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Ghosh M, Gupta PK, Behera LM, Rana S. Structure of Designer Antibody-like Peptides Binding to the Human C5a with Potential to Modulate the C5a Receptor Signaling. J Med Chem 2024. [PMID: 39051153 DOI: 10.1021/acs.jmedchem.4c00961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
C5a is an integral glycoprotein of the complement system that plays an important role in inflammation and immunity. The physiological concentration of C5a is observed to be elevated under various immunoinflammatory pathophysiological conditions in humans. The pathophysiology of C5a is linked to the "two-site" protein-protein interactions (PPIs) with two genomically related receptors, such as C5aR1 and C5aR2. Therefore, pharmacophores that can potentially block the PPIs between C5a-C5aR1 and C5a-C5aR2 have tremendous potential for development as future therapeutics. Notably, the FDA has already approved antibodies that target the precursors of C5a (Eculizumab, 148 kDa) and C5a (Vilobelimab, 149 kDa) for marketing as complement-targeted therapeutics. In this context, the current study reports the structural characterization of a pair of synthetic designer antibody-like peptides (DePA and DePA1; ≤3.8 kDa) that bind to hotspot regions on C5a and also demonstrates potential traits to neutralize the function of C5a under pathophysiological conditions.
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Affiliation(s)
- Manaswini Ghosh
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, Odisha 752050, India
| | - Pulkit Kr Gupta
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, Odisha 752050, India
| | - Lalita Mohan Behera
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, Odisha 752050, India
| | - Soumendra Rana
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, Odisha 752050, India
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2
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Santos-López J, de la Paz K, Fernández FJ, Vega MC. Structural biology of complement receptors. Front Immunol 2023; 14:1239146. [PMID: 37753090 PMCID: PMC10518620 DOI: 10.3389/fimmu.2023.1239146] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/16/2023] [Indexed: 09/28/2023] Open
Abstract
The complement system plays crucial roles in a wide breadth of immune and inflammatory processes and is frequently cited as an etiological or aggravating factor in many human diseases, from asthma to cancer. Complement receptors encompass at least eight proteins from four structural classes, orchestrating complement-mediated humoral and cellular effector responses and coordinating the complex cross-talk between innate and adaptive immunity. The progressive increase in understanding of the structural features of the main complement factors, activated proteolytic fragments, and their assemblies have spurred a renewed interest in deciphering their receptor complexes. In this review, we describe what is currently known about the structural biology of the complement receptors and their complexes with natural agonists and pharmacological antagonists. We highlight the fundamental concepts and the gray areas where issues and problems have been identified, including current research gaps. We seek to offer guidance into the structural biology of the complement system as structural information underlies fundamental and therapeutic research endeavors. Finally, we also indicate what we believe are potential developments in the field.
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Affiliation(s)
- Jorge Santos-López
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Karla de la Paz
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Research & Development, Abvance Biotech SL, Madrid, Spain
| | | | - M. Cristina Vega
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
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3
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Mechanism of activation and biased signaling in complement receptor C5aR1. Cell Res 2023; 33:312-324. [PMID: 36806352 PMCID: PMC9937529 DOI: 10.1038/s41422-023-00779-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 01/13/2023] [Indexed: 02/19/2023] Open
Abstract
The complement system plays an important role in the innate immune response to invading pathogens. The complement fragment C5a is one of its important effector components and exerts diverse physiological functions through activation of the C5a receptor 1 (C5aR1) and associated downstream G protein and β-arrestin signaling pathways. Dysfunction of the C5a-C5aR1 axis is linked to numerous inflammatory and immune-mediated diseases, but the structural basis for activation and biased signaling of C5aR1 remains elusive. Here, we present cryo-electron microscopy structures of the activated wild-type C5aR1-Gi protein complex bound to each of the following: C5a, the hexapeptidic agonist C5apep, and the G protein-biased agonist BM213. The structures reveal the landscape of the C5a-C5aR1 interaction as well as a common motif for the recognition of diverse orthosteric ligands. Moreover, combined with mutagenesis studies and cell-based pharmacological assays, we deciphered a framework for biased signaling using different peptide analogs and provided insight into the activation mechanism of C5aR1 by solving the structure of C5aR1I116A mutant-Gi signaling activation complex induced by C089, which exerts antagonism on wild-type C5aR1. In addition, unusual conformational changes in the intracellular end of transmembrane domain 7 and helix 8 upon agonist binding suggest a differential signal transduction process. Collectively, our study provides mechanistic understanding into the ligand recognition, biased signaling modulation, activation, and Gi protein coupling of C5aR1, which may facilitate the future design of therapeutic agents.
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Das A, Gupta PK, Rana S. C5aR2 receptor: The genomic twin of the flamboyant C5aR1. J Cell Biochem 2022; 123:1841-1856. [PMID: 35977039 DOI: 10.1002/jcb.30320] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 08/05/2022] [Indexed: 11/12/2022]
Abstract
The complement fragment C5a is one of the most potent proinflammatory glycoproteins liberated by the activation of the biochemical cascade of the complement system. C5a is established to interact with a set of genomically related transmembrane receptors, like C5aR1 (CD88, C5aR) and C5aR2 (GPR77, C5L2) with comparable affinity. The C5aR1 is a classical G-protein-coupled receptor (GPCR), whereas C5aR2 is a nonclassical GPCR that tailors immune cell activity potentially through β-arrestins rather than G-proteins. Currently, the exact function of the C5aR2 is actively debated in the context of C5aR1, even though both C5aR1 and C5aR2 are coexpressed on myriads of tissues. The functional relevance of C5aR2 appears to be context-dependent compared to the C5aR1, which has received enormous attention for its role in both acute and chronic inflammatory diseases. In addition, the structure of C5aR2 and its interaction specificity toward C5a is not structurally elucidated in the literature so far. The current study has attempted to close the gap by generating highly refined model structures of C5aR2, respectively in free (inactive), complexed to C-terminal peptide of C5a (meta-active) and the C5a (active), embedded to a model palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer. The computational modeling and the 1.5-μs molecular dynamics data presented in the current study are expected to further enrich the understanding of C5a-C5aR2 interaction compared to C5a-C5aR1, which will surely help in elaborating the currently debated biological function of C5aR2 better in the foreseeable future.
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Affiliation(s)
- Aurosikha Das
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Odisha, Bhubaneswar, India
| | - Pulkit K Gupta
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Odisha, Bhubaneswar, India
| | - Soumendra Rana
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Odisha, Bhubaneswar, India
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5
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Das A, Behera LM, Rana S. Interaction of Human C5a with the Major Peptide Fragments of C5aR1: Direct Evidence in Support of "Two-Site" Binding Paradigm. ACS OMEGA 2021; 6:22876-22887. [PMID: 34514259 PMCID: PMC8427777 DOI: 10.1021/acsomega.1c03400] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/18/2021] [Indexed: 05/26/2023]
Abstract
The C5a receptor's (C5aR1) physiological function in various tissues depends on its high-affinity binding to the cationic proinflammatory glycoprotein C5a, produced during the activation of the complement system. However, an overstimulated complement can quickly alter the C5a-C5aR1 function from physiological to pathological, as has been noted in the case of several chronic inflammation-induced diseases like asthma, lung injury, multiorgan failure, sepsis, and now COVID-19. In the absence of the structural data, the current study provides the confirmatory biophysical validation of the hypothesized "two-site" binding interactions of C5a, involving (i) the N-terminus (NT) peptide ("Site1") and (ii) the extracellular loop 2 (ECL2) peptide of the extracellular surface (ECS) of the C5aR1 ("Site2"), as illustrated earlier in the reported model structural complex of C5a-C5aR1. The biophysical and computational data elaborated in the study provides an improved understanding of the C5a-C5aR1 interaction at an atomistic resolution, highlighting the energetic importance of the aspartic acids on the NT-peptide of C5aR1 toward binding of C5a. The current study can potentially advance the search and optimization of new-generation alternative "antibodies" as well as "neutraligands" targeting the C5a to modulate its interaction with C5aR1.
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Nakamura Y, Asama R, Tabata T, Morita K, Maruyama T, Kondo A, Ishii J. Comparative analyses of site-directed mutagenesis of human melatonin MTNR1A and MTNR1B receptors using a yeast fluorescent biosensor. Biotechnol Bioeng 2020; 118:863-876. [PMID: 33095446 DOI: 10.1002/bit.27609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/22/2020] [Accepted: 10/22/2020] [Indexed: 11/08/2022]
Abstract
Melatonin is an indoleamine neurohormone made by the pineal gland. Its receptors, MTNR1A and MTNR1B, are members of the G-protein-coupled receptor (GPCR) family and are involved in sleep, circadian rhythm, and mood disorders, and in the inhibition of cancer growth. These receptors, therefore, represent significant molecular targets for insomnia, circadian sleep disorders, and cancer. The yeast Saccharomyces cerevisiae is an attractive host for assaying agonistic activity for human GPCR. We previously constructed a GPCR-based biosensor employing a high-sensitivity yeast strain that incorporated both a chimeric yeast-human Gα protein and a bright fluorescent reporter gene (ZsGreen). Similar approaches have been used for simple and convenient measurements of various GPCR activities. In the current study, we constructed a fluorescence-based yeast biosensor for monitoring the signaling activation of human melatonin receptors. We used this system to analyze point mutations, including previously unreported mutations of the consensus sequences of MTNR1A and MTNR1B melatonin receptors and compared their effects. Most mutations in the consensus sequences significantly affected the signaling capacities of both receptors, but several mutations showed differences between these subtype receptors. Thus, this yeast biosensor holds promise for revealing the functions of melatonin receptors.
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Affiliation(s)
- Yasuyuki Nakamura
- Engineering Biology Research Center, Kobe University, Kobe, Japan.,Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Ririka Asama
- Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Takuya Tabata
- Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Kenta Morita
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Tatsuo Maruyama
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Akihiko Kondo
- Engineering Biology Research Center, Kobe University, Kobe, Japan.,Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan.,Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan.,Center for Sustainable Resource Science, RIKEN, Yokohama, Japan
| | - Jun Ishii
- Engineering Biology Research Center, Kobe University, Kobe, Japan.,Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
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Herrera-Zúñiga LD, Moreno-Vargas LM, Ballaud L, Correa-Basurto J, Prada-Gracia D, Pastré D, Curmi PA, Arrang JM, Maroun RC. Molecular dynamics of the histamine H3 membrane receptor reveals different mechanisms of GPCR signal transduction. Sci Rep 2020; 10:16889. [PMID: 33037273 PMCID: PMC7547658 DOI: 10.1038/s41598-020-73483-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 09/11/2020] [Indexed: 02/02/2023] Open
Abstract
In this work, we studied the mechanisms of classical activation and inactivation of signal transduction by the histamine H3 receptor, a 7-helix transmembrane bundle G-Protein Coupled Receptor through long-time-scale atomistic molecular dynamics simulations of the receptor embedded in a hydrated double layer of dipalmitoyl phosphatidyl choline, a zwitterionic polysaturated ordered lipid. Three systems were prepared: the apo receptor, representing the constitutively active receptor; and two holo-receptors-the receptor coupled to the antagonist/inverse agonist ciproxifan, representing the inactive state of the receptor, and the receptor coupled to the endogenous agonist histamine and representing the active state of the receptor. An extensive analysis of the simulation showed that the three states of H3R present significant structural and dynamical differences as well as a complex behavior given that the measured properties interact in multiple and interdependent ways. In addition, the simulations described an unexpected escape of histamine from the orthosteric binding site, in agreement with the experimental modest affinities and rapid off-rates of agonists.
