1
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Hale WD, Montaño Romero A, Gonzalez CU, Jayaraman V, Lau AY, Huganir RL, Twomey EC. Allosteric competition and inhibition in AMPA receptors. Nat Struct Mol Biol 2024:10.1038/s41594-024-01328-0. [PMID: 38834914 DOI: 10.1038/s41594-024-01328-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 05/03/2024] [Indexed: 06/06/2024]
Abstract
Excitatory neurotransmission is principally mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-subtype ionotropic glutamate receptors (AMPARs). Negative allosteric modulators are therapeutic candidates that inhibit AMPAR activation and can compete with positive modulators to control AMPAR function through unresolved mechanisms. Here we show that allosteric inhibition pushes AMPARs into a distinct state that prevents both activation and positive allosteric modulation. We used cryo-electron microscopy to capture AMPARs bound to glutamate, while a negative allosteric modulator, GYKI-52466, and positive allosteric modulator, cyclothiazide, compete for control of the AMPARs. GYKI-52466 binds in the ion channel collar and inhibits AMPARs by decoupling the ligand-binding domains from the ion channel. The rearrangement of the ligand-binding domains ruptures the cyclothiazide site, preventing positive modulation. Our data provide a framework for understanding allostery of AMPARs and for rational design of therapeutics targeting AMPARs in neurological diseases.
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Affiliation(s)
- W Dylan Hale
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Alejandra Montaño Romero
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Cuauhtemoc U Gonzalez
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Albert Y Lau
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Richard L Huganir
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Edward C Twomey
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- The Beckman Center for Cryo-EM at Johns Hopkins, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Diana Helis Henry Medical Research Foundation, New Orleans, LA, USA.
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2
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Gangwar SP, Yelshanskaya MV, Nadezhdin KD, Yen LY, Newton TP, Aktolun M, Kurnikova MG, Sobolevsky AI. Kainate receptor channel opening and gating mechanism. Nature 2024; 630:762-768. [PMID: 38778115 PMCID: PMC11186766 DOI: 10.1038/s41586-024-07475-0] [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: 02/05/2024] [Accepted: 04/26/2024] [Indexed: 05/25/2024]
Abstract
Kainate receptors, a subclass of ionotropic glutamate receptors, are tetrameric ligand-gated ion channels that mediate excitatory neurotransmission1-4. Kainate receptors modulate neuronal circuits and synaptic plasticity during the development and function of the central nervous system and are implicated in various neurological and psychiatric diseases, including epilepsy, depression, schizophrenia, anxiety and autism5-11. Although structures of kainate receptor domains and subunit assemblies are available12-18, the mechanism of kainate receptor gating remains poorly understood. Here we present cryo-electron microscopy structures of the kainate receptor GluK2 in the presence of the agonist glutamate and the positive allosteric modulators lectin concanavalin A and BPAM344. Concanavalin A and BPAM344 inhibit kainate receptor desensitization and prolong activation by acting as a spacer between the amino-terminal and ligand-binding domains and a stabilizer of the ligand-binding domain dimer interface, respectively. Channel opening involves the kinking of all four pore-forming M3 helices. Our structures reveal the molecular basis of kainate receptor gating, which could guide the development of drugs for treatment of neurological disorders.
