1
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Shang Z, Zhao J, Yang M, Xiao Y, Chu W, Xu S, Zhang X, Yi X, Lin M, Xia F. Precise control of transmembrane current via regulating bionic lipid membrane composition. SCIENCE ADVANCES 2024; 10:eadq0118. [PMID: 39213352 PMCID: PMC11364097 DOI: 10.1126/sciadv.adq0118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Accepted: 07/25/2024] [Indexed: 09/04/2024]
Abstract
The transport of ions through biological ion channels is regulated not only by their structural characteristics but also by the composition of the phospholipid membrane, which serves as a carrier for nanochannels. Inspired by the modulation of ion currents by lipid membrane composition, exemplified by the activation of the K+ channel of Streptomyces A by anionic lipids, we present a biomimetic nanochannel system based on combining DNA nanotechnology with two-dimensional graphene oxide (GO) nanosheets. By designing multibranched DNA nanowires, we assemble programmable DNA scaffold networks (DSNs) on the GO surface to precisely control membrane composition. Modulating the DSN layers from one to five enhances DNA composition, yielding a maximum 12-fold enhancement in ion current, primarily due to charge effects. Incorporating DNAzymes facilitates reversible modulation of membrane composition, enabling cyclic conversion of ion current. This approach offers a pathway for creating devices with highly efficient, tunable ion transport, applicable in diverse fields like mass transport, environmental protection, biomimetic channels, and biosensors.
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Affiliation(s)
- Zhiwei Shang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Jing Zhao
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Mengyu Yang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Yuling Xiao
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Wenjing Chu
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Shijun Xu
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Xiaojin Zhang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Xiaoqing Yi
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases, Ministry of Education, Gannan Medical University, Ganzhou 341000, China
| | - Meihua Lin
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Fan Xia
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074, China
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2
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Sikorskaya TV, Ermolenko EV, Ginanova TT, Boroda AV, Efimova KV, Bogdanov M. Membrane vectorial lipidomic features of coral host cells' plasma membrane and lipid profiles of their endosymbionts Cladocopium. Commun Biol 2024; 7:878. [PMID: 39025984 PMCID: PMC11258240 DOI: 10.1038/s42003-024-06578-8] [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: 01/14/2024] [Accepted: 07/11/2024] [Indexed: 07/20/2024] Open
Abstract
The symbiotic relationships between coral animal host and autotrophic dinoflagellates are based on the mutual exchange and tight control of nutritional inputs supporting successful growth. The corals Sinularia heterospiculata and Acropora aspera were cultivated using a flow-through circulation system supplying seawater during cold and warm seasons of the year, then sorted into host cells and symbionts and subjected to phylogenetic, morphological, and advanced lipid analyses. Here we show, that the lipidomes of the dinoflagellates Cladocopium C1/C3 and acroporide-specific Cladocopium hosted by the corals, are determined by lipidomic features of different thermosensitivity and unique betaine- and phospholipid molecular species. Phosphatidylserines and ceramiaminoethylphosphonates are not detected in the symbionts and predominantly localized on the inner leaflet of the S. heterospiculata host plasma membrane. The transmembrane distribution of phosphatidylethanolamines of S. heterospiculata host changes during different seasons of the year, possibly contributing to mutualistic nutritional exchange across this membrane complex to provide the host with a secure adaptive mechanism and ecological benefits.
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Affiliation(s)
- Tatyana V Sikorskaya
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russian Federation.
| | - Ekaterina V Ermolenko
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russian Federation
| | - Taliya T Ginanova
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russian Federation
| | - Andrey V Boroda
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russian Federation
| | - Kseniya V Efimova
- A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russian Federation
| | - Mikhail Bogdanov
- Department of Biochemistry and Molecular Biology, the University of Texas Health Science Center, McGovern Medical School, Houston, TX, USA.
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3
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Zhao C. Limitations in membrane protein structure determination by lipid nanodiscs. Trends Biochem Sci 2024; 49:475-476. [PMID: 38538407 DOI: 10.1016/j.tibs.2024.03.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 06/09/2024]
Abstract
Lipid nanodiscs are popular mimetics of biological membranes for determining membrane protein structures. However, a recent study revealed that the choice of nanodisc scaffold directly influenced the structure of an ion channel. This finding prompts us to be cautious and calls for improved membrane mimetics for structure determination.