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Affiliation(s)
- Leonardo David Herrera-Zúñiga
- UMR-S U1204, Structure et Activité de Biomolécules Normales et Pathologiques, INSERM/Université d'Evry-Val d'Essonne/Université Paris-Saclay, 91000, Evry, France
- Laboratoire de Neurobiologie et Pharmacologie Moléculaire, INSERM U894, Centre de Psychiatrie et Neurosciences, 75014, Paris, France
- Área de Estudios de Posgrado e Investigación, Tecnológico de Estudios Superiores del Oriente del Estado de México, Los Reyes Acaquilpan, Mexico
| | - Liliana Marisol Moreno-Vargas
- Computational Biology and Drug Design Research Unit, Federico Gómez Children's Hospital of Mexico City, Mexico City, Mexico
- Laboratoire de Neurobiologie et Pharmacologie Moléculaire, INSERM U894, Centre de Psychiatrie et Neurosciences, 75014, Paris, France
| | - Luck Ballaud
- Laboratoire de Neurobiologie et Pharmacologie Moléculaire, INSERM U894, Centre de Psychiatrie et Neurosciences, 75014, Paris, France
| | - José Correa-Basurto
- UMR-S U1204, Structure et Activité de Biomolécules Normales et Pathologiques, INSERM/Université d'Evry-Val d'Essonne/Université Paris-Saclay, 91000, Evry, France
- Laboratorio de Modelado Molecular y Bioinformática, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Diego Prada-Gracia
- Computational Biology and Drug Design Research Unit, Federico Gómez Children's Hospital of Mexico City, Mexico City, Mexico
| | - David Pastré
- UMR-S U1204, Structure et Activité de Biomolécules Normales et Pathologiques, INSERM/Université d'Evry-Val d'Essonne/Université Paris-Saclay, 91000, Evry, France
| | - Patrick A Curmi
- UMR-S U1204, Structure et Activité de Biomolécules Normales et Pathologiques, INSERM/Université d'Evry-Val d'Essonne/Université Paris-Saclay, 91000, Evry, France
| | - Jean Michel Arrang
- Laboratoire de Neurobiologie et Pharmacologie Moléculaire, INSERM U894, Centre de Psychiatrie et Neurosciences, 75014, Paris, France
| | - Rachid C Maroun
- UMR-S U1204, Structure et Activité de Biomolécules Normales et Pathologiques, INSERM/Université d'Evry-Val d'Essonne/Université Paris-Saclay, 91000, Evry, France.
- Laboratoire de Neurobiologie et Pharmacologie Moléculaire, INSERM U894, Centre de Psychiatrie et Neurosciences, 75014, Paris, France.
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8
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Wölfel A, Sättele M, Zechmeister C, Nikolaev VO, Lohse MJ, Boege F, Jahns R, Boivin-Jahns V. Unmasking features of the auto-epitope essential for β 1 -adrenoceptor activation by autoantibodies in chronic heart failure. ESC Heart Fail 2020; 7:1830-1841. [PMID: 32436653 PMCID: PMC7373925 DOI: 10.1002/ehf2.12747] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 03/31/2020] [Accepted: 04/21/2020] [Indexed: 12/15/2022] Open
Abstract
Aims Chronic heart failure (CHF) can be caused by autoantibodies stimulating the heart via binding to first and/or second extracellular loops of cardiac β1‐adrenoceptors. Allosteric receptor activation depends on conformational features of the autoantibody binding site. Elucidating these features will pave the way for the development of specific diagnostics and therapeutics. Our aim was (i) to fine‐map the conformational epitope within the second extracellular loop of the human β1‐adrenoceptor (β1ECII) that is targeted by stimulating β1‐receptor (auto)antibodies and (ii) to generate competitive cyclopeptide inhibitors of allosteric receptor activation, which faithfully conserve the conformational auto‐epitope. Methods and results Non‐conserved amino acids within the β1ECII loop (compared with the amino acids constituting the ECII loop of the β2‐adrenoceptor) were one by one replaced with alanine; potential intra‐loop disulfide bridges were probed by cysteine–serine exchanges. Effects on antibody binding and allosteric receptor activation were assessed (i) by (auto)antibody neutralization using cyclopeptides mimicking β1ECII ± the above replacements, and (ii) by (auto)antibody stimulation of human β1‐adrenoceptors bearing corresponding point mutations. With the use of stimulating β1‐receptor (auto)antibodies raised in mice, rats, or rabbits and isolated from exemplary dilated cardiomyopathy patients, our series of experiments unmasked two features of the β1ECII loop essential for (auto)antibody binding and allosteric receptor activation: (i) the NDPK211–214 motif and (ii) the intra‐loop disulfide bond C209↔C215. Of note, aberrant intra‐loop disulfide bond C209↔C216 almost fully disrupted the functional auto‐epitope in cyclopeptides. Conclusions The conformational auto‐epitope targeted by cardio‐pathogenic β1‐receptor autoantibodies is faithfully conserved in cyclopeptide homologues of the β1ECII loop bearing the NDPK211–214 motif and the C209↔C215 bridge while lacking cysteine C216. Such molecules provide promising tools for novel diagnostic and therapeutic approaches in β1‐autoantibody‐positive CHF.
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Affiliation(s)
- Angela Wölfel
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, D-97078, Wuerzburg, Germany.,Rudolf-Virchow-Centre, Josef-Schneider-Str. 2, 97080, Würzburg, Germany.,Rudolf-Virchow-Centre, Pierre Fabre Dermo-Kosmetik GmbH, Jechtinger Straße 13, 79111, Freiburg, Germany
| | - Mathias Sättele
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, D-97078, Wuerzburg, Germany
| | - Christina Zechmeister
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, D-97078, Wuerzburg, Germany.,Interdisciplinary Bank of Biomaterials and Data (ibdw), University Hospital of Würzburg, Straubmühlweg 2A, D-97078, Würzburg, Germany.,Comprehensive Heart Failure Centre (CFHC), Am Schwarzenberg 11, 978078, Würzburg, Germany
| | - Viacheslav O Nikolaev
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, D-97078, Wuerzburg, Germany.,Institute for Molecular Cardiology, Department of Cardiology and Pneumology, University Hospital Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany
| | - Martin J Lohse
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, D-97078, Wuerzburg, Germany.,Rudolf-Virchow-Centre, Josef-Schneider-Str. 2, 97080, Würzburg, Germany.,Institute Max Delbrück Center for Molecular Research, Berlin-Buch, Robert-Koch-Str. 40, 1000, Berlin, Germany
| | - Fritz Boege
- Rudolf-Virchow-Centre, Institute of Clinical Chemistry and Laboratory Diagnostics, University Hospital, Moorenstraße 5, 40225, Düsseldorf, Germany
| | - Roland Jahns
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, D-97078, Wuerzburg, Germany.,Interdisciplinary Bank of Biomaterials and Data (ibdw), University Hospital of Würzburg, Straubmühlweg 2A, D-97078, Würzburg, Germany.,Comprehensive Heart Failure Centre (CFHC), Am Schwarzenberg 11, 978078, Würzburg, Germany
| | - Valérie Boivin-Jahns
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, D-97078, Wuerzburg, Germany.,Comprehensive Heart Failure Centre (CFHC), Am Schwarzenberg 11, 978078, Würzburg, Germany
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9
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De Filippo E, Hinz S, Pellizzari V, Deganutti G, El-Tayeb A, Navarro G, Franco R, Moro S, Schiedel AC, Müller CE. A2A and A2B adenosine receptors: The extracellular loop 2 determines high (A2A) or low affinity (A2B) for adenosine. Biochem Pharmacol 2020; 172:113718. [DOI: 10.1016/j.bcp.2019.113718] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 11/13/2019] [Indexed: 12/21/2022]
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10
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Mishra R, Rana S. A rational search for discovering potential neutraligands of human complement fragment 5a (hC5a). Bioorg Med Chem 2019; 27:115052. [DOI: 10.1016/j.bmc.2019.115052] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 08/15/2019] [Accepted: 08/17/2019] [Indexed: 12/13/2022]
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11
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Chimeric protein probes for C5a receptors through fusion of the anaphylatoxin C5a core region with a small-molecule antagonist. Sci China Chem 2019. [DOI: 10.1007/s11426-019-9513-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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12
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Wink LH, Baker DL, Cole JA, Parrill AL. A benchmark study of loop modeling methods applied to G protein-coupled receptors. J Comput Aided Mol Des 2019; 33:573-595. [PMID: 31123958 PMCID: PMC6628340 DOI: 10.1007/s10822-019-00196-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/12/2019] [Indexed: 11/25/2022]
Abstract
G protein-coupled receptors (GPCR) are important drug discovery targets. Despite progress, many GPCR structures have not yet been solved. For these targets, comparative modeling is used in virtual ligand screening to prioritize experimental efforts. However, the structure of extracellular loop 2 (ECL2) is often poorly predicted. This is significant due to involvement of ECL2 in ligand binding for many Class A GPCR. Here we examine the performance of loop modeling protocols available in the Rosetta (cyclic coordinate descent [CCD], KIC with fragments [KICF] and next generation KIC [NGK]) and Molecular Operating Environment (MOE) software suites (de novo search). ECL2 from GPCR crystal structures served as the structure prediction targets and were divided into four sets depending on loop length. Results suggest that KICF and NGK sampled and scored more loop models with sub-angstrom and near-atomic accuracy than CCD or de novo search for loops of 24 or fewer residues. None of the methods were able to sample loop conformations with near-atomic accuracy for the longest targets ranging from 25 to 32 residues based on 1000 models generated. For these long loop targets, increased conformational sampling is necessary. The strongly conserved disulfide bond between Cys3.25 and Cys45.50 in ECL2 proved an effective filter. Setting an upper limit of 5.1 Å on the S-S distance improved the lowest RMSD model included in the top 10 scored structures in Groups 1-4 on average between 0.33 and 1.27 Å. Disulfide bond formation and geometry optimization of ECL2 provided an additional incremental benefit in structure quality.