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Affiliation(s)
- Shanti Pal Gangwar
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Kirill D Nadezhdin
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Laura Y Yen
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
- Cellular and Molecular Physiology and Biophysics Graduate Program, Columbia University Irving Medical Center, New York, NY, USA
| | - Thomas P Newton
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
- Integrated Program in Cellular, Molecular and Biomedical Studies, Columbia University Irving Medical Center, New York, NY, USA
| | - Muhammed Aktolun
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Maria G Kurnikova
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
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3
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Gonzalez CU, Jayaraman V. Structural dynamics in α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor gating. Curr Opin Struct Biol 2024; 87:102833. [PMID: 38733862 DOI: 10.1016/j.sbi.2024.102833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 04/05/2024] [Accepted: 04/22/2024] [Indexed: 05/13/2024]
Abstract
The ionotropic glutamate receptors (iGluRs) are comprised of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), N-methyl-d-aspartate receptor, kainate, and delta subtypes and are pivotal in neuronal plasticity. Recent structural studies on AMPA receptors reveal intricate conformational changes during activation and desensitization elucidating the steps from agonist binding to channel opening and desensitization. Additionally, interactions with auxiliary subunits, including transmembrane AMPA-receptor regulatory proteins, germ-cell-specific gene 1-like protein, and cornichon homologs, intricately modulate AMPA receptors. We discuss the recent high-resolution structures of these complexes that unveil stoichiometry, subunit positioning, and differences in specific side-chain interactions that influence these functional modulations.
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Affiliation(s)
- Cuauhtemoc U Gonzalez
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; MD Anderson Cancer Center and UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA. https://twitter.com/Cuau_Ulises
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; MD Anderson Cancer Center and UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA.
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4
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Bleier J, de Mendonca PRF, Habrian C, Stanley C, Vyklicky V, Isacoff EY. Conformational basis of subtype-specific allosteric control of NMDA receptor gating. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.10.579740. [PMID: 38370786 PMCID: PMC10871359 DOI: 10.1101/2024.02.10.579740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
N-methyl-D-aspartate receptors are ionotropic glutamate receptors that are integral to synaptic transmission and plasticity. Variable GluN2 subunits in diheterotetrameric receptors with identical GluN1 subunits set very different functional properties, which support their individual physiological roles in the nervous system. To understand the conformational basis of this diversity, we assessed the conformation of the common GluN1 subunit in receptors with different GluN2 subunits using single-molecule fluorescence resonance energy transfer (smFRET). We established smFRET sensors in the ligand binding domain and modulatory amino-terminal domain to study an apo-like state and partially liganded activation intermediates, which have been elusive to structural analysis. Our results demonstrate a strong, subtype-specific influence of apo and glutamate-bound GluN2 subunits on GluN1 rearrangements, suggesting a conformational basis for the highly divergent levels of receptor activity, desensitization and agonist potency. Chimeric analysis reveals structural determinants that contribute to the subtype differences. Our study provides a framework for understanding GluN2-dependent functional properties and could open new avenues for subtype-specific modulation.
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Affiliation(s)
- Julia Bleier
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, 94720 USA
| | | | - Chris Habrian
- Department of Molecular & Cell Biology, University of California, Berkeley, California, 94720 USA
- Current address: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA
| | - Cherise Stanley
- Department of Molecular & Cell Biology, University of California, Berkeley, California, 94720 USA
| | - Vojtech Vyklicky
- Department of Molecular & Cell Biology, University of California, Berkeley, California, 94720 USA
- Current address: DIANA Biotechnologies, a.s. Průmyslová 596, 252 50 Vestec, Czech Republic
| | - Ehud Y. Isacoff
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, 94720 USA
- Department of Molecular & Cell Biology, University of California, Berkeley, California, 94720 USA
- Weill Neurohub, University of California, Berkeley, California, 94720 USA
- Molecular Biology & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
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5
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Bogdanović N, Segura-Covarrubias G, Zhang L, Tajima N. Structural dynamics of GluK2 kainate receptors in apo and partial agonist bound states. RESEARCH SQUARE 2023:rs.3.rs-3592604. [PMID: 38076992 PMCID: PMC10705692 DOI: 10.21203/rs.3.rs-3592604/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Kainate receptors (KARs) belong to the family of ionotropic glutamate receptors (iGluRs) and are tetrameric ligand-gated ion channels that regulate neurotransmitter release and excitatory synaptic transmission in the central nervous system. While KARs share overall architectures with other iGluR subfamilies, their dynamics are significantly different from those of other iGluRs. KARs are activated by both full and partial agonists. While there is less efficacy with partial agonists than with full agonists, the detailed mechanism has remained elusive. Here, we used cryo-electron microscopy to determine the structures of homomeric rat GluK2 KARs in the absence of ligands (apo) and in complex with a partial agonist. Intriguingly, the apo state KARs were captured in desensitized conformation. This structure confirms the KAR desensitization prior to activation. Structures of KARs complexed to the partial agonist domoate populate in domoate bound desensitized and non-active/non-desensitized states. These previously unseen intermediate structures highlight the molecular mechanism of partial agonism in KARs. Additionally, we show how N-glycans stabilized the ligand-binding domain dimer via cation/anion binding and modulated receptor gating properties using electrophysiology. Our findings provide vital structural and functional insights into the unique KAR gating mechanisms.
