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Larsen AH, Perozzo AM, Biggin PC, Bowie D, Kastrup JS. Recovery from desensitization in GluA2 AMPA receptors is affected by a single mutation in the N-terminal domain interface. J Biol Chem 2024; 300:105717. [PMID: 38311178 PMCID: PMC10909779 DOI: 10.1016/j.jbc.2024.105717] [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: 11/14/2023] [Revised: 01/20/2024] [Accepted: 01/26/2024] [Indexed: 02/10/2024] Open
Abstract
AMPA-type ionotropic glutamate receptors (AMPARs) are central to various neurological processes, including memory and learning. They assemble as homo- or heterotetramers of GluA1, GluA2, GluA3, and GluA4 subunits, each consisting of an N-terminal domain (NTD), a ligand-binding domain, a transmembrane domain, and a C-terminal domain. While AMPAR gating is primarily controlled by reconfiguration in the ligand-binding domain layer, our study focuses on the NTDs, which also influence gating, yet the underlying mechanism remains enigmatic. In this investigation, we employ molecular dynamics simulations to evaluate the NTD interface strength in GluA1, GluA2, and NTD mutants GluA2-H229N and GluA1-N222H. Our findings reveal that GluA1 has a significantly weaker NTD interface than GluA2. The NTD interface of GluA2 can be weakened by a single point mutation in the NTD dimer-of-dimer interface, namely H229N, which renders GluA2 more GluA1-like. Electrophysiology recordings demonstrate that this mutation also leads to slower recovery from desensitization. Moreover, we observe that lowering the pH induces more splayed NTD states and enhances desensitization in GluA2. We hypothesized that H229 was responsible for this pH sensitivity; however, GluA2-H229N was also affected by pH, meaning that H229 is not solely responsible and that protons exert their effect across multiple domains of the AMPAR. In summary, our work unveils an allosteric connection between the NTD interface strength and AMPAR desensitization.
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Affiliation(s)
| | - Amanda M Perozzo
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Philip C Biggin
- Structural Bioinformatics and Computational Biochemistry, Department of Biochemistry, University of Oxford, Oxford, UK
| | - Derek Bowie
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Canada
| | - Jette Sandholm Kastrup
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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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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Lyu Y, Zhang J, Liu S. The impact of land price distortion on green development efficiency: mechanism discussion and empirical test. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:68376-68395. [PMID: 35536465 DOI: 10.1007/s11356-022-20571-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 04/28/2022] [Indexed: 06/14/2023]
Abstract
Based on the panel data of 30 Chinese provinces, the Cobb-Douglas production function and GML index were constructed to measure the degree of land price distortion and green development efficiency, respectively, in China, and the System Generalised Method of Moments model was employed to explore the relationship between land price distortion and green development efficiency, and a mediating effect model was further constructed to analyse the transmission mechanism. The results show that, first, land price in China is characterised by a negative distortion, but the degree of negative distortion tends to decrease after 2010. Second, land price distortion significantly inhibits the improvement of green development efficiency; this conclusion still holds after a series of robustness tests, and land price distortion significantly promotes the progress of green technology, while significantly inhibiting the improvement of green technology efficiency. Third, the results of the mediating effect show that the inhibiting effect of land price distortion on green development efficiency is mainly achieved through three channels: house price, industrial structure and infrastructure. Finally, policy recommendations for green sustainable development are put forward from the aspects of land supply structure adjustment and so on.
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Affiliation(s)
- Yanwei Lyu
- School of Business, Shandong University, Weihai, 264209, China
| | - Jinning Zhang
- School of Business, Shandong University, Weihai, 264209, China.
| | - Shali Liu
- School of Business, Shandong University, Weihai, 264209, China
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Hansen KB, Wollmuth LP, Bowie D, Furukawa H, Menniti FS, Sobolevsky AI, Swanson GT, Swanger SA, Greger IH, Nakagawa T, McBain CJ, Jayaraman V, Low CM, Dell'Acqua ML, Diamond JS, Camp CR, Perszyk RE, Yuan H, Traynelis SF. Structure, Function, and Pharmacology of Glutamate Receptor Ion Channels. Pharmacol Rev 2021; 73:298-487. [PMID: 34753794 PMCID: PMC8626789 DOI: 10.1124/pharmrev.120.000131] [Citation(s) in RCA: 252] [Impact Index Per Article: 84.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Many physiologic effects of l-glutamate, the major excitatory neurotransmitter in the mammalian central nervous system, are mediated via signaling by ionotropic glutamate receptors (iGluRs). These ligand-gated ion channels are critical to brain function and are centrally implicated in numerous psychiatric and neurologic disorders. There are different classes of iGluRs with a variety of receptor subtypes in each class that play distinct roles in neuronal functions. The diversity in iGluR subtypes, with their unique functional properties and physiologic roles, has motivated a large number of studies. Our understanding of receptor subtypes has advanced considerably since the first iGluR subunit gene was cloned in 1989, and the research focus has expanded to encompass facets of biology that have been recently discovered and to exploit experimental paradigms made possible by technological advances. Here, we review insights from more than 3 decades of iGluR studies with an emphasis on the progress that has occurred in the past decade. We cover structure, function, pharmacology, roles in neurophysiology, and therapeutic implications for all classes of receptors assembled from the subunits encoded by the 18 ionotropic glutamate receptor genes. SIGNIFICANCE STATEMENT: Glutamate receptors play important roles in virtually all aspects of brain function and are either involved in mediating some clinical features of neurological disease or represent a therapeutic target for treatment. Therefore, understanding the structure, function, and pharmacology of this class of receptors will advance our understanding of many aspects of brain function at molecular, cellular, and system levels and provide new opportunities to treat patients.
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Affiliation(s)
- Kasper B Hansen
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Lonnie P Wollmuth
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Derek Bowie
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Hiro Furukawa
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Frank S Menniti
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Alexander I Sobolevsky
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Geoffrey T Swanson
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Sharon A Swanger
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Ingo H Greger
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Terunaga Nakagawa
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Chris J McBain
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Vasanthi Jayaraman
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Chian-Ming Low
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Mark L Dell'Acqua
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Jeffrey S Diamond
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Chad R Camp
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Riley E Perszyk
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Hongjie Yuan
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
| | - Stephen F Traynelis
- Center for Structural and Functional Neuroscience, Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, MT (K.B.H.); Department of Neurobiology and Behavior, Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY (L.P.W.); Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada (D.B.); WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY (H.F.); MindImmune Therapeutics, Inc., The George & Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI (F.S.M.); Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY (A.I.S.); Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL (G.T.S.); Fralin Biomedical Research Institute at Virginia Tech Carilion, Virginia Tech, Roanoke, VA and Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA (S.A.S.); Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom (I.H.G.); Department of Molecular Physiology and Biophysics, Center for Structural Biology, Vanderbilt Brain Institute, Vanderbilt University, School of Medicine, Nashville, TN (T.N.); Eunice Kennedy Shriver National Institute of Child Health and Human Development (C.J.M.), and Synaptic Physiology Section, NINDS Intramural Research Program, National Institutes of Health, Bethesda, MD (J.S.D.); Department of Biochemistry and Molecular Biology, University of Texas Health Science Center, Houston, TX (V.J.); Department of Pharmacology, Department of Anaesthesia, Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore (C.-M.L.); Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO (M.L.D.); and Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA (C.R.C., R.E.P., H.Y., S.F.T.)
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5
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Structural Arrangement Produced by Concanavalin A Binding to Homomeric GluK2 Receptors. MEMBRANES 2021; 11:membranes11080613. [PMID: 34436376 PMCID: PMC8401665 DOI: 10.3390/membranes11080613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/07/2021] [Accepted: 08/09/2021] [Indexed: 11/17/2022]
Abstract
Kainate receptors are members of the ionotropic glutamate receptor family. They form cation-specific transmembrane channels upon binding glutamate that desensitize in the continued presence of agonists. Concanavalin A (Con-A), a lectin, stabilizes the active open-channel state of the kainate receptor and reduces the extent of desensitization. In this study, we used single-molecule fluorescence resonance energy transfer (smFRET) to investigate the conformational changes underlying kainate receptor modulation by Con-A. These studies showed that Con-A binding to GluK2 homomeric kainate receptors resulted in closer proximity of the subunits at the dimer–dimer interface at the amino-terminal domain as well as between the subunits at the dimer interface at the agonist-binding domain. Additionally, the modulation of receptor functions by monovalent ions, which bind to the dimer interface at the agonist-binding domain, was not observed in the presence of Con-A. Based on these results, we conclude that Con-A modulation of kainate receptor function is mediated by a shift in the conformation of the kainate receptor toward a tightly packed extracellular domain.
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6
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Mayer ML. Structural biology of kainate receptors. Neuropharmacology 2021; 190:108511. [PMID: 33798545 DOI: 10.1016/j.neuropharm.2021.108511] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 12/31/2022]
Abstract
This review summarizes structural studies on kainate receptors that explain unique functional properties of this receptor family. A large number of structures have been solved for ligand binding domain dimer assemblies, giving insight into the subtype selective pharmacology of agonists, antagonists, and allosteric modulators. Structures and biochemical studies on the amino terminal domain reveal mechanisms that play a key role in assembly of heteromeric receptors. Surprisingly, structures of full length homomeric GluK2, GluK3 and heteromeric GluK2/GluK5, receptors reveal a novel structure for the desensitized state that is strikingly different from that for AMPA receptors.
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Affiliation(s)
- Mark L Mayer
- Porter Neuroscience Research Center, NINDS, NIH, 35A Convent Drive Room 3D 904, Bethesda, MD, 20892, USA.