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Affiliation(s)
- Chen Zhao
- Department of Biochemistry and Molecular Biology, University of Florida, College of Medicine, Gainesville, FL 32611, USA.
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4
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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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5
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Bharambe N, Li Z, Seiferth D, Balakrishna AM, Biggin PC, Basak S. Cryo-EM structures of prokaryotic ligand-gated ion channel GLIC provide insights into gating in a lipid environment. Nat Commun 2024; 15:2967. [PMID: 38580666 PMCID: PMC10997623 DOI: 10.1038/s41467-024-47370-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 03/28/2024] [Indexed: 04/07/2024] Open
Abstract
GLIC, a proton-activated prokaryotic ligand-gated ion channel, served as a model system for understanding the eukaryotic counterparts due to their structural and functional similarities. Despite extensive studies conducted on GLIC, the molecular mechanism of channel gating in the lipid environment requires further investigation. Here, we present the cryo-EM structures of nanodisc-reconstituted GLIC at neutral and acidic pH in the resolution range of 2.6 - 3.4 Å. In our apo state at pH 7.5, the extracellular domain (ECD) displays conformational variations compared to the existing apo structures. At pH 4.0, three distinct conformational states (C1, C2 and O states) are identified. The protonated structures exhibit a compacted and counter-clockwise rotated ECD compared with our apo state. A gradual widening of the pore in the TMD is observed upon reducing the pH, with the widest pore in O state, accompanied by several layers of water pentagons. The pore radius and molecular dynamics (MD) simulations suggest that the O state represents an open conductive state. We also observe state-dependent interactions between several lipids and proteins that may be involved in the regulation of channel gating. Our results provide comprehensive insights into the importance of lipids impact on gating.
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Affiliation(s)
- Nikhil Bharambe
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - Zhuowen Li
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore
| | - David Seiferth
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Philip C Biggin
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, UK
| | - Sandip Basak
- School of Biological Sciences, Nanyang Technological University, Singapore, 637551, Singapore.
- NTU Institute of Structural Biology, Nanyang Technological University, Singapore, 639798, Singapore.
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6
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Sandberg JW, Santiago-McRae E, Ennis J, Brannigan G. The density-threshold affinity: Calculating lipid binding affinities from unbiased coarse-grained molecular dynamics simulations. Methods Enzymol 2024; 701:47-82. [PMID: 39025580 DOI: 10.1016/bs.mie.2024.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Many membrane proteins are sensitive to their local lipid environment. As structural methods for membrane proteins have improved, there is growing evidence of direct, specific binding of lipids to protein surfaces. Unfortunately the workhorse of understanding protein-small molecule interactions, the binding affinity for a given site, is experimentally inaccessible for these systems. Coarse-grained molecular dynamics simulations can be used to bridge this gap, and are relatively straightforward to learn. Such simulations allow users to observe spontaneous binding of lipids to membrane proteins and quantify localized densities of individual lipids or lipid fragments. In this chapter we outline a protocol for extracting binding affinities from these localized distributions, known as the "density threshold affinity." The density threshold affinity uses an adaptive and flexible definition of site occupancy that alleviates the need to distinguish between "bound'' lipids and bulk lipids that are simply diffusing through the site. Furthermore, the method allows "bead-level" resolution that is suitable for the case where lipids share binding sites, and circumvents ambiguities about a relevant reference state. This approach provides a convenient and straightforward method for comparing affinities of a single lipid species for multiple sites, multiple lipids for a single site, and/or a single lipid species modeled using multiple forcefields.
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Affiliation(s)
- Jesse W Sandberg
- Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, United States
| | - Ezry Santiago-McRae
- Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, United States
| | - Jahmal Ennis
- Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, United States
| | - Grace Brannigan
- Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, United States; Department of Physics, Rutgers University, Camden, NJ, United States.
