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Edmond MA, Hinojo-Perez A, Efrem M, Yi-Chun L, Shams I, Hayoz S, de la Cruz A, Perez Rodriguez ME, Diaz-Solares M, Dykxhoorn DM, Luo YL, Barro-Soria R. Lipophilic compounds restore function to neurodevelopmental-associated KCNQ3 mutations. Commun Biol 2024; 7:1181. [PMID: 39300259 DOI: 10.1038/s42003-024-06873-4] [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: 05/07/2024] [Accepted: 09/10/2024] [Indexed: 09/22/2024] Open
Abstract
A major driver of neuronal hyperexcitability is dysfunction of K+ channels, including voltage-gated KCNQ2/3 channels. Their hyperpolarized midpoint of activation and slow activation and deactivation kinetics produce a current that regulates membrane potential and impedes repetitive firing. Inherited mutations in KCNQ2 and KCNQ3 are linked to a wide spectrum of neurodevelopmental disorders (NDDs), ranging from benign familial neonatal seizures to severe epileptic encephalopathies and autism spectrum disorders. However, the impact of these variants on the molecular mechanisms underlying KCNQ3 channel function remains poorly understood and existing treatments have significant side effects. Here, we use voltage clamp fluorometry, molecular dynamic simulations, and electrophysiology to investigate NDD-associated variants in KCNQ3 channels. We identified two distinctive mechanisms by which loss- and gain-of function NDD-associated mutations in KCNQ3 affect channel gating: one directly affects S4 movement while the other changes S4-to-pore coupling. MD simulations and electrophysiology revealed that polyunsaturated fatty acids (PUFAs) primarily target the voltage-sensing domain in its activated conformation and form a weaker interaction with the channel's pore. Consistently, two such compounds yielded partial and complete functional restoration in R227Q- and R236C-containing channels, respectively. Our results reveal the potential of PUFAs to be developed into therapies for diverse KCNQ3-based channelopathies.
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Affiliation(s)
- Michaela A Edmond
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, USA
- Texas A&M University Health Science Center, Department of Neuroscience & Experimental Therapeutics, Bryan, USA
| | - Andy Hinojo-Perez
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Mekedlawit Efrem
- Department of Biotechnology and Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA, USA
| | - Lin Yi-Chun
- Department of Biotechnology and Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA, USA
| | - Iqra Shams
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Sebastien Hayoz
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, USA
- Department of Physiology, University of Arizona, Tucson, USA
| | - Alicia de la Cruz
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, USA
- Linkoping University, Department of Biomedical and Clinical Sciences (BKV), Linkoping, Sweden
| | | | - Maykelis Diaz-Solares
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Derek M Dykxhoorn
- John P. Hussman Institute for Human Genomics, John T. Macdonald Foundation Department of Human Genetics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Yun Lyna Luo
- Department of Biotechnology and Pharmaceutical Sciences, College of Pharmacy, Western University of Health Sciences, Pomona, CA, USA
| | - Rene Barro-Soria
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, USA.
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2
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Ananchenko A, Gao RY, Dehez F, Baenziger JE. State-dependent binding of cholesterol and an anionic lipid to the muscle-type Torpedo nicotinic acetylcholine receptor. Commun Biol 2024; 7:437. [PMID: 38600247 PMCID: PMC11006840 DOI: 10.1038/s42003-024-06106-8] [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: 08/28/2023] [Accepted: 03/25/2024] [Indexed: 04/12/2024] Open
Abstract
The ability of the Torpedo nicotinic acetylcholine receptor (nAChR) to undergo agonist-induced conformational transitions requires the presence of cholesterol and/or anionic lipids. Here we use recently solved structures along with multiscale molecular dynamics simulations to examine lipid binding to the nAChR in bilayers that have defined effects on nAChR function. We examine how phosphatidic acid and cholesterol, lipids that support conformational transitions, individually compete for binding with phosphatidylcholine, a lipid that does not. We also examine how the two lipids work synergistically to stabilize an agonist-responsive nAChR. We identify rapidly exchanging lipid binding sites, including both phospholipid sites with a high affinity for phosphatidic acid and promiscuous cholesterol binding sites in the grooves between adjacent transmembrane α-helices. A high affinity cholesterol site is confirmed in the inner leaflet framed by a key tryptophan residue on the MX α-helix. Our data provide insight into the dynamic nature of lipid-nAChR interactions and set the stage for a detailed understanding of the mechanisms by which lipids facilitate nAChR function at the neuromuscular junction.
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Affiliation(s)
- Anna Ananchenko
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Rui Yan Gao
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - François Dehez
- CNRS, LPCT, Université de Lorraine, F-54000 Nancy, France.
| | - John E Baenziger
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada.
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3
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Parthasarathi KTS, Mandal S, George JP, Gaikwad KB, Sasidharan S, Gundimeda S, Jolly MK, Pandey A, Sharma J. Aberrations in ion channels interacting with lipid metabolism and epithelial-mesenchymal transition in esophageal squamous cell carcinoma. Front Mol Biosci 2023; 10:1201459. [PMID: 37529379 PMCID: PMC10388552 DOI: 10.3389/fmolb.2023.1201459] [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: 04/12/2023] [Accepted: 06/27/2023] [Indexed: 08/03/2023] Open
Abstract
Esophageal squamous cell carcinoma (ESCC) is the most prevalent malignant gastrointestinal tumor. Ion channels contribute to tumor growth and progression through interactions with their neighboring molecules including lipids. The dysregulation of membrane ion channels and lipid metabolism may contribute to the epithelial-mesenchymal transition (EMT), leading to metastatic progression. Herein, transcriptome profiles of patients with ESCC were analyzed by performing differential gene expression and weighted gene co-expression network analysis to identify the altered ion channels, lipid metabolism- and EMT-related genes in ESCC. A total of 1,081 differentially expressed genes, including 113 ion channels, 487 lipid metabolism-related, and 537 EMT-related genes, were identified in patients with ESCC. Thereafter, EMT scores were correlated with altered co-expressed genes. The altered co-expressed genes indicated a correlation with EMT signatures. Interactions among 22 ion channels with 3 hub lipid metabolism- and 13 hub EMT-related proteins were determined using protein-protein interaction networks. A pathway map was generated to depict deregulated signaling pathways including insulin resistance and the estrogen receptor-Ca2+ signaling pathway in ESCC. The relationship between potential ion channels and 5-year survival rates in ESCC was determined using Kaplan-Meier plots and Cox proportional hazard regression analysis. Inositol 1,4,5-trisphosphate receptor type 3 (ITPR3) was found to be associated with poor prognosis of patients with ESCC. Additionally, drugs interacting with potential ion channels, including GJA1 and ITPR3, were identified. Understanding alterations in ion channels with lipid metabolism and EMT in ESCC pathophysiology would most likely provide potential targets for the better treatment of patients with ESCC.