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7
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Khanra N, Brown PMGE, Perozzo AM, Bowie D, Meyerson JR. Architecture and structural dynamics of the heteromeric GluK2/K5 kainate receptor. eLife 2021; 10:e66097. [PMID: 33724189 PMCID: PMC7997659 DOI: 10.7554/elife.66097] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 03/05/2021] [Indexed: 12/15/2022] Open
Abstract
Kainate receptors (KARs) are L-glutamate-gated ion channels that regulate synaptic transmission and modulate neuronal circuits. KARs have strict assembly rules and primarily function as heteromeric receptors in the brain. A longstanding question is how KAR heteromer subunits organize and coordinate together to fulfill their signature physiological roles. Here we report structures of the GluK2/GluK5 heteromer in apo, antagonist-bound, and desensitized states. The receptor assembles with two copies of each subunit, ligand binding domains arranged as two heterodimers and GluK5 subunits proximal to the channel. Strikingly, during desensitization, GluK2, but not GluK5, subunits undergo major structural rearrangements to facilitate channel closure. We show how the large conformational differences between antagonist-bound and desensitized states are mediated by the linkers connecting the pore helices to the ligand binding domains. This work presents the first KAR heteromer structure, reveals how its subunits are organized, and resolves how the heteromer can accommodate functionally distinct closed channel structures.
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Affiliation(s)
- Nandish Khanra
- Department of Physiology and Biophysics, Weill Cornell Medical CollegeNew YorkUnited States
| | - Patricia MGE Brown
- Department of Pharmacology and Therapeutics, McGill UniversityMontréalCanada
| | - Amanda M Perozzo
- Department of Pharmacology and Therapeutics, McGill UniversityMontréalCanada
| | - Derek Bowie
- Department of Pharmacology and Therapeutics, McGill UniversityMontréalCanada
| | - Joel R Meyerson
- Department of Physiology and Biophysics, Weill Cornell Medical CollegeNew YorkUnited States
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8
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Bada Juarez JF, Judge PJ, Adam S, Axford D, Vinals J, Birch J, Kwan TOC, Hoi KK, Yen HY, Vial A, Milhiet PE, Robinson CV, Schapiro I, Moraes I, Watts A. Structures of the archaerhodopsin-3 transporter reveal that disordering of internal water networks underpins receptor sensitization. Nat Commun 2021; 12:629. [PMID: 33504778 PMCID: PMC7840839 DOI: 10.1038/s41467-020-20596-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 12/10/2020] [Indexed: 12/11/2022] Open
Abstract
Many transmembrane receptors have a desensitized state, in which they are unable to respond to external stimuli. The family of microbial rhodopsin proteins includes one such group of receptors, whose inactive or dark-adapted (DA) state is established in the prolonged absence of light. Here, we present high-resolution crystal structures of the ground (light-adapted) and DA states of Archaerhodopsin-3 (AR3), solved to 1.1 Å and 1.3 Å resolution respectively. We observe significant differences between the two states in the dynamics of water molecules that are coupled via H-bonds to the retinal Schiff Base. Supporting QM/MM calculations reveal how the DA state permits a thermodynamic equilibrium between retinal isomers to be established, and how this same change is prevented in the ground state in the absence of light. We suggest that the different arrangement of internal water networks in AR3 is responsible for the faster photocycle kinetics compared to homologs.
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Affiliation(s)
- Juan F Bada Juarez
- Biochemistry Department, Oxford University, South Parks Road, Oxford, OX1 3QU, UK
| | - Peter J Judge
- Biochemistry Department, Oxford University, South Parks Road, Oxford, OX1 3QU, UK
| | - Suliman Adam
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
| | - Danny Axford
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Javier Vinals
- Biochemistry Department, Oxford University, South Parks Road, Oxford, OX1 3QU, UK
| | - James Birch
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
- Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0FA, UK
| | - Tristan O C Kwan
- Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0FA, UK
- National Physical Laboratory, Hampton Road, Teddington, London, TW11 0LW, UK
| | - Kin Kuan Hoi
- Chemistry Research Laboratory, Oxford University, Mansfield Road, Oxford, OX1 3TA, UK
| | - Hsin-Yung Yen
- OMass Therapeutics, The Schrodinger Building, Oxford Science Park, Oxford, OX4 4GE, UK
| | - Anthony Vial
- Centre de Biochimie Structurale (CBS), INSERM, CNRS, University of Montpellier, Montpellier, France
| | - Pierre-Emmanuel Milhiet
- Centre de Biochimie Structurale (CBS), INSERM, CNRS, University of Montpellier, Montpellier, France
| | - Carol V Robinson
- Chemistry Research Laboratory, Oxford University, Mansfield Road, Oxford, OX1 3TA, UK
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics Research, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem, 9190401, Israel
| | - Isabel Moraes
- Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0FA, UK.
- National Physical Laboratory, Hampton Road, Teddington, London, TW11 0LW, UK.
| | - Anthony Watts
- Biochemistry Department, Oxford University, South Parks Road, Oxford, OX1 3QU, UK.
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9
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Chou TH, Tajima N, Romero-Hernandez A, Furukawa H. Structural Basis of Functional Transitions in Mammalian NMDA Receptors. Cell 2020; 182:357-371.e13. [PMID: 32610085 PMCID: PMC8278726 DOI: 10.1016/j.cell.2020.05.052] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 04/22/2020] [Accepted: 05/27/2020] [Indexed: 12/18/2022]
Abstract
Excitatory neurotransmission meditated by glutamate receptors including N-methyl-D-aspartate receptors (NMDARs) is pivotal to brain development and function. NMDARs are heterotetramers composed of GluN1 and GluN2 subunits, which bind glycine and glutamate, respectively, to activate their ion channels. Despite importance in brain physiology, the precise mechanisms by which activation and inhibition occur via subunit-specific binding of agonists and antagonists remain largely unknown. Here, we show the detailed patterns of conformational changes and inter-subunit and -domain reorientation leading to agonist-gating and subunit-dependent competitive inhibition by providing multiple structures in distinct ligand states at 4 Å or better. The structures reveal that activation and competitive inhibition by both GluN1 and GluN2 antagonists occur by controlling the tension of the linker between the ligand-binding domain and the transmembrane ion channel of the GluN2 subunit. Our results provide detailed mechanistic insights into NMDAR pharmacology, activation, and inhibition, which are fundamental to the brain physiology.
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Affiliation(s)
- Tsung-Han Chou
- WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Nami Tajima
- WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Annabel Romero-Hernandez
- WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Hiro Furukawa
- WM Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
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10
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Kokolaki ML, Fauquier A, Renner M. Molecular Crowding and Diffusion-Capture in Synapses. iScience 2020; 23:101382. [PMID: 32739837 PMCID: PMC7399191 DOI: 10.1016/j.isci.2020.101382] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/23/2020] [Accepted: 07/14/2020] [Indexed: 12/17/2022] Open
Abstract
Cell membranes often contain domains with important physiological functions. A typical example are neuronal synapses, whose capacity to capture receptors for neurotransmitters is central to neuronal functions. Receptors diffuse in the membrane until they are stabilized by interactions with stable elements, the scaffold. Single particle tracking experiments demonstrated that these interactions are rather weak and that lateral diffusion is strongly impaired in the post-synaptic membrane due to molecular crowding. We investigated how the distribution of scaffolding molecules and molecular crowding affect the capture of receptors. In particle-based Monte Carlo simulations, based on experimental data of molecular diffusion and organization, crowding enhanced the receptor-scaffold interaction but reduced the capture of new molecules. The distribution of scaffolding sites in several clusters reduced crowding and fostered the exchange of molecules accelerating synaptic plasticity. Synapses could switch between two regimes, becoming more stable or more plastic depending on the internal distribution of molecules. The good: molecular crowding enhances the interaction receptors-scaffold The bad: the exchange of molecules with extrasynaptic areas is reduced by crowding Molecular crowding helps synapses to be stable Nanoclusters of scaffold sites reduce crowding effects and favor synaptic plasticity
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Affiliation(s)
| | - Aurélien Fauquier
- Sorbonne Université UMR-S 1270 INSERM, Institut du Fer à Moulin (IFM), 75005 Paris, France
| | - Marianne Renner
- Sorbonne Université UMR-S 1270 INSERM, Institut du Fer à Moulin (IFM), 75005 Paris, France.
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11
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Litwin DB, Paudyal N, Carrillo E, Berka V, Jayaraman V. The structural arrangement and dynamics of the heteromeric GluK2/GluK5 kainate receptor as determined by smFRET. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183001. [PMID: 31194959 PMCID: PMC6899175 DOI: 10.1016/j.bbamem.2019.05.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 05/14/2019] [Accepted: 05/31/2019] [Indexed: 01/08/2023]
Abstract
Kainate receptors, which are glutamate activated excitatory neurotransmitter receptors, predominantly exist as heteromers of GluK2 and GluK5 subunits in the mammalian central nervous system. There are currently no structures of the full-length heteromeric kainate receptors. Here, we have used single molecule FRET to determine the specific arrangement of the GluK2 and GluK5 subunits within the dimer of dimers configuration in a full-length receptor. Additionally, we have also studied the dynamics and conformational heterogeneity of the amino-terminal and agonist-binding domain interfaces associated with the resting and desensitized states of the full-length heteromeric kainate receptor using FRET-based methods. The smFRET data are compared to similar experiments performed on the homomeric kainate receptor to provide insight into the differences in conformational dynamics that distinguish the two functionally. This article is part of a Special Issue entitled: Molecular biophysics of membranes and membrane proteins.
