1
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Strauss A, Gonzalez-Hernandez AJ, Lee J, Abreu N, Selvakumar P, Salas-Estrada L, Kristt M, Arefin A, Huynh K, Marx DC, Gilliland K, Melancon BJ, Filizola M, Meyerson J, Levitz J. Structural basis of positive allosteric modulation of metabotropic glutamate receptor activation and internalization. Nat Commun 2024; 15:6498. [PMID: 39090128 PMCID: PMC11294631 DOI: 10.1038/s41467-024-50548-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 07/12/2024] [Indexed: 08/04/2024] Open
Abstract
The metabotropic glutamate receptors (mGluRs) are neuromodulatory family C G protein coupled receptors which assemble as dimers and allosterically couple extracellular ligand binding domains (LBDs) to transmembrane domains (TMDs) to drive intracellular signaling. Pharmacologically, mGluRs can be targeted at the LBDs by glutamate and synthetic orthosteric compounds or at the TMDs by allosteric modulators. Despite the potential of allosteric compounds as therapeutics, an understanding of the functional and structural basis of their effects is limited. Here we use multiple approaches to dissect the functional and structural effects of orthosteric versus allosteric ligands. We find, using electrophysiological and live cell imaging assays, that both agonists and positive allosteric modulators (PAMs) can drive activation and internalization of group II and III mGluRs. The effects of PAMs are pleiotropic, boosting the maximal response to orthosteric agonists and serving independently as internalization-biased agonists across mGluR subtypes. Motivated by this and intersubunit FRET analyses, we determine cryo-electron microscopy structures of mGluR3 in the presence of either an agonist or antagonist alone or in combination with a PAM. These structures reveal PAM-driven re-shaping of intra- and inter-subunit conformations and provide evidence for a rolling TMD dimer interface activation pathway that controls G protein and beta-arrestin coupling.
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Affiliation(s)
- Alexa Strauss
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, 10065, USA
- Tri-Institutional Program in Chemical Biology, New York, NY, 10065, USA
| | | | - Joon Lee
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Nohely Abreu
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Purushotham Selvakumar
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Leslie Salas-Estrada
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Melanie Kristt
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Anisul Arefin
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Kevin Huynh
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Dagan C Marx
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Kristen Gilliland
- Warren Center for Neuroscience Drug Discovery at Vanderbilt University, Vanderbilt University, Nashville, TN, 37232, USA
| | - Bruce J Melancon
- Warren Center for Neuroscience Drug Discovery at Vanderbilt University, Vanderbilt University, Nashville, TN, 37232, USA
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Joel Meyerson
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, 10065, USA.
- Tri-Institutional Program in Chemical Biology, New York, NY, 10065, USA.
- Department of Psychiatry, Weill Cornell Medicine, New York, NY, 10065, USA.
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2
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Cristiano N, Cabayé A, Brabet I, Glatthar R, Tora A, Goudet C, Bertrand HO, Goupil-Lamy A, Flor PJ, Pin JP, McCort-Tranchepain I, Acher FC. Novel Inhibitory Site Revealed by XAP044 Mode of Action on the Metabotropic Glutamate 7 Receptor Venus Flytrap Domain. J Med Chem 2024; 67:11662-11687. [PMID: 38691510 DOI: 10.1021/acs.jmedchem.3c01924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2024]
Abstract
Metabotropic glutamate (mGlu) receptors play a key role in modulating most synapses in the brain. The mGlu7 receptors inhibit presynaptic neurotransmitter release and offer therapeutic possibilities for post-traumatic stress disorders or epilepsy. Screening campaigns provided mGlu7-specific allosteric modulators as the inhibitor XAP044 (Gee et al. J. Biol. Chem. 2014). In contrast to other mGlu receptor allosteric modulators, XAP044 does not bind in the transmembrane domain but to the extracellular domain of the mGlu7 receptor and not at the orthosteric site. Here, we identified the mode of action of XAP044, combining synthesis of derivatives, modeling and docking experiments, and mutagenesis. We propose a unique mode of action of these inhibitors, preventing the closure of the Venus flytrap agonist binding domain. While acting as a noncompetitive antagonist of L-AP4, XAP044 and derivatives act as apparent competitive antagonists of LSP4-2022. These data revealed more potent XAP044 analogues and new possibilities to target mGluRs.
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Affiliation(s)
- Nunzia Cristiano
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université Paris Cité, CNRS UMR 8601, 75006 Paris, France
| | - Alexandre Cabayé
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université Paris Cité, CNRS UMR 8601, 75006 Paris, France
- BIOVIA Dassault Systèmes, F-78140 Vélizy-Villacoublay Cedex, France
| | - Isabelle Brabet
- Institute of Functional Genomics, University of Montpellier, CNRS, Inserm, 34094 Montpellier, France
| | - Ralf Glatthar
- Novartis Biomedical Research, CH-4002 Basel, Switzerland
| | - Amelie Tora
- Institute of Functional Genomics, University of Montpellier, CNRS, Inserm, 34094 Montpellier, France
| | - Cyril Goudet
- Institute of Functional Genomics, University of Montpellier, CNRS, Inserm, 34094 Montpellier, France
| | | | - Anne Goupil-Lamy
- BIOVIA Dassault Systèmes, F-78140 Vélizy-Villacoublay Cedex, France
| | - Peter J Flor
- Laboratory of Molecular and Cellular Neurobiology, Faculty of Biology and Preclinical Medicine, University of Regensburg, 93053 Regensburg, Germany
| | - Jean-Philippe Pin
- Institute of Functional Genomics, University of Montpellier, CNRS, Inserm, 34094 Montpellier, France
| | - Isabelle McCort-Tranchepain
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université Paris Cité, CNRS UMR 8601, 75006 Paris, France
| | - Francine C Acher
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université Paris Cité, CNRS UMR 8601, 75006 Paris, France
- Saints-Pères Paris Institute for the Neurosciences, Université Paris Cité, CNRS UMR 8003, 75006 Paris, France
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3
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Eshak F, Pion L, Scholler P, Nevoltris D, Chames P, Rondard P, Pin JP, Acher FC, Goupil-Lamy A. Epitope Identification of an mGlu5 Receptor Nanobody Using Physics-Based Molecular Modeling and Deep Learning Techniques. J Chem Inf Model 2024; 64:4436-4461. [PMID: 38423996 DOI: 10.1021/acs.jcim.3c01620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
The world has witnessed a revolution in therapeutics with the development of biological medicines such as antibodies and antibody fragments, notably nanobodies. These nanobodies possess unique characteristics including high specificity and modulatory activity, making them promising candidates for therapeutic applications. Identifying their binding mode is essential for their development. Experimental structural techniques are effective to get such information, but they are expensive and time-consuming. Here, we propose a computational approach, aiming to identify the epitope of a nanobody that acts as an agonist and a positive allosteric modulator at the rat metabotropic glutamate receptor 5. We employed multiple structure modeling tools, including various artificial intelligence algorithms for epitope mapping. The computationally identified epitope was experimentally validated, confirming the success of our approach. Additional dynamics studies provided further insights on the modulatory activity of the nanobody. The employed methodologies and approaches initiate a discussion on the efficacy of diverse techniques for epitope mapping and later nanobody engineering.
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Affiliation(s)
- Floriane Eshak
- SPPIN CNRS UMR 8003, Université Paris Cité, 75006 Paris, France
| | - Léo Pion
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, Inserm, 34094 Montpellier, France
| | - Pauline Scholler
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, Inserm, 34094 Montpellier, France
| | - Damien Nevoltris
- Aix Marseille University, CNRS, Inserm, Institut Paoli-Calmettes, CRCM, 13009 Marseille, France
| | - Patrick Chames
- Aix Marseille University, CNRS, Inserm, Institut Paoli-Calmettes, CRCM, 13009 Marseille, France
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, Inserm, 34094 Montpellier, France
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle, Université Montpellier, CNRS, Inserm, 34094 Montpellier, France
| | | | - Anne Goupil-Lamy
- BIOVIA Science Council, Dassault Systèmes, 78140 Vélizy-Villacoublay, France
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4
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Zhao J, Elgeti M, O'Brien ES, Sár CP, Ei Daibani A, Heng J, Sun X, White E, Che T, Hubbell WL, Kobilka BK, Chen C. Ligand efficacy modulates conformational dynamics of the µ-opioid receptor. Nature 2024; 629:474-480. [PMID: 38600384 PMCID: PMC11078757 DOI: 10.1038/s41586-024-07295-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 03/11/2024] [Indexed: 04/12/2024]
Abstract
The µ-opioid receptor (µOR) is an important target for pain management1 and molecular understanding of drug action on µOR will facilitate the development of better therapeutics. Here we show, using double electron-electron resonance and single-molecule fluorescence resonance energy transfer, how ligand-specific conformational changes of µOR translate into a broad range of intrinsic efficacies at the transducer level. We identify several conformations of the cytoplasmic face of the receptor that interconvert on different timescales, including a pre-activated conformation that is capable of G-protein binding, and a fully activated conformation that markedly reduces GDP affinity within the ternary complex. Interaction of β-arrestin-1 with the μOR core binding site appears less specific and occurs with much lower affinity than binding of Gi.
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Affiliation(s)
- Jiawei Zhao
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China
- Tsinghua-Peking Joint Center for Life Sciences, School of Medicine, Tsinghua University, Beijing, China
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Matthias Elgeti
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA.
- Institute for Drug Discovery, University of Leipzig Medical Center, Leipzig, Germany.
| | - Evan S O'Brien
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Cecília P Sár
- Institute of Organic and Medicinal Chemistry, School of Pharmaceutical Sciences, University of Pécs, Pécs, Hungary
| | - Amal Ei Daibani
- Department of Anesthesiology, Washington University School of Medicine, St Louis, MO, USA
| | - Jie Heng
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China
- Tsinghua-Peking Joint Center for Life Sciences, School of Medicine, Tsinghua University, Beijing, China
| | - Xiaoou Sun
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China
- Tsinghua-Peking Joint Center for Life Sciences, School of Medicine, Tsinghua University, Beijing, China
| | - Elizabeth White
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Tao Che
- Department of Anesthesiology, Washington University School of Medicine, St Louis, MO, USA
| | - Wayne L Hubbell
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.
| | - Chunlai Chen
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China.
- School of Life Sciences, Tsinghua University, Beijing, China.