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Affiliation(s)
- K. T. Shreya Parthasarathi
- Institute of Bioinformatics, International Technology Park, Bangalore, India
- Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | - Susmita Mandal
- Center for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India
| | - John Philip George
- Institute of Bioinformatics, International Technology Park, Bangalore, India
- Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | | | - Sruthi Sasidharan
- Institute of Bioinformatics, International Technology Park, Bangalore, India
| | - Seetaramanjaneyulu Gundimeda
- Institute of Bioinformatics, International Technology Park, Bangalore, India
- Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
| | - Mohit Kumar Jolly
- Center for BioSystems Science and Engineering, Indian Institute of Science, Bangalore, India
| | - Akhilesh Pandey
- Department of Laboratory Medicine and Pathology, Rochester, MN, United States
- Center for Molecular Medicine, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India
- Center for Individualized Medicine, Rochester, MN, United States
| | - Jyoti Sharma
- Institute of Bioinformatics, International Technology Park, Bangalore, India
- Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, India
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4
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Schmidpeter PAM, Wu D, Rheinberger J, Riegelhaupt PM, Tang H, Robinson CV, Nimigean CM. Anionic lipids unlock the gates of select ion channels in the pacemaker family. Nat Struct Mol Biol 2022; 29:1092-1100. [PMID: 36352139 PMCID: PMC10022520 DOI: 10.1038/s41594-022-00851-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 09/25/2022] [Indexed: 11/11/2022]
Abstract
Lipids play important roles in regulating membrane protein function, but the molecular mechanisms used are elusive. Here we investigated how anionic lipids modulate SthK, a bacterial pacemaker channel homolog, and HCN2, whose activity contributes to pacemaking in the heart and brain. Using SthK allowed the reconstitution of purified channels in controlled lipid compositions for functional and structural assays that are not available for the eukaryotic channels. We identified anionic lipids bound tightly to SthK and their exact binding locations and determined that they potentiate channel activity. Cryo-EM structures in the most potentiating lipids revealed an open state and identified a nonannular lipid bound with its headgroup near an intersubunit salt bridge that clamps the intracellular channel gate shut. Breaking this conserved salt bridge abolished lipid modulation in SthK and eukaryotic HCN2 channels, indicating that anionic membrane lipids facilitate channel opening by destabilizing these interactions. Our findings underline the importance of state-dependent protein-lipid interactions.
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Affiliation(s)
| | - Di Wu
- Department of Chemistry, University of Oxford, Oxford, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Jan Rheinberger
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA
- Department of Structural Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | | | - Haiping Tang
- Department of Chemistry, University of Oxford, Oxford, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, Oxford, UK
- Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, UK
| | - Crina M Nimigean
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, USA.
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5
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Cheng WWL, Arcario MJ, Petroff JT. Druggable Lipid Binding Sites in Pentameric Ligand-Gated Ion Channels and Transient Receptor Potential Channels. Front Physiol 2022; 12:798102. [PMID: 35069257 PMCID: PMC8777383 DOI: 10.3389/fphys.2021.798102] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 12/02/2021] [Indexed: 12/17/2022] Open
Abstract
Lipids modulate the function of many ion channels, possibly through direct lipid-protein interactions. The recent outpouring of ion channel structures by cryo-EM has revealed many lipid binding sites. Whether these sites mediate lipid modulation of ion channel function is not firmly established in most cases. However, it is intriguing that many of these lipid binding sites are also known sites for other allosteric modulators or drugs, supporting the notion that lipids act as endogenous allosteric modulators through these sites. Here, we review such lipid-drug binding sites, focusing on pentameric ligand-gated ion channels and transient receptor potential channels. Notable examples include sites for phospholipids and sterols that are shared by anesthetics and vanilloids. We discuss some implications of lipid binding at these sites including the possibility that lipids can alter drug potency or that understanding protein-lipid interactions can guide drug design. Structures are only the first step toward understanding the mechanism of lipid modulation at these sites. Looking forward, we identify knowledge gaps in the field and approaches to address them. These include defining the effects of lipids on channel function in reconstituted systems using asymmetric membranes and measuring lipid binding affinities at specific sites using native mass spectrometry, fluorescence binding assays, and computational approaches.
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Affiliation(s)
- Wayland W L Cheng
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO, United States
| | - Mark J Arcario
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO, United States
| | - John T Petroff
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, MO, United States
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6
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PIP 2-dependent coupling of voltage sensor and pore domains in K v7.2 channel. Commun Biol 2021; 4:1189. [PMID: 34650221 PMCID: PMC8517023 DOI: 10.1038/s42003-021-02729-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 09/23/2021] [Indexed: 01/10/2023] Open
Abstract
Phosphatidylinositol-4,5-bisphosphate (PIP2) is a signaling lipid which regulates voltage-gated Kv7/KCNQ potassium channels. Altered PIP2 sensitivity of neuronal Kv7.2 channel is involved in KCNQ2 epileptic encephalopathy. However, the molecular action of PIP2 on Kv7.2 gating remains largely elusive. Here, we use molecular dynamics simulations and electrophysiology to characterize PIP2 binding sites in a human Kv7.2 channel. In the closed state, PIP2 localizes to the periphery of the voltage-sensing domain (VSD). In the open state, PIP2 binds to 4 distinct interfaces formed by the cytoplasmic ends of the VSD, the gate, intracellular helices A and B and their linkers. PIP2 binding induces bilayer-interacting conformation of helices A and B and the correlated motion of the VSD and the pore domain, whereas charge-neutralizing mutations block this coupling and reduce PIP2 sensitivity of Kv7.2 channels by disrupting PIP2 binding. These findings reveal the allosteric role of PIP2 in Kv7.2 channel activation. Pant et al. describe the mechanism by which PIP2 might regulate homomeric Kv7.2 channels. They identify sites important in the binding of the PIP2 lipid to Kv7.2 channels and propose that the PIP2 binding to a specific site results in the coupling between the voltage sensor domain (VSD) and pore domain (PD), which stabilizes the open state of the channel.
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7
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Chen AY, Brooks BR, Damjanovic A. Determinants of conductance of a bacterial voltage-gated sodium channel. Biophys J 2021; 120:3050-3069. [PMID: 34214541 DOI: 10.1016/j.bpj.2021.06.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 05/22/2021] [Accepted: 06/08/2021] [Indexed: 10/21/2022] Open
Abstract
Through molecular dynamics (MD) and free energy simulations in electric fields, we examine the factors influencing conductance of bacterial voltage-gated sodium channel NavMs. The channel utilizes four glutamic acid residues in the selectivity filter (SF). Previously, we have shown, through constant pH and free energy calculations of pKa values, that fully deprotonated, singly protonated, and doubly protonated states are all feasible at physiological pH, depending on how many ions are bound in the SF. With 173 MD simulations of 450 or 500 ns and additional free energy simulations, we determine that the conductance is highest for the deprotonated state and decreases with each additional proton bound. We also determine that the pKa value of the four glutamic residues for the transition between deprotonated and singly protonated states is close to the physiological pH and that there is a small voltage dependence. The pKa value and conductance trends are in agreement with experimental work on bacterial Nav channels, which show a decrease in maximal conductance with lowering of pH, with pKa in the physiological range. We examine binding sites for Na+ in the SF, compare with previous work, and note a dependence on starting structures. We find that narrowing of the gate backbone to values lower than the crystal structure's backbone radius reduces the conductance, whereas increasing the gate radius further does not affect the conductance. Simulations with some amount of negatively charged lipids as opposed to purely neutral lipids increases the conductance, as do simulations at higher voltages.