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Affiliation(s)
- Lee H Wink
- Department of Chemistry, The University of Memphis, Memphis, TN, 38152, USA
| | - Daniel L Baker
- Department of Chemistry, The University of Memphis, Memphis, TN, 38152, USA
| | - Judith A Cole
- Department of Biological Sciences, The University of Memphis, Memphis, TN, 38152, USA
| | - Abby L Parrill
- Department of Chemistry, The University of Memphis, Memphis, TN, 38152, USA.
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13
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Song W, Yen HY, Robinson CV, Sansom MSP. State-dependent Lipid Interactions with the A2a Receptor Revealed by MD Simulations Using In Vivo-Mimetic Membranes. Structure 2019; 27:392-403.e3. [PMID: 30581046 PMCID: PMC7031699 DOI: 10.1016/j.str.2018.10.024] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 10/02/2018] [Accepted: 10/25/2018] [Indexed: 01/01/2023]
Abstract
Membranes are known to have modulatory effects on G protein-coupled receptors (GPCRs) via specific lipid interactions. However, the mechanisms of such modulations in physiological conditions and how they influence GPCR functions remain unclear. Here we report coarse-grained molecular dynamics simulations on the Adenosine A2a receptor in different conformational states embedded in an in vivo-mimetic membrane model. Nine lipid interaction sites were revealed. The strength of lipid interactions with these sites showed a degree of dependence on the conformational states of the receptor, suggesting that these lipids may regulate the conformational dynamics of the receptor. In particular, we revealed a dual role of PIP2 on A2aR activation that involves both stabilization of the characteristic outward tilt of TM6 and enhancement of A2aR-mini-Gs association. Our results demonstrated that the bound lipids allosterically regulate the functional properties of GPCRs. These protein-lipid interactions provide a springboard for design of allosteric modulators of GPCRs.
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Affiliation(s)
- Wanling Song
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Hsin-Yung Yen
- Chemical Research Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QY, UK
| | - Carol V Robinson
- Chemical Research Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QY, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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14
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Dong F, Rues RB, Kazemi S, Dötsch V, Bernhard F. Molecular Determinants for Ligand Selectivity of the Cell-Free Synthesized Human Endothelin B Receptor. J Mol Biol 2018; 430:5105-5119. [PMID: 30342934 DOI: 10.1016/j.jmb.2018.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 10/02/2018] [Accepted: 10/12/2018] [Indexed: 01/14/2023]
Abstract
Extracellular domains of G-protein-coupled receptors act as initial molecular selectivity filters for subtype specific ligands and drugs. Chimeras of the human endothelin-B receptor containing structural units from the extracellular domains of the endothelin-A receptor were analyzed after their co-translational insertion into preformed nanodiscs. A short β-strand and a linker region in the second extracellular loop as well as parts of the extracellular N-terminal domain were identified as molecular discrimination sites for the endothelin-B receptor-selective agonists IRL1620, sarafotoxin 6c, 4Ala-ET-1 and ET-3, but not for the non-selective agonist ET-1 recognized by both endothelin receptors. A proposed second disulfide bridge in the endothelin-B receptor tethering the N-terminal domain with the third extracellular loop was not essential for ET-1 recognition and binding, but increased the receptor thermostability. We further demonstrate an experimental approach with cell-free synthesized engineered agonists to analyze the differential discrimination of peptide ligand topologies by the two endothelin receptors. The study is based on the engineering and cell-free insertion of G-protein-coupled receptors into defined membranes and may become interesting also for other targets as an alternative platform to reveal molecular details of ligand selectivity and ligand binding mechanisms.
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Affiliation(s)
- Fang Dong
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University, Frankfurt am Main, Germany
| | - Ralf B Rues
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University, Frankfurt am Main, Germany
| | - Sina Kazemi
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University, Frankfurt am Main, Germany
| | - Volker Dötsch
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University, Frankfurt am Main, Germany
| | - Frank Bernhard
- Institute of Biophysical Chemistry, Centre for Biomolecular Magnetic Resonance, J.W. Goethe-University, Frankfurt am Main, Germany.
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Clement N, Renault N, Guillaume J, Cecon E, Journé A, Laurent X, Tadagaki K, Cogé F, Gohier A, Delagrange P, Chavatte P, Jockers R. Importance of the second extracellular loop for melatonin MT 1 receptor function and absence of melatonin binding in GPR50. Br J Pharmacol 2018; 175:3281-3297. [PMID: 28898928 PMCID: PMC6057912 DOI: 10.1111/bph.14029] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 08/09/2017] [Accepted: 09/03/2017] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Recent crystal structures of GPCRs have emphasized the previously unappreciated role of the second extracellular (E2) loop in ligand binding and gating and receptor activation. Here, we have assessed the role of the E2 loop in the activation of the melatonin MT1 receptor and in the inactivation of the closely related orphan receptor GPR50. EXPERIMENTAL APPROACH Chimeric MT1 -GPR50 receptors were generated and functionally analysed in terms of 2-[125 I]iodomelatonin binding, Gi /cAMP signalling and β-arrestin2 recruitment. We also used computational molecular dynamics (MD) simulations. KEY RESULTS MD simulations of 300 ns revealed (i) the tight hairpin structure of the E2 loop of the MT1 receptor (ii) the most suitable features for melatonin binding in MT1 receptors and (iii) major predicted rearrangements upon MT1 receptor activation, stabilizing interaction networks between Phe179 or Gln181 in the E2 loop and transmembrane helixes 5 and 6. Functional assays confirmed these predictions, because reciprocal replacement of MT1 and GPR50 residues/domains led to the predicted loss- and gain-of-melatonin action of MT1 receptors and GPR50 respectively. CONCLUSIONS AND IMPLICATIONS Our work demonstrated the crucial role of the E2 loop for MT1 receptor and GPR50 function by proposing a model in which the E2 loop is important in stabilizing active MT1 receptor conformations and by showing how evolutionary processes appear to have selected for modifications in the E2 loop in order to make GPR50 unresponsive to melatonin. LINKED ARTICLES This article is part of a themed section on Recent Developments in Research of Melatonin and its Potential Therapeutic Applications. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.16/issuetoc.
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Affiliation(s)
- Nathalie Clement
- Inserm, U1016, Institut CochinParisFrance
- CNRS UMR 8104ParisFrance
- Univ. Paris Descartes, Sorbonne Paris CitéParisFrance
| | - Nicolas Renault
- Univ. Lille, Inserm, CHU Lille, U995 – LIRIC – Lille Inflammation Research International CenterLilleFrance
| | - Jean‐Luc Guillaume
- Inserm, U1016, Institut CochinParisFrance
- CNRS UMR 8104ParisFrance
- Univ. Paris Descartes, Sorbonne Paris CitéParisFrance
| | - Erika Cecon
- Inserm, U1016, Institut CochinParisFrance
- CNRS UMR 8104ParisFrance
- Univ. Paris Descartes, Sorbonne Paris CitéParisFrance
| | - Anne‐Sophie Journé
- Inserm, U1016, Institut CochinParisFrance
- CNRS UMR 8104ParisFrance
- Univ. Paris Descartes, Sorbonne Paris CitéParisFrance
| | - Xavier Laurent
- Univ. Lille, Inserm, CHU Lille, U995 – LIRIC – Lille Inflammation Research International CenterLilleFrance
| | - Kenjiro Tadagaki
- Inserm, U1016, Institut CochinParisFrance
- CNRS UMR 8104ParisFrance
- Univ. Paris Descartes, Sorbonne Paris CitéParisFrance
| | - Francis Cogé
- Pôle d'Innovation Thérapeutique NeuropsychiatrieInstitut de Recherches SERVIERCroissy/SeineFrance
| | - Arnaud Gohier
- Pôle d'Innovation Thérapeutique NeuropsychiatrieInstitut de Recherches SERVIERCroissy/SeineFrance
| | - Philippe Delagrange
- Pôle d'Innovation Thérapeutique NeuropsychiatrieInstitut de Recherches SERVIERCroissy/SeineFrance
| | - Philippe Chavatte
- Univ. Lille, Inserm, CHU Lille, U995 – LIRIC – Lille Inflammation Research International CenterLilleFrance
| | - Ralf Jockers
- Inserm, U1016, Institut CochinParisFrance
- CNRS UMR 8104ParisFrance
- Univ. Paris Descartes, Sorbonne Paris CitéParisFrance
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Won J, Lee GR, Park H, Seok C. GalaxyGPCRloop: Template-Based and Ab Initio Structure Sampling of the Extracellular Loops of G-Protein-Coupled Receptors. J Chem Inf Model 2018; 58:1234-1243. [DOI: 10.1021/acs.jcim.8b00148] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jonghun Won
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Gyu Rie Lee
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Hahnbeom Park
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Chaok Seok
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
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17
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Sahoo AR, Mishra R, Rana S. The Model Structures of the Complement Component 5a Receptor (C5aR) Bound to the Native and Engineered hC5a. Sci Rep 2018; 8:2955. [PMID: 29440703 PMCID: PMC5811428 DOI: 10.1038/s41598-018-21290-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 01/31/2018] [Indexed: 12/13/2022] Open
Abstract
The interaction of hC5a with C5aR, previously hypothesized to involve a “two-site” binding, (i) recognition of the bulk of hC5a by the N-terminus (NT) of C5aR (“site1”), and (ii) recognition of C-terminus (CT) of hC5a by the extra cellular surface (ECS) of the C5aR (“site2”). However, the pharmacological landscapes of such recognition sites are yet to be illuminated at atomistic resolution. In the context, unique model complexes of C5aR, harboring pharmacophores of diverse functionality at the “site2” has recently been described. The current study provides a rational illustration of the “two-site” binding paradigm in C5aR, by recruiting the native agonist hC5a and engineered antagonist hC5a(A8). The hC5a-C5aR and hC5a(A8)-C5aR complexes studied over 250 ns of molecular dynamics (MD) each in POPC bilayer illuminate the hallmark of activation mechanism in C5aR. The intermolecular interactions in the model complexes are well supported by the molecular mechanics Poisson–Boltzmann surface area (MM-PBSA) based binding free energy calculation, strongly correlating with the reported mutational studies. Exemplified in two unique and contrasting molecular complexes, the study provides an exceptional understanding of the pharmacological divergence observed in C5aR, which will certainly be useful for search and optimization of new generation “neutraligands” targeting the hC5a-C5aR interaction.
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Affiliation(s)
- Amita Rani Sahoo
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, Odisha, 752050, India
| | - Richa Mishra
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, Odisha, 752050, India
| | - Soumendra Rana
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, Odisha, 752050, India.
