane Integral Pyrophosphatases From Whole Organism to Single Molecule. Front Mol Biosci 2019; 6:132. [PMID: 31824962 PMCID: PMC6882861 DOI: 10.3389/fmolb.2019.00132] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 11/08/2019] [Indexed: 12/02/2022] Open
Abstract
Membrane integral pyrophosphatases (mPPases) are responsible for the hydrolysis of pyrophosphate. This enzymatic mechanism is coupled to the pumping of H+ or Na+ across membranes in a process that can be K+ dependent or independent. Understanding the movements and dynamics throughout the mPPase catalytic cycle is important, as this knowledge is essential for improving or impeding protein function. mPPases have been shown to play a crucial role in plant maturation and abiotic stress tolerance, and so have the potential to be engineered to improve plant survival, with implications for global food security. mPPases are also selectively toxic drug targets, which could be pharmacologically modulated to reduce the virulence of common human pathogens. The last few years have seen the publication of many new insights into the function and structure of mPPases. In particular, there is a new body of evidence that the catalytic cycle is more complex than originally proposed. There are structural and functional data supporting a mechanism involving half-of-the-sites reactivity, inter-subunit communication, and exit channel motions. A more advanced and in-depth understanding of mPPases has begun to be uncovered, leaving the field of research with multiple interesting avenues for further exploration and investigation.
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Affiliation(s)
- Alexandra O. M. Holmes
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Antreas C. Kalli
- Leeds Institute of Cardiovascular and Metabolic Medicine and Astbury Centre for Structural Biology, University of Leeds, Leeds, United Kingdom
| | - Adrian Goldman
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
- Research Program in Molecular and Integrative Biosciences, University of Helsinki, Helsinki, Finland
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Martens C, Shekhar M, Lau AM, Tajkhorshid E, Politis A. Integrating hydrogen-deuterium exchange mass spectrometry with molecular dynamics simulations to probe lipid-modulated conformational changes in membrane proteins. Nat Protoc 2019; 14:3183-3204. [PMID: 31605097 PMCID: PMC7058097 DOI: 10.1038/s41596-019-0219-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 06/20/2019] [Indexed: 12/20/2022]
Abstract
Biological membranes define the boundaries of cells and are composed primarily of phospholipids and membrane proteins. It has become increasingly evident that direct interactions of membrane proteins with their surrounding lipids play key roles in regulating both protein conformations and function. However, the exact nature and structural consequences of these interactions remain difficult to track at the molecular level. Here, we present a protocol that specifically addresses this challenge. First, hydrogen-deuterium exchange mass spectrometry (HDX-MS) of membrane proteins incorporated into nanodiscs of controlled lipid composition is used to obtain information on the lipid species that are involved in modulating the conformational changes in the membrane protein. Then molecular dynamics (MD) simulations in lipid bilayers are used to pinpoint likely lipid-protein interactions, which can be tested experimentally using HDX-MS. By bringing together the MD predictions with the conformational readouts from HDX-MS, we have uncovered key lipid-protein interactions implicated in stabilizing important functional conformations. This protocol can be applied to virtually any integral membrane protein amenable to classic biophysical studies and for which a near-atomic-resolution structure or homology model is available. This protocol takes ~4 d to complete, excluding the time for data analysis and MD simulations, which depends on the size of the protein under investigation.