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Affiliation(s)
- Douglas B Litwin
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Nabina Paudyal
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA; MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Elisa Carrillo
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Vladimir Berka
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
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12
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Li YJ, Duan GF, Sun JH, Wu D, Ye C, Zang YY, Chen GQ, Shi YY, Wang J, Zhang W, Shi YS. Neto proteins regulate gating of the kainate-type glutamate receptor GluK2 through two binding sites. J Biol Chem 2019; 294:17889-17902. [PMID: 31628192 PMCID: PMC6879349 DOI: 10.1074/jbc.ra119.008631] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 10/15/2019] [Indexed: 12/14/2022] Open
Abstract
The neuropilin and tolloid-like (Neto) proteins Neto1 and Neto2 are auxiliary subunits of kainate-type glutamate receptors (KARs) that regulate KAR trafficking and gating. However, how Netos bind and regulate the biophysical functions of KARs remains unclear. Here, we found that the N-terminal domain (NTD) of glutamate receptor ionotropic kainate 2 (GluK2) binds the first complement C1r/C1s-Uegf-BMP (CUB) domain of Neto proteins (i.e. NTD-CUB1 interaction) and that the core of GluK2 (GluK2ΔNTD) binds Netos through domains other than CUB1s (core-Neto interaction). Using electrophysiological analysis in HEK293T cells, we examined the effects of these interactions on GluK2 gating, including deactivation, desensitization, and recovery from desensitization. We found that NTD deletion does not affect GluK2 fast gating kinetics, the desensitization, and the deactivation. We also observed that Neto1 and Neto2 differentially regulate GluK2 fast gating kinetics, which largely rely on the NTD-CUB1 interactions. NTD removal facilitated GluK2 recovery from desensitization, indicating that the NTD stabilizes the GluK2 desensitization state. Co-expression with Neto1 or Neto2 also accelerated GluK2 recovery from desensitization, which fully relied on the NTD-CUB1 interactions. Moreover, we demonstrate that the NTD-CUB1 interaction involves electric attraction between positively charged residues in the GluK2_NTD and negatively charged ones in the CUB1 domains. Neutralization of these charges eliminated the regulatory effects of the NTD-CUB1 interaction on GluK2 gating. We conclude that KARs bind Netos through at least two sites and that the NTD-CUB1 interaction critically regulates Neto-mediated GluK2 gating.
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Affiliation(s)
- Yan-Jun Li
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210032, China
| | - Gui-Fang Duan
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210032, China
| | - Jia-Hui Sun
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210032, China
| | - Dan Wu
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210032, China
| | - Chang Ye
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210032, China
| | - Yan-Yu Zang
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210032, China
| | - Gui-Quan Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210032, China
- Institute for Brain Sciences, Nanjing University, Nanjing 210032, China
| | - Yong-Yun Shi
- Department of Orthopaedics, Luhe People's Hospital Affiliated to Yangzhou University, Nanjing 211500, China
| | - Jun Wang
- Ministry of Education Key Laboratory of Modern Toxicology, Department of Toxicology, School of Public Health, Nanjing Medical University, Nanjing 211166, China
| | - Wei Zhang
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang 050017, China
| | - Yun Stone Shi
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Affiliated Drum Tower Hospital of Nanjing University Medical School, and Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing 210032, China
- Institute for Brain Sciences, Nanjing University, Nanjing 210032, China
- Chemistry and Biomedicine Innovation Center, Nanjing University, Nanjing 210032, China
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13
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Litwin DB, Carrillo E, Shaikh SA, Berka V, Jayaraman V. The structural arrangement at intersubunit interfaces in homomeric kainate receptors. Sci Rep 2019; 9:6969. [PMID: 31061516 PMCID: PMC6502836 DOI: 10.1038/s41598-019-43360-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 04/23/2019] [Indexed: 02/02/2023] Open
Abstract
Kainate receptors are glutamate-gated cation-selective channels involved in excitatory synaptic signaling and are known to be modulated by ions. Prior functional and structural studies suggest that the dimer interface at the agonist-binding domain plays a key role in activation, desensitization, and ion modulation in kainate receptors. Here we have used fluorescence-based methods to investigate the changes and conformational heterogeneity at these interfaces associated with the resting, antagonist-bound, active, desensitized, and ion-modulated states of the receptor. These studies show that in the presence of Na+ ions the interfaces exist primarily in the coupled state in the apo, antagonist-bound and activated (open channel) states. Under desensitizing conditions, the largely decoupled dimer interface at the agonist-binding domain as seen in the cryo-EM structure is one of the states observed. However, in addition to this state there are several additional states with lower levels of decoupling. Replacing Na+ with Cs+ does not alter the FRET efficiencies of the states significantly, but shifts the population to the more decoupled states in both resting and desensitized states, which can be correlated with the lower activation seen in the presence of Cs+.
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Affiliation(s)
- Douglas B Litwin
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas, 77030, USA
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, University of Texas Health Science Center at Houston, Houston, Texas, 77030, USA
| | - Elisa Carrillo
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas, 77030, USA
| | - Sana A Shaikh
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas, 77030, USA
| | - Vladimir Berka
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas, 77030, USA
| | - Vasanthi Jayaraman
- Center for Membrane Biology, Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Houston, Texas, 77030, USA.
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14
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Zhao H, Lomash S, Chittori S, Glasser C, Mayer ML, Schuck P. Preferential assembly of heteromeric kainate and AMPA receptor amino terminal domains. eLife 2017; 6:32056. [PMID: 29058671 PMCID: PMC5665649 DOI: 10.7554/elife.32056] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 10/22/2017] [Indexed: 12/29/2022] Open
Abstract
Ion conductivity and the gating characteristics of tetrameric glutamate receptor ion channels are determined by their subunit composition. Competitive homo- and hetero-dimerization of their amino-terminal domains (ATDs) is a key step controlling assembly. Here we measured systematically the thermodynamic stabilities of homodimers and heterodimers of kainate and AMPA receptors using fluorescence-detected sedimentation velocity analytical ultracentrifugation. Measured affinities span many orders of magnitude, and complexes show large differences in kinetic stabilities. The association of kainate receptor ATD dimers is generally weaker than the association of AMPA receptor ATD dimers, but both show a general pattern of increased heterodimer stability as compared to the homodimers of their constituents, matching well physiologically observed receptor combinations. The free energy maps of AMPA and kainate receptor ATD dimers provide a framework for the interpretation of observed receptor subtype combinations and possible assembly pathways.
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Affiliation(s)
- Huaying Zhao
- Dynamics of Molecular Assembly Section, Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering Institutes of Health, National Institutes of Health, Bethesda, United States
| | - Suvendu Lomash
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Sagar Chittori
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Carla Glasser
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Mark L Mayer
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, United States
| | - Peter Schuck
- Dynamics of Molecular Assembly Section, Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering Institutes of Health, National Institutes of Health, Bethesda, United States
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15
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The Challenge of Interpreting Glutamate-Receptor Ion-Channel Structures. Biophys J 2017; 113:2143-2151. [PMID: 28844473 DOI: 10.1016/j.bpj.2017.07.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/12/2017] [Accepted: 07/25/2017] [Indexed: 11/24/2022] Open
Abstract
Ion channels activated by glutamate mediate excitatory synaptic transmission in the central nervous system. Similar to other ligand-gated ion channels, their gating cycle begins with transitions from a ligand-free closed state to glutamate-bound active and desensitized states. In an attempt to reveal the molecular mechanisms underlying gating, numerous structures for glutamate receptors have been solved in complexes with agonists, antagonists, allosteric modulators, and auxiliary proteins. The embarrassingly rich library of structures emerging from this work reveals very dynamic molecules with a more complex conformational spectrum than anticipated from functional studies. Unanticipated conformations solved for complexes with competitive antagonists and a lack of understanding of the structural basis for ion channel subconductance states further highlight challenges that have yet to be addressed.
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16
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Yonkunas M, Buddhadev M, Flores Canales JC, Kurnikova MG. Configurational Preference of the Glutamate Receptor Ligand Binding Domain Dimers. Biophys J 2017; 112:2291-2300. [PMID: 28591602 DOI: 10.1016/j.bpj.2017.04.042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 04/11/2017] [Accepted: 04/24/2017] [Indexed: 01/26/2023] Open
Abstract
Ionotropic glutamate receptors are a family of tetrameric ion channels with functional states consisting of nonconducting, conducting, and desensitized states that are starting to become well characterized by electrophysiological and biophysical studies. However, the structure and relative energetics of these states beyond the general structure of the receptor are still not well understood. It is known that the interface between monomeric subunits of the tetramer plays a major role in distinguishing these functional states. We have used umbrella sampling and multimicrosecond molecular dynamics simulations of the GluA2 AMPA subtype glutamate receptor ligand-binding domain (LBD) dimers to characterize a natural propensity of the LBD dimers for various configurational states. Our results show a proposed desensitized conformation of the LBD dimer is a highly preferable conformation of the LBD dimer without the influence of other receptor domains or crystallographic conditions. This has been demonstrated by both free protein simulations of 5 μs duration, as well as by computed free energy difference between the active and desensitized states. At the same time, the simulations performed using the same protocols revealed that for the LBD mutant L483Y, known to lack desensitization, the postulated active state of the LBD dimer is indeed the preferred configurational state, which remained stable in the simulations. Our findings pave the path for developing more detailed hypotheses of the full receptor activation mechanism. Combined with the energetics of glutamate binding to the LBD and the energy required to open the transmembrane pore helices, our results strongly support a hypothesis that the low absolute free-energy state is the desensitized state of the intact AMPA receptor.
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Affiliation(s)
- Michael Yonkunas
- Chemistry Department, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Maiti Buddhadev
- Chemistry Department, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | | | - Maria G Kurnikova
- Chemistry Department, Carnegie Mellon University, Pittsburgh, Pennsylvania.
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17
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Musgaard M, Biggin PC. Steered Molecular Dynamics Simulations Predict Conformational Stability of Glutamate Receptors. J Chem Inf Model 2016; 56:1787-97. [PMID: 27482759 DOI: 10.1021/acs.jcim.6b00297] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The stability of protein-protein interfaces can be essential for protein function. For ionotropic glutamate receptors, a family of ligand-gated ion channels vital for normal function of the central nervous system, such an interface exists between the extracellular ligand binding domains (LBDs). In the full-length protein, the LBDs are arranged as a dimer of dimers. Agonist binding to the LBDs opens the ion channel, and briefly after activation the receptor desensitizes. Several residues at the LBD dimer interface are known to modulate desensitization, and conformational changes around these residues are believed to be involved in the state transition. The general hypothesis is that the interface is disrupted upon desensitization, and structural evidence suggests that the disruption might be substantial. However, when cross-linking the central part of this interface, functional data suggest that the receptor can still undergo desensitization, contradicting the hypothesis of major interface disruption. Here, we illustrate how opening the dimer interface using steered molecular dynamics (SMD) simulations, and analyzing the work values required, provides a quantitative measure for interface stability. For one subtype of glutamate receptors, which is regulated by ion binding to the dimer interface, we show that opening the interface without ions bound requires less work than with ions present, suggesting that ion binding indeed stabilizes the interface. Likewise, for interface mutants with longer-lived active states, the interface is more stable, while the work required to open the interface is reduced for less active mutants. Moreover, a cross-linked mutant can still undergo initial interface opening motions similar to the native receptor and at similar energetic cost. Thus, our results support that interface opening is involved in desensitization. Furthermore, they provide reconciliation of apparently opposing data and demonstrate that SMD simulations can give relevant biological insight into longer time scale processes without the need for expensive calculations.