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5
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Zhang M, Chen T, Lu X, Lan X, Chen Z, Lu S. G protein-coupled receptors (GPCRs): advances in structures, mechanisms, and drug discovery. Signal Transduct Target Ther 2024; 9:88. [PMID: 38594257 PMCID: PMC11004190 DOI: 10.1038/s41392-024-01803-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 02/19/2024] [Accepted: 03/13/2024] [Indexed: 04/11/2024] Open
Abstract
G protein-coupled receptors (GPCRs), the largest family of human membrane proteins and an important class of drug targets, play a role in maintaining numerous physiological processes. Agonist or antagonist, orthosteric effects or allosteric effects, and biased signaling or balanced signaling, characterize the complexity of GPCR dynamic features. In this study, we first review the structural advancements, activation mechanisms, and functional diversity of GPCRs. We then focus on GPCR drug discovery by revealing the detailed drug-target interactions and the underlying mechanisms of orthosteric drugs approved by the US Food and Drug Administration in the past five years. Particularly, an up-to-date analysis is performed on available GPCR structures complexed with synthetic small-molecule allosteric modulators to elucidate key receptor-ligand interactions and allosteric mechanisms. Finally, we highlight how the widespread GPCR-druggable allosteric sites can guide structure- or mechanism-based drug design and propose prospects of designing bitopic ligands for the future therapeutic potential of targeting this receptor family.
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Affiliation(s)
- Mingyang Zhang
- Key Laboratory of Protection, Development and Utilization of Medicinal Resources in Liupanshan Area, Ministry of Education, Peptide & Protein Drug Research Center, School of Pharmacy, Ningxia Medical University, Yinchuan, 750004, China
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Ting Chen
- Department of Cardiology, Changzheng Hospital, Affiliated to Naval Medical University, Shanghai, 200003, China
| | - Xun Lu
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Xiaobing Lan
- Key Laboratory of Protection, Development and Utilization of Medicinal Resources in Liupanshan Area, Ministry of Education, Peptide & Protein Drug Research Center, School of Pharmacy, Ningxia Medical University, Yinchuan, 750004, China
| | - Ziqiang Chen
- Department of Orthopedics, Changhai Hospital, Affiliated to Naval Medical University, Shanghai, 200433, China.
| | - Shaoyong Lu
- Key Laboratory of Protection, Development and Utilization of Medicinal Resources in Liupanshan Area, Ministry of Education, Peptide & Protein Drug Research Center, School of Pharmacy, Ningxia Medical University, Yinchuan, 750004, China.
- Medicinal Chemistry and Bioinformatics Center, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
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6
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Bernard C, Carotenuto AR, Pugno NM, Fraldi M, Deseri L. Modelling lipid rafts formation through chemo-mechanical interplay triggered by receptor-ligand binding. Biomech Model Mechanobiol 2024; 23:485-505. [PMID: 38060155 DOI: 10.1007/s10237-023-01787-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 10/21/2023] [Indexed: 12/08/2023]
Abstract
Cell membranes, mediator of many biological mechanisms from adhesion and metabolism up to mutation and infection, are highly dynamic and heterogeneous environments exhibiting a strong coupling between biochemical events and structural re-organisation. This involves conformational changes induced, at lower scales, by lipid order transitions and by the micro-mechanical interplay of lipids with transmembrane proteins and molecular diffusion. Particular attention is focused on lipid rafts, ordered lipid microdomains rich of signalling proteins, that co-localise to enhance substance trafficking and activate different intracellular biochemical pathways. In this framework, the theoretical modelling of the dynamic clustering of lipid rafts implies a full multiphysics coupling between the kinetics of phase changes and the mechanical work performed by transmembrane proteins on lipids, involving the bilayer elasticity. This mechanism produces complex interspecific dynamics in which membrane stresses and chemical potentials do compete by determining different morphological arrangements, alteration in diffusive walkways and coalescence phenomena, with a consequent influence on both signalling potential and intracellular processes. Therefore, after identifying the leading chemo-mechanical interactions, the present work investigates from a modelling perspective the spatio-temporal evolution of raft domains to theoretically explain co-localisation and synergy between proteins' activation and raft formation, by coupling diffusive and mechanical phenomena to observe different morphological patterns and clustering of ordered lipids. This could help to gain new insights into the remodelling of cell membranes and could potentially suggest mechanically based strategies to control their selectivity, by orienting intracellular functions and mechanotransduction.
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Affiliation(s)
- Chiara Bernard
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy
| | - Angelo Rosario Carotenuto
- Department of Structures for Engineering and Architecture, University of Naples "Federico II", Naples, Italy
- Laboratory of Integrated Mechanics and Imaging for Testing and Simulation (LIMITS), University of Naples "Federico II", Naples, Italy
| | - Nicola Maria Pugno
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy
- Laboratory for Bioinspired, Bionic, Nano, Meta Materials and Mechanics, University of Trento, Trento, Italy
- School of Engineering and Materials Science, Queen Mary University of London, London, UK
| | - Massimiliano Fraldi
- Department of Structures for Engineering and Architecture, University of Naples "Federico II", Naples, Italy
- Laboratory of Integrated Mechanics and Imaging for Testing and Simulation (LIMITS), University of Naples "Federico II", Naples, Italy
- Département de Physique, LPENS, École Normale Supérieure-PSL, Paris, France
| | - Luca Deseri
- Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy.
- Department of Mechanical Engineering and Material Sciences, MEMS-SSoE, University of Pittsburgh, Pittsburgh, USA.
- Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, USA.
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, USA.
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7
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Latorraca NR, Sabaat S, Habrian C, Bleier J, Stanley C, Marqusee S, Isacoff EY. Domain coupling in activation of a family C GPCR. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582567. [PMID: 38464305 PMCID: PMC10925283 DOI: 10.1101/2024.02.28.582567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
The G protein-coupled metabotropic glutamate receptors form homodimers and heterodimers with highly diverse responses to glutamate and varying physiological function. The molecular basis for this diversity remains poorly delineated. We employ molecular dynamics, single-molecule spectroscopy, and hydrogen-deuterium exchange to dissect the pathway of activation triggered by glutamate. We find that activation entails multiple loosely coupled steps and identify a novel pre-active intermediate whose transition to the active state forms dimer interactions that set signaling efficacy. Such subunit interactions generate functional diversity that differs across homodimers and heterodimers. The agonist-bound receptor is remarkably dynamic, with low occupancy of G protein-coupling conformations, providing considerable headroom for modulation of the landscape by allosteric ligands. Sites of sequence diversity within the dimerization interface and diverse coupling between activation rearrangements may contribute to precise decoding of glutamate signals and transients over broad spatial and temporal scales.
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Affiliation(s)
- Naomi R. Latorraca
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
| | - Sam Sabaat
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
| | - Chris Habrian
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
| | - Julia Bleier
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
| | - Cherise Stanley
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
| | - Susan Marqusee
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
- Department of Chemistry, University of California, Berkeley, California, 94720 USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158
- California Institute for Quantitative Biosciences, University of California, Berkeley, California, 94720 USA
| | - Ehud Y. Isacoff
- Department of Molecular and Cell Biology, University of California, Berkeley, California, 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, California, 94720 USA
- Molecular Biology & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
- Weill Neurohub, University of California, Berkeley, California, 94720 USA
- Molecular Biology & Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
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8
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Benndorf K, Schulz E. Identifiability of equilibrium constants for receptors with two to five binding sites. J Gen Physiol 2023; 155:e202313423. [PMID: 37882789 PMCID: PMC10602793 DOI: 10.1085/jgp.202313423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 08/22/2023] [Accepted: 10/07/2023] [Indexed: 10/27/2023] Open
Abstract
Ligand-gated ion channels (LGICs) are regularly oligomers containing between two and five binding sites for ligands. Neither in homomeric nor heteromeric LGICs the activation process evoked by the ligand binding is fully understood. Here, we show on theoretical grounds that for LGICs with two to five binding sites, the cooperativity upon channel activation can be determined in considerable detail. The main requirements for our strategy are a defined number of binding sites in a channel, which can be achieved by concatenation, a systematic mutation of all binding sites and a global fit of all concentration-activation relationships (CARs) with corresponding intimately coupled Markovian state models. We take advantage of translating these state models to cubes with dimensions 2, 3, 4, and 5. We show that the maximum possible number of CARs for these LGICs specify all 7, 13, 23, and 41 independent model parameters, respectively, which directly provide all equilibrium constants within the respective schemes. Moreover, a fit that uses stochastically varied scaled unitary start vectors enables the determination of all parameters, without any bias imposed by specific start vectors. A comparison of the outcome of the analyses for the models with 2 to 5 binding sites showed that the identifiability of the parameters is best for a case with 5 binding sites and 41 parameters. Our strategy can be used to analyze experimental data of other LGICs and may be applicable to voltage-gated ion channels and metabotropic receptors.
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Affiliation(s)
- Klaus Benndorf
- Institute of Physiology II, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Eckhard Schulz
- Faculty of Electrical Engineering, Schmalkalden University of Applied Sciences, Schmalkalden, Germany
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9
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Schmauder R, Eick T, Schulz E, Sammler G, Voigt E, Mayer G, Ginter H, Ditze G, Benndorf K. Fast functional mapping of ligand-gated ion channels. Commun Biol 2023; 6:1003. [PMID: 37783870 PMCID: PMC10545696 DOI: 10.1038/s42003-023-05340-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 09/11/2023] [Indexed: 10/04/2023] Open
Abstract
Ligand-gated ion channels are formed by three to five subunits that control the opening of the pore in a cooperative fashion. We developed a microfluidic chip-based technique for studying ion currents and fluorescence signals in either excised membrane patches or whole cells to measure activation and deactivation kinetics of the channels as well as ligand binding and unbinding when using confocal patch-clamp fluorometry. We show how this approach produces in a few seconds either unidirectional concentration-activation relationships at or near equilibrium and, moreover, respective time courses of activation and deactivation for a large number of freely designed steps of the ligand concentration. The short measuring period strongly minimizes the contribution of disturbing superimposing effects such as run-down phenomena and desensitization effects. To validate gating mechanisms, complex kinetic schemes are quantified without the requirement to have data at equilibrium. The new method has potential for functionally analyzing any ligand-gated ion channel and, beyond, also for other receptors.
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Affiliation(s)
- Ralf Schmauder
- Institut für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, 07743, Jena, Germany.
| | - Thomas Eick
- Institut für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, 07743, Jena, Germany
| | - Eckhard Schulz
- Hochschule Schmalkalden, Fakultät Elektrotechnik, Blechhammer, 98574, Schmalkalden, Germany
| | - Günther Sammler
- Zentrale Forschungswerkstätten, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, 07743, Jena, Germany
| | - Elmar Voigt
- Leibniz Institut für Photonische Technologien e.V., Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Günter Mayer
- Leibniz Institut für Photonische Technologien e.V., Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Holger Ginter
- Zentrale Forschungswerkstätten, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, 07743, Jena, Germany
| | - Günter Ditze
- Zentrale Forschungswerkstätten, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, 07743, Jena, Germany
| | - Klaus Benndorf
- Institut für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, 07743, Jena, Germany.