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18
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Jończyk J, Malawska B, Bajda M. Hybrid approach to structure modeling of the histamine H3 receptor: Multi-level assessment as a tool for model verification. PLoS One 2017; 12:e0186108. [PMID: 28982153 PMCID: PMC5629032 DOI: 10.1371/journal.pone.0186108] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 09/25/2017] [Indexed: 12/18/2022] Open
Abstract
The crucial role of G-protein coupled receptors and the significant achievements associated with a better understanding of the spatial structure of known receptors in this family encouraged us to undertake a study on the histamine H3 receptor, whose crystal structure is still unresolved. The latest literature data and availability of different software enabled us to build homology models of higher accuracy than previously published ones. The new models are expected to be closer to crystal structures; and therefore, they are much more helpful in the design of potential ligands. In this article, we describe the generation of homology models with the use of diverse tools and a hybrid assessment. Our study incorporates a hybrid assessment connecting knowledge-based scoring algorithms with a two-step ligand-based docking procedure. Knowledge-based scoring employs probability theory for global energy minimum determination based on information about native amino acid conformation from a dataset of experimentally determined protein structures. For a two-step docking procedure two programs were applied: GOLD was used in the first step and Glide in the second. Hybrid approaches offer advantages by combining various theoretical methods in one modeling algorithm. The biggest advantage of hybrid methods is their intrinsic ability to self-update and self-refine when additional structural data are acquired. Moreover, the diversity of computational methods and structural data used in hybrid approaches for structure prediction limit inaccuracies resulting from theoretical approximations or fuzziness of experimental data. The results of docking to the new H3 receptor model allowed us to analyze ligand-receptor interactions for reference compounds.
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Affiliation(s)
- Jakub Jończyk
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Barbara Malawska
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
| | - Marek Bajda
- Department of Physicochemical Drug Analysis, Faculty of Pharmacy, Jagiellonian University Medical College, Krakow, Poland
- * E-mail:
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19
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Flavonoid allosteric modulation of mutated visual rhodopsin associated with retinitis pigmentosa. Sci Rep 2017; 7:11167. [PMID: 28894166 PMCID: PMC5593859 DOI: 10.1038/s41598-017-11391-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/22/2017] [Indexed: 11/08/2022] Open
Abstract
Dietary flavonoids exhibit many biologically-relevant functions and can potentially have beneficial effects in the treatment of pathological conditions. In spite of its well known antioxidant properties, scarce structural information is available on the interaction of flavonoids with membrane receptors. Advances in the structural biology of a specific class of membrane receptors, the G protein-coupled receptors, have significantly increased our understanding of drug action and paved the way for developing improved therapeutic approaches. We have analyzed the effect of the flavonoid quercetin on the conformation, stability and function of the G protein-coupled receptor rhodopsin, and the G90V mutant associated with the retinal degenerative disease retinitis pigmentosa. By using a combination of experimental and computational methods, we suggest that quercetin can act as an allosteric modulator of opsin regenerated with 9-cis-retinal and more importantly, that this binding has a positive effect on the stability and conformational properties of the G90V mutant associated with retinitis pigmentosa. These results open new possibilities to use quercetin and other flavonoids, in combination with specific retinoids like 9-cis-retinal, for the treatment of retinal degeneration associated with retinitis pigmentosa. Moreover, the use of flavonoids as allosteric modulators may also be applicable to other members of the G protein-coupled receptors superfamily.
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20
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Iglesias A, Cimadevila M, la Fuente RAD, Martí-Solano M, Cadavid MI, Castro M, Selent J, Loza MI, Brea J. Serotonin 2A receptor disulfide bridge integrity is crucial for ligand binding to different signalling states but not for its homodimerization. Eur J Pharmacol 2017; 815:138-146. [PMID: 28899696 DOI: 10.1016/j.ejphar.2017.09.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/28/2017] [Accepted: 09/08/2017] [Indexed: 02/06/2023]
Abstract
The serotonin 2A (5-HT2A) receptor is a G-protein coupled receptor (GPCR) with a conserved disulfide bridge formed by Cys148 (transmembrane helix 3, TM3) and Cys227 (extracellular loop 2, ECL-2). We hypothesized that disulfide bridges may determine serotonin 5-HT2A receptor functions such as receptor activation, functional selectivity and ligand recognition. We used the reducing agent dithiothreitol (DTT) to determine how the reduction of disulfide bridges affects radioligand binding, second messenger mobilization and receptor dimerization. A DTT-induced decrease in the number of binding sites (1190 ± 63.55 fmol/mg protein for control cells compared with 921.2 ± 60.84 fmol/mg protein for DTT-treated cells) as well as in the efficacy of both signalling pathways characterized was observed, although the affinity and potency were unchanged. Bioluminiscence resonance energy transfer (BRET) assays revealed the DTT treatment did not modify the homodimeric nature of serotonin 5-HT2A receptors. In molecular dynamic simulations, the ECL-2 of the receptor with a broken cysteine bond adopts a wider variety of conformations, some of which protrude deeper into the receptor orthosteric binding pocket leading to collapse of the pocket. A shrunken binding pocket would be incapable of accommodating lysergic acid diethylamide (LSD). Our findings suggest that the decrease of efficacy may be due to disruption of disulfide bridge between TM3 and ECL-2. This reveals the integrity of the ECL-2 epitope, which should be explored in the development of novel ligands acting as allosteric modulators of serotonin 5-HT2A receptors.
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Affiliation(s)
- Alba Iglesias
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - Marta Cimadevila
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - Rocío Ailim de la Fuente
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain; Molecular Pharmacology of G Protein-coupled Receptors Laboratory, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - María Martí-Solano
- GPCR Drug Discovery Group, Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM) - Department of Experimental and Health Sciences of Pompeu Fabra University (UPF), Barcelona, Spain
| | - María Isabel Cadavid
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - Marián Castro
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain; Molecular Pharmacology of G Protein-coupled Receptors Laboratory, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain
| | - Jana Selent
- GPCR Drug Discovery Group, Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM) - Department of Experimental and Health Sciences of Pompeu Fabra University (UPF), Barcelona, Spain
| | - María Isabel Loza
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain.
| | - José Brea
- BioFarma Research Group, Centro Singular de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS), Universidade de Santiago de Compostela, Avenida de Barcelona 22, 15782 Santiago de Compostela, Spain.
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21
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Rana S, Sahoo AR, Majhi BK. Structural complexes of the agonist, inverse agonist and antagonist bound C5a receptor: insights into pharmacology and signaling. MOLECULAR BIOSYSTEMS 2017; 12:1586-99. [PMID: 26978009 DOI: 10.1039/c6mb00031b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The C5a receptor (C5aR) is a pharmacologically important G-protein coupled receptor (GPCR) that interacts with (h)C5a, by recruiting both the "orthosteric" sites (site1 at the N-terminus and site2 at the ECS, extra cellular surface) on C5aR in a two site-binding model. However, the complex pharmacological landscape and the distinguishing chemistry operating either at the "orthosteric" site1 or at the functionally important "orthosteric" site2 of C5aR are still not clear, which greatly limits the understanding of C5aR pharmacology. One of the major bottlenecks is the lack of an experimental structure or a refined model structure of C5aR with appropriately defined active sites. The study attempts to understand the pharmacology at the "orthosteric" site2 of C5aR rationally by generating a highly refined full-blown model structure of C5aR through advanced molecular modeling techniques, and further subjecting it to automated docking and molecular dynamics (MD) studies in the POPC bilayer. The first series of structural complexes of C5aR respectively bound to a linear native peptide agonist ((h)C5a-CT), a small molecule inverse agonist (NDT) and a cyclic peptide antagonist (PMX53) are reported, apparently establishing the unique pharmacological landscape of the "orthosteric" site2, which also illustrates an energetically distinct but coherent competitive chemistry ("cation-π" vs. "π-π" interactions) involved in distinguishing the established ligands known for targeting the "orthosteric" site2 of C5aR. Over a total of 1 μs molecular dynamics (MD) simulation in the POPC bilayer, it is evidenced that while the agonist prefers a "cation-π" interaction, the inverse agonist prefers a "cogwheel/L-shaped" interaction in contrast to the "edge-to-face/T-shaped" type π-π interactions demonstrated by the antagonist by engaging the F275(7.28) of the C5aR. In the absence of a NMR or crystallographically guided model structure of C5aR, the computational model complexes not only provide valuable insights for understanding the C5aR pharmacology, but also emerge as a promising platform for the design and discovery of future potential drug candidates targeting the (h)C5a-C5aR signaling axes.
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Affiliation(s)
- Soumendra Rana
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology, Bhubaneswar, Odisha 751007, India.
| | - Amita Rani Sahoo
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology, Bhubaneswar, Odisha 751007, India.
| | - Bharat Kumar Majhi
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology, Bhubaneswar, Odisha 751007, India.
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22
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Woolley MJ, Conner AC. Understanding the common themes and diverse roles of the second extracellular loop (ECL2) of the GPCR super-family. Mol Cell Endocrinol 2017; 449:3-11. [PMID: 27899324 DOI: 10.1016/j.mce.2016.11.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 11/02/2016] [Accepted: 11/24/2016] [Indexed: 11/16/2022]
Abstract
The extracellular loops (ECLs) of G protein-coupled receptors (GPCRs) can bind directly to docked orthosteric or allosteric ligands, they can contain transient contact points for ligand entry into the transmembrane (TM) bundle and they can regulate the activation of the receptor signalling pathways. Of the three ECLs, ECL2 is the largest and most structurally diverse reflecting its functional importance. This has been shown through biochemical techniques and has been supported by the many subsequent crystal structures of GPCRs bound to both agonists and antagonists. ECL2 shares common structural features between (and sometimes across) receptor sub-families and can facilitate ligand entry to the TM core or act directly as a surface of the ligand-binding pocket. Structural similarities seem to underpin common binding mechanisms; however, where these exist, variations in primary sequence ensure ligand-binding specificity. This review will compare current understanding of the structural themes and main functional roles of ECL2 in ligand binding, activation and regulation of the major families of GPCRs.
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Affiliation(s)
- Michael J Woolley
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - Alex C Conner
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
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23
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Yellapu NK. Molecular Modelling, Dynamics, and Docking of Membrane Proteins. PHARMACEUTICAL SCIENCES 2017. [DOI: 10.4018/978-1-5225-1762-7.ch029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Computational tools and techniques are now most popular and promising to progress the research at rapid rate. Molecular modelling studies contribute their maximum role in wide variety of disciplines especially in proteomics and drug discovery strategies. Molecular dynamics and molecular docking algorithms are now became an essential part in daily research activities of every laboratory throughout the world. These strategies are now well established and standardised to study any specific protein of interest and drug molecule. But still there exist considerable drawbacks in a special concern with membrane proteins as the presently available tools and methods cannot be applied directly to them. Modelling, dynamics and docking studies of membrane proteins need a special care and attention as several challenges are to be crossed with an intensive care to produce a reliable result. This chapter is aimed to discuss such challenges and solutions to handle membrane proteins.