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Affiliation(s)
- Ada Y Chen
- Department of Physics & Astronomy, Johns Hopkins University, Baltimore, Maryland; Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Bernard R Brooks
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Ana Damjanovic
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; Department of Biophysics, Johns Hopkins University, Baltimore, Maryland.
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8
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Silverå Ejneby M, Gromova A, Ottosson NE, Borg S, Estrada-Mondragón A, Yazdi S, Apostolakis P, Elinder F, Delemotte L. Resin-acid derivatives bind to multiple sites on the voltage-sensor domain of the Shaker potassium channel. J Gen Physiol 2021; 153:211862. [PMID: 33683319 PMCID: PMC7944402 DOI: 10.1085/jgp.202012676] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/30/2020] [Accepted: 01/27/2021] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated potassium (KV) channels can be opened by negatively charged resin acids and their derivatives. These resin acids have been proposed to attract the positively charged voltage-sensor helix (S4) toward the extracellular side of the membrane by binding to a pocket located between the lipid-facing extracellular ends of the transmembrane segments S3 and S4. By contrast to this proposed mechanism, neutralization of the top gating charge of the Shaker KV channel increased resin-acid-induced opening, suggesting other mechanisms and sites of action. Here, we explore the binding of two resin-acid derivatives, Wu50 and Wu161, to the activated/open state of the Shaker KV channel by a combination of in silico docking, molecular dynamics simulations, and electrophysiology of mutated channels. We identified three potential resin-acid-binding sites around S4: (1) the S3/S4 site previously suggested, in which positively charged residues introduced at the top of S4 are critical to keep the compound bound, (2) a site in the cleft between S4 and the pore domain (S4/pore site), in which a tryptophan at the top of S6 and the top gating charge of S4 keeps the compound bound, and (3) a site located on the extracellular side of the voltage-sensor domain, in a cleft formed by S1-S4 (the top-VSD site). The multiple binding sites around S4 and the anticipated helical-screw motion of the helix during activation make the effect of resin-acid derivatives on channel function intricate. The propensity of a specific resin acid to activate and open a voltage-gated channel likely depends on its exact binding dynamics and the types of interactions it can form with the protein in a state-specific manner.
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Affiliation(s)
- Malin Silverå Ejneby
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Arina Gromova
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Nina E Ottosson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Stina Borg
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | | | - Samira Yazdi
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Panagiotis Apostolakis
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Fredrik Elinder
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Lucie Delemotte
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Stockholm, Sweden
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9
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Effertz T, Moser T, Oliver D. Recent advances in cochlear hair cell nanophysiology: subcellular compartmentalization of electrical signaling in compact sensory cells. Fac Rev 2021; 9:24. [PMID: 33659956 PMCID: PMC7886071 DOI: 10.12703/r/9-24] [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] [Indexed: 12/22/2022] Open
Abstract
In recent years, genetics, physiology, and structural biology have advanced into the molecular details of the sensory physiology of auditory hair cells. Inner hair cells (IHCs) and outer hair cells (OHCs) mediate two key functions: active amplification and non-linear compression of cochlear vibrations by OHCs and sound encoding by IHCs at their afferent synapses with the spiral ganglion neurons. OHCs and IHCs share some molecular physiology, e.g. mechanotransduction at the apical hair bundles, ribbon-type presynaptic active zones, and ionic conductances in the basolateral membrane. Unique features enabling their specific function include prestin-based electromotility of OHCs and indefatigable transmitter release at the highest known rates by ribbon-type IHC active zones. Despite their compact morphology, the molecular machineries that either generate electrical signals or are driven by these signals are essentially all segregated into local subcellular structures. This review provides a brief account on recent insights into the molecular physiology of cochlear hair cells with a specific focus on organization into membrane domains.
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Affiliation(s)
- Thomas Effertz
- InnerEarLab, Department of Otorhinolaryngology, University Medical Center Göttingen, 37099 Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, 37075 Göttingen, Germany
| | - Dominik Oliver
- Institute for Physiology and Pathophysiology, Philipps University, Deutschhausstraße 2, 35037 Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Germany
- DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodelling, GRK 2213, Philipps University, Marburg, Germany
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10
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Orädd F, Andersson M. Tracking Membrane Protein Dynamics in Real Time. J Membr Biol 2021; 254:51-64. [PMID: 33409541 PMCID: PMC7936944 DOI: 10.1007/s00232-020-00165-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 12/11/2020] [Indexed: 12/14/2022]
Abstract
Abstract Membrane proteins govern critical cellular processes and are central to human health and associated disease. Understanding of membrane protein function is obscured by the vast ranges of structural dynamics—both in the spatial and time regime—displayed in the protein and surrounding membrane. The membrane lipids have emerged as allosteric modulators of membrane protein function, which further adds to the complexity. In this review, we discuss several examples of membrane dependency. A particular focus is on how molecular dynamics (MD) simulation have aided to map membrane protein dynamics and how enhanced sampling methods can enable observing the otherwise inaccessible biological time scale. Also, time-resolved X-ray scattering in solution is highlighted as a powerful tool to track membrane protein dynamics, in particular when combined with MD simulation to identify transient intermediate states. Finally, we discuss future directions of how to further develop this promising approach to determine structural dynamics of both the protein and the surrounding lipids. Graphic Abstract ![]()
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Affiliation(s)
- Fredrik Orädd
- Department of Chemistry, Umeå University, Umeå, Sweden
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11
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Ko W, Jung SR, Kim KW, Yeon JH, Park CG, Nam JH, Hille B, Suh BC. Allosteric modulation of alternatively spliced Ca 2+-activated Cl - channels TMEM16A by PI(4,5)P 2 and CaMKII. Proc Natl Acad Sci U S A 2020; 117:30787-30798. [PMID: 33199590 PMCID: PMC7720229 DOI: 10.1073/pnas.2014520117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Transmembrane 16A (TMEM16A, anoctamin1), 1 of 10 TMEM16 family proteins, is a Cl- channel activated by intracellular Ca2+ and membrane voltage. This channel is also regulated by the membrane phospholipid phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. We find that two splice variants of TMEM16A show different sensitivity to endogenous PI(4,5)P2 degradation, where TMEM16A(ac) displays higher channel activity and more current inhibition by PI(4,5)P2 depletion than TMEM16A(a). These two channel isoforms differ in the alternative splicing of the c-segment (exon 13). The current amplitude and PI(4,5)P2 sensitivity of both TMEM16A(ac) and (a) are significantly strengthened by decreased free cytosolic ATP and by conditions that decrease phosphorylation by Ca2+/calmodulin-dependent protein kinase II (CaMKII). Noise analysis suggests that the augmentation of currents is due to a rise of single-channel current (i), but not of channel number (N) or open probability (PO). Mutagenesis points to arginine 486 in the first intracellular loop as a putative binding site for PI(4,5)P2, and to serine 673 in the third intracellular loop as a site for regulatory channel phosphorylation that modulates the action of PI(4,5)P2 In silico simulation suggests how phosphorylation of S673 allosterically and differently changes the structure of the distant PI(4,5)P2-binding site between channel splice variants with and without the c-segment exon. In sum, our study reveals the following: differential regulation of alternatively spliced TMEM16A(ac) and (a) by plasma membrane PI(4,5)P2, modification of these effects by channel phosphorylation, identification of the molecular sites, and mechanistic explanation by in silico simulation.