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7
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Thompson MJ, Mansoub Bekarkhanechi F, Ananchenko A, Nury H, Baenziger JE. A release of local subunit conformational heterogeneity underlies gating in a muscle nicotinic acetylcholine receptor. Nat Commun 2024; 15:1803. [PMID: 38413583 PMCID: PMC10899235 DOI: 10.1038/s41467-024-46028-x] [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: 05/26/2023] [Accepted: 02/12/2024] [Indexed: 02/29/2024] Open
Abstract
Synaptic receptors respond to neurotransmitters by opening an ion channel across the post-synaptic membrane to elicit a cellular response. Here we use recent Torpedo acetylcholine receptor structures and functional measurements to delineate a key feature underlying allosteric communication between the agonist-binding extracellular and channel-gating transmembrane domains. Extensive mutagenesis at this inter-domain interface re-affirms a critical energetically coupled role for the principal α subunit β1-β2 and M2-M3 loops, with agonist binding re-positioning a key β1-β2 glutamate/valine to facilitate the outward motions of a conserved M2-M3 proline to open the channel gate. Notably, the analogous structures in non-α subunits adopt a locally active-like conformation in the apo state even though each L9' hydrophobic gate residue in each pore-lining M2 α-helix is closed. Agonist binding releases local conformational heterogeneity transitioning all five subunits into a conformationally symmetric open state. A release of conformational heterogeneity provides a framework for understanding allosteric communication in pentameric ligand-gated ion channels.
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Affiliation(s)
- Mackenzie J Thompson
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | | | - Anna Ananchenko
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Hugues Nury
- Université Grenoble Alpes, CNRS, CEA, IBS, F-38000, Grenoble, France
| | - John E Baenziger
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON, K1H 8M5, Canada.
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8
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Bergh C, Rovšnik U, Howard R, Lindahl E. Discovery of lipid binding sites in a ligand-gated ion channel by integrating simulations and cryo-EM. eLife 2024; 12:RP86016. [PMID: 38289224 PMCID: PMC10945520 DOI: 10.7554/elife.86016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024] Open
Abstract
Ligand-gated ion channels transduce electrochemical signals in neurons and other excitable cells. Aside from canonical ligands, phospholipids are thought to bind specifically to the transmembrane domain of several ion channels. However, structural details of such lipid contacts remain elusive, partly due to limited resolution of these regions in experimental structures. Here, we discovered multiple lipid interactions in the channel GLIC by integrating cryo-electron microscopy and large-scale molecular simulations. We identified 25 bound lipids in the GLIC closed state, a conformation where none, to our knowledge, were previously known. Three lipids were associated with each subunit in the inner leaflet, including a buried interaction disrupted in mutant simulations. In the outer leaflet, two intrasubunit sites were evident in both closed and open states, while a putative intersubunit site was preferred in open-state simulations. This work offers molecular details of GLIC-lipid contacts particularly in the ill-characterized closed state, testable hypotheses for state-dependent binding, and a multidisciplinary strategy for modeling protein-lipid interactions.
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Affiliation(s)
- Cathrine Bergh
- Science for Life Laboratory & Swedish e-Science Research Center, Department of Applied Physics, KTH Royal Institute of TechnologyStockholmSweden
| | - Urška Rovšnik
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm UniversityStockholmSweden
| | - Rebecca Howard
- Science for Life Laboratory & Swedish e-Science Research Center, Department of Applied Physics, KTH Royal Institute of TechnologyStockholmSweden
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm UniversityStockholmSweden
| | - Erik Lindahl
- Science for Life Laboratory & Swedish e-Science Research Center, Department of Applied Physics, KTH Royal Institute of TechnologyStockholmSweden
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm UniversityStockholmSweden
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9
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Dalal V, Arcario MJ, Petroff JT, Tan BK, Dietzen NM, Rau MJ, Fitzpatrick JAJ, Brannigan G, Cheng WWL. Lipid nanodisc scaffold and size alter the structure of a pentameric ligand-gated ion channel. Nat Commun 2024; 15:25. [PMID: 38167383 PMCID: PMC10762164 DOI: 10.1038/s41467-023-44366-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 12/11/2023] [Indexed: 01/05/2024] Open
Abstract
Lipid nanodiscs have become a standard tool for studying membrane proteins, including using single particle cryo-electron microscopy (cryo-EM). We find that reconstituting the pentameric ligand-gated ion channel (pLGIC), Erwinia ligand-gated ion channel (ELIC), in different nanodiscs produces distinct structures by cryo-EM. The effect of the nanodisc on ELIC structure extends to the extracellular domain and agonist binding site. Additionally, molecular dynamic simulations indicate that nanodiscs of different size impact ELIC structure and that the nanodisc scaffold directly interacts with ELIC. These findings suggest that the nanodisc plays a crucial role in determining the structure of pLGICs, and that reconstitution of ion channels in larger nanodiscs may better approximate a lipid membrane environment.