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Affiliation(s)
- Nebojša Bogdanović
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Ohio, 44106, USA
- Equal contribution
| | - Guadalupe Segura-Covarrubias
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Ohio, 44106, USA
- Equal contribution
| | - Lisa Zhang
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Ohio, 44106, USA
| | - Nami Tajima
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Ohio, 44106, USA
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6
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Wu E, Zhang J, Zhang J, Zhu S. Structural insights into gating mechanism and allosteric regulation of NMDA receptors. Curr Opin Neurobiol 2023; 83:102806. [PMID: 37950957 DOI: 10.1016/j.conb.2023.102806] [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: 05/04/2023] [Revised: 09/28/2023] [Accepted: 10/13/2023] [Indexed: 11/13/2023]
Abstract
N-methyl-d-aspartate receptors (NMDARs) belong to the ionotropic glutamate receptors (iGluRs) superfamily and act as coincidence detectors that are crucial to neuronal development and synaptic plasticity. They typically assemble as heterotetramers of two obligatory GluN1 subunits and two alternative GluN2 (from 2A to 2D) and/or GluN3 (3A and 3B) subunits. These alternative subunits mainly determine the diverse biophysical and pharmacological properties of different NMDAR subtypes. Over the past decade, the unprecedented advances in structure elucidation of these tetrameric NMDARs have provided atomic insights into channel gating, allosteric modulation and the action of therapeutic drugs. A wealth of structural and functional information would accelerate the artificial intelligence-based drug design to exploit more NMDAR subtype-specific molecules for the treatment of neurological and psychiatric disorders.
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Affiliation(s)
- Enjiang Wu
- Shanghai Key Laboratory of Compound Chinese Medicines, The Ministry of Education Key Laboratory for Standardization of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai, China; Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China. https://twitter.com/DuDaDa_Flower
| | - Jilin Zhang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jiwei Zhang
- Shanghai Key Laboratory of Compound Chinese Medicines, The Ministry of Education Key Laboratory for Standardization of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
| | - Shujia Zhu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing, China.
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7
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Hale WD, Romero AM, Huganir RL, Twomey EC. Structure of Transmembrane AMPA Receptor Regulatory Protein Subunit γ2. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.28.569079. [PMID: 38076787 PMCID: PMC10705454 DOI: 10.1101/2023.11.28.569079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Transmembrane AMPA receptor regulatory proteins (TARPs) are claudin-like proteins that tightly regulate AMPA receptors (AMPARs) and are fundamental for excitatory neurotransmission. We used cryo-electron microscopy (cryo-EM) to reconstruct the 36 kDa TARP subunit γ2 to 2.3 Å and reveal the structural diversity of TARPs. Our data reveals critical motifs that distinguish TARPs from claudins and define how sequence variations within TARPs differentiate subfamilies and their regulation of AMPARs.