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10
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Strauss A, Gonzalez-Hernandez AJ, Lee J, Abreu N, Selvakumar P, Salas-Estrada L, Kristt M, Marx DC, Gilliland K, Melancon BJ, Filizola M, Meyerson J, Levitz J. Structural basis of allosteric modulation of metabotropic glutamate receptor activation and desensitization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.13.552748. [PMID: 37645747 PMCID: PMC10461995 DOI: 10.1101/2023.08.13.552748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The metabotropic glutamate receptors (mGluRs) are neuromodulatory family C G protein coupled receptors which assemble as dimers and allosterically couple extracellular ligand binding domains (LBDs) to transmembrane domains (TMDs) to drive intracellular signaling. Pharmacologically, mGluRs can be targeted either at the LBDs by glutamate and synthetic orthosteric compounds or at the TMDs by allosteric modulators. Despite the potential of allosteric TMD-targeting compounds as therapeutics, an understanding of the functional and structural basis of their effects on mGluRs is limited. Here we use a battery of approaches to dissect the distinct functional and structural effects of orthosteric versus allosteric ligands. We find using electrophysiological and live cell imaging assays that both agonists and positive allosteric modulators (PAMs) can drive activation and desensitization of mGluRs. The effects of PAMs are pleiotropic, including both the ability to boost the maximal response to orthosteric agonists and to serve independently as desensitization-biased agonists across mGluR subtypes. Conformational sensors reveal PAM-driven inter-subunit re-arrangements at both the LBD and TMD. Motivated by this, we determine cryo-electron microscopy structures of mGluR3 in the presence of either an agonist or antagonist alone or in combination with a PAM. These structures reveal PAM-driven re-shaping of intra- and inter-subunit conformations and provide evidence for a rolling TMD dimer interface activation pathway that controls G protein and beta-arrestin coupling. Highlights -Agonists and PAMs drive mGluR activation, desensitization, and endocytosis-PAMs are desensitization-biased and synergistic with agonists-Four combinatorial ligand conditions reveal an ensemble of full-length mGluR structures with novel interfaces-Activation and desensitization involve rolling TMD interfaces which are re-shaped by PAM.
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11
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Lecat-Guillet N, Quast RB, Liu H, Bourrier E, Møller TC, Rovira X, Soldevila S, Lamarque L, Trinquet E, Liu J, Pin JP, Rondard P, Margeat E. Concerted conformational changes control metabotropic glutamate receptor activity. SCIENCE ADVANCES 2023; 9:eadf1378. [PMID: 37267369 PMCID: PMC10413646 DOI: 10.1126/sciadv.adf1378] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 04/27/2023] [Indexed: 06/04/2023]
Abstract
Allosteric modulators bear great potential to fine-tune neurotransmitter action. Promising targets are metabotropic glutamate (mGlu) receptors, which are associated with numerous brain diseases. Orthosteric and allosteric ligands act in synergy to control the activity of these multidomain dimeric GPCRs. Here, we analyzed the effect of such molecules on the concerted conformational changes of full-length mGlu2 at the single-molecule level. We first established FRET sensors through genetic code expansion combined with click chemistry to monitor conformational changes on live cells. We then used single-molecule FRET and show that orthosteric agonist binding leads to the stabilization of most of the glutamate binding domains in their closed state, while the reorientation of the dimer into the active state remains partial. Allosteric modulators, interacting with the transmembrane domain, are required to stabilize the fully reoriented active dimer. These results illustrate how concerted conformational changes within multidomain proteins control their activity, and how these are modulated by allosteric ligands.
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Affiliation(s)
- Nathalie Lecat-Guillet
- Institut de Génomique Fonctionnelle, Univ. Montpellier, CNRS, INSERM, 141 rue de la Cardonille, 34094, Montpellier Cedex 05, France
| | - Robert B. Quast
- Centre de Biologie Structurale (CBS), Univ. Montpellier, CNRS, INSERM, Montpellier, France
| | - Hongkang Liu
- Institut de Génomique Fonctionnelle, Univ. Montpellier, CNRS, INSERM, 141 rue de la Cardonille, 34094, Montpellier Cedex 05, France
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | | | - Thor C. Møller
- Institut de Génomique Fonctionnelle, Univ. Montpellier, CNRS, INSERM, 141 rue de la Cardonille, 34094, Montpellier Cedex 05, France
| | - Xavier Rovira
- Institut de Génomique Fonctionnelle, Univ. Montpellier, CNRS, INSERM, 141 rue de la Cardonille, 34094, Montpellier Cedex 05, France
| | | | | | - Eric Trinquet
- PerkinElmer Cisbio, Parc Marcel Boiteux, 30200 Codolet, France
| | - Jianfeng Liu
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle, Univ. Montpellier, CNRS, INSERM, 141 rue de la Cardonille, 34094, Montpellier Cedex 05, France
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle, Univ. Montpellier, CNRS, INSERM, 141 rue de la Cardonille, 34094, Montpellier Cedex 05, France
| | - Emmanuel Margeat
- Centre de Biologie Structurale (CBS), Univ. Montpellier, CNRS, INSERM, Montpellier, France
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12
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Chen G, Obal D. Detecting and measuring of GPCR signaling - comparison of human induced pluripotent stem cells and immortal cell lines. Front Endocrinol (Lausanne) 2023; 14:1179600. [PMID: 37293485 PMCID: PMC10244570 DOI: 10.3389/fendo.2023.1179600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 04/12/2023] [Indexed: 06/10/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are a large family of transmembrane proteins that play a major role in many physiological processes, and thus GPCR-targeted drug development has been widely promoted. Although research findings generated in immortal cell lines have contributed to the advancement of the GPCR field, the homogenous genetic backgrounds, and the overexpression of GPCRs in these cell lines make it difficult to correlate the results with clinical patients. Human induced pluripotent stem cells (hiPSCs) have the potential to overcome these limitations, because they contain patient specific genetic information and can differentiate into numerous cell types. To detect GPCRs in hiPSCs, highly selective labeling and sensitive imaging techniques are required. This review summarizes existing resonance energy transfer and protein complementation assay technologies, as well as existing and new labeling methods. The difficulties of extending existing detection methods to hiPSCs are discussed, as well as the potential of hiPSCs to expand GPCR research towards personalized medicine.
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Affiliation(s)
- Gaoxian Chen
- Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University, Stanford, CA, United States
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA, United States
| | - Detlef Obal
- Department of Anesthesiology, Perioperative, and Pain Medicine, Stanford University, Stanford, CA, United States
- Stanford Cardiovascular Institute, Stanford University, Stanford, CA, United States
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13
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Zhao J, Elgeti M, O’Brien ES, Sár CP, EI Daibani A, Heng J, Sun X, Che T, Hubbell WL, Kobilka BK, Chen C. Conformational dynamics of the μ-opioid receptor determine ligand intrinsic efficacy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.28.538657. [PMID: 37163120 PMCID: PMC10168371 DOI: 10.1101/2023.04.28.538657] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The μ-opioid receptor (μOR) is an important target for pain management and the molecular understanding of drug action will facilitate the development of better therapeutics. Here we show, using double electron-electron resonance (DEER) and single-molecule fluorescence resonance energy transfer (smFRET), how ligand-specific conformational changes of the μOR translate into a broad range of intrinsic efficacies at the transducer level. We identify several cytoplasmic receptor conformations interconverting on different timescales, including a pre-activated receptor conformation which is capable of G protein binding, and a fully activated conformation which dramatically lowers GDP affinity within the ternary complex. Interaction of β-arrestin-1 with the μOR core binding site appears less specific and occurs with much lower affinity than binding of G protein Gi.
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Affiliation(s)
- Jiawei Zhao
- Tsinghua-Peaking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University; Beijing, 100084, China
| | - Matthias Elgeti
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California; Los Angeles, Los Angeles, CA 90095, USA
| | - Evan S. O’Brien
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine; Stanford, CA 94305, USA
| | - Cecília P. Sár
- Institute of Organic and Medicinal Chemistry, School of Pharmaceutical Sciences, University of Pécs; Szigeti st. 12, H-7624 Pécs, Hungary
| | - Amal EI Daibani
- Department of Anesthesiology, Washington University School of Medicine; Saint Louis, MO 63110, USA
| | - Jie Heng
- Tsinghua-Peaking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University; Beijing, 100084, China
| | - Xiaoou Sun
- Tsinghua-Peaking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University; Beijing, 100084, China
| | - Tao Che
- Department of Anesthesiology, Washington University School of Medicine; Saint Louis, MO 63110, USA
| | - Wayne L. Hubbell
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California; Los Angeles, Los Angeles, CA 90095, USA
| | - Brian K. Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine; Stanford, CA 94305, USA
| | - Chunlai Chen
- Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University; Beijing, 100084, China
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14
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Kinetic fingerprinting of metabotropic glutamate receptors. Commun Biol 2023; 6:104. [PMID: 36707695 PMCID: PMC9883448 DOI: 10.1038/s42003-023-04468-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 01/12/2023] [Indexed: 01/28/2023] Open
Abstract
Dimeric metabotropic glutamate receptors (mGluRs) are abundantly expressed in neurons. In mammals, eight subunit isoforms, mGluR1-8, have been identified, forming the groups I, II, and III. We investigated receptor dimerization and kinetics of these mGluR isoforms in excised membrane patches by FRET and confocal patch-clamp fluorometry. We show that 5 out of 8 homodimeric receptors develop characteristic glutamate-induced on- and off-kinetics, as do 11 out of 28 heterodimers. Glutamate-responsive heterodimers were identified within each group, between groups I and II as well as between groups II and III, but not between groups I and III. The glutamate-responsive heterodimers showed heterogeneous activation and deactivation kinetics. Interestingly, mGluR7, not generating a kinetic response in homodimers, showed fast on-kinetics in mGluR2/7 and mGluR3/7 while off-kinetics retained the speed of mGluR2 or mGluR3 respectively. In conclusion, glutamate-induced conformational changes in heterodimers appear within each group and between groups if one group II subunit is present.