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Affiliation(s)
- Chloe Martens
- Department of Chemistry, King's College London, London, UK
- Department of Chemistry, Center for Structural Biology and Bioinformatics, Université Libre de Bruxelles, Brussels, Belgium
| | - Mrinal Shekhar
- Center for Biophysics and Quantitative Biology, Department of Biochemistry, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Andy M Lau
- Department of Chemistry, King's College London, London, UK
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology, Department of Biochemistry, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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42
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Saouros S, Cecchetti C, Jones A, Cameron AD, Byrne B. Strategies for successful isolation of a eukaryotic transporter. Protein Expr Purif 2019; 166:105522. [PMID: 31654736 DOI: 10.1016/j.pep.2019.105522] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 10/18/2019] [Accepted: 10/20/2019] [Indexed: 11/24/2022]
Abstract
The isolation of integral membrane proteins for structural analysis remains challenging and this is particularly the case for eukaryotic membrane proteins. Here we describe our efforts to isolate OsBOR3, a boron transporter from Oryza sativa. OsBOR3 was expressed as both full length and a C-terminally truncated form lacking residues 643-672 (OsBOR3Δ1-642). While both express well as C-terminal GFP fusion proteins in Saccharomyces cerevisiae, the full length protein isolates poorly in the detergent dodecyl-β-d-maltoside (DDM). The OsBOR3Δ1-642 isolated in DDM in large quantities but was contaminated with GFP tagged protein, indicated incomplete protease removal of the tag. Addition of the reducing agent dithiothreitol (DTT) had no effect on isolation. Detergent screening indicated that the neopentyl glycol detergents, LMNG, UDMNG and DMNG conferred greater stability on the OsBOR3Δ1-642 than DDM. Isolation of OsBOR3Δ1-642 in LMNG both in the presence and absence of DTT produced large quantities of protein but contaminated with GFP tagged protein. Isolation of OsBOR3Δ1-642 in DMNG + DTT resulted in protein sample that does not contain any detectable GFP but elutes at a higher retention volume than that seen for protein isolated in either DDM or LMNG. Mass spectrometry confirmed that the LMNG and DMNG purified protein is OsBOR3Δ1-642 indicating that the DMNG isolated protein is monomer compared to the dimer isolated using LMNG. This was further supported by single particle electron microscopic analysis revealing that the DMNG protein particles are roughly half the size of the LMNG protein particles.
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Affiliation(s)
- Savvas Saouros
- Department of Life Sciences, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Cristina Cecchetti
- Department of Life Sciences, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Alex Jones
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Alexander D Cameron
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Bernadette Byrne
- Department of Life Sciences, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
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43
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Diallinas G, Martzoukou O. Transporter membrane traffic and function: lessons from a mould. FEBS J 2019; 286:4861-4875. [DOI: 10.1111/febs.15078] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/26/2019] [Accepted: 09/30/2019] [Indexed: 12/16/2022]
Affiliation(s)
- George Diallinas
- Department of Biology National and Kapodistrian University of Athens Greece
| | - Olga Martzoukou
- Department of Biology National and Kapodistrian University of Athens Greece
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44
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Brosseau N, Ramotar D. The human organic cation transporter OCT1 and its role as a target for drug responses. Drug Metab Rev 2019; 51:389-407. [PMID: 31564168 DOI: 10.1080/03602532.2019.1670204] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The human organic cation uptake transporter OCT1, encoded by the SLC22A1 gene, is highly expressed in the liver and reported to possess a broad substrate specificity. OCT1 operates by facilitated diffusion and allows the entry of nutrients into cells. Recent findings revealed that OCT1 can mediate the uptake of drugs for treating various diseases such as cancers. The levels of OCT1 expression correlate with the responses towards many drugs and functionally defective OCT1 lead to drug resistance. It has been recently proposed that OCT1 should be amongst the crucial drug targets used for pharmacogenomic analyses. Several single nucleotide polymorphisms exist and are distributed across the entire OCT1 gene. While there are differences in the OCT1 gene polymorphisms between populations, there are at least five variants that warrant consideration in any genetic screen. To date, and despite two decades of research into OCT1 functional role, it still remains uncertain what are the define substrates for this uptake transporter, although studies from mice revealed that one of the substrates is vitamin B1. It is also unclear how OCT1 recognizes a broad array of ligands and whether this involves specific modifications and interactions with other proteins. In this review, we highlight the current findings related to OCT1 with the aim of propelling further studies on this key uptake transporter.