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Affiliation(s)
- W. Dylan Hale
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Alejandra Montaño Romero
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Richard L. Huganir
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Edward C. Twomey
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD USA
- The Beckman Center for Cryo-EM at Johns Hopkins, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Diana Helis Henry Medical Research Foundation, New Orleans, LA USA
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8
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Hale WD, Romero AM, Gonzalez CU, Jayaraman V, Lau AY, Huganir RL, Twomey EC. Allosteric Competition and Inhibition in AMPA Receptors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.28.569057. [PMID: 38076818 PMCID: PMC10705377 DOI: 10.1101/2023.11.28.569057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Excitatory neurotransmission is principally mediated by AMPA-subtype ionotropic glutamate receptors (AMPARs). Dysregulation of AMPARs is the cause of many neurological disorders and how therapeutic candidates such as negative allosteric modulators inhibit AMPARs is unclear. Here, we show that non-competitive inhibition desensitizes AMPARs to activation and prevents positive allosteric modulation. We dissected the noncompetitive inhibition mechanism of action by capturing AMPARs bound to glutamate and the prototypical negative allosteric modulator, GYKI-52466, with cryo-electron microscopy. Noncompetitive inhibition by GYKI-52466, which binds in the transmembrane collar region surrounding the ion channel, negatively modulates AMPARs by decoupling glutamate binding in the ligand binding domain from the ion channel. Furthermore, during allosteric competition between negative and positive modulators, negative allosteric modulation by GKYI-52466 outcompetes positive allosteric modulators to control AMPAR function. Our data provide a new framework for understanding allostery of AMPARs and foundations for rational design of therapeutics targeting AMPARs in neurological diseases.
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Affiliation(s)
- W. Dylan Hale
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Alejandra Montaño Romero
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Cuauhtemoc U. Gonzalez
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, TX, USA
| | - Albert Y. Lau
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Richard L. Huganir
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Edward C. Twomey
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD USA
- The Beckman Center for Cryo-EM at Johns Hopkins, Johns Hopkins University School of Medicine, Baltimore, MD USA
- Diana Helis Henry Medical Research Foundation, New Orleans, LA USA
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9
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Perozzo AM, Schwenk J, Kamalova A, Nakagawa T, Fakler B, Bowie D. GSG1L-containing AMPA receptor complexes are defined by their spatiotemporal expression, native interactome and allosteric sites. Nat Commun 2023; 14:6799. [PMID: 37884493 PMCID: PMC10603098 DOI: 10.1038/s41467-023-42517-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 10/12/2023] [Indexed: 10/28/2023] Open
Abstract
Transmembrane AMPA receptor regulatory proteins (TARPs) and germ cell-specific gene 1-like protein (GSG1L) are claudin-type AMPA receptor (AMPAR) auxiliary subunits that profoundly regulate glutamatergic synapse strength and plasticity. While AMPAR-TARP complexes have been extensively studied, less is known about GSG1L-containing AMPARs. Here, we show that GSG1L's spatiotemporal expression, native interactome and allosteric sites are distinct. GSG1L generally expresses late during brain development in a region-specific manner, constituting about 5% of all AMPAR complexes in adulthood. While GSG1L can co-assemble with TARPs or cornichons (CNIHs), it also assembles as the sole auxiliary subunit. Unexpectedly, GSG1L acts through two discrete evolutionarily-conserved sites on the agonist-binding domain with a weak allosteric interaction at the TARP/KGK site to slow desensitization, and a stronger interaction at a different site that slows recovery from desensitization. Together, these distinctions help explain GSG1L's evolutionary past and how it fulfills a unique signaling role within glutamatergic synapses.
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Affiliation(s)
- Amanda M Perozzo
- Integrated Program in Neuroscience, McGill University, Montreal, QC, H3A 1A1, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, H3G 1Y6, Canada
| | - Jochen Schwenk
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Hermann-Herder-Str. 7, 79104, Freiburg, Germany
| | - Aichurok Kamalova
- Department of Molecular Physiology and Biophysics, Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
- Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine, University of Freiburg, Hermann-Herder-Str. 7, 79104, Freiburg, Germany
- Signaling Research Centers BIOSS and CIBSS, University of Freiburg, Schänzlestr. 18, 79104, Freiburg, Germany
| | - Derek Bowie
- Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, H3G 1Y6, Canada.