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15
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Abstract
G protein–coupled receptors (GPCRs) constitute the largest and pharmacologically most important family of cell-surface receptors. Some GPCRs interact specifically with receptor-activity-modifying proteins (RAMPs), but the consequences of this interaction for the receptor activation mechanism are not well understood. Using a set of fluorescent biosensors for the parathyroid hormone 1 receptor (PTH1R) and its downstream signaling partners, we show here that RAMP2 induces a unique, preactivated receptor state that shows faster activation and altered downstream signaling. This type of GPCR modulation may open new methods of drug design. Receptor-activity-modifying proteins (RAMPs) are ubiquitously expressed membrane proteins that associate with different G protein–coupled receptors (GPCRs), including the parathyroid hormone 1 receptor (PTH1R), a class B GPCR and an important modulator of mineral ion homeostasis and bone metabolism. However, it is unknown whether and how RAMP proteins may affect PTH1R function. Using different optical biosensors to measure the activation of PTH1R and its downstream signaling, we describe here that RAMP2 acts as a specific allosteric modulator of PTH1R, shifting PTH1R to a unique preactivated state that permits faster activation in a ligand-specific manner. Moreover, RAMP2 modulates PTH1R downstream signaling in an agonist-dependent manner, most notably increasing the PTH-mediated Gi3 signaling sensitivity. Additionally, RAMP2 increases both PTH- and PTHrP-triggered β-arrestin2 recruitment to PTH1R. Employing homology modeling, we describe the putative structural molecular basis underlying our functional findings. These data uncover a critical role of RAMPs in the activation and signaling of a GPCR that may provide a new venue for highly specific modulation of GPCR function and advanced drug design.
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16
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Nanobody-based sensors reveal a high proportion of mGlu heterodimers in the brain. Nat Chem Biol 2022; 18:894-903. [PMID: 35681029 DOI: 10.1038/s41589-022-01050-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 04/29/2022] [Indexed: 11/08/2022]
Abstract
Membrane proteins, including ion channels, receptors and transporters, are often composed of multiple subunits and can form large complexes. Their specific composition in native tissues is difficult to determine and remains largely unknown. In this study, we developed a method for determining the subunit composition of endogenous cell surface protein complexes from isolated native tissues. Our method relies on nanobody-based sensors, which enable proximity detection between subunits in time-resolved Förster resonance energy transfer (FRET) measurements. Additionally, given conformation-specific nanobodies, the activation of these complexes can be recorded in native brain tissue. Applied to the metabotropic glutamate receptors in different brain regions, this approach revealed the clear existence of functional metabotropic glutamate (mGlu)2-mGlu4 heterodimers in addition to mGlu2 and mGlu4 homodimers. Strikingly, the mGlu4 subunits appear to be mainly heterodimers in the brain. Overall, these versatile biosensors can determine the presence and activity of endogenous membrane proteins in native tissues with high fidelity and convenience.
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17
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Liauw BWH, Foroutan A, Schamber MR, Lu W, Samareh Afsari H, Vafabakhsh R. Conformational fingerprinting of allosteric modulators in metabotropic glutamate receptor 2. eLife 2022; 11:78982. [PMID: 35775730 PMCID: PMC9299836 DOI: 10.7554/elife.78982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 06/30/2022] [Indexed: 11/13/2022] Open
Abstract
Activation of G protein-coupled receptors (GPCRs) is an allosteric process. It involves conformational coupling between the orthosteric ligand binding site and the G protein binding site. Factors that bind at non-cognate ligand binding sites to alter the allosteric activation process are classified as allosteric modulators and represent a promising class of therapeutics with distinct modes of binding and action. For many receptors, how modulation of signaling is represented at the structural level is unclear. Here, we developed FRET sensors to quantify receptor modulation at each of the three structural domains of metabotropic glutamate receptor 2 (mGluR2). We identified the conformational fingerprint for several allosteric modulators in live cells. This approach enabled us to derive a receptor-centric representation of allosteric modulation and to correlate structural modulation to the standard signaling modulation metrics. Single-molecule FRET analysis revealed that a NAM increases the occupancy of one of the intermediate states while a PAM increases the occupancy of the active state. Moreover, we found that the effect of allosteric modulators on the receptor dynamics is complex and depend on the orthosteric ligand. Collectively, our findings provide a structural mechanism of allosteric modulation in mGluR2 and suggest possible strategies for design of future modulators.
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Affiliation(s)
| | - Arash Foroutan
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Michael R Schamber
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Weifeng Lu
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | | | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
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18
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Parray ZA, Shahid M, Islam A. Insights into Fluctuations of Structure of Proteins: Significance of Intermediary States in Regulating Biological Functions. Polymers (Basel) 2022; 14:polym14081539. [PMID: 35458289 PMCID: PMC9025146 DOI: 10.3390/polym14081539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/30/2022] [Accepted: 04/05/2022] [Indexed: 02/01/2023] Open
Abstract
Proteins are indispensable to cellular communication and metabolism. The structure on which cells and tissues are developed is deciphered from proteins. To perform functions, proteins fold into a three-dimensional structural design, which is specific and fundamentally determined by their characteristic sequence of amino acids. Few of them have structural versatility, allowing them to adapt their shape to the task at hand. The intermediate states appear momentarily, while protein folds from denatured (D) ⇔ native (N), which plays significant roles in cellular functions. Prolific effort needs to be taken in characterizing these intermediate species if detected during the folding process. Protein folds into its native structure through definite pathways, which involve a limited number of transitory intermediates. Intermediates may be essential in protein folding pathways and assembly in some cases, as well as misfolding and aggregation folding pathways. These intermediate states help to understand the machinery of proper folding in proteins. In this review article, we highlight the various intermediate states observed and characterized so far under in vitro conditions. Moreover, the role and significance of intermediates in regulating the biological function of cells are discussed clearly.
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Affiliation(s)
- Zahoor Ahmad Parray
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India;
- Department of Chemistry, Indian Institute of Technology Delhi, IIT Campus, Hauz Khas, New Delhi 110016, India
| | - Mohammad Shahid
- Department of Basic Medical Sciences, College of Medicine, Prince Sattam bin Abdulaziz University, Al Kharj 11942, Saudi Arabia;
| | - Asimul Islam
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India;
- Correspondence: ; Tel.: +91-93-1281-2007
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19
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Sattler C, Benndorf K. Enlightening activation gating in P2X receptors. Purinergic Signal 2022; 18:177-191. [PMID: 35188598 PMCID: PMC9123132 DOI: 10.1007/s11302-022-09850-w] [Citation(s) in RCA: 6] [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: 11/01/2021] [Accepted: 02/04/2022] [Indexed: 12/20/2022] Open
Abstract
P2X receptors are trimeric nonselective cation channels gated by ATP. They assemble from seven distinct subunit isoforms as either homo- or heteromeric complexes and contain three extracellularly located binding sites for ATP. P2X receptors are expressed in nearly all tissues and are there involved in physiological processes like synaptic transmission, pain, and inflammation. Thus, they are a challenging pharmacological target. The determination of crystal and cryo-EM structures of several isoforms in the last decade in closed, open, and desensitized states has provided a firm basis for interpreting the huge amount of functional and biochemical data. Electrophysiological characterization in conjugation with optical approaches has generated significant insights into structure–function relationships of P2X receptors. This review focuses on novel optical and related approaches to better understand the conformational changes underlying the activation of these receptors.
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Affiliation(s)
- Christian Sattler
- Institut Für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, 07740, Jena, Germany.
| | - Klaus Benndorf
- Institut Für Physiologie II, Universitätsklinikum Jena, Friedrich-Schiller-Universität Jena, 07740, Jena, Germany.
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20
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Allosteric modulators enhance agonist efficacy by increasing the residence time of a GPCR in the active state. Nat Commun 2021; 12:5426. [PMID: 34521824 PMCID: PMC8440590 DOI: 10.1038/s41467-021-25620-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 08/20/2021] [Indexed: 01/17/2023] Open
Abstract
Much hope in drug development comes from the discovery of positive allosteric modulators (PAM) that display target subtype selectivity and act by increasing agonist potency and efficacy. How such compounds can allosterically influence agonist action remains unclear. Metabotropic glutamate receptors (mGlu) are G protein-coupled receptors that represent promising targets for brain diseases, and for which PAMs acting in the transmembrane domain have been developed. Here, we explore the effect of a PAM on the structural dynamics of mGlu2 in optimized detergent micelles using single molecule FRET at submillisecond timescales. We show that glutamate only partially stabilizes the extracellular domains in the active state. Full activation is only observed in the presence of a PAM or the Gi protein. Our results provide important insights on the role of allosteric modulators in mGlu activation, by stabilizing the active state of a receptor that is otherwise rapidly oscillating between active and inactive states. Here, the authors use smFRET to assess the structural dynamics of metabotropic glutamate receptor mGlu2 and show that a positive allosteric modulator or the Gi protein stabilize mGlu2 in the glutamate-induced active state, leading to the full activation of the receptor.
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21
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Lu S, He X, Yang Z, Chai Z, Zhou S, Wang J, Rehman AU, Ni D, Pu J, Sun J, Zhang J. Activation pathway of a G protein-coupled receptor uncovers conformational intermediates as targets for allosteric drug design. Nat Commun 2021; 12:4721. [PMID: 34354057 PMCID: PMC8342441 DOI: 10.1038/s41467-021-25020-9] [Citation(s) in RCA: 103] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 07/17/2021] [Indexed: 02/07/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are the most common proteins targeted by approved drugs. A complete mechanistic elucidation of large-scale conformational transitions underlying the activation mechanisms of GPCRs is of critical importance for therapeutic drug development. Here, we apply a combined computational and experimental framework integrating extensive molecular dynamics simulations, Markov state models, site-directed mutagenesis, and conformational biosensors to investigate the conformational landscape of the angiotensin II (AngII) type 1 receptor (AT1 receptor) - a prototypical class A GPCR-activation. Our findings suggest a synergistic transition mechanism for AT1 receptor activation. A key intermediate state is identified in the activation pathway, which possesses a cryptic binding site within the intracellular region of the receptor. Mutation of this cryptic site prevents activation of the downstream G protein signaling and β-arrestin-mediated pathways by the endogenous AngII octapeptide agonist, suggesting an allosteric regulatory mechanism. Together, these findings provide a deeper understanding of AT1 receptor activation at an atomic level and suggest avenues for the design of allosteric AT1 receptor modulators with a broad range of applications in GPCR biology, biophysics, and medicinal chemistry.
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Affiliation(s)
- Shaoyong Lu
- College of Pharmacy, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region, China.
- State Key Laboratory of Oncogenes and Related Genes, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai, China.
| | - Xinheng He
- The CAS Key Laboratory of Receptor Research, Shanghai Institute of Material Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhao Yang
- Department of Biochemistry and Molecular Biology, Key Laboratory Experimental Teratology of Chinese Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Zongtao Chai
- Department of Hepatic Surgery VI, Eastern Hepatobiliary Surgery Hospital, Second Military Medical University, Shanghai, China
| | - Shuhua Zhou
- Department of Biochemistry and Molecular Biology, Key Laboratory Experimental Teratology of Chinese Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Junyan Wang
- Department of Biochemistry and Molecular Biology, Key Laboratory Experimental Teratology of Chinese Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong, China
| | - Ashfaq Ur Rehman
- State Key Laboratory of Oncogenes and Related Genes, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Duan Ni
- State Key Laboratory of Oncogenes and Related Genes, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Jun Pu
- Department of Cardiology, Renji Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
| | - Jinpeng Sun
- Department of Biochemistry and Molecular Biology, Key Laboratory Experimental Teratology of Chinese Ministry of Education, School of Medicine, Shandong University, Jinan, Shandong, China.
| | - Jian Zhang
- College of Pharmacy, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region, China.