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24
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Kleist AB, Getschman AE, Ziarek JJ, Nevins AM, Gauthier PA, Chevigné A, Szpakowska M, Volkman BF. New paradigms in chemokine receptor signal transduction: Moving beyond the two-site model. Biochem Pharmacol 2016; 114:53-68. [PMID: 27106080 DOI: 10.1016/j.bcp.2016.04.007] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 04/13/2016] [Indexed: 10/21/2022]
Abstract
Chemokine receptor (CKR) signaling forms the basis of essential immune cellular functions, and dysregulated CKR signaling underpins numerous disease processes of the immune system and beyond. CKRs, which belong to the seven transmembrane domain receptor (7TMR) superfamily, initiate signaling upon binding of endogenous, secreted chemokine ligands. Chemokine-CKR interactions are traditionally described by a two-step/two-site mechanism, in which the CKR N-terminus recognizes the chemokine globular core (i.e. site 1 interaction), followed by activation when the unstructured chemokine N-terminus is inserted into the receptor TM bundle (i.e. site 2 interaction). Several recent studies challenge the structural independence of sites 1 and 2 by demonstrating physical and allosteric links between these supposedly separate sites. Others contest the functional independence of these sites, identifying nuanced roles for site 1 and other interactions in CKR activation. These developments emerge within a rapidly changing landscape in which CKR signaling is influenced by receptor PTMs, chemokine and CKR dimerization, and endogenous non-chemokine ligands. Simultaneous advances in the structural and functional characterization of 7TMR biased signaling have altered how we understand promiscuous chemokine-CKR interactions. In this review, we explore new paradigms in CKR signal transduction by considering studies that depict a more intricate architecture governing the consequences of chemokine-CKR interactions.
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Affiliation(s)
- Andrew B Kleist
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
| | - Anthony E Getschman
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
| | - Joshua J Ziarek
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115, USA.
| | - Amanda M Nevins
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
| | - Pierre-Arnaud Gauthier
- Department of Infection and Immunity, Luxembourg Institute of Health, L-4354 Esch-sur-Alzette, Luxembourg.
| | - Andy Chevigné
- Department of Infection and Immunity, Luxembourg Institute of Health, L-4354 Esch-sur-Alzette, Luxembourg.
| | - Martyna Szpakowska
- Department of Infection and Immunity, Luxembourg Institute of Health, L-4354 Esch-sur-Alzette, Luxembourg.
| | - Brian F Volkman
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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De Filippo E, Namasivayam V, Zappe L, El-Tayeb A, Schiedel AC, Müller CE. Role of extracellular cysteine residues in the adenosine A2A receptor. Purinergic Signal 2016; 12:313-29. [PMID: 26969588 DOI: 10.1007/s11302-016-9506-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 02/29/2016] [Indexed: 12/13/2022] Open
Abstract
The G protein-coupled A2A adenosine receptor represents an important drug target. Crystal structures and modeling studies indicated that three disulfide bonds are formed between ECL1 and ECL2 (I, Cys71(2.69)-Cys159(45.43); II, Cys74(3.22)-Cys146(45.30), and III, Cys77(3.25)-Cys166(45.50)). However, the A2BAR subtype appears to require only disulfide bond III for proper function. In this study, each of the three disulfide bonds in the A2AAR was disrupted by mutation of one of the cysteine residues to serine. The mutant receptors were stably expressed in Chinese hamster ovary cells and analyzed in cyclic adenosine monophosphate (cAMP) accumulation and radioligand binding studies using structurally diverse agonists: adenosine, NECA, CGS21680, and PSB-15826. Results were rationalized by molecular modeling. The observed effects were dependent on the investigated agonist. Loss of disulfide bond I led to a widening of the orthosteric binding pocket resulting in a strong reduction in the potency of adenosine, but not of NECA or 2-substituted nucleosides. Disruption of disulfide bond II led to a significant reduction in the agonists' efficacy indicating its importance for receptor activation. Disulfide bond III disruption reduced potency and affinity of the small adenosine agonists and NECA, but not of the larger 2-substituted agonists. While all the three disulfide bonds were essential for high potency or efficacy of adenosine, structural modification of the nucleoside could rescue affinity or efficacy at the mutant receptors. At present, it cannot be excluded that formation of the extracellular disulfide bonds in the A2AAR is dynamic. This might add another level of G protein-coupled receptor (GPCR) modulation, in particular for the cysteine-rich A2A and A2BARs.
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Affiliation(s)
- Elisabetta De Filippo
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Vigneshwaran Namasivayam
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Lukas Zappe
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Ali El-Tayeb
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Anke C Schiedel
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany
| | - Christa E Müller
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany.
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Sandal M, Behrens M, Brockhoff A, Musiani F, Giorgetti A, Carloni P, Meyerhof W. Evidence for a Transient Additional Ligand Binding Site in the TAS2R46 Bitter Taste Receptor. J Chem Theory Comput 2015; 11:4439-49. [PMID: 26575934 DOI: 10.1021/acs.jctc.5b00472] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Most human G protein coupled receptors (GPCRs) are activated by small molecules binding to their 7-transmembrane (7-TM) helix bundle. They belong to basally diverging branches: the 25 bitter taste 2 receptors and most members of the very large rhodopsin-like/class A GPCRs subfamily. Some members of the class A branch have been suggested to feature not only an orthosteric agonist-binding site but also a more extracellular or "vestibular" site, involved in the binding process. Here we use a hybrid molecular mechanics/coarse-grained (MM/CG) molecular dynamics approach on a widely studied bitter taste receptor (TAS2R46) receptor in complex with its agonist strychnine. Three ∼1 μs molecular simulation trajectories find two sites hosting the agonist, which together elucidate experimental data measured previously and in this work. This mechanism shares similarities with the one suggested for the evolutionarily distant class A GPCRs. It might be instrumental for the remarkably broad but specific spectrum of agonists of these chemosensory receptors.
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Affiliation(s)
- Massimo Sandal
- Computational Biophysics, German Research School for Simulation Sciences , 52425 Jülich, Germany
| | - Maik Behrens
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) , Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
| | - Anne Brockhoff
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) , Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
| | - Francesco Musiani
- Scuola Internazionale Superiore di Studi Avanzati (SISSA/ISAS) , Via Bonomea 265, 34151 Trieste, Italy.,Laboratory of Bioinorganic Chemistry, Department of Pharmacy and Biotechnology (FaBIT), University of Bologna , Viale Giuseppe Fanin 40, I-40127, Bologna, Italy
| | - Alejandro Giorgetti
- Computational Biophysics, German Research School for Simulation Sciences , 52425 Jülich, Germany.,Department of Biotechnology, University of Verona , Ca' Vignal 1, Strada Le Grazie 15, 37134 Verona, Italy
| | - Paolo Carloni
- Computational Biophysics, German Research School for Simulation Sciences , 52425 Jülich, Germany
| | - Wolfgang Meyerhof
- Department of Molecular Genetics, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) , Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
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Abrogation of immune complex glomerulonephritis by native carboxypeptidase and pharmacological antagonism of the C5a receptor. Cell Mol Immunol 2015; 13:651-7. [PMID: 26166765 PMCID: PMC5037280 DOI: 10.1038/cmi.2015.45] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 04/27/2015] [Accepted: 04/27/2015] [Indexed: 12/11/2022] Open
Abstract
Activation of complement generates C5a which leads to signaling through C5aR1. This is tightly controlled, including by the plasma proteins factor H (FH) and carboxypeptidase N. Here we studied a chronic serum sickness (CSS) model of glomerulonephritis (GN) in which there is an active humoral immune response, formation of glomerular immune complexes (ICs), and resulting glomerular inflammation. The antibody response, glomerular IC deposition, the degree of GN, and consequent renal functional insufficiency in CSS were all worse in FH−/− mice compared to wild-type FH+/+ animals. This was ameliorated in the former by giving a C5aR1 antagonist for the final 3 weeks of the 5-week protocol. In contrast, blocking CP-mediated inactivation of C5a increased these disease measures. Thus, complement regulation by both plasma FH and CP to limit the quantity of active C5a is important in conditions where the humoral immune response is directed to a continuously present foreign antigen. Signaling through C5aR1 enhances the humoral immune response as well as the inflammatory response to ICs that have formed in glomeruli. Both effects are relevant even after disease has begun. Thus, pharmacological targeting of C5a in IC-mediated GN has potential clinical relevance.
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Nakamura Y, Ishii J, Kondo A. Applications of yeast-based signaling sensor for characterization of antagonist and analysis of site-directed mutants of the human serotonin 1A receptor. Biotechnol Bioeng 2015; 112:1906-15. [DOI: 10.1002/bit.25597] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 02/26/2015] [Accepted: 03/03/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Yasuyuki Nakamura
- Department of Chemical Science and Engineering, Graduate School of Engineering; Kobe University; 1-1 Rokkodai, Nada Kobe 657-8501 Japan
| | - Jun Ishii
- Organization of Advanced Science and Technology; Kobe University; Kobe Japan
| | - Akihiko Kondo
- Department of Chemical Science and Engineering, Graduate School of Engineering; Kobe University; 1-1 Rokkodai, Nada Kobe 657-8501 Japan
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Merle NS, Church SE, Fremeaux-Bacchi V, Roumenina LT. Complement System Part I - Molecular Mechanisms of Activation and Regulation. Front Immunol 2015; 6:262. [PMID: 26082779 PMCID: PMC4451739 DOI: 10.3389/fimmu.2015.00262] [Citation(s) in RCA: 984] [Impact Index Per Article: 109.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/11/2015] [Indexed: 12/12/2022] Open
Abstract
Complement is a complex innate immune surveillance system, playing a key role in defense against pathogens and in host homeostasis. The complement system is initiated by conformational changes in recognition molecular complexes upon sensing danger signals. The subsequent cascade of enzymatic reactions is tightly regulated to assure that complement is activated only at specific locations requiring defense against pathogens, thus avoiding host tissue damage. Here, we discuss the recent advances describing the molecular and structural basis of activation and regulation of the complement pathways and their implication on physiology and pathology. This article will review the mechanisms of activation of alternative, classical, and lectin pathways, the formation of C3 and C5 convertases, the action of anaphylatoxins, and the membrane-attack-complex. We will also discuss the importance of structure-function relationships using the example of atypical hemolytic uremic syndrome. Lastly, we will discuss the development and benefits of therapies using complement inhibitors.
