1
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Yamaguchi H, Kitajima S, Suzuki H, Suzuki S, Nishikawa K, Kamegawa A, Fujiyoshi Y, Takahashi K, Tagami U, Maruyama Y, Kuroda M, Sugiki M. Cryo-EM structure of the calcium-sensing receptor complexed with the kokumi substance γ-glutamyl-valyl-glycine. Sci Rep 2025; 15:3894. [PMID: 39890873 PMCID: PMC11785791 DOI: 10.1038/s41598-025-87999-1] [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: 09/25/2024] [Accepted: 01/23/2025] [Indexed: 02/03/2025] Open
Abstract
Taste is a key element for food palatability and is strongly influenced by the five basic tastes and other taste sensations, such as fatty orosensation, and koku perception, which indicates taste complexity, mouthfulness and lastingness. This study focuses on the taste modifier γ-glutamyl-valyl-glycine (γ-EVG), a potent kokumi substance that enhances taste and koku perception by modulating the calcium-sensing receptor (CaSR). We used cryo-electron microscopy to determine the structure of the CaSR/γ-EVG complex at a resolution of 3.55 Å. Structural analysis revealed important interactions between γ-EVG and the CaSR, involving key residues, such as Pro39, Phe42, Arg66, Ser147, and Glu297. Mutagenesis experiments demonstrated the importance of these residues in peptide binding. Each γ-EVG residue contributed to its binding to the orthosteric ligand binding site of the CaSR. These findings elucidate the molecular basis of kokumi peptide recognition by the CaSR and contribute to a better understanding of positive allosteric modulators of the CaSR. In addition, this research provides valuable insights into the functionality of class C G-protein-coupled receptors in taste perception, potentially informing the development of new taste modifiers and advancing the field of food science.
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Affiliation(s)
- Hiroki Yamaguchi
- Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, 210-8681, Japan.
- Advanced Research Initiative, Institute of Integrated Research, Institute of Science Tokyo, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8501, Japan.
| | - Seiji Kitajima
- Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, 210-8681, Japan.
| | - Hiroshi Suzuki
- Advanced Research Initiative, Institute of Integrated Research, Institute of Science Tokyo, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8501, Japan
| | - Shota Suzuki
- Advanced Research Initiative, Institute of Integrated Research, Institute of Science Tokyo, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8501, Japan
| | - Kouki Nishikawa
- CeSPIA Inc., 2-1-1 Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan
- Joint Research Course for Advanced Biomolecular Characterization, Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo, 183-8509, Japan
| | - Akiko Kamegawa
- Advanced Research Initiative, Institute of Integrated Research, Institute of Science Tokyo, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8501, Japan
- CeSPIA Inc., 2-1-1 Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan
- Joint Research Course for Advanced Biomolecular Characterization, Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo, 183-8509, Japan
| | - Yoshinori Fujiyoshi
- Advanced Research Initiative, Institute of Integrated Research, Institute of Science Tokyo, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8501, Japan
- CeSPIA Inc., 2-1-1 Otemachi, Chiyoda-ku, Tokyo, 100-0004, Japan
- Joint Research Course for Advanced Biomolecular Characterization, Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo, 183-8509, Japan
| | - Kazutoshi Takahashi
- Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, 210-8681, Japan
| | - Uno Tagami
- Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, 210-8681, Japan
| | - Yutaka Maruyama
- Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, 210-8681, Japan
| | - Motonaka Kuroda
- Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, 210-8681, Japan
| | - Masayuki Sugiki
- Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, 210-8681, Japan
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2
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Kordon SP, Cechova K, Bandekar SJ, Leon K, Dutka P, Siffer G, Kossiakoff AA, Vafabakhsh R, Araç D. Conformational coupling between extracellular and transmembrane domains modulates holo-adhesion GPCR function. Nat Commun 2024; 15:10545. [PMID: 39627215 PMCID: PMC11615224 DOI: 10.1038/s41467-024-54836-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Accepted: 11/20/2024] [Indexed: 12/06/2024] Open
Abstract
Adhesion G Protein-Coupled Receptors (aGPCRs) are key cell-adhesion molecules involved in numerous physiological functions. aGPCRs have large multi-domain extracellular regions (ECRs) containing a conserved GAIN domain that precedes their seven-pass transmembrane domain (7TM). Ligand binding and mechanical force applied on the ECR regulate receptor function. However, how the ECR communicates with the 7TM remains elusive, because the relative orientation and dynamics of the ECR and 7TM within a holoreceptor is unclear. Here, we describe the cryo-EM reconstruction of an aGPCR, Latrophilin3/ADGRL3, and reveal that the GAIN domain adopts a parallel orientation to the transmembrane region and has constrained movement. Single-molecule FRET experiments unveil three slow-exchanging FRET states of the ECR relative to the transmembrane region within the holoreceptor. GAIN-targeted antibodies, and cancer-associated mutations at the GAIN-7TM interface, alter FRET states, cryo-EM conformations, and receptor signaling. Altogether, this data demonstrates conformational and functional coupling between the ECR and 7TM, suggesting an ECR-mediated mechanism for aGPCR activation.