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Affiliation(s)
- Vikram Dalal
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Mark J Arcario
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - John T Petroff
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Brandon K Tan
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Noah M Dietzen
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Michael J Rau
- Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO, USA
| | - James A J Fitzpatrick
- Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO, USA
| | - Grace Brannigan
- Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, USA
- Department of Physics, Rutgers University, Camden, NJ, USA
| | - Wayland W L Cheng
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA.
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10
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Ansell TB, Song W, Coupland CE, Carrique L, Corey RA, Duncan AL, Cassidy CK, Geurts MMG, Rasmussen T, Ward AB, Siebold C, Stansfeld PJ, Sansom MSP. LipIDens: simulation assisted interpretation of lipid densities in cryo-EM structures of membrane proteins. Nat Commun 2023; 14:7774. [PMID: 38012131 PMCID: PMC10682427 DOI: 10.1038/s41467-023-43392-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 11/07/2023] [Indexed: 11/29/2023] Open
Abstract
Cryo-electron microscopy (cryo-EM) enables the determination of membrane protein structures in native-like environments. Characterising how membrane proteins interact with the surrounding membrane lipid environment is assisted by resolution of lipid-like densities visible in cryo-EM maps. Nevertheless, establishing the molecular identity of putative lipid and/or detergent densities remains challenging. Here we present LipIDens, a pipeline for molecular dynamics (MD) simulation-assisted interpretation of lipid and lipid-like densities in cryo-EM structures. The pipeline integrates the implementation and analysis of multi-scale MD simulations for identification, ranking and refinement of lipid binding poses which superpose onto cryo-EM map densities. Thus, LipIDens enables direct integration of experimental and computational structural approaches to facilitate the interpretation of lipid-like cryo-EM densities and to reveal the molecular identities of protein-lipid interactions within a bilayer environment. We demonstrate this by application of our open-source LipIDens code to ten diverse membrane protein structures which exhibit lipid-like densities.
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Affiliation(s)
- T Bertie Ansell
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Wanling Song
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
- MSD R&D Innovation Centre, 120 Moorgate, London, EC2M 6UR, UK
| | - Claire E Coupland
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - Loic Carrique
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Robin A Corey
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
| | - Anna L Duncan
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
- Department of Chemistry, Aarhus University, Lagelsandsgade 140, 8000, Aarhus C, Denmark
| | - C Keith Cassidy
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
- Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | - Maxwell M G Geurts
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Tim Rasmussen
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, Haus D15, Josef-Schneider-Str. 2, 97080, Würzburg, Germany
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Phillip J Stansfeld
- School of Life Sciences & Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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11
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Papadourakis M, Sinenka H, Matricon P, Hénin J, Brannigan G, Pérez-Benito L, Pande V, van Vlijmen H, de Graaf C, Deflorian F, Tresadern G, Cecchini M, Cournia Z. Alchemical Free Energy Calculations on Membrane-Associated Proteins. J Chem Theory Comput 2023; 19:7437-7458. [PMID: 37902715 PMCID: PMC11017255 DOI: 10.1021/acs.jctc.3c00365] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Indexed: 10/31/2023]
Abstract
Membrane proteins have diverse functions within cells and are well-established drug targets. The advances in membrane protein structural biology have revealed drug and lipid binding sites on membrane proteins, while computational methods such as molecular simulations can resolve the thermodynamic basis of these interactions. Particularly, alchemical free energy calculations have shown promise in the calculation of reliable and reproducible binding free energies of protein-ligand and protein-lipid complexes in membrane-associated systems. In this review, we present an overview of representative alchemical free energy studies on G-protein-coupled receptors, ion channels, transporters as well as protein-lipid interactions, with emphasis on best practices and critical aspects of running these simulations. Additionally, we analyze challenges and successes when running alchemical free energy calculations on membrane-associated proteins. Finally, we highlight the value of alchemical free energy calculations calculations in drug discovery and their applicability in the pharmaceutical industry.