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10
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Certain N, Gan Q, Bennett J, Hsieh H, Wollmuth LP. Differential regulation of tetramerization of the AMPA receptor glutamate-gated ion channel by auxiliary subunits. J Biol Chem 2023; 299:105227. [PMID: 37673338 PMCID: PMC10558804 DOI: 10.1016/j.jbc.2023.105227] [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: 02/21/2023] [Revised: 08/21/2023] [Accepted: 08/24/2023] [Indexed: 09/08/2023] Open
Abstract
α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) auxiliary subunits are specialized, nontransient binding partners of AMPARs that modulate AMPAR channel gating properties and pharmacology, as well as their biogenesis and trafficking. The most well-characterized families of auxiliary subunits are transmembrane AMPAR regulatory proteins (TARPs), cornichon homologs (CNIHs), and the more recently discovered GSG1-L. These auxiliary subunits can promote or reduce surface expression of AMPARs (composed of GluA1-4 subunits) in neurons, thereby impacting their functional role in membrane signaling. Here, we show that CNIH-2 enhances the tetramerization of WT and mutant AMPARs, presumably by increasing the overall stability of the tetrameric complex, an effect that is mainly mediated by interactions with the transmembrane domain of the receptor. We also find CNIH-2 and CNIH-3 show receptor subunit-specific actions in this regard with CNIH-2 enhancing both GluA1 and GluA2 tetramerization, whereas CNIH-3 only weakly enhances GluA1 tetramerization. These results are consistent with the proposed role of CNIHs as endoplasmic reticulum cargo transporters for AMPARs. In contrast, TARP γ-2, TARP γ-8, and GSG1-L have no or negligible effect on AMPAR tetramerization. On the other hand, TARP γ-2 can enhance receptor tetramerization but only when directly fused with the receptor at a maximal stoichiometry. Notably, surface expression of functional AMPARs was enhanced by CNIH-2 to a greater extent than TARP γ-2, suggesting that this distinction aids in maturation and membrane expression. These experiments define a functional distinction between CNIHs and other auxiliary subunits in the regulation of AMPAR biogenesis.
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Affiliation(s)
- Noele Certain
- Graduate Program in Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, New York, USA
| | - Quan Gan
- Graduate Program in Neuroscience, Stony Brook University, Stony Brook, New York, USA
| | - Joseph Bennett
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, New York, USA
| | - Helen Hsieh
- Department of Surgery, Renaissance School of Medicine, Stony Brook University, Stony Brook, New York, USA; Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York, USA
| | - Lonnie P Wollmuth
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, New York, USA; Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York, USA; Department of Biochemistry & Cell Biology, Stony Brook University, Stony Brook, New York, USA.
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11
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Gangwar SP, Yen LY, Yelshanskaya MV, Korman A, Jones DR, Sobolevsky AI. Modulation of GluA2-γ5 synaptic complex desensitization, polyamine block and antiepileptic perampanel inhibition by auxiliary subunit cornichon-2. Nat Struct Mol Biol 2023; 30:1481-1494. [PMID: 37653241 PMCID: PMC10584687 DOI: 10.1038/s41594-023-01080-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 07/26/2023] [Indexed: 09/02/2023]
Abstract
Synaptic complexes of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors (AMPARs) with auxiliary subunits mediate most excitatory neurotransmission and can be targeted to treat neuropsychiatric and neurological disorders, including epilepsy. Here we present cryogenic-electron microscopy structures of rat GluA2 AMPAR complexes with inhibitory mouse γ5 and potentiating human cornichon-2 (CNIH2) auxiliary subunits. CNIH2 appears to destabilize the desensitized state of the complex by reducing the separation of the upper lobes in ligand-binding domain dimers. At the same time, CNIH2 stabilizes binding of polyamine spermidine to the selectivity filter of the closed ion channel. Nevertheless, CNIH2, and to a lesser extent γ5, attenuate polyamine block of the open channel and reduce the potency of the antiepileptic drug perampanel that inhibits the synaptic complex allosterically by binding to sites in the ion channel extracellular collar. These findings illustrate the fine-tuning of synaptic complex structure and function in an auxiliary subunit-dependent manner, which is critical for the study of brain region-specific neurotransmission and design of therapeutics for disease treatment.