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Affiliation(s)
- Szymon P Kordon
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Neuroscience Institute, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA
- Center for Mechanical Excitability, University of Chicago, Chicago, IL, USA
| | - Kristina Cechova
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Sumit J Bandekar
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Neuroscience Institute, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA
- Center for Mechanical Excitability, University of Chicago, Chicago, IL, USA
| | - Katherine Leon
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Neuroscience Institute, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA
| | - Przemysław Dutka
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Department of Structural Biology, Genentech, South San Francisco, CA, USA
| | - Gracie Siffer
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA.
| | - Demet Araç
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
- Neuroscience Institute, The University of Chicago, Chicago, IL, USA.
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA.
- Center for Mechanical Excitability, University of Chicago, Chicago, IL, USA.
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3
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Kannan A, Naganathan AN. Engineering the native ensemble to tune protein function: Diverse mutational strategies and interlinked molecular mechanisms. Curr Opin Struct Biol 2024; 89:102940. [PMID: 39393291 DOI: 10.1016/j.sbi.2024.102940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Revised: 09/15/2024] [Accepted: 09/16/2024] [Indexed: 10/13/2024]
Abstract
Natural proteins are fragile entities, intrinsically sensitive to perturbations both at the level of sequence and their immediate environment. Here, we highlight the diverse strategies available for engineering function through mutations influencing backbone conformational entropy, charge-charge interactions, and in the loops and hinge regions, many of which are located far from the active site. It thus appears that there are potentially numerous ways to microscopically vary the identity of residues and the constituent interactions to tune function. Functional modulation could occur via changes in native-state stability, altered thermodynamic coupling extents within the folded structure, redistributed dynamics, or through modulation of the population of conformational substates. As these mechanisms are intrinsically linked and given the pervasive long-range effects of mutations, it is crucial to consider the interaction network as a whole and fully map the native conformational landscape to place mutational effects in the context of allostery and protein evolution.
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Affiliation(s)
- Adithi Kannan
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Athi N Naganathan
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
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Isu U, Polasa A, Moradi M. Differential Behavior of Conformational Dynamics in Active and Inactive States of Cannabinoid Receptor 1. J Phys Chem B 2024; 128:8437-8447. [PMID: 39169808 PMCID: PMC11382280 DOI: 10.1021/acs.jpcb.4c02828] [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: 04/30/2024] [Revised: 08/05/2024] [Accepted: 08/15/2024] [Indexed: 08/23/2024]
Abstract
Cannabinoid receptor 1 (CB1) is a G protein-coupled receptor that regulates critical physiological processes including pain, appetite, and cognition. Understanding the conformational dynamics of CB1 associated with transitions between inactive and active signaling states is imperative for developing targeted modulators. Using microsecond-level all-atom molecular dynamics simulations, we identified marked differences in the conformational ensembles of inactive and active CB1 in apo. The inactive state exhibited substantially increased structural heterogeneity and plasticity compared to the more rigidified active state in the absence of stabilizing ligands. Transmembrane helices TM3 and TM7 were identified as distinguishing factors modulating the state-dependent dynamics. TM7 displayed amplified fluctuations selectively in the inactive state simulations attributed to disruption of conserved electrostatic contacts anchoring it to surrounding helices in the active state. Additionally, we identified significant reorganizations in key salt bridge and hydrogen bond networks contributing to the CB1 activation/inactivation. For instance, D213-Y224 hydrogen bond and D184-K192 salt bridge showed marked rearrangements between the states. Collectively, these findings reveal the specialized role of TM7 in directing state-dependent CB1 dynamics through electrostatic switch mechanisms. By elucidating the intrinsic enhanced flexibility of inactive CB1, this study provides valuable insights into the conformational landscape enabling functional transitions. Our perspective advances understanding of CB1 activation mechanisms and offers opportunities for structure-based drug discovery targeting the state-specific conformational dynamics of this receptor.