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Affiliation(s)
- Michail Papadourakis
- Biomedical
Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
| | - Hryhory Sinenka
- Institut
de Chimie de Strasbourg, UMR7177, CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France
| | - Pierre Matricon
- Sosei
Heptares, Steinmetz Building,
Granta Park, Great Abington, Cambridge CB21 6DG, United
Kingdom
| | - Jérôme Hénin
- Laboratoire
de Biochimie Théorique UPR 9080, CNRS and Université Paris Cité, 75005 Paris, France
| | - Grace Brannigan
- Center
for Computational and Integrative Biology, Rutgers University−Camden, Camden, New Jersey 08103, United States of America
- Department
of Physics, Rutgers University−Camden, Camden, New Jersey 08102, United States
of America
| | - Laura Pérez-Benito
- CADD,
In Silico Discovery, Janssen Research &
Development, Turnhoutseweg 30, 2340 Beerse, Belgium
| | - Vineet Pande
- CADD,
In Silico Discovery, Janssen Research &
Development, Turnhoutseweg 30, 2340 Beerse, Belgium
| | - Herman van Vlijmen
- CADD,
In Silico Discovery, Janssen Research &
Development, Turnhoutseweg 30, 2340 Beerse, Belgium
| | - Chris de Graaf
- Sosei
Heptares, Steinmetz Building,
Granta Park, Great Abington, Cambridge CB21 6DG, United
Kingdom
| | - Francesca Deflorian
- Sosei
Heptares, Steinmetz Building,
Granta Park, Great Abington, Cambridge CB21 6DG, United
Kingdom
| | - Gary Tresadern
- CADD,
In Silico Discovery, Janssen Research &
Development, Turnhoutseweg 30, 2340 Beerse, Belgium
| | - Marco Cecchini
- Institut
de Chimie de Strasbourg, UMR7177, CNRS, Université de Strasbourg, F-67083 Strasbourg Cedex, France
| | - Zoe Cournia
- Biomedical
Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
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12
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Cowgill J, Fan C, Haloi N, Tobiasson V, Zhuang Y, Howard RJ, Lindahl E. Structure and dynamics of differential ligand binding in the human ρ-type GABA A receptor. Neuron 2023; 111:3450-3464.e5. [PMID: 37659407 DOI: 10.1016/j.neuron.2023.08.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 08/01/2023] [Accepted: 08/07/2023] [Indexed: 09/04/2023]
Abstract
The neurotransmitter γ-aminobutyric acid (GABA) drives critical inhibitory processes in and beyond the nervous system, partly via ionotropic type-A receptors (GABAARs). Pharmacological properties of ρ-type GABAARs are particularly distinctive, yet the structural basis for their specialization remains unclear. Here, we present cryo-EM structures of a lipid-embedded human ρ1 GABAAR, including a partial intracellular domain, under apo, inhibited, and desensitized conditions. An apparent resting state, determined first in the absence of modulators, was recapitulated with the specific inhibitor (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid and blocker picrotoxin and provided a rationale for bicuculline insensitivity. Comparative structures, mutant recordings, and molecular simulations with and without GABA further explained the sensitized but slower activation of ρ1 relative to canonical subtypes. Combining GABA with picrotoxin also captured an apparent uncoupled intermediate state. This work reveals structural mechanisms of gating and modulation with applications to ρ-specific pharmaceutical design and to our biophysical understanding of ligand-gated ion channels.
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Affiliation(s)
- John Cowgill
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden
| | - Chen Fan
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden
| | - Nandan Haloi
- Department of Applied Physics, SciLifeLab, KTH Royal Institute of Technology, 17121 Solna, Sweden
| | - Victor Tobiasson
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden
| | - Yuxuan Zhuang
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden
| | - Rebecca J Howard
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden.
| | - Erik Lindahl
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, 17121 Solna, Sweden; Department of Applied Physics, SciLifeLab, KTH Royal Institute of Technology, 17121 Solna, Sweden.
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13
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Bogdanov M. The power and challenge of lipid (a)symmetry across the membrane and cell. Emerg Top Life Sci 2023; 7:1-6. [PMID: 36988943 PMCID: PMC10725184 DOI: 10.1042/etls20220088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 02/02/2023] [Accepted: 02/02/2023] [Indexed: 03/30/2023]
Abstract
Membrane asymmetry means that the two sides of membrane are structurally, physically and functionally different. Membrane asymmetry is largely related to the lipid sidedness and particularly to compositional (lipid head and acyl group) and physical (lipid packing order, charge, hydration and H-bonding interactions) differences in the inner and outer leaflets of lipid bilayer. Chemically, structurally and conformationally different non-covalent bound lipid molecules are physically fluid and deformable and enable to interact dynamically to form transient arrangements with asymmetry both perpendicular and parallel to the plane of the lipid bilayer. Although biological membranes are almost universally asymmetric however the asymmetry is not absolute since only drastic difference in the number of lipids per leaflet is found and symmetric arrangements are possible. Asymmetry is thought to direct and influence many core biological functions by altering the membrane's collective biochemical, biophysical and structural properties. Asymmetric transbilayer lipid distribution is found across all lipid classes, cells and near all endomembrane compartments. Why cell membranes are (a)symmetric and adopt almost exclusively highly entropically disfavored asymmetric state?