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Affiliation(s)
- Nicolas Brosseau
- Department of Medicine, Maisonneuve-Rosemont Hospital, Research Center, Université de Montréal, Montréal, Québec, Canada
| | - Dindial Ramotar
- Department of Medicine, Maisonneuve-Rosemont Hospital, Research Center, Université de Montréal, Montréal, Québec, Canada
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Pyle E, Guo C, Hofmann T, Schmidt C, Ribiero O, Politis A, Byrne B. Protein–Lipid Interactions Stabilize the Oligomeric State of BOR1p from Saccharomyces cerevisiae. Anal Chem 2019; 91:13071-13079. [DOI: 10.1021/acs.analchem.9b03271] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Euan Pyle
- Department of Life Sciences, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
- Department of Chemistry, Kings College London, 7 Trinity Street, London SE1 1DB, U.K
| | - Chengzhi Guo
- Department of Life Sciences, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Tommy Hofmann
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Centre, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str 3a, D-06120 Halle, Germany
| | - Carla Schmidt
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Centre, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Str 3a, D-06120 Halle, Germany
| | - Orquidea Ribiero
- Department of Life Sciences, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
| | - Argyris Politis
- Department of Chemistry, Kings College London, 7 Trinity Street, London SE1 1DB, U.K
| | - Bernadette Byrne
- Department of Life Sciences, Imperial College London, Exhibition Road, London SW7 2AZ, U.K
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46
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De Vecchis D, Reithmeier RAF, Kalli AC. Molecular Simulations of Intact Anion Exchanger 1 Reveal Specific Domain and Lipid Interactions. Biophys J 2019; 117:1364-1379. [PMID: 31540709 PMCID: PMC6818359 DOI: 10.1016/j.bpj.2019.08.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/30/2019] [Accepted: 08/22/2019] [Indexed: 12/23/2022] Open
Abstract
Anion exchanger 1 (AE1) is responsible for the exchange of bicarbonate and chloride across the erythrocyte plasma membrane. Human AE1 consists of a cytoplasmic and a membrane domain joined by a 33-residue flexible linker. Crystal structures of the individual domains have been determined, but the intact AE1 structure remains elusive. In this study, we use molecular dynamics simulations and modeling to build intact AE1 structures in a complex lipid bilayer that resembles the native erythrocyte plasma membrane. AE1 models were evaluated using available experimental data to provide an atomistic view of the interaction and dynamics of the cytoplasmic domain, the membrane domain, and the connecting linker in a complete model of AE1 in a lipid bilayer. Anionic lipids were found to interact strongly with AE1 at specific amino acid residues that are linked to diseases and blood group antigens. Cholesterol was found in the dimeric interface of AE1, suggesting that it may regulate subunit interactions and anion transport.
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Affiliation(s)
- Dario De Vecchis
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom
| | | | - Antreas C Kalli
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom; Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.
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47
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Frick M, Schmidt C. Mass spectrometry—A versatile tool for characterising the lipid environment of membrane protein assemblies. Chem Phys Lipids 2019; 221:145-157. [DOI: 10.1016/j.chemphyslip.2019.04.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/28/2019] [Accepted: 04/01/2019] [Indexed: 01/02/2023]
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48
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Abstract
Cell nutrition, detoxification, signalling, homeostasis and response to drugs, processes related to cell growth, differentiation and survival are all mediated by plasma membrane (PM) proteins called transporters. Despite their distinct fine structures, mechanism of function, energetic requirements, kinetics and substrate specificities, all transporters are characterized by a main hydrophobic body embedded in the PM as a series of tightly packed, often intertwined, α-helices that traverse the lipid bilayer in a zigzag mode, connected with intracellular or extracellular loops and hydrophilic N- and C-termini. Whereas longstanding genetic, biochemical and biophysical evidence suggests that specific transmembrane segments, and also their connecting loops, are responsible for substrate recognition and transport dynamics, emerging evidence also reveals the functional importance of transporter N- and C-termini, in respect to transport catalysis, substrate specificity, subcellular expression, stability and signalling. This review highlights selected prototypic examples of transporters in which their termini play important roles in their functioning.