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Affiliation(s)
- Shanti Pal Gangwar
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Laura Y Yen
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
- Cellular and Molecular Physiology and Biophysics Graduate Program, Columbia University Irving Medical Center, New York, NY, USA
| | - Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Aryeh Korman
- Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Drew R Jones
- Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
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Hu Z, Zheng X, Yang J. Conformational trajectory of allosteric gating of the human cone photoreceptor cyclic nucleotide-gated channel. Nat Commun 2023; 14:4284. [PMID: 37463923 DOI: 10.1038/s41467-023-39971-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 07/05/2023] [Indexed: 07/20/2023] Open
Abstract
Cyclic nucleotide-gated (CNG) channels transduce chemical signals into electrical signals in sensory receptors and neurons. They are activated by cGMP or cAMP, which bind to the cyclic nucleotide-binding domain (CNBD) to open a gate located 50-60 Å away in the central cavity. Structures of closed and open vertebrate CNG channels have been solved, but the conformational landscape of this allosteric gating remains to be elucidated and enriched. Here, we report structures of the cGMP-activated human cone photoreceptor CNGA3/CNGB3 channel in closed, intermediate, pre-open and open states in detergent or lipid nanodisc, all with fully bound cGMP. The pre-open and open states are obtained only in the lipid nanodisc, suggesting a critical role of lipids in tuning the energetic landscape of CNGA3/CNGB3 activation. The different states exhibit subunit-unique, incremental and distinct conformational rearrangements that originate in the CNBD, propagate through the gating ring to the transmembrane domain, and gradually open the S6 cavity gate. Our work illustrates a spatial conformational-change wave of allosteric gating of a vertebrate CNG channel by its natural ligand and provides an expanded framework for studying CNG properties and channelopathy.
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Affiliation(s)
- Zhengshan Hu
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Xiangdong Zheng
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Jian Yang
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA.
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13
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Zhang D, Lape R, Shaikh SA, Kohegyi BK, Watson JF, Cais O, Nakagawa T, Greger IH. Modulatory mechanisms of TARP γ8-selective AMPA receptor therapeutics. Nat Commun 2023; 14:1659. [PMID: 36966141 PMCID: PMC10039940 DOI: 10.1038/s41467-023-37259-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 03/09/2023] [Indexed: 03/27/2023] Open
Abstract
AMPA glutamate receptors (AMPARs) mediate excitatory neurotransmission throughout the brain. Their signalling is uniquely diversified by brain region-specific auxiliary subunits, providing an opportunity for the development of selective therapeutics. AMPARs associated with TARP γ8 are enriched in the hippocampus, and are targets of emerging anti-epileptic drugs. To understand their therapeutic activity, we determined cryo-EM structures of the GluA1/2-γ8 receptor associated with three potent, chemically diverse ligands. We find that despite sharing a lipid-exposed and water-accessible binding pocket, drug action is differentially affected by binding-site mutants. Together with patch-clamp recordings and MD simulations we also demonstrate that ligand-triggered reorganisation of the AMPAR-TARP interface contributes to modulation. Unexpectedly, one ligand (JNJ-61432059) acts bifunctionally, negatively affecting GluA1 but exerting positive modulatory action on GluA2-containing AMPARs, in a TARP stoichiometry-dependent manner. These results further illuminate the action of TARPs, demonstrate the sensitive balance between positive and negative modulatory action, and provide a mechanistic platform for development of both positive and negative selective AMPAR modulators.
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Affiliation(s)
- Danyang Zhang
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Remigijus Lape
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Saher A Shaikh
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Bianka K Kohegyi
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Jake F Watson
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
- IST Austria, Klosterneuburg, Austria
| | - Ondrej Cais
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, Vanderbilt University, School of Medicine, Nashville, USA
| | - Ingo H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK.