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Affiliation(s)
- Ugochi
H. Isu
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Adithya Polasa
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
| | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701, United States
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5
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Isu UH, Polasa A, Moradi M. Differential Behavior of Conformational Dynamics in Active and Inactive States of Cannabinoid Receptor 1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.17.589939. [PMID: 38659869 PMCID: PMC11042334 DOI: 10.1101/2024.04.17.589939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The cannabinoid receptor CB1 is a G protein-coupled receptor that regulates critical physiological processes including pain, appetite, and cognition. Understanding the conformational dynamics of CB1 associated with transitions between inactive and active signaling states is imperative for developing targeted modulators. Using microsecond-level all-atom molecular dynamics simulations, we identified marked differences in the conformational ensembles of inactive and active CB1 states in apo conditions. The inactive state exhibited substantially increased structural heterogeneity and plasticity compared to the more rigidified active state in the absence of stabilizing ligands. Transmembrane helices TM3 and TM7 were identified as distinguishing factors modulating the state-dependent dynamics. TM7 displayed amplified fluctuations selectively in the inactive state simulations attributed to disruption of conserved electrostatic contacts anchoring it to surrounding helices in the active state. Additionally, we identified significant reorganization of key salt bridge and hydrogen bond networks known to control CB1 activation between states. For instance, a conserved D213-Y224 hydrogen bond and D184-K192 salt bridge interactions showed marked rearrangements between the states. Collectively, these findings reveal the specialized role of TM7 in directing state-dependent CB1 dynamics through electrostatic switch mechanisms. By elucidating the intrinsic enhanced flexibility of inactive CB1, this study provides valuable insights into the conformational landscape enabling functional transitions. Our perspective advances understanding of CB1 activation mechanisms and offers opportunities for structure-based drug discovery targeting the state-specific conformational dynamics of this receptor.
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6
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Ma S, Yin X, Pin JP, Rondard P, Yi P, Liu J. Absence of calcium-sensing receptor basal activity due to inter-subunit disulfide bridges. Commun Biol 2024; 7:501. [PMID: 38664468 PMCID: PMC11045811 DOI: 10.1038/s42003-024-06189-3] [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: 08/21/2023] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
G protein-coupled receptors naturally oscillate between inactive and active states, often resulting in receptor constitutive activity with important physiological consequences. Among the class C G protein-coupled receptors that typically sense amino-acids and their derivatives, the calcium sensing receptor (CaSR) tightly controls blood calcium levels. Its constitutive activity has not yet been studied. Here, we demonstrate the importance of the inter-subunit disulfide bridges in maintaining the inactive state of CaSR, resulting in undetectable constitutive activity, unlike the other class C receptors. Deletion of these disulfide bridges results in strong constitutive activity that is abolished by mutations preventing amino acid binding. It shows that this inter-subunit disulfide link is necessary to limit the agonist effect of amino acids on CaSR. Furthermore, human genetic mutations deleting these bridges and associated with hypocalcemia result in elevated CaSR constitutive activity. These results highlight the physiological importance of fine tuning the constitutive activity of G protein-coupled receptors.