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Affiliation(s)
- Mikhail Bogdanov
- Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, TX 77030, U.S.A
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14
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Barrantes FJ. Structure and function meet at the nicotinic acetylcholine receptor-lipid interface. Pharmacol Res 2023; 190:106729. [PMID: 36931540 DOI: 10.1016/j.phrs.2023.106729] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023]
Abstract
The nicotinic acetylcholine receptor (nAChR) is a transmembrane protein that mediates fast intercellular communication in response to the endogenous neurotransmitter acetylcholine. It is the best characterized and archetypal molecule in the superfamily of pentameric ligand-gated ion channels (pLGICs). As a typical transmembrane macromolecule, it interacts extensively with its vicinal lipid microenvironment. Experimental evidence provides a wealth of information on receptor-lipid crosstalk: the nAChR exerts influence on its immediate membrane environment and conversely, the lipid moiety modulates ligand binding, affinity state transitions and gating of ion translocation functions of the receptor protein. Recent cryogenic electron microscopy (cryo-EM) studies have unveiled the occurrence of sites for phospholipids and cholesterol on the lipid-exposed regions of neuronal and electroplax nAChRs, confirming early spectroscopic and affinity labeling studies demonstrating the close contact of lipid molecules with the receptor transmembrane segments. This new data provides structural support to the postulated "lipid sensor" ability displayed by the outer ring of M4 transmembrane domains and their modulatory role on nAChR function, as we postulated a decade ago. Borrowing from the best characterized nAChR, the electroplax (muscle-type) receptor, and exploiting new structural information on the neuronal nAChR, it is now possible to achieve an improved depiction of these sites. In combination with site-directed mutagenesis, single-channel electrophysiology, and molecular dynamics studies, the new structural information delivers a more comprehensive portrayal of these lipid-sensitive loci, providing mechanistic explanations for their ability to modulate nAChR properties and raising the possibility of targetting them in disease.
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Affiliation(s)
- Francisco J Barrantes
- Laboratory of Molecular Neurobiology, Biomedical Research Institute, Faculty of Medical Sciences, Pontifical Catholic University of Argentina (UCA) - Argentine Scientific & Technol. Research Council (CONICET), Av. Alicia Moreau de Justo 1600, C1107AAZ Buenos Aires, Argentina.
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15
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Krompers M, Heerklotz H. A Guide to Your Desired Lipid-Asymmetric Vesicles. MEMBRANES 2023; 13:267. [PMID: 36984654 PMCID: PMC10054703 DOI: 10.3390/membranes13030267] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/14/2023] [Accepted: 02/18/2023] [Indexed: 06/18/2023]
Abstract
Liposomes are prevalent model systems for studies on biological membranes. Recently, increasing attention has been paid to models also representing the lipid asymmetry of biological membranes. Here, we review in-vitro methods that have been established to prepare free-floating vesicles containing different compositions of the classic two-chain glycero- or sphingolipids in their outer and inner leaflet. In total, 72 reports are listed and assigned to four general strategies that are (A) enzymatic conversion of outer leaflet lipids, (B) re-sorting of lipids between leaflets, (C) assembly from different monolayers and (D) exchange of outer leaflet lipids. To guide the reader through this broad field of available techniques, we attempt to draw a road map that leads to the lipid-asymmetric vesicles that suit a given purpose. Of each method, we discuss advantages and limitations. In addition, various verification strategies of asymmetry as well as the role of cholesterol are briefly discussed. The ability to specifically induce lipid asymmetry in model membranes offers insights into the biological functions of asymmetry and may also benefit the technical applications of liposomes.
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Affiliation(s)
- Mona Krompers
- Department of Pharmaceutical Technology and Biopharmacy, Institute for Pharmaceutical Sciences, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Heiko Heerklotz
- Department of Pharmaceutical Technology and Biopharmacy, Institute for Pharmaceutical Sciences, University of Freiburg, 79104 Freiburg im Breisgau, Germany
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3M2, Canada
- Signalling Research Centers BIOSS and CIBSS, University of Freiburg, 79085 Freiburg im Breisgau, Germany
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