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14
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Certain N, Gan Q, Bennett J, Hsieh H, Wollmuth LP. Differential regulation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) receptor tetramerization by auxiliary subunits. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.07.527516. [PMID: 36798164 PMCID: PMC9934675 DOI: 10.1101/2023.02.07.527516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
AMPA receptor (AMPAR) auxiliary subunits are specialized, non-transient binding partners of AMPARs that modulate their ion channel gating properties and pharmacology, as well as their biogenesis and trafficking. The most well characterized families of auxiliary subunits are transmembrane AMPAR regulatory proteins (TARPs) and cornichon homologs (CNIHs) and the more recently discovered GSG1-L. These auxiliary subunits can promote or reduce surface expression of AMPARs in neurons, thereby impacting their functional role in membrane signaling. Here, we show that CNIH-2 enhances the tetramerization of wild type and mutant AMPARs, possibly by increasing the overall stability of the tetrameric complex, an effect that is mainly mediated by interactions with the transmembrane domain of the receptor. We also find CNIH-2 and CNIH-3 show receptor subunit-specific actions in this regard with CNIH-2 enhancing both GluA1 and GluA2 tetramerization whereas CNIH-3 only weakly enhances GluA1 tetramerization. These results are consistent with the proposed role of CNIHs as endoplasmic reticulum cargo transporters for AMPARs. In contrast, TARP γ-2, TARP γ-8, and GSG1-L have no or negligible effect on AMPAR tetramerization. On the other hand, TARP γ-2 can enhance receptor tetramerization but only when directly fused with the receptor at a maximal stoichiometry. Notably, surface expression of functional AMPARs was enhanced by CNIH-2 to a greater extent than TARP γ-2 suggesting that this distinction aids in maturation and membrane expression. These experiments define a functional distinction between CNIHs and other auxiliary subunits in the regulation of AMPAR biogenesis.
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15
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GluR2Q and GluR2R AMPA Subunits are not Targets of lypd2 Interaction. PLoS One 2022; 17:e0278278. [PMID: 36441793 PMCID: PMC9704558 DOI: 10.1371/journal.pone.0278278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 11/12/2022] [Indexed: 11/30/2022] Open
Abstract
A large family of prototoxin-like molecules endogenous to mammals, Ly6 proteins have been implicated in the regulation of cell signaling processes across multiple species. Previous work has shown that certain members of the Ly6 family are expressed in the brain and target nicotinic acetylcholine receptor and potassium channel function. Structural similarities between Ly6 proteins and alpha-neurotoxins suggest the possibility of additional ionotropic receptor targets. Here, we investigated the possibility of lypd2 as a novel regulator of AMPA receptor (AMPAR) function. In particular, we focused on potential interactions with the Q/R isoforms of the GluR2 subunit, which have profound impacts on AMPAR permeability to calcium during neuronal stimulation. We find that although lypd2 and GluR2 share overlapping expression patterns in the mouse hippocampus, there was no interaction between lypd2 and either GluR2Q or GluR2R isoform. These results underscore the importance of continuing to investigate novel targets for Ly6 interaction and regulation.
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16
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Gating intermediates reveal inhibitory role of the voltage sensor in a cyclic nucleotide-modulated ion channel. Nat Commun 2022; 13:6919. [PMID: 36376326 PMCID: PMC9663499 DOI: 10.1038/s41467-022-34673-z] [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: 07/07/2022] [Accepted: 11/02/2022] [Indexed: 11/16/2022] Open
Abstract
Understanding how ion channels gate is important for elucidating their physiological roles and targeting them in pathophysiological states. Here, we used SthK, a cyclic nucleotide-modulated channel from Spirochaeta thermophila, to define a ligand-gating trajectory that includes multiple on-pathway intermediates. cAMP is a poor partial agonist for SthK and depolarization increases SthK activity. Tuning the energy landscape by gain-of-function mutations in the voltage sensor domain (VSD) allowed us to capture multiple intermediates along the ligand-activation pathway, highlighting the allosteric linkage between VSD, cyclic nucleotide-binding (CNBD) and pore domains. Small, lateral displacements of the VSD S4 segment were necessary to open the intracellular gate, pointing to an inhibitory VSD at rest. We propose that in wild-type SthK, depolarization leads to such VSD displacements resulting in release of inhibition. In summary, we report conformational transitions along the activation pathway that reveal allosteric couplings between key sites integrating to open the intracellular gate.