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Affiliation(s)
- Shumin Ma
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xueliang Yin
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, Cedex 5, France
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, Cedex 5, France.
| | - Ping Yi
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Jianfeng Liu
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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7
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Lin CM, Ding YX, Huang SM, Chen YC, Lee HJ, Sung CC, Lin SH. Identification and characterization of a novel CASR mutation causing familial hypocalciuric hypercalcemia. Front Endocrinol (Lausanne) 2024; 15:1291160. [PMID: 38487341 PMCID: PMC10937390 DOI: 10.3389/fendo.2024.1291160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 01/22/2024] [Indexed: 03/17/2024] Open
Abstract
Context Although a monoallelic mutation in the calcium-sensing receptor (CASR) gene causes familial hypocalciuric hypercalcemia (FHH), the functional characterization of the identified CASR mutation linked to the clinical response to calcimimetics therapy is still limited. Objective A 45-year-old male presenting with moderate hypercalcemia, hypocalciuria, and inappropriately high parathyroid hormone (PTH) had a good response to cinacalcet (total serum calcium (Ca2+) from 12.5 to 10.1 mg/dl). We identified the genetic mutation and characterized the functional and pathophysiological mechanisms, and then linked the mutation to calcimimetics treatment in vitro. Design Sanger sequencing of the CASR, GNA11, and AP2S1 genes was performed in his family. The simulation model was used to predict the function of the identified mutant. In vitro studies, including immunoblotting, immunofluorescence, a cycloheximide chase study, Calbryte™ 520 Ca2+ detection, and half-maximal effective concentration (EC50), were examined. Results This proband was found to carry a de novo heterozygous missense I554N in the cysteine-rich domain of CASR, which was pathogenic based on the different software prediction models and ACGME criteria. The simulation model showed that CASR I554N mutation decreased its binding energy with Ca2+. Human CASR I554N mutation attenuated the stability of CASR protein, reduced the expression of p-ERK 1/2, and blunted the intracellular Ca2+ response to gradient extracellular Ca2+ (eCa2+) concentration. The EC50 study also demonstrated the correctable effect of calcimimetics on the function of the CASR I554N mutation. Conclusion This novel CASR I554N mutation causing FHH attenuates CASR stability, its binding affinity with Ca2+, and the response to eCa2+ corrected by therapeutic calcimimetics.
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Affiliation(s)
- Chien-Ming Lin
- Department of Pediatrics, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Yi-Xuan Ding
- Department of Pediatrics, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Shih-Ming Huang
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan
| | - Ying-Chuan Chen
- Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan
| | - Hwei-Jen Lee
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan
| | - Chih-Chien Sung
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Shih-Hua Lin
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
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8
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Kordon SP, Cechova K, Bandekar SJ, Leon K, Dutka P, Siffer G, Kossiakoff AA, Vafabakhsh R, Araç D. Structural analysis and conformational dynamics of a holo-adhesion GPCR reveal interplay between extracellular and transmembrane domains. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.25.581807. [PMID: 38464178 PMCID: PMC10925191 DOI: 10.1101/2024.02.25.581807] [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
Adhesion G Protein-Coupled Receptors (aGPCRs) are key cell-adhesion molecules involved in numerous physiological functions. aGPCRs have large multi-domain extracellular regions (ECR) containing a conserved GAIN domain that precedes their seven-pass transmembrane domain (7TM). Ligand binding and mechanical force applied on the ECR regulate receptor function. However, how the ECR communicates with the 7TM remains elusive, because the relative orientation and dynamics of the ECR and 7TM within a holoreceptor is unclear. Here, we describe the cryo-EM reconstruction of an aGPCR, Latrophilin3/ADGRL3, and reveal that the GAIN domain adopts a parallel orientation to the membrane and has constrained movement. Single-molecule FRET experiments unveil three slow-exchanging FRET states of the ECR relative to the 7TM within the holoreceptor. GAIN-targeted antibodies, and cancer-associated mutations at the GAIN-7TM interface, alter FRET states, cryo-EM conformations, and receptor signaling. Altogether, this data demonstrates conformational and functional coupling between the ECR and 7TM, suggesting an ECR-mediated mechanism of aGPCR activation.