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Affiliation(s)
- Nicolas S Merle
- UMR_S 1138, Cordeliers Research Center, Complement and Diseases Team, INSERM , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France
| | - Sarah Elizabeth Church
- UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France ; UMR_S 1138, Cordeliers Research Center, Integrative Cancer Immunology Team, INSERM , Paris , France
| | - Veronique Fremeaux-Bacchi
- UMR_S 1138, Cordeliers Research Center, Complement and Diseases Team, INSERM , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France ; Service d'Immunologie Biologique, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges-Pompidou , Paris , France
| | - Lubka T Roumenina
- UMR_S 1138, Cordeliers Research Center, Complement and Diseases Team, INSERM , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France
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Stockert JA, Devi LA. Advancements in therapeutically targeting orphan GPCRs. Front Pharmacol 2015; 6:100. [PMID: 26005419 PMCID: PMC4424851 DOI: 10.3389/fphar.2015.00100] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 04/21/2015] [Indexed: 11/23/2022] Open
Abstract
G-protein coupled receptors (GPCRs) are popular biological targets for drug discovery and development. To date there are more than 140 orphan GPCRs, i.e., receptors whose endogenous ligands are unknown. Traditionally orphan GPCRs have been difficult to study and the development of therapeutic compounds targeting these receptors has been extremely slow although these GPCRs are considered important targets based on their distribution and behavioral phenotype as revealed by animals lacking the receptor. Recent advances in several methods used to study orphan receptors, including protein crystallography and homology modeling are likely to be useful in the identification of therapeutics targeting these receptors. In the past 13 years, over a dozen different Class A GPCRs have been crystallized; this trend is exciting, since homology modeling of GPCRs has previously been limited by the availability of solved structures. As the number of solved GPCR structures continues to grow so does the number of templates that can be used to generate increasingly accurate models of phylogenetically related orphan GPCRs. The availability of solved structures along with the advances in using multiple templates to build models (in combination with molecular dynamics simulations that reveal structural information not provided by crystallographic data and methods for modeling hard-to-predict flexible loop regions) have improved the quality of GPCR homology models. This, in turn, has improved the success rates of virtual ligand screens that use homology models to identify potential receptor binding compounds. Experimental testing of the predicted hits and validation using traditional GPCR pharmacological approaches can be used to drive ligand-based efforts to probe orphan receptor biology as well as to define the chemotypes and chemical scaffolds important for binding. As a result of these advances, orphan GPCRs are emerging from relative obscurity as a new class of drug targets.
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Affiliation(s)
- Jennifer A Stockert
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY USA
| | - Lakshmi A Devi
- Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY USA
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Rana S, Sahoo AR. Model structures of inactive and peptide agonist bound C5aR: Insights into agonist binding, selectivity and activation. Biochem Biophys Rep 2015; 1:85-96. [PMID: 29124137 PMCID: PMC5668562 DOI: 10.1016/j.bbrep.2015.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 03/10/2015] [Accepted: 03/11/2015] [Indexed: 11/30/2022] Open
Abstract
C5a receptor (C5aR) is one of the major chemoattractant receptors of the druggable proteome that binds C5a, the proinflammatory polypeptide of complement cascade, triggering inflammation and SEPSIS. Here, we report the model structures of C5aR in both inactive and peptide agonist (YSFKPMPLaR; a=D-Ala) bound meta-active state. Assembled in CYANA and evolved over molecular dynamics (MD) in POPC bilayer, the inactive C5aR demonstrates a topologically unique compact heptahelical bundle topology harboring a β-hairpin in extracellular loop 2 (ECL2), derived from the atomistic folding simulations. The peptide agonist bound meta-active C5aR deciphers the “site2” at an atomistic resolution in the extracellular surface (ECS), in contrast to the previously hypothesized inter-helical crevice. With estimated Ki≈2.75 μM, the meta-active C5aR excellently rationalizes the IC50 (0.1–13 μM) and EC50 (0.01–6 μM) values, displayed by the peptide agonist in several signaling studies. Moreover, with Ki≈5.3×105 μM, the “site2” also illustrates selectivity, by discriminating the stereochemical mutant peptide (YSFkPMPLaR; k=D-Lys), known to be inert toward C5aR, up to 1 mM concentration. Topologically juxtaposed between the structures of rhodopsin and CXCR1, the C5aR models also display excellent structural correlations with the other G-protein coupled receptors (GPCRs). The models elaborated in the current study unravel many important structural insights previously not known for regulating the agonist binding and activation mechanism of C5aR. Topologically unique inactive and meta-active atomistic models of C5aR. Model demonstrates excellent structural correlation with the other reported GPCRs. Model deciphers the “site2” in the ECS and also demonstrates agonist selectivity. Agonist binding and activation requires “cation–π” interaction with F275 of C5aR. Inactive to meta-active transition involves TM3–TM6 movements (ΔΘ≈+11.1°) in C5aR.
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Affiliation(s)
- Soumendra Rana
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Odisha 751007, India
| | - Amita Rani Sahoo
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Odisha 751007, India
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Plazinska A, Plazinski W, Jozwiak K. Agonist binding by the β2-adrenergic receptor: an effect of receptor conformation on ligand association-dissociation characteristics. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:149-63. [PMID: 25726162 PMCID: PMC4359354 DOI: 10.1007/s00249-015-1010-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 11/20/2014] [Accepted: 01/31/2015] [Indexed: 01/01/2023]
Abstract
The β2-adrenergic receptor (β2-AR), a G protein-coupled receptor (GPCR), is a physiologically important transmembrane protein that is a target for drugs used for treatment of asthma and cardiovascular diseases. Study of the first steps of ligand recognition and the molecular basis of ligand binding to the orthosteric site is essential for understanding the pharmacological properties of the receptor. In this work we investigated the characteristic features of the agonist association–dissociation process to and from the different conformational forms of β2-AR by use of advanced molecular modeling techniques. The investigation was focused on estimating the free energy profiles (FEPs) corresponding to the process of a full agonist ((R,R)-fenoterol) and an inverse agonist (carazolol) binding and unbinding to and from β2-AR. The two different conformational forms of β2-AR, i.e. active β2-AR–PDB: 3P0G and inactive β2-AR–PDB: 2RH1 were included in this stage of the study. We revealed several significant qualitative differences between FEPs characteristic of both conformational forms. Both FEPs suggest the existence of three transient binding sites in the extracellular domain of β2-AR. Comparison of the residues surrounding these transient binding sites in both β2-AR states revealed the importance of the aromatic residues F194, H932.64, H2966.58, and H178 (extracellular part of β2-AR) in the early stages of the binding process. In addition, slightly different exit and entry paths are preferred by the ligand molecule in the extracellular part of β2-AR, depending on the conformation of the receptor.
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Affiliation(s)
- Anita Plazinska
- Laboratory of Medicinal Chemistry and Neuroengineering, Department of Chemistry, Faculty of Pharmacy, Medical University of Lublin, W. Chodzki Str., 4a, 20-093, Lublin, Poland
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Wifling D, Bernhardt G, Dove S, Buschauer A. The extracellular loop 2 (ECL2) of the human histamine H4 receptor substantially contributes to ligand binding and constitutive activity. PLoS One 2015; 10:e0117185. [PMID: 25629160 PMCID: PMC4309601 DOI: 10.1371/journal.pone.0117185] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/21/2014] [Indexed: 11/25/2022] Open
Abstract
In contrast to the corresponding mouse and rat orthologs, the human histamine H4 receptor (hH4R) shows extraordinarily high constitutive activity. In the extracellular loop (ECL), replacement of F169 by V as in the mouse H4R significantly reduced constitutive activity. Stabilization of the inactive state was even more pronounced for a double mutant, in which, in addition to F169V, S179 in the ligand binding site was replaced by M. To study the role of the FF motif in ECL2, we generated the hH4R-F168A mutant. The receptor was co-expressed in Sf9 insect cells with the G-protein subunits Gαi2 and Gβ1γ2, and the membranes were studied in [3H]histamine binding and functional [35S]GTPγS assays. The potency of various ligands at the hH4R-F168A mutant decreased compared to the wild-type hH4R, for example by 30- and more than 100-fold in case of the H4R agonist UR-PI376 and histamine, respectively. The high constitutive activity of the hH4R was completely lost in the hH4R-F168A mutant, as reflected by neutral antagonism of thioperamide, a full inverse agonist at the wild-type hH4R. By analogy, JNJ7777120 was a partial inverse agonist at the hH4R, but a partial agonist at the hH4R-F168A mutant, again demonstrating the decrease in constitutive activity due to F168A mutation. Thus, F168 was proven to play a key role not only in ligand binding and potency, but also in the high constitutive activity of the hH4R.
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Affiliation(s)
- David Wifling
- Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry II, University of Regensburg, Regensburg, Germany
| | - Günther Bernhardt
- Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry II, University of Regensburg, Regensburg, Germany
| | - Stefan Dove
- Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry II, University of Regensburg, Regensburg, Germany
| | - Armin Buschauer
- Institute of Pharmacy, Pharmaceutical/Medicinal Chemistry II, University of Regensburg, Regensburg, Germany
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Kmiecik S, Jamroz M, Kolinski M. Structure prediction of the second extracellular loop in G-protein-coupled receptors. Biophys J 2015; 106:2408-16. [PMID: 24896119 PMCID: PMC4052351 DOI: 10.1016/j.bpj.2014.04.022] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 03/26/2014] [Accepted: 04/17/2014] [Indexed: 12/29/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) play key roles in living organisms. Therefore, it is important to determine their functional structures. The second extracellular loop (ECL2) is a functionally important region of GPCRs, which poses significant challenge for computational structure prediction methods. In this work, we evaluated CABS, a well-established protein modeling tool for predicting ECL2 structure in 13 GPCRs. The ECL2s (with between 13 and 34 residues) are predicted in an environment of other extracellular loops being fully flexible and the transmembrane domain fixed in its x-ray conformation. The modeling procedure used theoretical predictions of ECL2 secondary structure and experimental constraints on disulfide bridges. Our approach yielded ensembles of low-energy conformers and the most populated conformers that contained models close to the available x-ray structures. The level of similarity between the predicted models and x-ray structures is comparable to that of other state-of-the-art computational methods. Our results extend other studies by including newly crystallized GPCRs.
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Affiliation(s)
- Sebastian Kmiecik
- University of Warsaw, Faculty of Chemistry, Laboratory of Theory of Biopolymers, Pasteura 1, 02-093 Warsaw, Poland
| | - Michal Jamroz
- University of Warsaw, Faculty of Chemistry, Laboratory of Theory of Biopolymers, Pasteura 1, 02-093 Warsaw, Poland
| | - Michal Kolinski
- Mossakowski Medical Research Center, Polish Academy of Sciences, Bioinformatics Laboratory, Pawinskiego 5, 02-106 Warsaw, Poland.