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Yelshanskaya MV, Patel DS, Kottke CM, Kurnikova MG, Sobolevsky AI. Opening of glutamate receptor channel to subconductance levels. Nature 2022; 605:172-178. [PMID: 35444281 PMCID: PMC9068512 DOI: 10.1038/s41586-022-04637-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 03/14/2022] [Indexed: 12/15/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) are tetrameric ligand-gated ion channels that open their pores in response to binding of the agonist glutamate1-3. An ionic current through a single iGluR channel shows up to four discrete conductance levels (O1-O4)4-6. Higher conductance levels have been associated with an increased number of agonist molecules bound to four individual ligand-binding domains (LBDs)6-10. Here we determine structures of a synaptic complex of AMPA-subtype iGluR and the auxiliary subunit γ2 in non-desensitizing conditions with various occupancy of the LBDs by glutamate. We show that glutamate binds to LBDs of subunits B and D only after it is already bound to at least the same number of LBDs that belong to subunits A and C. Our structures combined with single-channel recordings, molecular dynamics simulations and machine-learning analysis suggest that channel opening requires agonist binding to at least two LBDs. Conversely, agonist binding to all four LBDs does not guarantee maximal channel conductance and favours subconductance states O1 and O2, with O3 and O4 being rare and not captured structurally. The lack of subunit independence and low efficiency coupling of glutamate binding to channel opening underlie the gating of synaptic complexes to submaximal conductance levels, which provide a potential for upregulation of synaptic activity.
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Affiliation(s)
- Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Dhilon S Patel
- Chemistry Department, Carnegie Mellon University, Pittsburgh, PA, USA
| | | | - Maria G Kurnikova
- Chemistry Department, Carnegie Mellon University, Pittsburgh, PA, USA.
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
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Becic A, Leifeld J, Shaukat J, Hollmann M. Tetraspanins as Potential Modulators of Glutamatergic Synaptic Function. Front Mol Neurosci 2022; 14:801882. [PMID: 35046772 PMCID: PMC8761850 DOI: 10.3389/fnmol.2021.801882] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 12/07/2021] [Indexed: 12/16/2022] Open
Abstract
Tetraspanins (Tspans) comprise a membrane protein family structurally defined by four transmembrane domains and intracellular N and C termini that is found in almost all cell types and tissues of eukaryotes. Moreover, they are involved in a bewildering multitude of diverse biological processes such as cell adhesion, motility, protein trafficking, signaling, proliferation, and regulation of the immune system. Beside their physiological roles, they are linked to many pathophysiological phenomena, including tumor progression regulation, HIV-1 replication, diabetes, and hepatitis. Tetraspanins are involved in the formation of extensive protein networks, through interactions not only with themselves but also with numerous other specific proteins, including regulatory proteins in the central nervous system (CNS). Interestingly, recent studies showed that Tspan7 impacts dendritic spine formation, glutamatergic synaptic transmission and plasticity, and that Tspan6 is correlated with epilepsy and intellectual disability (formerly known as mental retardation), highlighting the importance of particular tetraspanins and their involvement in critical processes in the CNS. In this review, we summarize the current knowledge of tetraspanin functions in the brain, with a particular focus on their impact on glutamatergic neurotransmission. In addition, we compare available resolved structures of tetraspanin family members to those of auxiliary proteins of glutamate receptors that are known for their modulatory effects.
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