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Affiliation(s)
- Woori Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Seung-Ryoung Jung
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Kwon-Woo Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Jun-Hee Yeon
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Cheon-Gyu Park
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea
| | - Joo Hyun Nam
- Department of Physiology, College of Medicine, Dongguk University, Gyeongju 38066, Republic of Korea
- Ion Channel Disease Research Center, College of Medicine, Dongguk University, Goyang, Gyeonggi-do 10326, Republic of Korea
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195
| | - Byung-Chang Suh
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology, Daegu 42988, Republic of Korea;
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12
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Pantazis A, Kaneko M, Angelini M, Steccanella F, Westerlund AM, Lindström SH, Nilsson M, Delemotte L, Saitta SC, Olcese R. Tracking the motion of the K V1.2 voltage sensor reveals the molecular perturbations caused by a de novo mutation in a case of epilepsy. J Physiol 2020; 598:5245-5269. [PMID: 32833227 PMCID: PMC8923147 DOI: 10.1113/jp280438] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 08/14/2020] [Indexed: 12/28/2022] Open
Abstract
KEY POINTS KV1.2 channels, encoded by the KCNA2 gene, regulate neuronal excitability by conducting K+ upon depolarization. A new KCNA2 missense variant was discovered in a patient with epilepsy, causing amino acid substitution F302L at helix S4, in the KV1.2 voltage-sensing domain. Immunocytochemistry and flow cytometry showed that F302L does not impair KCNA2 subunit surface trafficking. Molecular dynamics simulations indicated that F302L alters the exposure of S4 residues to membrane lipids. Voltage clamp fluorometry revealed that the voltage-sensing domain of KV1.2-F302L channels is more sensitive to depolarization. Accordingly, KV1.2-F302L channels opened faster and at more negative potentials; however, they also exhibited enhanced inactivation: that is, F302L causes both gain- and loss-of-function effects. Coexpression of KCNA2-WT and -F302L did not fully rescue these effects. The proband's symptoms are more characteristic of patients with loss of KCNA2 function. Enhanced KV1.2 inactivation could lead to increased synaptic release in excitatory neurons, steering neuronal circuits towards epilepsy. ABSTRACT An exome-based diagnostic panel in an infant with epilepsy revealed a previously unreported de novo missense variant in KCNA2, which encodes voltage-gated K+ channel KV1.2. This variant causes substitution F302L, in helix S4 of the KV1.2 voltage-sensing domain (VSD). F302L does not affect KCNA2 subunit membrane trafficking. However, it does alter channel functional properties, accelerating channel opening at more hyperpolarized membrane potentials, indicating gain of function. F302L also caused loss of KV1.2 function via accelerated inactivation onset, decelerated recovery and shifted inactivation voltage dependence to more negative potentials. These effects, which are not fully rescued by coexpression of wild-type and mutant KCNA2 subunits, probably result from the enhancement of VSD function, as demonstrated by optically tracking VSD depolarization-evoked conformational rearrangements. In turn, molecular dynamics simulations suggest altered VSD exposure to membrane lipids. Compared to other encephalopathy patients with KCNA2 mutations, the proband exhibits mild neurological impairment, more characteristic of patients with KCNA2 loss of function. Based on this information, we propose a mechanism of epileptogenesis based on enhanced KV1.2 inactivation leading to increased synaptic release preferentially in excitatory neurons, and hence the perturbation of the excitatory/inhibitory balance of neuronal circuits.
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Affiliation(s)
- Antonios Pantazis
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, Linköping, Sweden
- Wallenberg Center for Molecular Medicine, Linköping University, Linköping, Sweden
| | - Maki Kaneko
- Center for Personalized Medicine, Children's Hospital, Los Angeles, Los Angeles, CA, USA
- Division of Genomic Medicine, Department of Pathology, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Marina Angelini
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Federica Steccanella
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Annie M Westerlund
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden
| | - Sarah H Lindström
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, Linköping, Sweden
| | - Michelle Nilsson
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, Linköping, Sweden
| | - Lucie Delemotte
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden
| | - Sulagna C Saitta
- Department of Obstetrics and Gynecology and Division of Medical Genetics, Department of Pediatrics, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
| | - Riccardo Olcese
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
- Brain Research Institute, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA
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13
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Grote F, Lyubartsev AP. Optimization of Slipids Force Field Parameters Describing Headgroups of Phospholipids. J Phys Chem B 2020; 124:8784-8793. [PMID: 32926619 PMCID: PMC7584372 DOI: 10.1021/acs.jpcb.0c06386] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The molecular mechanics force field Slipids developed in a series of works by Jämbeck and Lyubartsev (J. Phys. Chem. B 2012, 116, 3164-3179; J. Chem. Theory Comput. 2012, 8, 2938-2948) generally provides a good description of various lipid bilayer systems. However, it was also found that order parameters of C-H bonds in the glycerol moiety of the phosphatidylcholine headgroup deviate significantly from NMR results. In this work, the dihedral force field parameters have been reparameterized in order to improve the agreement with experiment. For this purpose, we have computed energies for a large amount of lipid headgroup conformations using density functional theory on the B3P86/cc-pvqz level and optimized dihedral angle parameters simultaneously to provide the best fit to the quantum chemical energies. The new parameter set was validated for three lipid bilayer systems against a number of experimental properties including order parameters, area per lipid, scattering form factors, bilayer thickness, area compressibility and lateral diffusion coefficients. In addition, the order parameter dependence on cholesterol content in the POPC bilayer was investigated. It is shown that the new force field significantly improves agreement with the experimental order parameters for the lipid headgroup while keeping good agreement with other experimentally measured properties.