- State Key Laboratory of Oncogenes and Related Genes, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University, School of Medicine, Shanghai, China.
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China.
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22
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Elgeti M, Hubbell WL. DEER Analysis of GPCR Conformational Heterogeneity. Biomolecules 2021; 11:778. [PMID: 34067265 PMCID: PMC8224605 DOI: 10.3390/biom11060778] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 05/18/2021] [Accepted: 05/19/2021] [Indexed: 02/06/2023] Open
Abstract
G protein-coupled receptors (GPCRs) represent a large class of transmembrane helical proteins which are involved in numerous physiological signaling pathways and therefore represent crucial pharmacological targets. GPCR function and the action of therapeutic molecules are defined by only a few parameters, including receptor basal activity, ligand affinity, intrinsic efficacy and signal bias. These parameters are encoded in characteristic receptor conformations existing in equilibrium and their populations, which are thus of paramount interest for the understanding of receptor (mal-)functions and rational design of improved therapeutics. To this end, the combination of site-directed spin labeling and EPR spectroscopy, in particular double electron-electron resonance (DEER), is exceedingly valuable as it has access to sub-Angstrom spatial resolution and provides a detailed picture of the number and populations of conformations in equilibrium. This review gives an overview of existing DEER studies on GPCRs with a focus on the delineation of structure/function frameworks, highlighting recent developments in data analysis and visualization. We introduce "conformational efficacy" as a parameter to describe ligand-specific shifts in the conformational equilibrium, taking into account the loose coupling between receptor segments observed for different GPCRs using DEER.
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Affiliation(s)
- Matthias Elgeti
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Wayne L. Hubbell
- Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
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23
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Shaye H, Stauch B, Gati C, Cherezov V. Molecular mechanisms of metabotropic GABA B receptor function. SCIENCE ADVANCES 2021; 7:7/22/eabg3362. [PMID: 34049877 PMCID: PMC8163086 DOI: 10.1126/sciadv.abg3362] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 04/14/2021] [Indexed: 05/06/2023]
Abstract
Metabotropic γ-aminobutyric acid G protein-coupled receptors (GABAB) represent one of the two main types of inhibitory neurotransmitter receptors in the brain. These receptors act both pre- and postsynaptically by modulating the transmission of neuronal signals and are involved in a range of neurological diseases, from alcohol addiction to epilepsy. A series of recent cryo-EM studies revealed critical details of the activation mechanism of GABAB Structures are now available for the receptor bound to ligands with different modes of action, including antagonists, agonists, and positive allosteric modulators, and captured in different conformational states from the inactive apo to the fully active state bound to a G protein. These discoveries provide comprehensive insights into the activation of the GABAB receptor, which not only broaden our understanding of its structure, pharmacology, and physiological effects but also will ultimately facilitate the discovery of new therapeutic drugs and neuromodulators.
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Affiliation(s)
- Hamidreza Shaye
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
- Bridge Institute, Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA, USA
| | - Benjamin Stauch
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
- Bridge Institute, Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA, USA
| | - Cornelius Gati
- Bridge Institute, Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA, USA
- Biosciences Division, SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Vadim Cherezov
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA.
- Bridge Institute, Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
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24
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Thibado JK, Tano JY, Lee J, Salas-Estrada L, Provasi D, Strauss A, Marcelo Lamim Ribeiro J, Xiang G, Broichhagen J, Filizola M, Lohse MJ, Levitz J. Differences in interactions between transmembrane domains tune the activation of metabotropic glutamate receptors. eLife 2021; 10:e67027. [PMID: 33880992 PMCID: PMC8102066 DOI: 10.7554/elife.67027] [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: 01/29/2021] [Accepted: 04/19/2021] [Indexed: 12/16/2022] Open
Abstract
The metabotropic glutamate receptors (mGluRs) form a family of neuromodulatory G-protein-coupled receptors that contain both a seven-helix transmembrane domain (TMD) and a large extracellular ligand-binding domain (LBD) which enables stable dimerization. Although numerous studies have revealed variability across subtypes in the initial activation steps at the level of LBD dimers, an understanding of inter-TMD interaction and rearrangement remains limited. Here, we use a combination of single molecule fluorescence, molecular dynamics, functional assays, and conformational sensors to reveal that distinct TMD assembly properties drive differences between mGluR subtypes. We uncover a variable region within transmembrane helix 4 (TM4) that contributes to homo- and heterodimerization in a subtype-specific manner and tunes orthosteric, allosteric, and basal activation. We also confirm a critical role for a conserved inter-TM6 interface in stabilizing the active state during orthosteric or allosteric activation. Together this study shows that inter-TMD assembly and dynamic rearrangement drive mGluR function with distinct properties between subtypes.
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Affiliation(s)
- Jordana K Thibado
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical SciencesNew YorkUnited States
| | | | - Joon Lee
- Department of Biochemistry, Weill Cornell MedicineNew YorkUnited States
| | - Leslie Salas-Estrada
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | - Davide Provasi
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | - Alexa Strauss
- Tri-Institutional PhD Program in Chemical BiologyNew YorkUnited States
| | | | - Guoqing Xiang
- Department of Biochemistry, Weill Cornell MedicineNew YorkUnited States
| | | | - Marta Filizola
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount SinaiNew YorkUnited States
| | - Martin J Lohse
- Max Delbrück Center for Molecular MedicineBerlinGermany
- ISAR Bioscience InstitutePlanegg-MunichGermany
| | - Joshua Levitz
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical SciencesNew YorkUnited States
- Department of Biochemistry, Weill Cornell MedicineNew YorkUnited States
- Tri-Institutional PhD Program in Chemical BiologyNew YorkUnited States
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25
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Hilger D. The role of structural dynamics in GPCR‐mediated signaling. FEBS J 2021; 288:2461-2489. [DOI: 10.1111/febs.15841] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/19/2021] [Accepted: 03/24/2021] [Indexed: 12/18/2022]
Affiliation(s)
- Daniel Hilger
- Department of Pharmaceutical Chemistry Philipps‐University Marburg Germany
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26
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Liauw BWH, Afsari HS, Vafabakhsh R. Conformational rearrangement during activation of a metabotropic glutamate receptor. Nat Chem Biol 2021; 17:291-297. [PMID: 33398167 PMCID: PMC7904630 DOI: 10.1038/s41589-020-00702-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 10/28/2020] [Indexed: 12/21/2022]
Abstract
G protein-coupled receptors (GPCRs) relay information across cell membranes through conformational coupling between the ligand-binding domain and cytoplasmic signaling domain. In dimeric class C GPCRs, the mechanism of this process, which involves propagation of local ligand-induced conformational changes over 12 nm through three distinct structural domains, is unknown. Here, we used single-molecule FRET (smFRET) and live-cell imaging and found that metabotropic glutamate receptor 2 (mGluR2) interconverts between four conformational states, two of which were previously unknown, and activation proceeds through the conformational selection mechanism. Furthermore, the conformation of the ligand-binding domains and downstream domains are weakly coupled. We show that the intermediate states act as conformational checkpoints for activation and control allosteric modulation of signaling. Our results demonstrate a mechanism for activation of mGluRs where ligand binding controls the proximity of signaling domains, analogous to some receptor kinases. This design principle may be generalizable to other biological allosteric sensors.
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Affiliation(s)
| | | | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA.
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27
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Shen C, Mao C, Xu C, Jin N, Zhang H, Shen DD, Shen Q, Wang X, Hou T, Chen Z, Rondard P, Pin JP, Zhang Y, Liu J. Structural basis of GABA B receptor-G i protein coupling. Nature 2021; 594:594-598. [PMID: 33911284 PMCID: PMC8222003 DOI: 10.1038/s41586-021-03507-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 03/29/2021] [Indexed: 02/03/2023]
Abstract
G-protein-coupled receptors (GPCRs) have central roles in intercellular communication1,2. Structural studies have revealed how GPCRs can activate G proteins. However, whether this mechanism is conserved among all classes of GPCR remains unknown. Here we report the structure of the class-C heterodimeric GABAB receptor, which is activated by the inhibitory transmitter GABA, in its active form complexed with Gi1 protein. We found that a single G protein interacts with the GB2 subunit of the GABAB receptor at a site that mainly involves intracellular loop 2 on the side of the transmembrane domain. This is in contrast to the G protein binding in a central cavity, as has been observed with other classes of GPCR. This binding mode results from the active form of the transmembrane domain of this GABAB receptor being different from that of other GPCRs, as it shows no outside movement of transmembrane helix 6. Our work also provides details of the inter- and intra-subunit changes that link agonist binding to G-protein activation in this heterodimeric complex.