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Affiliation(s)
- Maria Musgaard
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford, OX1 3QU, United Kingdom
| | - Philip C Biggin
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford, OX1 3QU, United Kingdom
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18
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Meyerson JR, Chittori S, Merk A, Rao P, Han TH, Serpe M, Mayer ML, Subramaniam S. Structural basis of kainate subtype glutamate receptor desensitization. Nature 2016; 537:567-571. [PMID: 27580033 PMCID: PMC5161608 DOI: 10.1038/nature19352] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 08/09/2016] [Indexed: 12/28/2022]
Abstract
Glutamate receptors are ligand-gated tetrameric ion channels that mediate synaptic transmission in the central nervous system. They are instrumental in vertebrate cognition and their dysfunction underlies diverse diseases. In both the resting and desensitized states of AMPA and kainate receptor subtypes, the ion channels are closed, whereas the ligand-binding domains, which are physically coupled to the channels, adopt markedly different conformations. Without an atomic model for the desensitized state, it is not possible to address a central problem in receptor gating: how the resting and desensitized receptor states both display closed ion channels, although they have major differences in the quaternary structure of the ligand-binding domain. Here, by determining the structure of the kainate receptor GluK2 subtype in its desensitized state by cryo-electron microscopy (cryo-EM) at 3.8 Å resolution, we show that desensitization is characterized by the establishment of a ring-like structure in the ligand-binding domain layer of the receptor. Formation of this 'desensitization ring' is mediated by staggered helix contacts between adjacent subunits, which leads to a pseudo-four-fold symmetric arrangement of the ligand-binding domains, illustrating subtle changes in symmetry that are important for the gating mechanism. Disruption of the desensitization ring is probably the key switch that enables restoration of the receptor to its resting state, thereby completing the gating cycle.
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Affiliation(s)
- Joel R Meyerson
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland 20892, USA
| | - Sagar Chittori
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland 20892, USA
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, NICHD, NIH, Bethesda, Maryland 20892, USA
| | - Alan Merk
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland 20892, USA
| | - Prashant Rao
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland 20892, USA
| | - Tae Hee Han
- Program in Cellular Regulation and Metabolism, NICHD, NIH, Bethesda, Maryland 20892, USA
| | - Mihaela Serpe
- Program in Cellular Regulation and Metabolism, NICHD, NIH, Bethesda, Maryland 20892, USA
| | - Mark L Mayer
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, NICHD, NIH, Bethesda, Maryland 20892, USA
| | - Sriram Subramaniam
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland 20892, USA
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19
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Zhu S, Gouaux E. Structure and symmetry inform gating principles of ionotropic glutamate receptors. Neuropharmacology 2016; 112:11-15. [PMID: 27663701 DOI: 10.1016/j.neuropharm.2016.08.034] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 08/24/2016] [Indexed: 12/29/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) transduce signals derived from release of the excitatory neurotransmitter glutamate from pre-synaptic neurons into excitation of post-synaptic neurons on a millisecond time-scale. In recent years, the elucidation of full-length iGluR structures of NMDA, AMPA and kainate receptors by X-ray crystallography and single particle cryo-electron microscopy has greatly enhanced our understanding of the interrelationships between receptor architecture and gating mechanism. Here we briefly review full-length iGluR structures and discuss the similarities and differences between NMDA receptors and non-NMDA iGluRs. We focus on distinct conformations, including ligand-free, agonist-bound active, agonist-bound desensitized and antagonist-bound conformations as well as modulator and auxiliary protein-bound states. These findings provide insights into structure-based mechanisms of iGluR gating and modulation which together shape the amplitude and time course of the excitatory postsynaptic potential. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'.
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Affiliation(s)
- Shujia Zhu
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland OR 97239, USA
| | - Eric Gouaux
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland OR 97239, USA; Howard Hughes Medical Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland OR 97239, USA.
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20
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Protein Crowding within the Postsynaptic Density Can Impede the Escape of Membrane Proteins. J Neurosci 2016; 36:4276-95. [PMID: 27076425 DOI: 10.1523/jneurosci.3154-15.2016] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 02/19/2016] [Indexed: 01/03/2023] Open
Abstract
UNLABELLED Mechanisms regulating lateral diffusion and positioning of glutamate receptors within the postsynaptic density (PSD) determine excitatory synaptic strength. Scaffold proteins in the PSD are abundant receptor binding partners, yet electron microscopy suggests that the PSD is highly crowded, potentially restricting the diffusion of receptors regardless of binding. However, the contribution of macromolecular crowding to receptor retention remains poorly understood. We combined experimental and computational approaches to test the effect of synaptic crowding on receptor movement and positioning in Sprague Dawley rat hippocampal neurons. We modeled AMPA receptor diffusion in synapses where the distribution of scaffold proteins was determined from photoactivated localization microscopy experiments, and receptor-scaffold association and dissociation rates were adjusted to fit single-molecule tracking and fluorescence recovery measurements. Simulations predicted that variation of receptor size strongly influences the fractional synaptic area the receptor may traverse, and the proportion that may exchange in and out of the synapse. To test the model experimentally, we designed a set of novel transmembrane (TM) probes. A single-pass TM protein with one PDZ binding motif concentrated in the synapse as do AMPARs yet was more mobile there than the much larger AMPAR. Furthermore, either the single binding motif or an increase in cytoplasmic bulk through addition of a single GFP slowed synaptic movement of a small TM protein. These results suggest that both crowding and binding limit escape of AMPARs from the synapse. Moreover, tight protein packing within the PSD may modulate the synaptic dwell time of many TM proteins important for synaptic function. SIGNIFICANCE STATEMENT Small alterations to the distribution within synapses of key transmembrane proteins, such as receptors, can dramatically change synaptic strength. Indeed, many diseases are thought to unbalance neural circuit function in this manner. Processes that regulate this in healthy synapses are unclear, however. By combining computer simulations with imaging methods that examined protein dynamics at multiple scales in space and time, we showed that both steric effects and protein-protein binding each regulate the mobility of receptors in the synapse. Our findings extend our knowledge of the synapse as a crowded environment that counteracts molecular diffusion, and support the idea that both molecular collisions and biochemical binding can be involved in the regulation of neural circuit performance.
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21
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Lessons from crystal structures of kainate receptors. Neuropharmacology 2016; 112:16-28. [PMID: 27236079 DOI: 10.1016/j.neuropharm.2016.05.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 05/19/2016] [Accepted: 05/22/2016] [Indexed: 11/22/2022]
Abstract
Kainate receptors belong to the family of ionotropic glutamate receptors. These receptors assemble from five subunits (GluK1-5) into tetrameric ion channels. Kainate receptors are located at both pre- and postsynaptic membranes in the central nervous system where they contribute to excitatory synaptic transmission and modulate network excitability by regulating neurotransmitter release. Dysfunction of kainate receptors has been implicated in several neurological disorders such as epilepsy, schizophrenia and depression. Here we provide a review on the current understanding of kainate receptor structure and how they bind agonists, antagonists and ions. The first structure of the ligand-binding domain of the GluK1 subunit was reported in 2005, seven years after publication of the crystal structure of a soluble construct of the ligand-binding domain of the AMPA-type subunit GluA2. Today, a full-length structure has been determined of GluK2 by cryo electron microscopy to 7.6 Å resolution as well as 84 high-resolution crystal structures of N-terminal domains and ligand-binding domains, including agonist and antagonist bound structures, modulatory ions and mutations. However, there are still many unanswered questions and challenges in front of us. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'.
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22
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García-Nafría J, Herguedas B, Watson JF, Greger IH. The dynamic AMPA receptor extracellular region: a platform for synaptic protein interactions. J Physiol 2016; 594:5449-58. [PMID: 26891027 DOI: 10.1113/jp271844] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 01/21/2016] [Indexed: 12/27/2022] Open
Abstract
AMPA receptors (AMPARs) are glutamate-gated cation channels that mediate fast excitatory neurotransmission and synaptic plasticity. Structures of GluA2 homotetramers in distinct functional states, together with simulations, emphasise the loose architecture of the AMPAR extracellular region (ECR). The ECR encompasses ∼80% of the receptor, and consists of the membrane-distal N-terminal domain (NTD) and ligand-binding domain (LBD), which is fused to the ion channel domain. Minimal contacts within and between layers, together with flexible peptide linkers connecting these three domains give rise to an organisation capable of dynamic rearrangements. This building plan is uniquely suited to engage interaction partners in the crowded environment of synapses, permitting the formation of new binding sites and the loss of existing ones. ECR motions are thereby expected to impact signalling as well as synaptic anchorage and may thereby influence AMPAR clustering during synaptic plasticity.
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Affiliation(s)
- J García-Nafría
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - B Herguedas
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - J F Watson
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - I H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK.
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23
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The structure and function of glutamate receptors: Mg 2+ block to X-ray diffraction. Neuropharmacology 2016; 112:4-10. [PMID: 27131921 DOI: 10.1016/j.neuropharm.2016.04.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/26/2016] [Indexed: 11/23/2022]
Abstract
Experiments on the action of glutamate on mammalian and amphibian nervous systems started back in the 1950s but decades passed before it became widely accepted that glutamate was the major excitatory neurotransmitter in the CNS. The pace of research greatly accelerated in the 1980s when selective ligands that identified glutamate receptor subtypes became widely available, and voltage clamp techniques, coupled with rapid perfusion, began to resolve the unique functional properties of what cloning subsequently revealed to be a large family of receptors with numerous subtypes. More recently the power of X-ray crystallography and cryo-EM has been applied to the study of glutamate receptors, revealing their atomic structures, and the conformational changes that underlie their gating. In this review I summarize the history of this field, viewed through the lens of a career in which I spent 3 decades working on the structure and function of glutamate receptor ion channels. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'.