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Affiliation(s)
- Fredrik Grote
- Department of Materials and Environmental Chemistry, Stockholm University, SE 106 91, Stockholm, Sweden
| | - Alexander P Lyubartsev
- Department of Materials and Environmental Chemistry, Stockholm University, SE 106 91, Stockholm, Sweden
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14
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Yang L, Lyman E. Local Enrichment of Unsaturated Chains around the A 2A Adenosine Receptor. Biochemistry 2019; 58:4096-4105. [PMID: 31496229 DOI: 10.1021/acs.biochem.9b00607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Two 15 μs all-atom simulations of the A2A adenosine receptor were obtained in a ternary mixture of cholesterol, saturated phosphatidylcholine lipids, and unsaturated phosphatidylcholine lipids. An analysis of local lipid solvation is reported on the basis of a Voronoi tessellation of the upper and lower leaflets, identifying first and second solvation shells. The local environments of both the inactive state and the partially active state of the receptor are significantly enriched with unsaturated chains but depleted of cholesterol and saturated chains, relative to the bulk membrane composition. In spite of the local depletion of cholesterol, the partially active receptor binds cholesterol at three locations during the entire simulation trajectory. These long-lived interactions represent the extreme of a very broad distribution of first-solvation shell lipid lifetimes, confounding sharp distinctions between lipid interactions. The broad distributions of lifetimes also make equilibrating the local lipid environment difficult, necessitating long simulation times.
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Affiliation(s)
- Lewen Yang
- Department of Epidemiology , University of Florida , Gainesville , Florida 32610 , United States
| | - Edward Lyman
- Department of Physics and Astronomy , University of Delaware , Newark , Delaware 19716 , United States.,Department of Chemistry and Biochemistry , University of Delaware , Newark , Delaware 19716 , United States
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15
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Duncan AL, Song W, Sansom MSP. Lipid-Dependent Regulation of Ion Channels and G Protein-Coupled Receptors: Insights from Structures and Simulations. Annu Rev Pharmacol Toxicol 2019; 60:31-50. [PMID: 31506010 DOI: 10.1146/annurev-pharmtox-010919-023411] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ion channels and G protein-coupled receptors (GPCRs) are regulated by lipids in their membrane environment. Structural studies combined with biophysical and molecular simulation investigations reveal interaction sites for specific lipids on membrane protein structures. For K channels, PIP2 plays a key role in regulating Kv and Kir channels. Likewise, several recent cryo-EM structures of TRP channels have revealed bound lipids, including PIP2 and cholesterol. Among the pentameric ligand-gated ion channel family, structural and biophysical studies suggest the M4 TM helix may act as a lipid sensor, e.g., forming part of the binding sites for neurosteroids on the GABAA receptor. Structures of GPCRs have revealed multiple cholesterol sites, which may modulate both receptor dynamics and receptor oligomerization. PIP2 also interacts with GPCRs and may modulate their interactions with G proteins. Overall, it is evident that multiple lipid binding sites exist on channels and receptors that modulate their function allosterically and are potential druggable sites.
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Affiliation(s)
- Anna L Duncan
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom;
| | - Wanling Song
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom;
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom;
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16
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Muller MP, Jiang T, Sun C, Lihan M, Pant S, Mahinthichaichan P, Trifan A, Tajkhorshid E. Characterization of Lipid-Protein Interactions and Lipid-Mediated Modulation of Membrane Protein Function through Molecular Simulation. Chem Rev 2019; 119:6086-6161. [PMID: 30978005 PMCID: PMC6506392 DOI: 10.1021/acs.chemrev.8b00608] [Citation(s) in RCA: 156] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The cellular membrane constitutes one of the most fundamental compartments of a living cell, where key processes such as selective transport of material and exchange of information between the cell and its environment are mediated by proteins that are closely associated with the membrane. The heterogeneity of lipid composition of biological membranes and the effect of lipid molecules on the structure, dynamics, and function of membrane proteins are now widely recognized. Characterization of these functionally important lipid-protein interactions with experimental techniques is however still prohibitively challenging. Molecular dynamics (MD) simulations offer a powerful complementary approach with sufficient temporal and spatial resolutions to gain atomic-level structural information and energetics on lipid-protein interactions. In this review, we aim to provide a broad survey of MD simulations focusing on exploring lipid-protein interactions and characterizing lipid-modulated protein structure and dynamics that have been successful in providing novel insight into the mechanism of membrane protein function.
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Affiliation(s)
- Melanie P. Muller
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Tao Jiang
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Chang Sun
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Muyun Lihan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Shashank Pant
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Paween Mahinthichaichan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Anda Trifan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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17
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Schumann-Gillett A, Blyth MT, O’Mara ML. Is protein structure enough? A review of the role of lipids in SLC6 transporter function. Neurosci Lett 2019; 700:64-69. [DOI: 10.1016/j.neulet.2018.05.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 05/09/2018] [Accepted: 05/11/2018] [Indexed: 12/17/2022]
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18
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DeMarco KR, Bekker S, Vorobyov I. Challenges and advances in atomistic simulations of potassium and sodium ion channel gating and permeation. J Physiol 2018; 597:679-698. [PMID: 30471114 DOI: 10.1113/jp277088] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Accepted: 10/15/2018] [Indexed: 12/19/2022] Open
Abstract
Ion channels are implicated in many essential physiological events such as electrical signal propagation and cellular communication. The advent of K+ and Na+ ion channel structure determination has facilitated numerous investigations of molecular determinants of their behaviour. At the same time, rapid development of computer hardware and molecular simulation methodologies has made computational studies of large biological molecules in all-atom representation tractable. The concurrent evolution of experimental structural biology with biomolecular computer modelling has yielded mechanistic details of fundamental processes unavailable through experiments alone, such as ion conduction and ion channel gating. This review is a short survey of the atomistic computational investigations of K+ and Na+ ion channels, focusing on KcsA and several voltage-gated channels from the KV and NaV families, which have garnered many successes and engendered several long-standing controversies regarding the nature of their structure-function relationship. We review the latest advancements and challenges facing the field of molecular modelling and simulation regarding the structural and energetic determinants of ion channel function and their agreement with experimental observations.
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Affiliation(s)
- Kevin R DeMarco
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA, USA.,Department of Pharmacology, School of Medicine, University of California, Davis, CA, USA
| | - Slava Bekker
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA, USA.,Chemistry Department, American River College, Sacramento, CA, USA
| | - Igor Vorobyov
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA, USA.,Department of Pharmacology, School of Medicine, University of California, Davis, CA, USA
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19
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Zakany F, Pap P, Papp F, Kovacs T, Nagy P, Peter M, Szente L, Panyi G, Varga Z. Determining the target of membrane sterols on voltage-gated potassium channels. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:312-325. [PMID: 30553843 DOI: 10.1016/j.bbalip.2018.12.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/30/2018] [Accepted: 12/12/2018] [Indexed: 12/18/2022]
Abstract
Cholesterol, an essential lipid component of cellular plasma membranes, regulates fluidity, mechanical integrity, raft structure and may specifically interact with membrane proteins. Numerous effects on ion channels by cholesterol, including changes in current amplitude, voltage dependence and gating kinetics, have been reported. We have previously described such changes in the voltage-gated potassium channel Kv1.3 of lymphocytes by cholesterol and its analog 7-dehydrocholesterol (7DHC). In voltage-gated channels membrane depolarization induces movement of the voltage sensor domains (VSD), which is transmitted by a coupling mechanism to the pore domain (PD) to open the channel. Here, we investigated whether cholesterol effects were mediated by the VSD to the pore or the PD was the direct target. Specificity was tested by comparing Kv1.3 and Kv10.1 channels having different VSD-PD coupling mechanisms. Current recordings were performed with two-electrode voltage-clamp fluorometry, where movement of the VSDs was monitored by attaching fluorophores to external cysteine residues introduced in the channel sequence. Loading the membrane with cholesterol or 7DHC using methyl-β-cyclodextrin induced changes in the steady-state and kinetic parameters of the ionic currents while leaving fluorescence parameters mostly unaffected in both channels. Non-stationary noise analysis revealed that reduction of single channel conductance rather than that of open probability caused the observed current decrease. Furthermore, confocal laser scanning and stimulated emission depletion microscopy demonstrated significant changes in the distribution of these ion channels in response to sterol loading. Our results indicate that sterol-induced effects on ion channel gating directly target the pore and do not act via the VSD.