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9
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He F, Wu CG, Gao Y, Rahman SN, Zaoralová M, Papasergi-Scott MM, Gu TJ, Robertson MJ, Seven AB, Li L, Mathiesen JM, Skiniotis G. Allosteric modulation and G-protein selectivity of the Ca 2+-sensing receptor. Nature 2024; 626:1141-1148. [PMID: 38326620 PMCID: PMC11929605 DOI: 10.1038/s41586-024-07055-2] [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: 06/02/2023] [Accepted: 01/10/2024] [Indexed: 02/09/2024]
Abstract
The calcium-sensing receptor (CaSR) is a family C G-protein-coupled receptor1 (GPCR) that has a central role in regulating systemic calcium homeostasis2,3. Here we use cryo-electron microscopy and functional assays to investigate the activation of human CaSR embedded in lipid nanodiscs and its coupling to functional Gi versus Gq proteins in the presence and absence of the calcimimetic drug cinacalcet. High-resolution structures show that both Gi and Gq drive additional conformational changes in the activated CaSR dimer to stabilize a more extensive asymmetric interface of the seven-transmembrane domain (7TM) that involves key protein-lipid interactions. Selective Gi and Gq coupling by the receptor is achieved through substantial rearrangements of intracellular loop 2 and the C terminus, which contribute differentially towards the binding of the two G-protein subtypes, resulting in distinct CaSR-G-protein interfaces. The structures also reveal that natural polyamines target multiple sites on CaSR to enhance receptor activation by zipping negatively charged regions between two protomers. Furthermore, we find that the amino acid L-tryptophan, a well-known ligand of CaSR extracellular domains, occupies the 7TM bundle of the G-protein-coupled protomer at the same location as cinacalcet and other allosteric modulators. Together, these results provide a framework for G-protein activation and selectivity by CaSR, as well as its allosteric modulation by endogenous and exogenous ligands.
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Affiliation(s)
- Feng He
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Cheng-Guo Wu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Yang Gao
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Cardiology of Sir Run Run Shaw Hospital and Liangzhu Laboratory, Zhejiang University School of Medicine, Hangzhou, China
| | - Sabrina N Rahman
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Magda Zaoralová
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Makaía M Papasergi-Scott
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Ting-Jia Gu
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA
| | - Michael J Robertson
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Alpay B Seven
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Lingjun Li
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI, USA
| | - Jesper M Mathiesen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.
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10
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Isu UH, Badiee SA, Khodadadi E, Moradi M. Cholesterol in Class C GPCRs: Role, Relevance, and Localization. MEMBRANES 2023; 13:301. [PMID: 36984688 PMCID: PMC10056374 DOI: 10.3390/membranes13030301] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/21/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
G-protein coupled receptors (GPCRs), one of the largest superfamilies of cell-surface receptors, are heptahelical integral membrane proteins that play critical roles in virtually every organ system. G-protein-coupled receptors operate in membranes rich in cholesterol, with an imbalance in cholesterol level within the vicinity of GPCR transmembrane domains affecting the structure and/or function of many GPCRs, a phenomenon that has been linked to several diseases. These effects of cholesterol could result in indirect changes by altering the mechanical properties of the lipid environment or direct changes by binding to specific sites on the protein. There are a number of studies and reviews on how cholesterol modulates class A GPCRs; however, this area of study is yet to be explored for class C GPCRs, which are characterized by a large extracellular region and often form constitutive dimers. This review highlights specific sites of interaction, functions, and structural dynamics involved in the cholesterol recognition of the class C GPCRs. We summarize recent data from some typical family members to explain the effects of membrane cholesterol on the structural features and functions of class C GPCRs and speculate on their corresponding therapeutic potential.