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Affiliation(s)
- Cangsong Shen
- grid.33199.310000 0004 0368 7223ZJU-HUST Joint Laboratory of Cellular Signaling, Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China ,grid.13402.340000 0004 1759 700XDepartment of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China ,grid.13402.340000 0004 1759 700XLiangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
| | - Chunyou Mao
- grid.13402.340000 0004 1759 700XDepartment of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China ,grid.13402.340000 0004 1759 700XLiangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China ,Zhejiang Provincial Key Laboratory of Immunity and Inflammatory Diseases, Hangzhou, China
| | - Chanjuan Xu
- grid.33199.310000 0004 0368 7223ZJU-HUST Joint Laboratory of Cellular Signaling, Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China ,grid.508040.9Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Nan Jin
- grid.33199.310000 0004 0368 7223ZJU-HUST Joint Laboratory of Cellular Signaling, Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China ,grid.13402.340000 0004 1759 700XDepartment of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China ,grid.13402.340000 0004 1759 700XLiangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China
| | - Huibing Zhang
- grid.13402.340000 0004 1759 700XDepartment of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China ,grid.13402.340000 0004 1759 700XLiangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China ,Zhejiang Provincial Key Laboratory of Immunity and Inflammatory Diseases, Hangzhou, China
| | - Dan-Dan Shen
- grid.13402.340000 0004 1759 700XDepartment of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China ,grid.13402.340000 0004 1759 700XLiangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China ,Zhejiang Provincial Key Laboratory of Immunity and Inflammatory Diseases, Hangzhou, China
| | - Qingya Shen
- grid.13402.340000 0004 1759 700XDepartment of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China ,grid.13402.340000 0004 1759 700XLiangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China ,Zhejiang Provincial Key Laboratory of Immunity and Inflammatory Diseases, Hangzhou, China
| | - Xiaomei Wang
- grid.33199.310000 0004 0368 7223ZJU-HUST Joint Laboratory of Cellular Signaling, Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China
| | - Tingjun Hou
- grid.13402.340000 0004 1759 700XInnovation Institute for Artificial Intelligence in Medicine of Zhejiang University, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Zhong Chen
- grid.268505.c0000 0000 8744 8924Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, Zhejiang Chinese Medical University, Hangzhou, China
| | - Philippe Rondard
- grid.121334.60000 0001 2097 0141Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - Jean-Philippe Pin
- grid.121334.60000 0001 2097 0141Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - Yan Zhang
- grid.13402.340000 0004 1759 700XDepartment of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China ,grid.13402.340000 0004 1759 700XLiangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, China ,Zhejiang Provincial Key Laboratory of Immunity and Inflammatory Diseases, Hangzhou, China ,grid.13402.340000 0004 1759 700XMOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianfeng Liu
- grid.33199.310000 0004 0368 7223ZJU-HUST Joint Laboratory of Cellular Signaling, Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, China ,grid.508040.9Bioland Laboratory, Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
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28
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Yano Y, Watanabe Y, Matsuzaki K. Thermodynamic and kinetic stabilities of transmembrane helix bundles as revealed by single-pair FRET analysis: Effects of the number of membrane-spanning segments and cholesterol. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1863:183532. [PMID: 33316240 DOI: 10.1016/j.bbamem.2020.183532] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/02/2020] [Accepted: 12/07/2020] [Indexed: 12/23/2022]
Abstract
The tertiary structures and conformational dynamics of transmembrane (TM) helical proteins are maintained by the interhelical interaction network in membranes, although it is complicated to analyze the underlying driving forces because the amino acid sequences can involve multiple and various types of interactions. To obtain insights into basal and common effects of the number of membrane-spanning segments and membrane cholesterol, we measured stabilities of helix bundles composed of simple TM helices (AALALAA)3 (1TM) and (AALALAA)3-G5-(AALALAA)3 (2TM). Association-dissociation dynamics for 1TM-1TM, 1TM-2TM, and 2TM-2TM pairs were monitored to compare stabilities of 2-, 3-, and 4-helical bundles, respectively, with single-pair fluorescence resonance energy transfer (sp-FRET) in liposome membranes. Both thermodynamic and kinetic stabilities of the helix bundles increased with a greater number of membrane-spanning segments in POPC. The presence of 30 mol% cholesterol strongly enhanced the formation of 1TM-1TM and 1TM-2TM bundles (~ - 9 kJ mol-1), whereas it only weakly stabilized the 2TM-2TM bundle (~ - 3 kJ mol-1). Fourier transform infrared-polarized attenuated total reflection (ATR-FTIR) spectroscopy revealed an ~30° tilt of the helix axis relative to bilayer normal for the 1TM-2TM pair in the presence of cholesterol, suggesting the formation of a tilted helix bundle to release high lateral pressure at the center of cholesterol-containing membranes. These results demonstrate that the number of membrane-spanning segments affects the stability and structure of the helix bundle, and their cholesterol-dependences. Such information is useful to understand the basics of folding and assembly of multispanning TM proteins.
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Affiliation(s)
- Yoshiaki Yano
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yuta Watanabe
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Katsumi Matsuzaki
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
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29
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Ellaithy A, Gonzalez-Maeso J, Logothetis DA, Levitz J. Structural and Biophysical Mechanisms of Class C G Protein-Coupled Receptor Function. Trends Biochem Sci 2020; 45:1049-1064. [PMID: 32861513 PMCID: PMC7642020 DOI: 10.1016/j.tibs.2020.07.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 07/22/2020] [Accepted: 07/30/2020] [Indexed: 02/07/2023]
Abstract
Groundbreaking structural and spectroscopic studies of class A G protein-coupled receptors (GPCRs), such as rhodopsin and the β2 adrenergic receptor, have provided a picture of how structural rearrangements between transmembrane helices control ligand binding, receptor activation, and effector coupling. However, the activation mechanism of other GPCR classes remains more elusive, in large part due to complexity in their domain assembly and quaternary structure. In this review, we focus on the class C GPCRs, which include metabotropic glutamate receptors (mGluRs) and gamma-aminobutyric acid B (GABAB) receptors (GABABRs) most prominently. We discuss the unique biophysical questions raised by the presence of large extracellular ligand-binding domains (LBDs) and constitutive homo/heterodimerization. Furthermore, we discuss how recent studies have begun to unravel how these fundamental class C GPCR features impact the processes of ligand binding, receptor activation, signal transduction, regulation by accessory proteins, and crosstalk with other GPCRs.
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Affiliation(s)
- Amr Ellaithy
- Department of Neurology, University of Iowa, Iowa City, IA 52242, USA; Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Javier Gonzalez-Maeso
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
| | - Diomedes A Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, MA 02115, USA; Department of Chemistry and Chemical Biology, College of Science and Center for Drug Discovery, Northeastern University, Boston, MA 02115, USA
| | - Joshua Levitz
- Department of Biochemistry, Weill Cornell Medicine, New York, NY 10065, USA.
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30
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Advanced fluorescence microscopy reveals disruption of dynamic CXCR4 dimerization by subpocket-specific inverse agonists. Proc Natl Acad Sci U S A 2020; 117:29144-29154. [PMID: 33148803 PMCID: PMC7682396 DOI: 10.1073/pnas.2013319117] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Class A G protein−coupled receptors (GPCRs) can form dimers and oligomers via poorly understood mechanisms. We show here that the chemokine receptor CXCR4, which is a major pharmacological target, has an oligomerization behavior modulated by its active conformation. Combining advanced, single-molecule, and single-cell optical tools with functional assays and computational approaches, we unveil three key features of CXCR4 quaternary organization: CXCR4 dimerization 1) is dynamic, 2) increases with receptor expression level, and 3) can be disrupted by stabilizing an inactive receptor conformation. Ligand binding motifs reveal a ligand binding subpocket essential to modulate both CXCR4 basal activity and dimerization. This is relevant to develop new strategies to design CXCR4-targeting drugs. Although class A G protein−coupled receptors (GPCRs) can function as monomers, many of them form dimers and oligomers, but the mechanisms and functional relevance of such oligomerization is ill understood. Here, we investigate this problem for the CXC chemokine receptor 4 (CXCR4), a GPCR that regulates immune and hematopoietic cell trafficking, and a major drug target in cancer therapy. We combine single-molecule microscopy and fluorescence fluctuation spectroscopy to investigate CXCR4 membrane organization in living cells at densities ranging from a few molecules to hundreds of molecules per square micrometer of the plasma membrane. We observe that CXCR4 forms dynamic, transient homodimers, and that the monomer−dimer equilibrium is governed by receptor density. CXCR4 inverse agonists that bind to the receptor minor pocket inhibit CXCR4 constitutive activity and abolish receptor dimerization. A mutation in the minor binding pocket reduced the dimer-disrupting ability of these ligands. In addition, mutating critical residues in the sixth transmembrane helix of CXCR4 markedly diminished both basal activity and dimerization, supporting the notion that CXCR4 basal activity is required for dimer formation. Together, these results link CXCR4 dimerization to its density and to its activity. They further suggest that inverse agonists binding to the minor pocket suppress both dimerization and constitutive activity and may represent a specific strategy to target CXCR4.
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31
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Lazaratos M, Karathanou K, Bondar AN. Graphs of dynamic H-bond networks: from model proteins to protein complexes in cell signaling. Curr Opin Struct Biol 2020; 64:79-87. [DOI: 10.1016/j.sbi.2020.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 05/28/2020] [Accepted: 06/08/2020] [Indexed: 12/13/2022]
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32
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Functionalization and Bioconjugation of Nanoruby for Long-Term, Ultrasensitive Imaging of Μu-Opioid Receptors. Methods Mol Biol 2020. [PMID: 32975789 DOI: 10.1007/978-1-0716-0884-5_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Sensitive and long-term fluorescence imaging of G-protein-coupled receptors enables exploration of molecular level details of these therapeutically relevant proteins, including their expression, localization, signaling, and intracellular trafficking. In this context, labeling these receptors with bright and photostable fluorescent probes is necessary to overcome current imaging problems such as optical background and photobleaching. Here, we describe the procedures to functionalize nanoruby (and other similar nanoparticles) with NeutrAvidin (a streptavidin analog) and to apply this bioconjugate for ultrasensitive, long-term imaging of μ-opioid receptors heterologously expressed in AtT-20 cells. The receptor targeting is mediated via a biotinylated primary antibody, rendering this methodology extendable to other G-protein-coupled or, more generally, cell-surface receptors. Nanoruby-based time-gated imaging enables indefinitely long visualization of single particles even in high-autofluorescence media, such as serum, by completely suppressing autofluorescence and any laser backscatter.
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33
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Lo Giudice C, Zhang H, Wu B, Alsteens D. Mechanochemical Activation of Class-B G-Protein-Coupled Receptor upon Peptide-Ligand Binding. NANO LETTERS 2020; 20:5575-5582. [PMID: 32578992 DOI: 10.1021/acs.nanolett.0c02333] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Glucagon binding to the class-B G-protein-coupled glucagon receptor (GCGR) triggers the release of glucose from the liver during fasting. Recently, GCGR crystal structures have highlighted the conformation and molecular details of inactive and active receptor states. However, the dynamics of the conformational changes accompanying GCGR activation remains unclear. Here, we use multiplex force-distance curve-based atomic force microscopy (FD-based AFM) to probe in situ glucagon binding to individual GCGRs and monitor dynamically the transition to the active conformer. After a "dock" step, in which glucagon is partially bound to the GCGR extracellular domain, further interactions of the N-terminus with the transmembrane domain trigger an increase in the stiffness of the complex, adopting a highly stable and rigid "lock" conformer. This mechanotransduction is key for G-protein recruitment.