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Affiliation(s)
- Florina Zakany
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary
| | - Pal Pap
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary; MTA-DE-NAP B Ion Channel Structure-Function Research Group, RCMM, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary
| | - Ferenc Papp
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary; MTA-DE-NAP B Ion Channel Structure-Function Research Group, RCMM, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary
| | - Tamas Kovacs
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary
| | - Peter Nagy
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary
| | - Maria Peter
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Temesvari Krt. 62, Szeged H-6726, Hungary
| | - Lajos Szente
- CycloLab Cyclodextrin R & D Laboratory Ltd., Illatos u. 7, Budapest H-1097, Hungary
| | - Gyorgy Panyi
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary; MTA-DE-NAP B Ion Channel Structure-Function Research Group, RCMM, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary
| | - Zoltan Varga
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary; MTA-DE-NAP B Ion Channel Structure-Function Research Group, RCMM, University of Debrecen, Egyetem ter 1, Debrecen H-4032, Hungary.
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20
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Shaitan KV. Features of Energy Landscape Topography in the Space of Torsion Angles for Macromolecules that Form Unique 3D Structures. Biophysics (Nagoya-shi) 2018. [DOI: 10.1134/s0006350918060246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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21
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A Closely Associated Phospholipase C Regulates Cation Channel Function through Phosphoinositide Hydrolysis. J Neurosci 2018; 38:7622-7634. [PMID: 30037836 DOI: 10.1523/jneurosci.0586-18.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/28/2018] [Accepted: 07/17/2018] [Indexed: 11/21/2022] Open
Abstract
In the hemaphroditic sea snail, Aplysia californica, reproduction is initiated when the bag cell neurons secrete egg-laying hormone during a protracted afterdischarge. A source of depolarization for the afterdischarge is a voltage-gated, nonselective cation channel, similar to transient receptor potential (TRP) channels. Once the afterdischarge is triggered, phospholipase C (PLC) is activated to hydrolyze phosphatidylinositol-4,5-bisphosphate (PIP2) into diacylglycerol (DAG) and inositol trisphosphate (IP3). We previously reported that a DAG analog, 1-oleoyl-2-acetyl-sn-glycerol (OAG), activates a prominent, inward whole-cell cationic current that is enhanced by IP3 To examine the underlying mechanism, we investigated the effect of exogenous OAG and IP3, as well as PLC activation, on cation channel activity and voltage dependence in excised, inside-out patches from cultured bag cell neurons. OAG transiently elevated channel open probability (PO) when applied to excised patches; however, coapplication of IP3 prolonged the OAG-induced response. In patches exposed to OAG and IP3, channel voltage dependence was left-shifted; this was also observed with OAG, but not to the same extent. Introducing the PLC activator, m-3M3FBS, to patches increased channel PO, suggesting PLC may be physically linked to the channels. Accordingly, blocking PLC with U-73122 ablated the m-3M3FBS-induced elevation in PO Treatment with m-3M3FBS left-shifted cation channel voltage dependence to a greater extent than exogenous OAG and IP3 Finally, OAG and IP3 potentiated the stimulatory effect of PKC, which is also associated with the channel. Thus, the PLC-PKC signaling system is physically localized such that PIP2 breakdown products liberated during the afterdischarge modulate the cation channel and temporally influence neuronal activity.SIGNIFICANCE STATEMENT Using excised patches from Aplysia bag cell neurons, we present the first evidence of a nonselective cation channel physically associating with phospholipase C (PLC) at the single-channel level. PLC-mediated breakdown of phospholipids generates diacylglycerol and inositol trisphosphate, which activate the cation channel. This is mimicked by exogenous lipids; furthermore, these second messengers left-shift channel voltage dependence and enhance the response of the channel to protein kinase C. PLC-mediated lipid signaling controls single-channel currents to ensure depolarization is maintained for an extended period of firing, termed the afterdischarge, when the bag cell neurons secrete egg-laying hormone to trigger reproduction.
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22
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Poveda JA, Marcela Giudici A, Lourdes Renart M, Morales A, González-Ros JM. Towards understanding the molecular basis of ion channel modulation by lipids: Mechanistic models and current paradigms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1507-1516. [PMID: 28408206 DOI: 10.1016/j.bbamem.2017.04.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 03/27/2017] [Accepted: 04/09/2017] [Indexed: 10/19/2022]
Abstract
Research on ion channel modulation has become a hot topic because of the key roles these membrane proteins play in both prokaryotic and eukaryotic organisms. In this respect, lipid modulation adds to the overall modulatory mechanisms as a potential via to find new pharmacological targets for drug design based on interfering with lipid/channel interactions. However, our knowledge in this field is scarce and often circumscribed to the sites where lipids bind and/or its final functional consequences. To fully understand this process it is necessary to improve our knowledge on its molecular basis, from the binding sites to the signalling pathways that derive in structural and functional effects on the ion channel. In this review, we have compiled information about such mechanisms and established a classification into four different modes of action. Afterwards, we have revised in more detail the lipid modulation of Cys-loop receptors and of the potassium channel KcsA, which were chosen as model channels modulated by specific lipids. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.
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Affiliation(s)
- José A Poveda
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, 03202 Alicante, Spain.
| | - A Marcela Giudici
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, 03202 Alicante, Spain
| | - M Lourdes Renart
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, 03202 Alicante, Spain
| | - Andrés Morales
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain
| | - José M González-Ros
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, 03202 Alicante, Spain.