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Zhu S, Stein RA, Yoshioka C, Lee CH, Goehring A, Mchaourab HS, Gouaux E. Mechanism of NMDA Receptor Inhibition and Activation. Cell 2016; 165:704-14. [PMID: 27062927 DOI: 10.1016/j.cell.2016.03.028] [Citation(s) in RCA: 158] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 03/06/2016] [Accepted: 03/18/2016] [Indexed: 11/24/2022]
Abstract
N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated, calcium-permeable ion channels that mediate synaptic transmission and underpin learning and memory. NMDAR dysfunction is directly implicated in diseases ranging from seizure to ischemia. Despite its fundamental importance, little is known about how the NMDAR transitions between inactive and active states and how small molecules inhibit or activate ion channel gating. Here, we report electron cryo-microscopy structures of the GluN1-GluN2B NMDA receptor in an ensemble of competitive antagonist-bound states, an agonist-bound form, and a state bound with agonists and the allosteric inhibitor Ro25-6981. Together with double electron-electron resonance experiments, we show how competitive antagonists rupture the ligand binding domain (LBD) gating "ring," how agonists retain the ring in a dimer-of-dimers configuration, and how allosteric inhibitors, acting within the amino terminal domain, further stabilize the LBD layer. These studies illuminate how the LBD gating ring is fundamental to signal transduction and gating in NMDARs.
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Affiliation(s)
- Shujia Zhu
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Richard A Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Craig Yoshioka
- Department of Biomedical Engineering, Oregon Health and Science University, 2730 SW Moody Ave, Portland, OR 97201, USA
| | - Chia-Hsueh Lee
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - April Goehring
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Eric Gouaux
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Howard Hughes Medical Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
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Herguedas B, García-Nafría J, Cais O, Fernández-Leiro R, Krieger J, Ho H, Greger IH. Structure and organization of heteromeric AMPA-type glutamate receptors. Science 2016; 352:aad3873. [PMID: 26966189 DOI: 10.1126/science.aad3873] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 02/24/2016] [Indexed: 12/22/2022]
Abstract
AMPA-type glutamate receptors (AMPARs), which are central mediators of rapid neurotransmission and synaptic plasticity, predominantly exist as heteromers of the subunits GluA1 to GluA4. Here we report the first AMPAR heteromer structures, which deviate substantially from existing GluA2 homomer structures. Crystal structures of the GluA2/3 and GluA2/4 N-terminal domains reveal a novel compact conformation with an alternating arrangement of the four subunits around a central axis. This organization is confirmed by cysteine cross-linking in full-length receptors, and it permitted us to determine the structure of an intact GluA2/3 receptor by cryogenic electron microscopy. Two models in the ligand-free state, at resolutions of 8.25 and 10.3 angstroms, exhibit substantial vertical compression and close associations between domain layers, reminiscent of N-methyl-D-aspartate receptors. Model 1 resembles a resting state and model 2 a desensitized state, thus providing snapshots of gating transitions in the nominal absence of ligand. Our data reveal organizational features of heteromeric AMPARs and provide a framework to decipher AMPAR architecture and signaling.
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Affiliation(s)
- Beatriz Herguedas
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | - Ondrej Cais
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | - James Krieger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Hinze Ho
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Ingo H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, UK
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26
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Gan Q, Dai J, Zhou HX, Wollmuth LP. The Transmembrane Domain Mediates Tetramerization of α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid (AMPA) Receptors. J Biol Chem 2016; 291:6595-606. [PMID: 26839312 DOI: 10.1074/jbc.m115.686246] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Indexed: 11/06/2022] Open
Abstract
AMPA receptors (AMPARs) mediate fast excitatory neurotransmission in the central nervous system. Functional AMPARs are tetrameric complexes with a highly modular structure, consisting of four evolutionarily distinct structural domains: an amino-terminal domain (ATD), a ligand-binding domain (LBD), a channel-forming transmembrane domain (TMD), and a carboxyl-terminal domain (CTD). Here we show that the isolated TMD of the GluA1 AMPAR is fully capable of tetramerization. Additionally, removal of the extracellular domains from the receptor did not affect membrane topology or surface delivery. Furthermore, whereas the ATD and CTD contribute positively to tetramerization, the LBD presents a barrier to the process by reducing the stability of the receptor complex. These experiments pinpoint the TMD as the "tetramerization domain" for AMPARs, with other domains playing modulatory roles. They also raise intriguing questions about the evolution of iGluRs as well as the mechanisms regulating the biogenesis of AMPAR complexes.
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Affiliation(s)
- Quan Gan
- Graduate Program in Neuroscience, From the Department of Neurobiology and Behavior
| | - Jian Dai
- the Department of Physics and Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306
| | - Huan-Xiang Zhou
- the Department of Physics and Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306
| | - Lonnie P Wollmuth
- From the Department of Neurobiology and Behavior, the Department of Biochemistry and Cell Biology, and the Center for Nervous System Disorders, Stony Brook University, Stony Brook, New York 11794-5230 and
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27
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Kristensen AS, Hansen KB, Naur P, Olsen L, Kurtkaya NL, Dravid SM, Kvist T, Yi F, Pøhlsgaard J, Clausen RP, Gajhede M, Kastrup JS, Traynelis SF. Pharmacology and Structural Analysis of Ligand Binding to the Orthosteric Site of Glutamate-Like GluD2 Receptors. Mol Pharmacol 2015; 89:253-62. [PMID: 26661043 DOI: 10.1124/mol.115.100909] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 12/07/2015] [Indexed: 11/22/2022] Open
Abstract
The GluD2 receptor is a fundamental component of postsynaptic sites in Purkinje neurons, and is required for normal cerebellar function. GluD2 and the closely related GluD1 are classified as members of the ionotropic glutamate receptor (iGluR) superfamily on the basis of sequence similarity, but do not bind l-glutamate. The amino acid neurotransmitter D-Ser is a GluD2 receptor ligand, and endogenous D-Ser signaling through GluD2 has recently been shown to regulate endocytosis of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type iGluRs during synaptic plasticity in the cerebellum, such as long-term depression. Here, we investigate the pharmacology of the orthosteric binding site in GluD2 by examining the activity of analogs of D-Ser and GluN1 glycine site competitive antagonists at GluD2 receptors containing the lurcher mutation (GluD2(LC)), which promotes spontaneous channel activation. We identify several compounds that modulate GluD2(LC), including a halogenated alanine analog as well as the kynurenic acid analog 7-chloro-4-oxo-1H-quinoline-2-carboxylic acid (7-chlorokynurenic acid; 7-CKA). By correlating thermodynamic and structural data for 7-CKA binding to the isolated GluD2 ligand binding domain (GluD2-LBD), we find that binding 7-CKA to GluD2-LBD differs from D-Ser by inducing an intermediate cleft closure of the clamshell-shaped LBD. The GluD2 ligands identified here can potentially serve as a starting point for development of GluD2-selective ligands useful as tools in studies of the signaling role of the GluD2 receptor in the brain.
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Affiliation(s)
- Anders S Kristensen
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Kasper B Hansen
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Peter Naur
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Lars Olsen
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Natalie L Kurtkaya
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Shashank M Dravid
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Trine Kvist
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Feng Yi
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Jacob Pøhlsgaard
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Rasmus P Clausen
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Michael Gajhede
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Jette S Kastrup
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
| | - Stephen F Traynelis
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (A.S.K., K.B.H., N.L.K., S.M.D., S.F.T.); Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark (A.S.K., P.N., L.O., T.K., J.P., R.P.C., M.G., J.S.K.); and Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, Montana (K.B.H., F.Y.)
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28
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Fisher JL. The auxiliary subunits Neto1 and Neto2 have distinct, subunit-dependent effects at recombinant GluK1- and GluK2-containing kainate receptors. Neuropharmacology 2015; 99:471-80. [PMID: 26277340 PMCID: PMC4655126 DOI: 10.1016/j.neuropharm.2015.08.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 07/29/2015] [Accepted: 08/11/2015] [Indexed: 10/23/2022]
Abstract
The kainate-type of ionotropic glutamate receptors are assembled from a combination of five different pore-forming subunits (GluK1-5), which confer distinct functional and pharmacological properties. These receptors are also modulated by co-assembly with the auxiliary subunits Neto1 and Neto2. To determine the impact of variation in subunit composition on the functional interaction between kainate receptors and Neto subunits, the Neto subunits were combined with either GluK1 or GluK2 in HEK-293T cells and responses to glutamate examined through patch-clamp recordings. Co-expression of GluK1 with either Neto1 or Neto2 caused a substantial increase in glutamate sensitivity and a slowing of the onset of desensitization at low agonist concentrations. However, at higher glutamate concentrations the primary effect of Neto2 was to slow the onset of desensitization, while that of Neto1 was to increase recovery from desensitization. In contrast, co-expression of Neto2 with GluK2 homomeric receptors had only modest effects on glutamate sensitivity, but increased the rate of recovery from desensitization as well as slowing its onset at all agonist concentrations. The properties of chimeric Neto1/Neto2 subunits suggested that the extracellular N-terminal region including the two CUB domains was largely responsible for the distinct regulatory effects of Neto1 and Neto2 on the desensitization properties of GluK1 homomeric receptors. These results further demonstrate that the functional effects of Neto subunits depend upon the subunit identity of both the auxiliary and the pore-forming subunits.
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Affiliation(s)
- Janet L Fisher
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, 29208, USA.