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Affiliation(s)
- Cristina Lo Giudice
- Louvain Institute of Biomolecular Science and Technology, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Haonan Zhang
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Beili Wu
- CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - David Alsteens
- Louvain Institute of Biomolecular Science and Technology, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
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34
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Evenseth LSM, Gabrielsen M, Sylte I. The GABA B Receptor-Structure, Ligand Binding and Drug Development. Molecules 2020; 25:molecules25133093. [PMID: 32646032 PMCID: PMC7411975 DOI: 10.3390/molecules25133093] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/02/2020] [Accepted: 07/06/2020] [Indexed: 11/17/2022] Open
Abstract
The γ-aminobutyric acid (GABA) type B receptor (GABAB-R) belongs to class C of the G-protein coupled receptors (GPCRs). Together with the GABAA receptor, the receptor mediates the neurotransmission of GABA, the main inhibitory neurotransmitter in the central nervous system (CNS). In recent decades, the receptor has been extensively studied with the intention being to understand pathophysiological roles, structural mechanisms and develop drugs. The dysfunction of the receptor is linked to a broad variety of disorders, including anxiety, depression, alcohol addiction, memory and cancer. Despite extensive efforts, few compounds are known to target the receptor, and only the agonist baclofen is approved for clinical use. The receptor is a mandatory heterodimer of the GABAB1 and GABAB2 subunits, and each subunit is composed of an extracellular Venus Flytrap domain (VFT) and a transmembrane domain of seven α-helices (7TM domain). In this review, we briefly present the existing knowledge about the receptor structure, activation and compounds targeting the receptor, emphasizing the role of the receptor in previous and future drug design and discovery efforts.
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Affiliation(s)
- Linn Samira Mari Evenseth
- Molecular Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway
| | - Mari Gabrielsen
- Molecular Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway
| | - Ingebrigt Sylte
- Molecular Pharmacology and Toxicology, Department of Medical Biology, Faculty of Health Sciences, UiT The Arctic University of Norway, NO-9037 Tromsø, Norway
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35
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Möller J, Isbilir A, Sungkaworn T, Osberg B, Karathanasis C, Sunkara V, Grushevskyi EO, Bock A, Annibale P, Heilemann M, Schütte C, Lohse MJ. Single-molecule analysis reveals agonist-specific dimer formation of µ-opioid receptors. Nat Chem Biol 2020; 16:946-954. [PMID: 32541966 DOI: 10.1038/s41589-020-0566-1] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 05/13/2020] [Indexed: 01/08/2023]
Abstract
G-protein-coupled receptors (GPCRs) are key signaling proteins that mostly function as monomers, but for several receptors constitutive dimer formation has been described and in some cases is essential for function. Using single-molecule microscopy combined with super-resolution techniques on intact cells, we describe here a dynamic monomer-dimer equilibrium of µ-opioid receptors (µORs), where dimer formation is driven by specific agonists. The agonist DAMGO, but not morphine, induces dimer formation in a process that correlates both temporally and in its agonist- and phosphorylation-dependence with β-arrestin2 binding to the receptors. This dimerization is independent from, but may precede, µOR internalization. These data suggest a new level of GPCR regulation that links dimer formation to specific agonists and their downstream signals.
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Affiliation(s)
- Jan Möller
- Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| | - Ali Isbilir
- Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| | - Titiwat Sungkaworn
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany.,Chakri Naruebodindra Medical Institute, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Samut Prakan, Thailand
| | - Brendan Osberg
- Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Max Delbrück Center for Molecular Medicine, Berlin Institute for Medical Systems Biology, Bioinformatics and Omics Data Science Platform, Berlin, Germany
| | - Christos Karathanasis
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | | | - Eugene O Grushevskyi
- Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| | - Andreas Bock
- Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| | - Paolo Annibale
- Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| | - Mike Heilemann
- Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Christof Schütte
- Zuse Institute Berlin, Berlin, Germany.,Free University of Berlin, Berlin, Germany
| | - Martin J Lohse
- Max Delbrück Center for Molecular Medicine, Berlin, Germany. .,Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany. .,Free University of Berlin, Berlin, Germany. .,ISAR Bioscience Institute, Munich/Planegg, Germany.
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36
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Perpiñá-Viciano C, Işbilir A, Zarca A, Caspar B, Kilpatrick LE, Hill SJ, Smit MJ, Lohse MJ, Hoffmann C. Kinetic Analysis of the Early Signaling Steps of the Human Chemokine Receptor CXCR4. Mol Pharmacol 2020; 98:72-87. [PMID: 32474443 PMCID: PMC7330677 DOI: 10.1124/mol.119.118448] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 05/06/2020] [Indexed: 01/14/2023] Open
Abstract
G protein–coupled receptors (GPCRs) are biologic switches that transduce extracellular stimuli into intracellular responses in the cell. Temporally resolving GPCR transduction pathways is key to understanding how cell signaling occurs. Here, we investigate the kinetics and dynamics of the activation and early signaling steps of the CXC chemokine receptor (CXCR) 4 in response to its natural ligands CXC chemokine ligand (CXCL) 12 and macrophage migration inhibitory factor (MIF), using Förster resonance energy transfer–based approaches. We show that CXCR4 presents a multifaceted response to CXCL12, with receptor activation (≈0.6 seconds) followed by a rearrangement in the receptor/G protein complex (≈1 seconds), a slower dimer rearrangement (≈1.7 seconds), and prolonged G protein activation (≈4 seconds). In comparison, MIF distinctly modulates every step of the transduction pathway, indicating distinct activation mechanisms and reflecting the different pharmacological properties of these two ligands. Our study also indicates that CXCR4 exhibits some degree of ligand-independent activity, a relevant feature for drug development.
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Affiliation(s)
- Cristina Perpiñá-Viciano
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), University Hospital Jena, University of Jena, Jena, Germany (C.P.-V., C.H.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (C.P.-V., A.I., M.J.L., C.H.); Max-Delbrück Center for Molecular Medicine, Berlin, Germany (A.I., M.J.L.); Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Vrije Universiteit, Amsterdam, The Netherlands (A.Z., M.J.S.); Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (B.C., L.E.K., S.J.H.); and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, United Kingdom (B.C., L.E.K., S.J.H.)
| | - Ali Işbilir
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), University Hospital Jena, University of Jena, Jena, Germany (C.P.-V., C.H.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (C.P.-V., A.I., M.J.L., C.H.); Max-Delbrück Center for Molecular Medicine, Berlin, Germany (A.I., M.J.L.); Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Vrije Universiteit, Amsterdam, The Netherlands (A.Z., M.J.S.); Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (B.C., L.E.K., S.J.H.); and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, United Kingdom (B.C., L.E.K., S.J.H.)
| | - Aurélien Zarca
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), University Hospital Jena, University of Jena, Jena, Germany (C.P.-V., C.H.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (C.P.-V., A.I., M.J.L., C.H.); Max-Delbrück Center for Molecular Medicine, Berlin, Germany (A.I., M.J.L.); Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Vrije Universiteit, Amsterdam, The Netherlands (A.Z., M.J.S.); Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (B.C., L.E.K., S.J.H.); and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, United Kingdom (B.C., L.E.K., S.J.H.)
| | - Birgit Caspar
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), University Hospital Jena, University of Jena, Jena, Germany (C.P.-V., C.H.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (C.P.-V., A.I., M.J.L., C.H.); Max-Delbrück Center for Molecular Medicine, Berlin, Germany (A.I., M.J.L.); Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Vrije Universiteit, Amsterdam, The Netherlands (A.Z., M.J.S.); Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (B.C., L.E.K., S.J.H.); and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, United Kingdom (B.C., L.E.K., S.J.H.)
| | - Laura E Kilpatrick
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), University Hospital Jena, University of Jena, Jena, Germany (C.P.-V., C.H.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (C.P.-V., A.I., M.J.L., C.H.); Max-Delbrück Center for Molecular Medicine, Berlin, Germany (A.I., M.J.L.); Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Vrije Universiteit, Amsterdam, The Netherlands (A.Z., M.J.S.); Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (B.C., L.E.K., S.J.H.); and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, United Kingdom (B.C., L.E.K., S.J.H.)
| | - Stephen J Hill
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), University Hospital Jena, University of Jena, Jena, Germany (C.P.-V., C.H.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (C.P.-V., A.I., M.J.L., C.H.); Max-Delbrück Center for Molecular Medicine, Berlin, Germany (A.I., M.J.L.); Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Vrije Universiteit, Amsterdam, The Netherlands (A.Z., M.J.S.); Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (B.C., L.E.K., S.J.H.); and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, United Kingdom (B.C., L.E.K., S.J.H.)
| | - Martine J Smit
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), University Hospital Jena, University of Jena, Jena, Germany (C.P.-V., C.H.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (C.P.-V., A.I., M.J.L., C.H.); Max-Delbrück Center for Molecular Medicine, Berlin, Germany (A.I., M.J.L.); Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Vrije Universiteit, Amsterdam, The Netherlands (A.Z., M.J.S.); Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (B.C., L.E.K., S.J.H.); and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, United Kingdom (B.C., L.E.K., S.J.H.)
| | - Martin J Lohse
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), University Hospital Jena, University of Jena, Jena, Germany (C.P.-V., C.H.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (C.P.-V., A.I., M.J.L., C.H.); Max-Delbrück Center for Molecular Medicine, Berlin, Germany (A.I., M.J.L.); Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Vrije Universiteit, Amsterdam, The Netherlands (A.Z., M.J.S.); Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (B.C., L.E.K., S.J.H.); and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, United Kingdom (B.C., L.E.K., S.J.H.)
| | - Carsten Hoffmann
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine (CMB), University Hospital Jena, University of Jena, Jena, Germany (C.P.-V., C.H.); Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany (C.P.-V., A.I., M.J.L., C.H.); Max-Delbrück Center for Molecular Medicine, Berlin, Germany (A.I., M.J.L.); Amsterdam Institute for Molecules Medicines and Systems (AIMMS), Division of Medicinal Chemistry, Vrije Universiteit, Amsterdam, The Netherlands (A.Z., M.J.S.); Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Medical School, Queen's Medical Centre, Nottingham, United Kingdom (B.C., L.E.K., S.J.H.); and Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, United Kingdom (B.C., L.E.K., S.J.H.)
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37
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Evenseth LSM, Ocello R, Gabrielsen M, Masetti M, Recanatini M, Sylte I, Cavalli A. Exploring Conformational Dynamics of the Extracellular Venus flytrap Domain of the GABA B Receptor: A Path-Metadynamics Study. J Chem Inf Model 2020; 60:2294-2303. [PMID: 32233432 PMCID: PMC7997371 DOI: 10.1021/acs.jcim.0c00163] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Indexed: 12/21/2022]
Abstract
γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central nervous system (CNS). Dysfunctional GABAergic neurotransmission is associated with numerous neurological and neuropsychiatric disorders. The GABAB receptor (GABAB-R) is a heterodimeric class C G protein-coupled receptor (GPCR) comprised of GABAB1a/b and GABAB2 subunits. The orthosteric binding site for GABA is located in the extracellular Venus flytrap (VFT) domain of the GABAB1a/b. Knowledge about molecular mechanisms and druggable receptor conformations associated with activation is highly important to understand the receptor function and for rational drug design. Currently, the conformational changes of the receptor upon activation are not well described. On the basis of other class C members, the VFT is proposed to fluctuate between an open/inactive and closed/active state and one of these conformations is stabilized upon ligand binding. In the present study, we investigated the dynamics of the GABAB1b-R VFT in the apo form by combining unbiased molecular dynamics with path-metadynamics. Our simulations confirmed the open/inactive and closed/active state as the main conformations adopted by the receptor. Sizeable energy barriers were found between stable minima, suggesting a relatively slow interconversion. Previously undisclosed metastable states were also identified, which might hold potential for future drug discovery efforts.