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Diepenhorst NA, Petrie EJ, Chen CZ, Wang A, Hossain MA, Bathgate RAD, Gooley PR. Investigation of interactions at the extracellular loops of the relaxin family peptide receptor 1 (RXFP1). J Biol Chem 2014; 289:34938-52. [PMID: 25352603 DOI: 10.1074/jbc.m114.600882] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Relaxin, an emerging pharmaceutical treatment for acute heart failure, activates the relaxin family peptide receptor (RXFP1), which is a class A G-protein-coupled receptor. In addition to the classic transmembrane (TM) domain, RXFP1 possesses a large extracellular domain consisting of 10 leucine-rich repeats and an N-terminal low density lipoprotein class A (LDLa) module. Relaxin-mediated activation of RXFP1 requires multiple coordinated interactions between the ligand and various receptor domains including a high affinity interaction involving the leucine-rich repeats and a predicted lower affinity interaction involving the extracellular loops (ELs). The LDLa is essential for signal activation; therefore the ELs/TM may additionally present an interaction site to facilitate this LDLa-mediated signaling. To overcome the many challenges of investigating relaxin and the LDLa module interactions with the ELs, we engineered the EL1 and EL2 loops onto a soluble protein scaffold, mapping specific ligand and loop interactions using nuclear magnetic resonance spectroscopy. Key EL residues were subsequently mutated in RXFP1, and changes in function and relaxin binding were assessed alongside the RXFP1 agonist ML290 to monitor the functional integrity of the TM domain of these mutant receptors. The outcomes of this work make an important contribution to understanding the mechanism of RXFP1 activation and will aid future development of small molecule RXFP1 agonists/antagonists.
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Affiliation(s)
- Natalie A Diepenhorst
- From the Florey Institute of Neuroscience and Mental Health, the Department of Biochemistry and Molecular Biology, and
| | - Emma J Petrie
- the Department of Biochemistry and Molecular Biology, and
| | - Catherine Z Chen
- the National Center for Advancing Translational Sciences, Division of Preclinical Innovation, National Institutes of Health, Rockville, Maryland 20850
| | - Amy Wang
- the National Center for Advancing Translational Sciences, Division of Preclinical Innovation, National Institutes of Health, Rockville, Maryland 20850
| | - Mohammed Akhter Hossain
- From the Florey Institute of Neuroscience and Mental Health, the School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia and
| | - Ross A D Bathgate
- From the Florey Institute of Neuroscience and Mental Health, the Department of Biochemistry and Molecular Biology, and
| | - Paul R Gooley
- the Department of Biochemistry and Molecular Biology, and
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Ragnarsson L, Andersson Å, Thomas WG, Lewis RJ. Extracellular Surface Residues of the α1B-Adrenoceptor Critical for G Protein–Coupled Receptor Function. Mol Pharmacol 2014; 87:121-9. [DOI: 10.1124/mol.114.094557] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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37
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Hutchings CJ, Cseke G, Osborne G, Woolard J, Zhukov A, Koglin M, Jazayeri A, Pandya-Pathak J, Langmead CJ, Hill SJ, Weir M, Marshall FH. Monoclonal anti-β1-adrenergic receptor antibodies activate G protein signaling in the absence of β-arrestin recruitment. MAbs 2014; 6:246-61. [PMID: 24253107 DOI: 10.4161/mabs.27226] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Thermostabilized G protein-coupled receptors used as antigens for in vivo immunization have resulted in the generation of functional agonistic anti-β1-adrenergic (β1AR) receptor monoclonal antibodies (mAbs). The focus of this study was to examine the pharmacology of these antibodies to evaluate their mechanistic activity at β1AR. Immunization with the β1AR stabilized receptor yielded five stable hybridoma clones, four of which expressed functional IgG, as determined in cell-based assays used to evaluate cAMP stimulation. The antibodies bind diverse epitopes associated with low nanomolar agonist activity at β1AR, and they appeared to show some degree of biased signaling as they were inactive in an assay measuring signaling through β-arrestin. In vitro characterization also verified different antibody receptor interactions reflecting the different epitopes on the extracellular surface of β1AR to which the mAbs bind. The anti-β1AR mAbs only demonstrated agonist activity when in dimeric antibody format, but not as the monomeric Fab format, suggesting that agonist activation may be mediated through promoting receptor dimerization. Finally, we have also shown that at least one of these antibodies exhibits in vivo functional activity at a therapeutically-relevant dose producing an increase in heart rate consistent with β1AR agonism.
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38
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Jiang X, Dias JA, He X. Structural biology of glycoprotein hormones and their receptors: insights to signaling. Mol Cell Endocrinol 2014; 382:424-451. [PMID: 24001578 DOI: 10.1016/j.mce.2013.08.021] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 08/20/2013] [Accepted: 08/24/2013] [Indexed: 01/18/2023]
Abstract
This article reviews the progress made in the field of glycoprotein hormones (GPH) and their receptors (GPHR) by several groups of structural biologists including ourselves aiming to gain insight into GPH signaling mechanisms. The GPH family consists of four members, with follicle-stimulating hormone (FSH) being the prototypic member. GPH members belong to the cystine-knot growth factor superfamily, and their receptors (GPHR), possessing unusually large N-terminal ectodomains, belong to the G-protein coupled receptor Family A. GPHR ectodomains can be divided into two subdomains: a high-affinity hormone binding subdomain primarily centered on the N-terminus, and a second subdomain that is located on the C-terminal region of the ectodomain that is involved in signal specificity. The two subdomains unexpectedly form an integral structure comprised of leucine-rich repeats (LRRs). Following the structure determination of hCG in 1994, the field of FSH structural biology has progressively advanced. Initially, the FSH structure was determined in partially glycosylated free form in 2001, followed by a structure of FSH bound to a truncated FSHR ectodomain in 2005, and the structure of FSH bound to the entire ectodomain in 2012. Comparisons of the structures in three forms led a proposal of a two-step monomeric receptor activation mechanism. First, binding of FSH to the FSHR high-affinity hormone-binding subdomain induces a conformational change in the hormone to form a binding pocket that is specific for a sulfated-tyrosine found as sTyr 335 in FSHR. Subsequently, the sTyr is drawn into the newly formed binding pocket, producing a lever effect on a helical pivot whereby the docking sTyr provides as the 'pull & lift' force. The pivot helix is flanked by rigid LRRs and locked by two disulfide bonds on both sides: the hormone-binding subdomain on one side and the last short loop before the first transmembrane helix on the other side. The lift of the sTyr loop frees the tethered extracellular loops of the 7TM domain, thereby releasing a putative inhibitory influence of the ectodomain, ultimately leading to the activating conformation of the 7TM domain. Moreover, the data lead us to propose that FSHR exists as a trimer and to present an FSHR activation mechanism consistent with the observed trimeric crystal form. A trimeric receptor provides resolution of the enigmatic, but important, biological roles played by GPH residues that are removed from the primary FSH-binding site, as well as several important GPCR phenomena, including negative cooperativity and asymmetric activation. Further reflection pursuant to this review process revealed additional novel structural characteristics such as the identification of a 'seat' sequence in GPH. Together with the 'seatbelt', the 'seat' enables a common heteodimeric mode of association of the common α subunit non-covalently and non-specifically with each of the three different β subunits. Moreover, it was possible to establish a dimensional order that can be used to estimate LRR curvatures. A potential binding pocket for small molecular allosteric modulators in the FSHR 7TM domain has also been identified.
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Affiliation(s)
- Xuliang Jiang
- EMD Serono Research & Development Institute, Billerica, MA 01821, United States.
| | - James A Dias
- Department of Biomedical Sciences, School of Public Health, University at Albany-SUNY, Albany, NY 12222, United States
| | - Xiaolin He
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States
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Khoury E, Clément S, Laporte SA. Allosteric and biased g protein-coupled receptor signaling regulation: potentials for new therapeutics. Front Endocrinol (Lausanne) 2014; 5:68. [PMID: 24847311 PMCID: PMC4021147 DOI: 10.3389/fendo.2014.00068] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 04/22/2014] [Indexed: 01/14/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are seven-transmembrane proteins that participate in many aspects of the endocrine function and are important targets for drug development. They transduce signals mainly, but not exclusively, via hetero-trimeric G proteins, leading to a diversity of intracellular signaling cascades. Ligands binding at the hormone orthosteric sites of receptors have been classified as agonists, antagonists, and/or inverse agonists based on their ability to mainly modulate G protein signaling. Accumulating evidence also indicates that such ligands, alone or in combination with other ones such as those acting outside the orthosteric hormone binding sites (e.g., allosteric modulators), have the ability to selectively engage subsets of signaling responses as compared to the natural endogenous ligands. Such modes of functioning have been variously referred to as "functional selectivity" or "ligand-biased signaling." In this review, we provide an overview of the current knowledge regarding GPCR-biased signaling and their functional regulation with a focus on the evolving concept that receptor domains can also be targeted to allosterically bias signaling, and discuss the usefulness of such modes of regulation for the design of more efficient therapeutics.
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Affiliation(s)
- Etienne Khoury
- Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal, QC, Canada
| | - Stéphanie Clément
- Department of Pharmacology and Therapeutics, McGill University Health Center Research Institute, McGill University, Montreal, QC, Canada
| | - Stéphane A. Laporte
- Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal, QC, Canada
- Department of Pharmacology and Therapeutics, McGill University Health Center Research Institute, McGill University, Montreal, QC, Canada
- Department of Anatomy and Cell Biology, McGill University Health Center Research Institute, McGill University, Montreal, QC, Canada
- *Correspondence: Stéphane A. Laporte, Department of Medicine, Polypeptide Lab, McGill University, Strathcona Anatomy and Dentistry Building, 3640 University Street, Room W315, Montreal, QC H3A 2B2, Canada e-mail:
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Soriano-Ursúa MA, Trujillo-Ferrara JG, Correa-Basurto J, Vilar S. Recent structural advances of β1 and β2 adrenoceptors yield keys for ligand recognition and drug design. J Med Chem 2013; 56:8207-23. [PMID: 23862978 DOI: 10.1021/jm400471z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Because they represent attractive drug targets, adrenoceptors have been widely studied. Recent progress in structural data of β-adrenoceptors allows us to understand and predict key interactions in ligand recognition and receptor activation. Nevertheless, an important aspect of this process has only begun to be explored: the stabilization of a conformational state of these receptors upon contact with a ligand and the capacity of a ligand to influence receptor conformation through allosteric modulation, biased signaling, and selectivity. The aim of the present Perspective is to identify the well-defined orthosteric binding site and possible allosteric sites and to analyze the importance of the ligand-receptor interaction in the stabilization of certain receptor conformations. For this purpose, we have reviewed recent advances made through the use of X-ray data from ligand-β-adrenoceptor (including ADRB1 and ADRB2) crystal structures. Most importantly, implications in the medicinal chemistry field are explored in relation to drug design.