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29
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Alberstein R, Grey R, Zimmet A, Simmons DK, Mayer ML. Glycine activated ion channel subunits encoded by ctenophore glutamate receptor genes. Proc Natl Acad Sci U S A 2015; 112:E6048-57. [PMID: 26460032 PMCID: PMC4640758 DOI: 10.1073/pnas.1513771112] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Recent genome projects for ctenophores have revealed the presence of numerous ionotropic glutamate receptors (iGluRs) in Mnemiopsis leidyi and Pleurobrachia bachei, among our earliest metazoan ancestors. Sequence alignments and phylogenetic analysis show that these form a distinct clade from the well-characterized AMPA, kainate, and NMDA iGluR subtypes found in vertebrates. Although annotated as glutamate and kainate receptors, crystal structures of the ML032222a and PbiGluR3 ligand-binding domains (LBDs) reveal endogenous glycine in the binding pocket, whereas ligand-binding assays show that glycine binds with nanomolar affinity; biochemical assays and structural analysis establish that glutamate is occluded from the binding cavity. Further analysis reveals ctenophore-specific features, such as an interdomain Arg-Glu salt bridge, present only in subunits that bind glycine, but also a conserved disulfide in loop 1 of the LBD that is found in all vertebrate NMDA but not AMPA or kainate receptors. We hypothesize that ctenophore iGluRs are related to an early ancestor of NMDA receptors, suggesting a common evolutionary path for ctenophores and bilaterian species, and suggest that future work should consider both glycine and glutamate as candidate neurotransmitters in ctenophore species.
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Affiliation(s)
- Robert Alberstein
- Laboratory of Cellular and Molecular Neurophysiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Richard Grey
- Laboratory of Cellular and Molecular Neurophysiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Austin Zimmet
- Laboratory of Cellular and Molecular Neurophysiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - David K Simmons
- The Whitney Laboratory for Marine Bioscience, University of Florida, St. Augustine, FL 32080
| | - Mark L Mayer
- Laboratory of Cellular and Molecular Neurophysiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892;
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30
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De Zorzi R, Mi W, Liao M, Walz T. Single-particle electron microscopy in the study of membrane protein structure. Microscopy (Oxf) 2015; 65:81-96. [PMID: 26470917 DOI: 10.1093/jmicro/dfv058] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 09/20/2015] [Indexed: 01/13/2023] Open
Abstract
Single-particle electron microscopy (EM) provides the great advantage that protein structure can be studied without the need to grow crystals. However, due to technical limitations, this approach played only a minor role in the study of membrane protein structure. This situation has recently changed dramatically with the introduction of direct electron detection device cameras, which allow images of unprecedented quality to be recorded, also making software algorithms, such as three-dimensional classification and structure refinement, much more powerful. The enhanced potential of single-particle EM was impressively demonstrated by delivering the first long-sought atomic model of a member of the biomedically important transient receptor potential channel family. Structures of several more membrane proteins followed in short order. This review recounts the history of single-particle EM in the study of membrane proteins, describes the technical advances that now allow this approach to generate atomic models of membrane proteins and provides a brief overview of some of the membrane protein structures that have been studied by single-particle EM to date.
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Affiliation(s)
- Rita De Zorzi
- Department of Cell Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA Howard Hughes Medical Institute, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Wei Mi
- Department of Cell Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Thomas Walz
- Department of Cell Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA Howard Hughes Medical Institute, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
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Structure, Dynamics, and Allosteric Potential of Ionotropic Glutamate Receptor N-Terminal Domains. Biophys J 2015; 109:1136-48. [PMID: 26255587 PMCID: PMC4576161 DOI: 10.1016/j.bpj.2015.06.061] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 06/22/2015] [Accepted: 06/30/2015] [Indexed: 12/26/2022] Open
Abstract
Ionotropic glutamate receptors (iGluRs) are tetrameric cation channels that mediate synaptic transmission and plasticity. They have a unique modular architecture with four domains: the intracellular C-terminal domain (CTD) that is involved in synaptic targeting, the transmembrane domain (TMD) that forms the ion channel, the membrane-proximal ligand-binding domain (LBD) that binds agonists such as L-glutamate, and the distal N-terminal domain (NTD), whose function is the least clear. The extracellular portion, comprised of the LBD and NTD, is loosely arranged, mediating complex allosteric regulation and providing a rich target for drug development. Here, we briefly review recent work on iGluR NTD structure and dynamics, and further explore the allosteric potential for the NTD in AMPA-type iGluRs using coarse-grained simulations. We also investigate mechanisms underlying the established NTD allostery in NMDA-type iGluRs, as well as the fold-related metabotropic glutamate and GABAB receptors. We show that the clamshell motions intrinsically favored by the NTD bilobate fold are coupled to dimeric and higher-order rearrangements that impact the iGluR LBD and ultimately the TMD. Finally, we explore the dynamics of intact iGluRs and describe how it might affect receptor operation in a synaptic environment.
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32
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Cooperative Dynamics of Intact AMPA and NMDA Glutamate Receptors: Similarities and Subfamily-Specific Differences. Structure 2015; 23:1692-1704. [PMID: 26256538 DOI: 10.1016/j.str.2015.07.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 06/19/2015] [Accepted: 07/01/2015] [Indexed: 01/03/2023]
Abstract
Ionotropic glutamate receptors (iGluRs) are tetrameric ion channels that mediate excitatory neurotransmission. Recent structures of α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and N-methyl-D-aspartate (NMDA) receptors permit a comparative analysis of whole-receptor dynamics for the first time. Despite substantial differences in the packing of their two-domain extracellular region, the two iGluRs share similar dynamics, elucidated by elastic network models. Motions accessible to either structure enable conformational interconversion, such as compression of the AMPA receptor toward the more tightly packed NMDA receptor conformation, which has been linked to allosteric regulation. Pivoting motions coupled to concerted rotations of the transmembrane ion channel are prominent between dimers of distal N-terminal domains in the loosely packed AMPA receptor. The occurrence and functional relevance of these motions is verified by cross-linking experiments designed to probe the computationally predicted distance changes. Together with the identification of hotspot residues acting as mediators of allosteric communication, our data provide a glimpse into the dynamic spectrum of iGluRs.
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33
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Emerging structural insights into the function of ionotropic glutamate receptors. Trends Biochem Sci 2015; 40:328-37. [PMID: 25941168 DOI: 10.1016/j.tibs.2015.04.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/07/2015] [Accepted: 04/08/2015] [Indexed: 01/16/2023]
Abstract
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that mediate excitatory neurotransmission crucial for brain development and function, including learning and memory formation. Recently a wealth of structural studies on iGluRs including AMPA receptors (AMPARs), kainate receptors, and NMDA receptors (NMDARs) became available. These studies showed structures of non-NMDARs including AMPAR and kainate receptor in various functional states, thereby providing the first visual sense of how non-NMDAR iGluRs may function in the context of homotetramers. Furthermore, they provided the first view of heterotetrameric NMDAR ion channels, and this illuminated the similarities with and differences from non-NMDARs, thus raising a mechanistic distinction between the two groups of iGluRs. We review mechanistic insights into iGluR functions gained through structural studies of multiple groups.
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Cheriyan J, Mezes C, Zhou N, Balsara RD, Castellino FJ. Heteromerization of ligand binding domains of N-methyl-D-aspartate receptor requires both coagonists, L-glutamate and glycine. Biochemistry 2015; 54:787-94. [PMID: 25544544 PMCID: PMC4310633 DOI: 10.1021/bi501437s] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
NMDA receptors (NMDAR) are voltage- and glutamate-gated heteromeric ion channels found at excitatory neuronal synapses, the functions of which are to mediate the mechanisms of brain plasticity and, thereby, its higher order functions. In addition to Glu, the activation of these heteromeric receptors requires Gly or d-Ser as a coagonist. However, it is not fully known as to why coagonism is required for the opening of NMDAR ion channels. We show herein that the ligand binding domains (LBD) of the GluN1 and GluN2A subunits of the NMDAR heterodimerize only when both coagonists, Glu and Gly/d-Ser, bind to their respective sites on GluN2 and GluN1. In the agonist-free state, these domains form homomeric interactions, which are disrupted by binding of their respective agonists. Also, in a heteromer formed by the LBDs, GluN2A is more sensitized to bind Glu, while the affinity of Gly for GluN1 remains unchanged. We thus provide direct evidence to show that coagonism is necessary for heteromeric pairing of LBDs, which is an essential step in forming functional ion channels in NMDARs.
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Affiliation(s)
- John Cheriyan
- W. M. Keck Center for Transgene Research and the Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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35
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Dawe GB, Aurousseau MR, Daniels BA, Bowie D. Retour aux sources: defining the structural basis of glutamate receptor activation. J Physiol 2015; 593:97-110. [PMID: 25556791 PMCID: PMC4293057 DOI: 10.1113/jphysiol.2014.277921] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 09/05/2014] [Indexed: 01/12/2023] Open
Abstract
Ionotropic glutamate receptors (iGluRs) are the major excitatory neurotransmitter receptor in the vertebrate CNS and, as a result, their activation properties lie at the heart of much of the neuronal network activity observed in the developing and adult brain. iGluRs have also been implicated in many nervous system disorders associated with postnatal development (e.g. autism, schizophrenia), cerebral insult (e.g. stroke, epilepsy), and disorders of the ageing brain (e.g. Alzheimer's disease, Parkinsonism). In view of this, an emphasis has been placed on understanding how iGluRs activate and desensitize in functional and structural terms. Early structural models of iGluRs suggested that the strength of the agonist response was primarily governed by the degree of closure induced in the ligand-binding domain (LBD). However, recent studies have suggested a more nuanced role for the LBD with current evidence identifying the iGluR LBD interface as a "hotspot" regulating agonist behaviour. Such ideas remain to be consolidated with recently solved structures of full-length iGluRs to account for the global changes that underlie channel activation and desensitization.