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Affiliation(s)
- Emmanuel Mikros
- Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis, 15771 Athens, Greece
| | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15781 Athens, Greece
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49
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Corradi V, Sejdiu BI, Mesa-Galloso H, Abdizadeh H, Noskov SY, Marrink SJ, Tieleman DP. Emerging Diversity in Lipid-Protein Interactions. Chem Rev 2019; 119:5775-5848. [PMID: 30758191 PMCID: PMC6509647 DOI: 10.1021/acs.chemrev.8b00451] [Citation(s) in RCA: 245] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Indexed: 02/07/2023]
Abstract
Membrane lipids interact with proteins in a variety of ways, ranging from providing a stable membrane environment for proteins to being embedded in to detailed roles in complicated and well-regulated protein functions. Experimental and computational advances are converging in a rapidly expanding research area of lipid-protein interactions. Experimentally, the database of high-resolution membrane protein structures is growing, as are capabilities to identify the complex lipid composition of different membranes, to probe the challenging time and length scales of lipid-protein interactions, and to link lipid-protein interactions to protein function in a variety of proteins. Computationally, more accurate membrane models and more powerful computers now enable a detailed look at lipid-protein interactions and increasing overlap with experimental observations for validation and joint interpretation of simulation and experiment. Here we review papers that use computational approaches to study detailed lipid-protein interactions, together with brief experimental and physiological contexts, aiming at comprehensive coverage of simulation papers in the last five years. Overall, a complex picture of lipid-protein interactions emerges, through a range of mechanisms including modulation of the physical properties of the lipid environment, detailed chemical interactions between lipids and proteins, and key functional roles of very specific lipids binding to well-defined binding sites on proteins. Computationally, despite important limitations, molecular dynamics simulations with current computer power and theoretical models are now in an excellent position to answer detailed questions about lipid-protein interactions.
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Affiliation(s)
- Valentina Corradi
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Besian I. Sejdiu
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Haydee Mesa-Galloso
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Haleh Abdizadeh
- Groningen
Biomolecular Sciences and Biotechnology Institute and Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Sergei Yu. Noskov
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Siewert J. Marrink
- Groningen
Biomolecular Sciences and Biotechnology Institute and Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - D. Peter Tieleman
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
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50
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Marrink SJ, Corradi V, Souza PC, Ingólfsson HI, Tieleman DP, Sansom MS. Computational Modeling of Realistic Cell Membranes. Chem Rev 2019; 119:6184-6226. [PMID: 30623647 PMCID: PMC6509646 DOI: 10.1021/acs.chemrev.8b00460] [Citation(s) in RCA: 422] [Impact Index Per Article: 84.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 12/15/2022]
Abstract
Cell membranes contain a large variety of lipid types and are crowded with proteins, endowing them with the plasticity needed to fulfill their key roles in cell functioning. The compositional complexity of cellular membranes gives rise to a heterogeneous lateral organization, which is still poorly understood. Computational models, in particular molecular dynamics simulations and related techniques, have provided important insight into the organizational principles of cell membranes over the past decades. Now, we are witnessing a transition from simulations of simpler membrane models to multicomponent systems, culminating in realistic models of an increasing variety of cell types and organelles. Here, we review the state of the art in the field of realistic membrane simulations and discuss the current limitations and challenges ahead.
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Affiliation(s)
- Siewert J. Marrink
- Groningen
Biomolecular Sciences and Biotechnology Institute & Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Valentina Corradi
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Paulo C.T. Souza
- Groningen
Biomolecular Sciences and Biotechnology Institute & Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Helgi I. Ingólfsson
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - D. Peter Tieleman
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Mark S.P. Sansom
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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