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Affiliation(s)
- Linn S. M. Evenseth
- Molecular
Pharmacology and Toxicology, Department of Medical Biology, Faculty
of Health Sciences, UiT—The Arctic
University of Norway, NO-9037Tromsø, Norway
| | - Riccardo Ocello
- Department
of Pharmacy and Biotechnology, Alma Mater
Studiorum—Università di Bologna, Via Belmeloro 6, I-40126 Bologna, Italy
- CompuNet, Istituto Italiano
di Tecnologia, Via Morego
30, I-16163 Genova, Italy
| | - Mari Gabrielsen
- Molecular
Pharmacology and Toxicology, Department of Medical Biology, Faculty
of Health Sciences, UiT—The Arctic
University of Norway, NO-9037Tromsø, Norway
| | - Matteo Masetti
- Department
of Pharmacy and Biotechnology, Alma Mater
Studiorum—Università di Bologna, Via Belmeloro 6, I-40126 Bologna, Italy
| | - Maurizio Recanatini
- Department
of Pharmacy and Biotechnology, Alma Mater
Studiorum—Università di Bologna, Via Belmeloro 6, I-40126 Bologna, Italy
| | - Ingebrigt Sylte
- Molecular
Pharmacology and Toxicology, Department of Medical Biology, Faculty
of Health Sciences, UiT—The Arctic
University of Norway, NO-9037Tromsø, Norway
| | - Andrea Cavalli
- Department
of Pharmacy and Biotechnology, Alma Mater
Studiorum—Università di Bologna, Via Belmeloro 6, I-40126 Bologna, Italy
- CompuNet, Istituto Italiano
di Tecnologia, Via Morego
30, I-16163 Genova, Italy
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38
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Lans I, Díaz Ó, Dalton JAR, Giraldo J. Exploring the Activation Mechanism of the mGlu5 Transmembrane Domain. Front Mol Biosci 2020; 7:38. [PMID: 32211419 PMCID: PMC7069277 DOI: 10.3389/fmolb.2020.00038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/18/2020] [Indexed: 01/14/2023] Open
Abstract
As a class C GPCR and regulator of synaptic activity, mGlu5 is an attractive drug target, potentially offering treatment for several neurologic and psychiatric disorders. As little is known about the activation mechanism of mGlu5 at a structural level, potential of mean force calculations linked to molecular dynamics simulations were performed on the mGlu5 transmembrane domain crystal structure to explore various internal mechanisms responsible for its activation. Our results suggest that the hydrophilic interactions between intracellular loop 1 and the intracellular side of TM6 have to be disrupted to reach a theoretically active-like conformation. In addition, interactions between residues that are key for mGlu5 activation (Tyr6593.44 and Ile7515.51) and mGlu5 inactivation (Tyr6593.44 and Ser8097.39) have been identified. Inasmuch as mGlu5 receptor signaling is poorly understood, potentially showing a complex network of micro-switches and subtle structure-activity relationships, the present study represents a step forward in the understanding of mGlu5 transmembrane domain activation.
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Affiliation(s)
- Isaias Lans
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Biophysics of Tropical Diseases, Max Planck Tandem Group, University of Antioquia, Medellín, Colombia
| | - Óscar Díaz
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Unitat de Neurociència Traslacional, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain.,Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Madrid, Spain
| | - James A R Dalton
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Unitat de Neurociència Traslacional, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain.,Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Madrid, Spain
| | - Jesús Giraldo
- Laboratory of Molecular Neuropharmacology and Bioinformatics, Unitat de Bioestadística and Institut de Neurociències, Universitat Autònoma de Barcelona, Bellaterra, Spain.,Unitat de Neurociència Traslacional, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí (I3PT), Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain.,Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM, Madrid, Spain
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39
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Sakairi H, Kamikubo Y, Abe M, Ikeda K, Ichiki A, Tabata T, Kano M, Sakurai T. G Protein-Coupled Glutamate and GABA Receptors Form Complexes and Mutually Modulate Their Signals. ACS Chem Neurosci 2020; 11:567-578. [PMID: 31977183 DOI: 10.1021/acschemneuro.9b00599] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Molecular networks containing various proteins mediate many types of cellular processes. Elucidation of how the proteins interact will improve our understanding of the molecular integration and physiological and pharmacological propensities of the network. One of the most complicated and unexplained interactions between proteins is the inter-G protein-coupled receptor (GPCR) interaction. Recently, many studies have suggested that an interaction between neurotransmitter GPCRs may mediate diverse modalities of neural responses. The B-type gamma-aminobutyric acid (GABA) receptor (GBR) and type-1 metabotropic glutamate receptor (mGluR1) are GPCRs for GABA and glutamate, respectively, and each plays distinct roles in controlling neurotransmission. We have previously reported the possibility of their functional interaction in central neurons. Here, we examined the interaction of these GPCRs using stable cell lines and rat cerebella. Cell-surface imaging and coimmunoprecipitation analysis revealed that these GPCRs interact on the cell surface. Furthermore, fluorometry revealed that these GPCRs mutually modulate signal transduction. These findings provide solid evidence that mGluR1 and GBR have intrinsic abilities to form complexes and to mutually modulate signaling. These findings indicate that synaptic plasticity relies on a network of proteins far more complex than previously assumed.
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Affiliation(s)
- Hakushun Sakairi
- Department of Pharmacology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Yuji Kamikubo
- Department of Pharmacology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Masayoshi Abe
- Laboratory for Biological Information Processing, Faculty of Engineering and Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
| | - Keisuke Ikeda
- Laboratory for Biological Information Processing, Faculty of Engineering and Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
| | - Arata Ichiki
- Laboratory for Biological Information Processing, Faculty of Engineering and Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
| | - Toshihide Tabata
- Laboratory for Biological Information Processing, Faculty of Engineering and Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama, Toyama 930-8555, Japan
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
| | - Takashi Sakurai
- Department of Pharmacology, Juntendo University School of Medicine, Hongo 2-1-1, Bunkyo-ku, Tokyo 113-8421, Japan
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40
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Lei T, Hu Z, Ding R, Chen J, Li S, Zhang F, Pu X, Zhao N. Exploring the Activation Mechanism of a Metabotropic Glutamate Receptor Homodimer via Molecular Dynamics Simulation. ACS Chem Neurosci 2020; 11:133-145. [PMID: 31815422 DOI: 10.1021/acschemneuro.9b00425] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Metabotropic glutamate receptors of class C GPCRs exist as constitutive dimers, which play important roles in activating excitatory synapses of the central nervous system. However, the activation mechanism induced by agonists has not been clarified in experiments. To address the problem, we used microsecond all-atom molecular dynamics (MD) simulation couple with protein structure network (PSN) to explore the glutamate-induced activation for the mGluR1 homodimer. The results indicate that glutamate binding stabilizes not only the closure of Venus flytrap domains but also the polar interaction of LB2-LB2, in turn keeping the extracelluar domain in the active state. The activation of the extracelluar domain drives transmembrane domains (TMDs) of the two protomers closer and induces asymmetric activation for the TMD domains of the two protomers. One protomer with lower binding affinity to the agonist is activated, while the other protomer with higher binding energy is still in the inactive state. The PSN analysis identifies the allosteric regulation pathway from the ligand-binding pocket in the extracellular domain to the G-protein binding site in the intracellular TMD region and further reveals that the asymmetric activation is attributed to a combination of trans-pathway and cis-pathway regulations from two glumatates, rather than a single activation pathway. These observations could provide valuable molecular information for understanding of the structure and the implications in drug efficacy for the class C GPCR dimers.
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Affiliation(s)
- Ting Lei
- College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Zhenxin Hu
- College of Computer Science, Sichuan University, Chengdu 610064, China
| | - Ruolin Ding
- West China School of Stomatology, Sichuan University, Chengdu 610041, China
| | - Jianfang Chen
- College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Shiqi Li
- College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Fuhui Zhang
- College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Xuemei Pu
- College of Chemistry, Sichuan University, Chengdu 610064, China
| | - Nanrong Zhao
- College of Chemistry, Sichuan University, Chengdu 610064, China
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41
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Gutzeit VA, Thibado J, Stor DS, Zhou Z, Blanchard SC, Andersen OS, Levitz J. Conformational dynamics between transmembrane domains and allosteric modulation of a metabotropic glutamate receptor. eLife 2019; 8:45116. [PMID: 31172948 PMCID: PMC6588349 DOI: 10.7554/elife.45116] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/06/2019] [Indexed: 01/01/2023] Open
Abstract
Metabotropic glutamate receptors (mGluRs) are class C, synaptic G-protein-coupled receptors (GPCRs) that contain large extracellular ligand binding domains (LBDs) and form constitutive dimers. Despite the existence of a detailed picture of inter-LBD conformational dynamics and structural snapshots of both isolated domains and full-length receptors, it remains unclear how mGluR activation proceeds at the level of the transmembrane domains (TMDs) and how TMD-targeting allosteric drugs exert their effects. Here, we use time-resolved functional and conformational assays to dissect the mechanisms by which allosteric drugs activate and modulate mGluR2. Single-molecule subunit counting and inter-TMD fluorescence resonance energy transfer measurements in living cells reveal LBD-independent conformational rearrangements between TMD dimers during receptor modulation. Using these assays along with functional readouts, we uncover heterogeneity in the magnitude, direction, and the timing of the action of both positive and negative allosteric drugs. Together our experiments lead to a three-state model of TMD activation, which provides a framework for understanding how inter-subunit rearrangements drive class C GPCR activation.
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Affiliation(s)
- Vanessa A Gutzeit
- Neuroscience Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States
| | - Jordana Thibado
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States
| | - Daniel Starer Stor
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States
| | - Zhou Zhou
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, United States
| | - Scott C Blanchard
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States.,Department of Physiology and Biophysics, Weill Cornell Medicine, New York, United States.,Tri-Institutional PhD Program in Chemical Biology, New York, United States
| | - Olaf S Andersen
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States.,Department of Physiology and Biophysics, Weill Cornell Medicine, New York, United States
| | - Joshua Levitz
- Physiology, Biophysics and Systems Biology Graduate Program, Weill Cornell Graduate School of Medical Sciences, New York, United States.,Tri-Institutional PhD Program in Chemical Biology, New York, United States.,Department of Biochemistry, Weill Cornell Medicine, New York, United States
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