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23
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Pearlstein RA, Dickson CJ, Hornak V. Contributions of the membrane dipole potential to the function of voltage-gated cation channels and modulation by small molecule potentiators. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:177-194. [PMID: 27836643 DOI: 10.1016/j.bbamem.2016.11.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 10/28/2016] [Accepted: 11/06/2016] [Indexed: 01/27/2023]
Abstract
The membrane dipole potential (Ψd) constitutes one of three electrical potentials generated by cell membranes. Ψd arises from the unfavorable parallel alignment of phospholipid and water dipoles, and varies in magnitude both longitudinally and laterally across the bilayer according to membrane composition and phospholipid packing density. In this work, we propose that dynamic counter-balancing between Ψd and the transmembrane potential (ΔΨm) governs the conformational state transitions of voltage-gated ion channels. Ψd consists of 1) static outer, and dynamic inner leaflet components (Ψd(extra) and Ψd(intra), respectively); and 2) a transmembrane component (ΔΨd(inner-outer)), ariing from differences in intra- and extracellular leaflet composition. Ψd(intra), which transitions between high and low energy states (Ψd(intra, high) and Ψd(intra, low)) as a function of channel conformation, is transduced by the pore domain. ΔΨd(inner-outer) is transduced by the voltage-sensing (VS) domain in summation with ΔΨm. Potentiation of voltage-gated ion channels is of interest for the treatment of cardiac, neuronal, and other disorders arising from inherited/acquired ion channel dysfunction. Potentiators are widely believed to alter the rates and voltage-dependencies of channel gating transitions by binding to pockets in the membrane-facing and other regions of ion channel targets. Here, we propose that potentiators alter Ψd(intra) and/or Ψd(extra), thereby increasing or decreasing the energy barriers governing channel gating transitions. We used quantum mechanical and molecular dynamics (MD) simulations to predict the overall Ψd-modulating effects of a series of published positive hERG potentiators partitioned into model DOPC bilayers. Our findings suggest a strong correlation between the magnitude of Ψd-lowering and positive hERG potentiation across the series.
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Affiliation(s)
- Robert A Pearlstein
- Global Discovery Chemistry, Computer-Aided Drug Discovery, Novartis Institutes for BioMedical Research, 181 Mass Ave., Cambridge, MA 02139, USA.
| | - Callum J Dickson
- Global Discovery Chemistry, Computer-Aided Drug Discovery, Novartis Institutes for BioMedical Research, 181 Mass Ave., Cambridge, MA 02139, USA
| | - Viktor Hornak
- Global Discovery Chemistry, Computer-Aided Drug Discovery, Novartis Institutes for BioMedical Research, 181 Mass Ave., Cambridge, MA 02139, USA
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24
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Taylor KC, Sanders CR. Regulation of KCNQ/Kv7 family voltage-gated K + channels by lipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:586-597. [PMID: 27818172 DOI: 10.1016/j.bbamem.2016.10.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/24/2016] [Accepted: 10/31/2016] [Indexed: 12/19/2022]
Abstract
Many years of studies have established that lipids can impact membrane protein structure and function through bulk membrane effects, by direct but transient annular interactions with the bilayer-exposed surface of protein transmembrane domains, and by specific binding to protein sites. Here, we focus on how phosphatidylinositol 4,5-bisphosphate (PIP2) and polyunsaturated fatty acids (PUFAs) impact ion channel function and how the structural details of the interactions of these lipids with ion channels are beginning to emerge. We focus on the Kv7 (KCNQ) subfamily of voltage-gated K+ channels, which are regulated by both PIP2 and PUFAs and play a variety of important roles in human health and disease. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Keenan C Taylor
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Charles R Sanders
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
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25
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1-Deoxysphingolipid-induced neurotoxicity involves N-methyl-d-aspartate receptor signaling. Neuropharmacology 2016; 110:211-222. [DOI: 10.1016/j.neuropharm.2016.03.033] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 03/11/2016] [Accepted: 03/22/2016] [Indexed: 11/17/2022]
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26
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Elzinga S, Wood P, Adams AA. Plasma Lipidomic and Inflammatory Cytokine Profiles of Horses With Equine Metabolic Syndrome. J Equine Vet Sci 2016. [DOI: 10.1016/j.jevs.2016.01.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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Pöyry S, Vattulainen I. Role of charged lipids in membrane structures - Insight given by simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2322-2333. [PMID: 27003126 DOI: 10.1016/j.bbamem.2016.03.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 03/09/2016] [Accepted: 03/11/2016] [Indexed: 01/28/2023]
Abstract
Lipids and proteins are the main components of cell membranes. It is becoming increasingly clear that lipids, in addition to providing an environment for proteins to work in, are in many cases also able to modulate the structure and function of those proteins. Particularly charged lipids such as phosphatidylinositols and phosphatidylserines are involved in several examples of such effects. Molecular dynamics simulations have proved an invaluable tool in exploring these aspects. This so-called computational microscope can provide both complementing explanations for the experimental results and guide experiments to fruitful directions. In this paper, we review studies that have utilized molecular dynamics simulations to unravel the roles of charged lipids in membrane structures. We focus on lipids as active constituents of the membranes, affecting both general membrane properties as well as non-lipid membrane components, mainly proteins. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
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Affiliation(s)
- Sanja Pöyry
- Department of Physics, Tampere University of Technology, POB 692, FI-33101 Tampere, Finland
| | - Ilpo Vattulainen
- Department of Physics, Tampere University of Technology, POB 692, FI-33101 Tampere, Finland; MEMPHYS - Center for Biomembrane Physics, University of Southern Denmark, Odense, Denmark; Department of Physics, University of Helsinki, POB 64, FI-00014 Helsinki, Finland.
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28
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Cournia Z, Allen TW, Andricioaei I, Antonny B, Baum D, Brannigan G, Buchete NV, Deckman JT, Delemotte L, del Val C, Friedman R, Gkeka P, Hege HC, Hénin J, Kasimova MA, Kolocouris A, Klein ML, Khalid S, Lemieux MJ, Lindow N, Roy M, Selent J, Tarek M, Tofoleanu F, Vanni S, Urban S, Wales DJ, Smith JC, Bondar AN. Membrane Protein Structure, Function, and Dynamics: a Perspective from Experiments and Theory. J Membr Biol 2015; 248:611-40. [PMID: 26063070 PMCID: PMC4515176 DOI: 10.1007/s00232-015-9802-0] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 03/26/2015] [Indexed: 01/05/2023]
Abstract
Membrane proteins mediate processes that are fundamental for the flourishing of biological cells. Membrane-embedded transporters move ions and larger solutes across membranes; receptors mediate communication between the cell and its environment and membrane-embedded enzymes catalyze chemical reactions. Understanding these mechanisms of action requires knowledge of how the proteins couple to their fluid, hydrated lipid membrane environment. We present here current studies in computational and experimental membrane protein biophysics, and show how they address outstanding challenges in understanding the complex environmental effects on the structure, function, and dynamics of membrane proteins.