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Affiliation(s)
| | | | | | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
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11
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Lazrak A, Song W, Yu Z, Zhang S, Nellore A, Hoopes CW, Woodworth BA, Matalon S. Low molecular weight hyaluronan inhibits lung epithelial ion channels by activating the calcium-sensing receptor. Matrix Biol 2023; 116:67-84. [PMID: 36758905 PMCID: PMC10012407 DOI: 10.1016/j.matbio.2023.02.002] [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: 10/20/2022] [Revised: 02/01/2023] [Accepted: 02/02/2023] [Indexed: 02/11/2023]
Abstract
Herein, we tested the hypothesis that low molecular weight hyaluronan (LMW-HA) inhibits lung epithelial ions transport in-vivo, ex-vivo, and in-vitro by activating the calcium-sensing receptor (CaSR). Twenty-four hours post intranasal instillation of 50-150 µg/ml LMW-HA to C57BL/6 mice, there was a 75% inhibition of alveolar fluid clearance (AFC), a threefold increase in the epithelial lining fluid (ELF) depth, and a 20% increase in lung wet/dry (W/D) ratio. Incubation of human and mouse precision cut lung slices with 150 µg/ml LMW-HA reduced the activity and the open probability (Po) of epithelial sodium channel (ENaC) in alveolar epithelial type 2 (ATII) cells, and in mouse tracheal epithelial cells (MTEC) monolayers as early as 4 h. The Cl- current through cystic fibrosis transmembrane conductance regulator (CFTR) and the activity of Na,K-ATPase were both inhibited by more than 66% at 24 h. The inhibitory effects of LMW-HA on ion channels were reversed by 1 µM NPS-2143, or 150 µg/ml high molecular weight hyaluronan (HMW-HA). In HEK-293 cells expressing the calcium-sensitive Cl- channel TMEM16-A, CaSR was required for the activation of the Cl- current by LMW-HA. This is the first demonstration of lung ions and water transport inhibition by LMW-HA, and its mediation through the activation of CaSR.
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Affiliation(s)
- Ahmed Lazrak
- Department of Anesthesiology and Perioperative Medicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA; Division of Molecular and Translational Biomedicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA; Pulmonary Injury and Repair Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA; Gregory Fleming James Cystic Fibrosis Research Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA.
| | - Weifeng Song
- Department of Anesthesiology and Perioperative Medicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA; Division of Molecular and Translational Biomedicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA
| | - Zhihong Yu
- Department of Anesthesiology and Perioperative Medicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA; Division of Molecular and Translational Biomedicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA; Pulmonary Injury and Repair Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA
| | - Shaoyan Zhang
- Department of Otolaryngology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA; Gregory Fleming James Cystic Fibrosis Research Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA
| | - Anoma Nellore
- Department of Medicine, Division of Infectious Diseases, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA
| | - Charles W Hoopes
- Division of Cardiothoracic Surgery, Heersink School of Medicine, University of Alabama at Birmingham, AL 35295, USA
| | - Bradford A Woodworth
- Department of Otolaryngology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA; Gregory Fleming James Cystic Fibrosis Research Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA
| | - Sadis Matalon
- Department of Anesthesiology and Perioperative Medicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA; Division of Molecular and Translational Biomedicine, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA; Pulmonary Injury and Repair Center, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35295, USA
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Banerjee C, Liauw BWH, Vafabakhsh R. Visualizing the Conformational Dynamics of Membrane Receptors Using Single-Molecule FRET. J Vis Exp 2022:10.3791/64254. [PMID: 36062999 PMCID: PMC11287711 DOI: 10.3791/64254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023] Open
Abstract
The ability of cells to respond to external signals is essential for cellular development, growth, and survival. To respond to a signal from the environment, a cell must be able to recognize and process it. This task mainly relies on the function of membrane receptors, whose role is to convert signals into the biochemical language of the cell. G protein-coupled receptors (GPCRs) constitute the largest family of membrane receptor proteins in humans. Among GPCRs, metabotropic glutamate receptors (mGluRs) are a unique subclass that function as obligate dimers and possess a large extracellular domain that contains the ligand-binding site. Recent advances in structural studies of mGluRs have improved the understanding of their activation process. However, the propagation of large-scale conformational changes through mGluRs during activation and modulation is poorly understood. Single-molecule fluorescence resonance energy transfer (smFRET) is a powerful technique to visualize and quantify the structural dynamics of biomolecules at the single-protein level. To visualize the dynamic process of mGluR2 activation, fluorescent conformational sensors based on unnatural amino acid (UAA) incorporation were developed that allowed site-specific protein labeling without perturbation of the native structure of receptors. The protocol described here explains how to perform these experiments, including the novel UAA labeling approach, sample preparation, and smFRET data acquisition and analysis. These strategies are generalizable and can be extended to investigate the conformational dynamics of a variety of membrane proteins.
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Affiliation(s)
| | | | - Reza Vafabakhsh
- Department of Molecular Biosciences, Northwestern University;
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