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Affiliation(s)
- G Brent Dawe
- Integrated Program in Neuroscience, McGill UniversityMontréal, Québec, Canada
- Department of Pharmacology and Therapeutics, McGill UniversityMontréal, Québec, Canada
| | - Mark R Aurousseau
- Graduate Program in Pharmacology, McGill UniversityMontréal, Québec, Canada
- Department of Pharmacology and Therapeutics, McGill UniversityMontréal, Québec, Canada
| | - Bryan A Daniels
- Department of Pharmacology and Therapeutics, McGill UniversityMontréal, Québec, Canada
| | - Derek Bowie
- Department of Pharmacology and Therapeutics, McGill UniversityMontréal, Québec, Canada
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Meyerson JR, Rao P, Kumar J, Chittori S, Banerjee S, Pierson J, Mayer ML, Subramaniam S. Self-assembled monolayers improve protein distribution on holey carbon cryo-EM supports. Sci Rep 2014; 4:7084. [PMID: 25403871 PMCID: PMC4235105 DOI: 10.1038/srep07084] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 10/20/2014] [Indexed: 01/04/2023] Open
Abstract
Poor partitioning of macromolecules into the holes of holey carbon support grids frequently limits structural determination by single particle cryo-electron microscopy (cryo-EM). Here, we present a method to deposit, on gold-coated carbon grids, a self-assembled monolayer whose surface properties can be controlled by chemical modification. We demonstrate the utility of this approach to drive partitioning of ionotropic glutamate receptors into the holes, thereby enabling 3D structural analysis using cryo-EM methods.
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Affiliation(s)
- Joel R. Meyerson
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892
| | - Prashant Rao
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892
| | - Janesh Kumar
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, NICHD, NIH, Bethesda MD 20892
| | - Sagar Chittori
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, NICHD, NIH, Bethesda MD 20892
| | - Soojay Banerjee
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892
| | | | - Mark L. Mayer
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, NICHD, NIH, Bethesda MD 20892
| | - Sriram Subramaniam
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892
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Meyerson JR, Kumar J, Chittori S, Rao P, Pierson J, Bartesaghi A, Mayer ML, Subramaniam S. Structural mechanism of glutamate receptor activation and desensitization. Nature 2014; 514:328-34. [PMID: 25119039 PMCID: PMC4199900 DOI: 10.1038/nature13603] [Citation(s) in RCA: 179] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 06/19/2014] [Indexed: 01/04/2023]
Abstract
Ionotropic glutamate receptors are ligand-gated ion channels that mediate excitatory synaptic transmission in the vertebrate brain. To gain a better understanding of how structural changes gate ion flux across the membrane, we trapped rat AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) and kainate receptor subtypes in their major functional states and analysed the resulting structures using cryo-electron microscopy. We show that transition to the active state involves a 'corkscrew' motion of the receptor assembly, driven by closure of the ligand-binding domain. Desensitization is accompanied by disruption of the amino-terminal domain tetramer in AMPA, but not kainate, receptors with a two-fold to four-fold symmetry transition in the ligand-binding domains in both subtypes. The 7.6 Å structure of a desensitized kainate receptor shows how these changes accommodate channel closing. These findings integrate previous physiological, biochemical and structural analyses of glutamate receptors and provide a molecular explanation for key steps in receptor gating.
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Affiliation(s)
- Joel R Meyerson
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland 20892, USA
| | - Janesh Kumar
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, NICHD, NIH, Bethesda, Maryland 20892, USA
| | - Sagar Chittori
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, NICHD, NIH, Bethesda, Maryland 20892, USA
| | - Prashant Rao
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland 20892, USA
| | | | - Alberto Bartesaghi
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland 20892, USA
| | - Mark L Mayer
- Laboratory of Cellular and Molecular Neurophysiology, Porter Neuroscience Research Center, NICHD, NIH, Bethesda, Maryland 20892, USA
| | - Sriram Subramaniam
- Laboratory of Cell Biology, Center for Cancer Research, NCI, NIH, Bethesda, Maryland 20892, USA
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38
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Cais O, Herguedas B, Krol K, Cull-Candy SG, Farrant M, Greger IH. Mapping the interaction sites between AMPA receptors and TARPs reveals a role for the receptor N-terminal domain in channel gating. Cell Rep 2014; 9:728-40. [PMID: 25373908 PMCID: PMC4405707 DOI: 10.1016/j.celrep.2014.09.029] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 08/12/2014] [Accepted: 09/19/2014] [Indexed: 11/18/2022] Open
Abstract
AMPA-type glutamate receptors (AMPARs) mediate fast neurotransmission at excitatory synapses. The extent and fidelity of postsynaptic depolarization triggered by AMPAR activation are shaped by AMPAR auxiliary subunits, including the transmembrane AMPAR regulatory proteins (TARPs). TARPs profoundly influence gating, an effect thought to be mediated by an interaction with the AMPAR ion channel and ligand binding domain (LBD). Here, we show that the distal N-terminal domain (NTD) contributes to TARP modulation. Alterations in the NTD-LBD linker result in TARP-dependent and TARP-selective changes in AMPAR gating. Using peptide arrays, we identify a TARP interaction region on the NTD and define the path of TARP contacts along the LBD surface. Moreover, we map key binding sites on the TARP itself and show that mutation of these residues mediates gating modulation. Our data reveal a TARP-dependent allosteric role for the AMPAR NTD and suggest that TARP binding triggers a drastic reorganization of the AMPAR complex. The NTD linker has a TARP-dependent and TARP-specific impact on AMPAR gating Peptide arrays reveal binding of TARPs to both extracellular domains of AMPARs A structural reorganization of AMPARs is triggered by TARP binding
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Affiliation(s)
- Ondrej Cais
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Beatriz Herguedas
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Karolina Krol
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Stuart G Cull-Candy
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Mark Farrant
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK
| | - Ingo H Greger
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
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Fisher MT, Fisher JL. Contributions of different kainate receptor subunits to the properties of recombinant homomeric and heteromeric receptors. Neuroscience 2014; 278:70-80. [PMID: 25139762 PMCID: PMC4172534 DOI: 10.1016/j.neuroscience.2014.08.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 08/11/2014] [Accepted: 08/11/2014] [Indexed: 01/20/2023]
Abstract
The tetrameric kainate receptors can be assembled from a combination of five different subunit subtypes. While GluK1-3 subunits can form homomeric receptors, GluK4 and GluK5 require a heteromeric partner to assemble, traffic to the membrane surface, and produce a functional channel. Previous studies have shown that incorporation of a GluK4 or GluK5 subunit changes both receptor pharmacology and channel kinetics. We directly compared the functional characteristics of recombinant receptors containing either GluK4 or GluK5 in combination with the GluK1 or GluK2 subunit. In addition, we took advantage of mutations within the agonist binding sites of GluK1, GluK2, or GluK5 to isolate the response of the wild-type partner within the heteromeric receptor. Our results suggest that GluK1 and GluK2 differ primarily in their pharmacological properties, but that GluK4 and GluK5 have distinct functional characteristics. In particular, while binding of agonist to only the GluK5 subunit appears to activate the channel to a non-desensitizing state, binding to GluK4 does produce some desensitization. This suggests that GluK4 and GluK5 differ fundamentally in their contribution to receptor desensitization. In addition, mutation of the agonist binding site of GluK5 results in a heteromeric receptor with a glutamate sensitivity similar to homomeric GluK1 or GluK2 receptors, but which requires higher agonist concentrations to produce desensitization. This suggests that onset of desensitization in heteromeric receptors is determined more by the number of subunits bound to agonist than by the identity of those subunits. The distinct, concentration-dependent properties observed with heteromeric receptors in response to glutamate or kainate are consistent with a model in which either subunit can activate the channel, but in which occupancy of both subunits within a dimer is needed to allow desensitization of GluK2/K5 receptors.
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Affiliation(s)
- M T Fisher
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA
| | - J L Fisher
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC, USA.
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40
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Petzoldt A, Lee YH, Khorramshahi O, Reynolds E, Plested A, Herzel H, Sigrist S. Gating Characteristics Control Glutamate Receptor Distribution and Trafficking In Vivo. Curr Biol 2014; 24:2059-65. [DOI: 10.1016/j.cub.2014.07.051] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 06/20/2014] [Accepted: 07/18/2014] [Indexed: 11/29/2022]
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41
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Yelshanskaya MV, Li M, Sobolevsky AI. Structure of an agonist-bound ionotropic glutamate receptor. Science 2014; 345:1070-4. [PMID: 25103407 DOI: 10.1126/science.1256508] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) mediate most excitatory neurotransmission in the central nervous system and function by opening their ion channel in response to binding of agonist glutamate. Here, we report a structure of a homotetrameric rat GluA2 receptor in complex with partial agonist (S)-5-nitrowillardiine. Comparison of this structure with the closed-state structure in complex with competitive antagonist ZK 200775 suggests conformational changes that occur during iGluR gating. Guided by the structures, we engineered disulfide cross-links to probe domain interactions that are important for iGluR gating events. The combination of structural information, kinetic modeling, and biochemical and electrophysiological experiments provides insight into the mechanism of iGluR gating.
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Affiliation(s)
- Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY 10032, USA
| | - Minfen Li
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY 10032, USA
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY 10032, USA.
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42
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Dürr KL, Chen L, Stein RA, De Zorzi R, Folea IM, Walz T, Mchaourab HS, Gouaux E. Structure and dynamics of AMPA receptor GluA2 in resting, pre-open, and desensitized states. Cell 2014; 158:778-792. [PMID: 25109876 DOI: 10.1016/j.cell.2014.07.023] [Citation(s) in RCA: 162] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 07/21/2014] [Accepted: 07/22/2014] [Indexed: 10/24/2022]
Abstract
Ionotropic glutamate receptors (iGluRs) mediate the majority of fast excitatory signaling in the nervous system. Despite the profound importance of iGluRs to neurotransmission, little is known about the structures and dynamics of intact receptors in distinct functional states. Here, we elucidate the structures of the intact GluA2 AMPA receptor in an apo resting/closed state, in an activated/pre-open state bound with partial agonists and a positive allosteric modulator, and in a desensitized/closed state in complex with fluorowilliardiine. To probe the conformational properties of these states, we carried out double electron-electron resonance experiments on cysteine mutants and cryoelectron microscopy studies. We show how agonist binding modulates the conformation of the ligand-binding domain "layer" of the intact receptors and how, upon desensitization, the receptor undergoes large conformational rearrangements of the amino-terminal and ligand-binding domains. We define mechanistic principles by which to understand antagonism, activation, and desensitization in AMPA iGluRs.