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Affiliation(s)
- Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece
| | - Toby W. Allen
- School of Applied Sciences & Health Innovations Research Institute, RMIT University, GPO Box 2476, Melbourne, Vic, 3001, Australia; and Department of Chemistry, University of California, Davis. Davis, CA 95616, USA
| | - Ioan Andricioaei
- Department of Chemistry, University of California, Irvine, CA 92697
| | - Bruno Antonny
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis and Centre National de la Recherche Scientifique, UMR 7275, 06560 Valbonne, France
| | - Daniel Baum
- Department of Visualization and Data Analysis, Zuse Institute Berlin, Takustrasse 7, D-14195 Berlin, Germany
| | - Grace Brannigan
- Center for Computational and Integrative Biology and Department of Physics, Rutgers University-Camden, Camden, NJ, USA
| | - Nicolae-Viorel Buchete
- School of Physics and Complex and Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4, Ireland
| | | | - Lucie Delemotte
- Institute of Computational and Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Coral del Val
- Department of Artificial Intelligence, University of Granada, E-18071 Granada, Spain
| | - Ran Friedman
- Linnæus University, Department of Chemistry and Biomedical Sciences & Centre for Biomaterials Chemistry, 391 82 Kalmar, Sweden
| | - Paraskevi Gkeka
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece
| | - Hans-Christian Hege
- Department of Visualization and Data Analysis, Zuse Institute Berlin, Takustrasse 7, D-14195 Berlin, Germany
| | - Jérôme Hénin
- Laboratoire de Biochimie Théorique, IBPC and CNRS, Paris, France
| | - Marina A. Kasimova
- Université de Lorraine, SRSMC, UMR 7565, Vandoeuvre-lès-Nancy, F-54500, France
- Lomonosov Moscow State University, Moscow, 119991, Russian Federation
| | - Antonios Kolocouris
- Faculty of Pharmacy, Department of Pharmaceutical Chemistry, University of Athens, Panepistimioupolis-Zografou, 15771 Athens, Greece
| | - Michael L. Klein
- Institute of Computational and Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Syma Khalid
- Department of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, UK
| | - M. Joanne Lemieux
- Department of Biochemistry, Faculty of Medicine & Dentistry, Membrane Protein Disease Research Group, and Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Norbert Lindow
- Department of Visualization and Data Analysis, Zuse Institute Berlin, Takustrasse 7, D-14195 Berlin, Germany
| | - Mahua Roy
- Department of Chemistry, University of California, Irvine
| | - Jana Selent
- Research Programme on Biomedical Informatics (GRIB), Department of Experimental and Health Sciences, Universitat Pompeu Fabra, IMIM (Hospital del Mar Medical Research Institute), Dr. Aiguader 88, E-08003 Barcelona, Spain
| | - Mounir Tarek
- Université de Lorraine, SRSMC, UMR 7565, Vandoeuvre-lès-Nancy, F-54500, France
- CNRS, SRSMC, UMR 7565, Vandoeuvre-lès-Nancy, F-54500, France
| | - Florentina Tofoleanu
- School of Physics and Complex and Adaptive Systems Laboratory, University College Dublin, Belfield, Dublin 4, Ireland
| | - Stefano Vanni
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis and Centre National de la Recherche Scientifique, UMR 7275, 06560 Valbonne, France
| | - Sinisa Urban
- Johns Hopkins University School of Medicine, Howard Hughes Medical Institute, Department of Molecular Biology & Genetics, 725 N. Wolfe Street, 507 Preclinical Teaching Building, Baltimore, MD 21205, USA
| | - David J. Wales
- University Chemical Laboratories, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Jeremy C. Smith
- Oak Ridge National Laboratory, PO BOX 2008 MS6309, Oak Ridge, TN 37831-6309, USA
| | - Ana-Nicoleta Bondar
- Theoretical Molecular Biophysics, Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
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29
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Kasimova MA, Zaydman MA, Cui J, Tarek M. PIP₂-dependent coupling is prominent in Kv7.1 due to weakened interactions between S4-S5 and S6. Sci Rep 2015; 5:7474. [PMID: 25559286 PMCID: PMC4284513 DOI: 10.1038/srep07474] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 11/21/2014] [Indexed: 02/06/2023] Open
Abstract
Among critical aspects of voltage-gated potassium (Kv) channels' functioning is the effective communication between their two composing domains, the voltage sensor (VSD) and the pore. This communication, called coupling, might be transmitted directly through interactions between these domains and, as recently proposed, indirectly through interactions with phosphatidylinositol-4,5-bisphosphate (PIP₂), a minor lipid of the inner plasma membrane leaflet. Here, we show how the two components of coupling, mediated by protein-protein or protein-lipid interactions, both contribute in the Kv7.1 functioning. On the one hand, using molecular dynamics simulations, we identified a Kv7.1 PIP₂ binding site that involves residues playing a key role in PIP₂-dependent coupling. On the other hand, combined theoretical and experimental approaches have shown that the direct interaction between the segments of the VSD (S4-S5) and the pore (S6) is weakened by electrostatic repulsion. Finally, we conclude that due to weakened protein-protein interactions, the PIP2-dependent coupling is especially prominent in Kv7.1.
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Affiliation(s)
- Marina A Kasimova
- 1] Université de Lorraine, Theory, Modeling and Simulations, UMR 7565, Vandoeuvre-lés-Nancy, F-54506 France [2] Lomonosov Moscow State University, Moscow, 119991, Russian Federation
| | - Mark A Zaydman
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, MO 63130-4862
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Diseases, Cardiac Bioelectricity and Arrhythmia Center, Washington University in St. Louis, St. Louis, MO 63130-4862
| | - Mounir Tarek
- 1] Université de Lorraine, Theory, Modeling and Simulations, UMR 7565, Vandoeuvre-lés-Nancy, F-54506 France [2] Centre National de la Recherche Scientifique, UMR 7565, Vandoeuvre-lés-Nancy, F-54506 France
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30
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Abstract
Lipid metabolism is regulated by multiple signaling pathways, and generates a variety of bioactive lipid molecules. These bioactive lipid molecules known as signaling molecules, such as fatty acid, eicosanoids, diacylglycerol, phosphatidic acid, lysophophatidic acid, ceramide, sphingosine, sphingosine-1-phosphate, phosphatidylinositol-3 phosphate, and cholesterol, are involved in the activation or regulation of different signaling pathways. Lipid metabolism participates in the regulation of many cellular processes such as cell growth, proliferation, differentiation, survival, apoptosis, inflammation, motility, membrane homeostasis, chemotherapy response, and drug resistance. Bioactive lipid molecules promote apoptosis via the intrinsic pathway by modulating mitochondrial membrane permeability and activating different enzymes including caspases. In this review, we discuss recent data in the fields of lipid metabolism, lipid-mediated apoptosis, and cancer therapy. In conclusion, understanding the underlying molecular mechanism of lipid metabolism and the function of different lipid molecules could provide the basis for cancer cell death rationale, discover novel and potential targets, and develop new anticancer drugs for cancer therapy.
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31
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Mertins B, Psakis G, Essen LO. Voltage-dependent anion channels: the wizard of the mitochondrial outer membrane. Biol Chem 2014; 395:1435-42. [DOI: 10.1515/hsz-2014-0203] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 08/18/2014] [Indexed: 11/15/2022]
Abstract
Abstract
Voltage dependent anion channels (VDACs) are the most abundant proteins in the outer mitochondrial membrane. Although they are essential in metabolite exchange, cell defense and apoptosis, the molecular mechanism of these VDAC-mediated processes remains elusive. Here we review recent progress in terms of VDACs’ structure and regulation, with a special focus on the molecular aspects of gating and the interaction with effector proteins.
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