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Affiliation(s)
- Katharina L Dürr
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Lei Chen
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Richard A Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Rita De Zorzi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - I Mihaela Folea
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Thomas Walz
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Eric Gouaux
- Vollum Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Howard Hughes Medical Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
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43
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Green T, Nayeem N. The multifaceted subunit interfaces of ionotropic glutamate receptors. J Physiol 2014; 593:73-81. [PMID: 25556789 DOI: 10.1113/jphysiol.2014.273409] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 05/30/2014] [Indexed: 01/14/2023] Open
Abstract
The past fifteen years has seen a revolution in our understanding of ionotropic glutamate receptor (iGluR) structure, starting with the first view of the ligand binding domain (LBD) published in 1998, and in many ways culminating in the publication of the full-length structure of GluA2 in 2009. These reports have revealed not only the central role played by subunit interfaces in iGluR function, but also myriad binding sites within interfaces for endogenous and exogenous factors. Changes in the conformation of inter-subunit interfaces are central to transmission of ligand gating into pore opening (itself a rearrangement of interfaces), and subsequent closure through desensitization. With the exception of the agonist binding site, which is located entirely within individual subunits, almost all modulatory factors affecting iGluRs appear to bind to sites in subunit interfaces. This review seeks to summarize what we currently understand about the diverse roles interfaces play in iGluR function, and to highlight questions for future research.
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Affiliation(s)
- Tim Green
- Department of Pharmacology, University of Liverpool, Ashton Street, Liverpool L69 3GE, UK
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Abstract
There has been a great level of enthusiasm to downregulate overactive N-methyl-D-aspartate (NMDA) receptors to protect neurons from excitotoxicity. NMDA receptors play pivotal roles in basic brain development and functions as well as in neurological disorders and diseases. However, mechanistic understanding of antagonism in NMDA receptors is limited due to complete lack of antagonist-bound structures for the L-glutamate-binding GluN2 subunits. Here, we report the crystal structures of GluN1/GluN2A NMDA receptor ligand-binding domain (LBD) heterodimers in complex with GluN1- and GluN2-targeting antagonists. The crystal structures reveal that the antagonists, D-(-)-2-amino-5-phosphonopentanoic acid (D-AP5) and 1-(phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid (PPDA), have discrete binding modes and mechanisms for opening of the bilobed architecture of GluN2A LBD compared to the agonist-bound form. The current study shows distinct ways by which the conformations of NMDA receptor LBDs may be controlled and coupled to receptor inhibition and provides possible strategies to develop therapeutic compounds with higher subtype-specificity.
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45
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Möykkynen T, Coleman SK, Semenov A, Keinänen K. The N-terminal domain modulates α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor desensitization. J Biol Chem 2014; 289:13197-205. [PMID: 24652293 DOI: 10.1074/jbc.m113.526301] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
AMPA receptors are tetrameric glutamate-gated ion channels that mediate fast synaptic neurotransmission in mammalian brain. Their subunits contain a two-lobed N-terminal domain (NTD) that comprises over 40% of the mature polypeptide. The NTD is not obligatory for the assembly of tetrameric receptors, and its functional role is still unclear. By analyzing full-length and NTD-deleted GluA1-4 AMPA receptors expressed in HEK 293 cells, we found that the removal of the NTD leads to a significant reduction in receptor transport to the plasma membrane, a higher steady state-to-peak current ratio of glutamate responses, and strongly increased sensitivity to glutamate toxicity in cell culture. Further analyses showed that NTD-deleted receptors display both a slower onset of desensitization and a faster recovery from desensitization of agonist responses. Our results indicate that the NTD promotes the biosynthetic maturation of AMPA receptors and, for membrane-expressed channels, enhances the stability of the desensitized state. Moreover, these findings suggest that interactions of the NTD with extracellular/synaptic ligands may be able to fine-tune AMPA receptor-mediated responses, in analogy with the allosteric regulatory role demonstrated for the NTD of NMDA receptors.
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Affiliation(s)
- Tommi Möykkynen
- From the Division of Biochemistry and Biotechnology, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
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46
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Abstract
Ionotropic glutamate receptors (iGluRs) are ubiquitous in the mammalian brain, and the AMPA-subtype is essential for fast, glutamate-activated postsynaptic currents. We incorporated photoactive crosslinkers into AMPA receptors using genetically encoded unnatural amino acid mutagenesis in a mammalian cell line. Receptors rescued by incorporation of unnatural amino acids, including p-benzoyl-l-phenylalanine (BzF, also known as Bpa), had largely similar properties to wild-type channels and were expressed at similar levels. BzF incorporation at subunit interfaces afforded photocrosslinking of subunits, as assessed by biochemical experiments. In electrophysiological recordings, BzF incorporation allowed selective and potent UV-driven photoinactivation of both homomeric (GluA2) and heteromeric (GluA2:GluA1) AMPA receptors. State dependence of trapping at two sites in the lower lobe of the ligand binding domain is consistent with deformation of these domains as well as intersubunit rearrangements during AMPA receptor desensitization.
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47
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Sobolevsky AI. Structure and gating of tetrameric glutamate receptors. J Physiol 2013; 593:29-38. [PMID: 25556785 DOI: 10.1113/jphysiol.2013.264911] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 10/25/2013] [Indexed: 11/08/2022] Open
Abstract
Ionotropic glutamate receptors (iGluRs) are ligand-gated ion channels that open their ion-conducting pores in response to the binding of agonist glutamate. In recent years, significant progress has been achieved in studies of iGluRs by determining numerous structures of isolated water-soluble ligand-binding and amino-terminal domains, as well as solving the first crystal structure of the full-length AMPA receptor in the closed, antagonist-bound state. These structural data combined with electrophysiological and fluorescence recordings, biochemical experiments, mutagenesis and molecular dynamics simulations have greatly improved our understanding of iGluR assembly, activation and desensitization processes. This article reviews the recent structural and functional advances in the iGluR field and summarizes them in a simplified model of full-length iGluR gating.
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Affiliation(s)
- Alexander I Sobolevsky
- Department of Biochemistry & Molecular Biophysics, Columbia University, 650 West 168th Street, Black Bldg. 513, New York, NY, 10032, USA
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48
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Dawe GB, Musgaard M, Andrews ED, Daniels BA, Aurousseau MR, Biggin PC, Bowie D. Defining the structural relationship between kainate-receptor deactivation and desensitization. Nat Struct Mol Biol 2013; 20:1054-61. [PMID: 23955023 PMCID: PMC4972573 DOI: 10.1038/nsmb.2654] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 07/17/2013] [Indexed: 01/15/2023]
Abstract
Desensitization is an important mechanism curtailing the activity of ligand-gated ion channels (LGICs). Although the structural basis of desensitization is not fully resolved, it is thought to be governed by physicochemical properties of bound ligands. Here, we show the importance of an allosteric cation-binding pocket in controlling transitions between activated and desensitized states of rat kainate-type (KAR) ionotropic glutamate receptors (iGluRs). Tethering a positive charge to this pocket sustains KAR activation, preventing desensitization, whereas mutations that disrupt cation binding eliminate channel gating. These different outcomes explain the structural distinction between deactivation and desensitization. Deactivation occurs when the ligand unbinds before the cation, whereas desensitization proceeds if a ligand is bound without cation pocket occupancy. This sequence of events is absent from AMPA-type iGluRs; thus, cations are identified as gatekeepers of KAR gating, a role unique among even closely related LGICs.
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Affiliation(s)
- G. Brent Dawe
- Integrated Program in Neuroscience, McGill University, Montréal, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada
| | - Maria Musgaard
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Elizabeth D. Andrews
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada
| | - Bryan A. Daniels
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada
| | - Mark R.P. Aurousseau
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada
| | - Philip C. Biggin
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Derek Bowie
- Department of Pharmacology and Therapeutics, McGill University, Montréal, Canada
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49
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Fisher JL, Mott DD. Modulation of homomeric and heteromeric kainate receptors by the auxiliary subunit Neto1. J Physiol 2013; 591:4711-24. [PMID: 23798491 DOI: 10.1113/jphysiol.2013.256776] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The ionotropic glutamate receptors are primary mediators of fast excitatory neurotransmission, and their properties are determined both by their subunit composition and their association with auxiliary subunits. The neuropilin and tolloid-like 1 and 2 proteins (Neto1 and Neto2) have been recently identified as auxiliary subunits for kainate-type glutamate receptors. Heteromeric kainate receptors (KARs) can be assembled from varying combinations of low-affinity (GluK1-GluK3) and high-affinity (GluK4-GluK5) subunits. To better understand the functional impact of auxiliary subunits on KARs, we examined the effect of Neto1 on the responses of recombinant homomeric and heteromeric KARs to varying concentrations of glutamate. We found that co-expression of Neto1 with homomeric GluK2 receptors had a small effect on sensitivity of the receptors to glutamate, but decreased the onset of desensitization while speeding recovery from desensitization. In the absence of Neto1, addition of GluK5 subunits to form GluK2/GluK5 heteromeric receptors slowed the onset of desensitization at low glutamate concentrations, compared with GluK2 homomers. Co-expression of Neto1 with GluK2/GluK5 receptors further enhanced these effects, essentially eliminating desensitization at μm glutamate concentrations without altering the EC50 for activation by glutamate. In addition, a prominent rebound current was observed upon removal of the agonist. The rate of recovery from desensitization was increased to the same degree by Neto1 for both homomeric GluK2 and heteromeric GluK2/GluK5 receptors. Expression of Neto1 with GluK1/GluK5, GluK3/GluK5 or GluK2/GluK4 receptors produced qualitatively similar effects on whole-cell currents, suggesting that the impact of Neto1 on the desensitization properties of heteromeric receptors was not subunit dependent. These results provide greater insight into the functional effects of the auxiliary subunit Neto1 on both homomeric and heteromeric KARs. Alteration of the characteristics of desensitization at both sub-maximal and saturating glutamate concentrations could influence the responsiveness of these receptors to repeated stimuli. As a result, assembly of KARs with the Neto auxiliary subunits could change the kinetic properties of the neuronal response to glutamatergic input.
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Affiliation(s)
- Janet L Fisher
- J. L. Fisher: USC-School of Medicine, Department of Pharmacology, Physiology and Neuroscience, 6439 Garners Ferry Road, Columbia, SC 29209, USA.
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