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Affiliation(s)
- Marvin A Soriano-Ursúa
- Departments of Biochemistry and Physiology, Laboratory of Molecular Modeling and Bioinformatics, Postgraduate Research Section, Escuela Superior de Medicina, Instituto Politécnico Nacional , Plan de San Luis y Dı́az Mirón s/n, Mexico City, 11340, Mexico
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Zhang X, Tan F, Skidgel RA. Carboxypeptidase M is a positive allosteric modulator of the kinin B1 receptor. J Biol Chem 2013; 288:33226-40. [PMID: 24108126 DOI: 10.1074/jbc.m113.520791] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ligand binding to extracellular domains of G protein-coupled receptors can result in novel and nuanced allosteric effects on receptor signaling. We previously showed that the protein-protein interaction of carboxypeptidase M (CPM) and kinin B1 receptor (B1R) enhances B1R signaling in two ways; 1) kinin binding to CPM causes a conformational activation of the B1R, and 2) CPM-generated des-Arg-kinin agonist is efficiently delivered to the B1R. Here, we show CPM is also a positive allosteric modulator of B1R signaling to its agonist, des-Arg(10)-kallidin (DAKD). In HEK cells stably transfected with B1R, co-expression of CPM enhanced DAKD-stimulated increases in intracellular Ca(2+) or phosphoinositide turnover by a leftward shift of the dose-response curve without changing the maximum. CPM increased B1R affinity for DAKD by ∼5-fold but had no effect on basal B1R-dependent phosphoinositide turnover. Soluble, recombinant CPM bound to HEK cells expressing B1Rs without stimulating receptor signaling. CPM positive allosteric action was independent of enzyme activity but depended on interaction of its C-terminal domain with the B1R extracellular loop 2. Disruption of the CPM/B1R interaction or knockdown of CPM in cytokine-treated primary human endothelial cells inhibited the allosteric enhancement of CPM on B1R DAKD binding or ERK1/2 activation. CPM also enhanced the DAKD-induced B1R conformational change as detected by increased intramolecular fluorescence or bioluminescence resonance energy transfer. Thus, CPM binding to extracellular loop 2 of the B1R results in positive allosteric modulation of B1R signaling, and disruption of this interaction could provide a novel therapeutic approach to reduce pathological B1R signaling.
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The complexity of G-protein coupled receptor-ligand interactions. Sci China Chem 2013. [DOI: 10.1007/s11426-013-4911-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Nguyen ED, Norn C, Frimurer TM, Meiler J. Assessment and challenges of ligand docking into comparative models of G-protein coupled receptors. PLoS One 2013; 8:e67302. [PMID: 23844000 PMCID: PMC3699586 DOI: 10.1371/journal.pone.0067302] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Accepted: 05/16/2013] [Indexed: 01/09/2023] Open
Abstract
The rapidly increasing number of high-resolution X-ray structures of G-protein coupled receptors (GPCRs) creates a unique opportunity to employ comparative modeling and docking to provide valuable insight into the function and ligand binding determinants of novel receptors, to assist in virtual screening and to design and optimize drug candidates. However, low sequence identity between receptors, conformational flexibility, and chemical diversity of ligands present an enormous challenge to molecular modeling approaches. It is our hypothesis that rapid Monte-Carlo sampling of protein backbone and side-chain conformational space with Rosetta can be leveraged to meet this challenge. This study performs unbiased comparative modeling and docking methodologies using 14 distinct high-resolution GPCRs and proposes knowledge-based filtering methods for improvement of sampling performance and identification of correct ligand-receptor interactions. On average, top ranked receptor models built on template structures over 50% sequence identity are within 2.9 Å of the experimental structure, with an average root mean square deviation (RMSD) of 2.2 Å for the transmembrane region and 5 Å for the second extracellular loop. Furthermore, these models are consistently correlated with low Rosetta energy score. To predict their binding modes, ligand conformers of the 14 ligands co-crystalized with the GPCRs were docked against the top ranked comparative models. In contrast to the comparative models themselves, however, it remains difficult to unambiguously identify correct binding modes by score alone. On average, sampling performance was improved by 103 fold over random using knowledge-based and energy-based filters. In assessing the applicability of experimental constraints, we found that sampling performance is increased by one order of magnitude for every 10 residues known to contact the ligand. Additionally, in the case of DOR, knowledge of a single specific ligand-protein contact improved sampling efficiency 7 fold. These findings offer specific guidelines which may lead to increased success in determining receptor-ligand complexes.
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Affiliation(s)
- Elizabeth Dong Nguyen
- Center for Structural Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Christoffer Norn
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Thomas M. Frimurer
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
- Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt Program in Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Chemistry and the Institute for Chemical Biology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- * E-mail:
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Nichols AS, Floyd DH, Bruinsma SP, Narzinski K, Baranski TJ. Frizzled receptors signal through G proteins. Cell Signal 2013; 25:1468-75. [PMID: 23524329 PMCID: PMC3640709 DOI: 10.1016/j.cellsig.2013.03.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Revised: 02/23/2013] [Accepted: 03/06/2013] [Indexed: 10/27/2022]
Abstract
Frizzled receptors have long been thought to couple to G proteins but biochemical evidence supporting such an interaction has been lacking. Here we expressed mammalian Wnt-Frizzled fusion proteins in Saccharomyces cerevisiae and tested the receptors' ability to activate the yeast mitogen-activated protein kinase (MAPK) pathway via heterotrimeric G proteins. Our results show that Frizzled receptors can interact with Gαi, Gαq, and Gαs proteins, thus confirming that Frizzled functions as a G protein coupled receptor (GPCR). However, the activity level of Frizzled-mediated G protein signaling was much lower than that of a typical GPCR and, surprisingly, was highest when coupled to Gαs. The Frizzled/Gαs interaction was further established in vivo as Drosophila expressing a loss-of-function Gαs allele rescued the photoreceptor differentiation phenotype of Frizzled mutant flies. Together, these data point to an important role for Frizzled as a nontraditional GPCR that preferentially couples to Gαs heterotrimeric G proteins.
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Affiliation(s)
- Andrea S. Nichols
- Department of Medicine, Washington University School of Medicine, 660 South Euclid Ave., St. Louis, MO 63110, USA
| | - Desiree H. Floyd
- Department of Medicine, Washington University School of Medicine, 660 South Euclid Ave., St. Louis, MO 63110, USA
| | - Stephen P. Bruinsma
- Department of Medicine, Washington University School of Medicine, 660 South Euclid Ave., St. Louis, MO 63110, USA
| | - Kirk Narzinski
- Department of Medicine, Washington University School of Medicine, 660 South Euclid Ave., St. Louis, MO 63110, USA
| | - Thomas J. Baranski
- Department of Medicine, Washington University School of Medicine, 660 South Euclid Ave., St. Louis, MO 63110, USA
- Department of Developmental Biology, Washington University School of Medicine, 660 South Euclid Ave., St. Louis, MO 63110, USA
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Klos A, Wende E, Wareham KJ, Monk PN. International Union of Basic and Clinical Pharmacology. [corrected]. LXXXVII. Complement peptide C5a, C4a, and C3a receptors. Pharmacol Rev 2013; 65:500-43. [PMID: 23383423 DOI: 10.1124/pr.111.005223] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The activation of the complement cascade, a cornerstone of the innate immune response, produces a number of small (74-77 amino acid) fragments, originally termed anaphylatoxins, that are potent chemoattractants and secretagogues that act on a wide variety of cell types. These fragments, C5a, C4a, and C3a, participate at all levels of the immune response and are also involved in other processes such as neural development and organ regeneration. Their primary function, however, is in inflammation, so they are important targets for the development of antiinflammatory therapies. Only three receptors for complement peptides have been found, but there are no satisfactory antagonists as yet, despite intensive investigation. In humans, there is a single receptor for C3a (C3a receptor), no known receptor for C4a, and two receptors for C5a (C5a₁ receptor and C5a₂ receptor). The most recently characterized receptor, the C5a₂ receptor (previously known as C5L2 or GPR77), has been regarded as a passive binding protein, but signaling activities are now ascribed to it, so we propose that it be formally identified as a receptor and be given a name to reflect this. Here, we describe the complex biology of the complement peptides, introduce a new suggested nomenclature, and review our current knowledge of receptor pharmacology.
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Affiliation(s)
- Andreas Klos
- Department for Medical Microbiology, Medical School Hannover, Hannover, Germany
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Brueckner F, Piscitelli CL, Tsai CJ, Standfuss J, Deupi X, Schertler GFX. Structure of β-adrenergic receptors. Methods Enzymol 2013; 520:117-51. [PMID: 23332698 DOI: 10.1016/b978-0-12-391861-1.00006-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
β-Adrenergic receptors (βARs) control key physiological functions by transducing signals encoded in catecholamine hormones and neurotransmitters to activate intracellular signaling pathways. As members of the large family of G protein-coupled receptors (GPCRs), βARs have a seven-transmembrane helix topology and signal via G protein- and arrestin-dependent pathways. Until 2007, three-dimensional structural information of GPCRs activated by diffusible ligands, including βARs, was limited to homology models that used the related photoreceptor rhodopsin as a template. Over many years, several labs have developed strategies that have finally allowed the structures of the turkey β(1)AR and the human β(2)AR to be determined experimentally. The challenges to overcome included heterologous receptor overexpression, design of stabilized and crystallizable modified receptor constructs, ligand-affinity purification of active receptor and the development of novel techniques in crystallization and microcrystallography. The structures of βARs in complex with inverse agonists, antagonists, and agonists have revealed the binding mode of ligands with different efficacies, have allowed to obtain insights into ligand selectivity, and have provided better templates for drug design. Also, the structures of β(2)AR in complex with a G protein and a G protein-mimicking nanobody have provided important insights into the mechanism of receptor activation and G protein coupling. This chapter summarizes the strategies and methods that have been successfully applied to the structural studies of βARs. These are exemplified with detailed protocols toward the structure determination of stabilized turkey β(1)AR-ligand complexes. We also discuss the spectacular insights into adrenergic receptor function that were obtained from the structures.
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Affiliation(s)
- Florian Brueckner
- Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen PSI, Switzerland
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Unal H, Jagannathan R, Bhatnagar A, Tirupula K, Desnoyer R, Karnik SS. Long range effect of mutations on specific conformational changes in the extracellular loop 2 of angiotensin II type 1 receptor. J Biol Chem 2012; 288:540-51. [PMID: 23139413 DOI: 10.1074/jbc.m112.392514] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The topology of the second extracellular loop (ECL2) and its interaction with ligands is unique in each G protein-coupled receptor. When the orthosteric ligand pocket located in the transmembrane (TM) domain is occupied, ligand-specific conformational changes occur in the ECL2. In more than 90% of G protein-coupled receptors, ECL2 is tethered to the third TM helix via a disulfide bond. Therefore, understanding the extent to which the TM domain and ECL2 conformations are coupled is useful. To investigate this, we examined conformational changes in ECL2 of the angiotensin II type 1 receptor (AT1R) by introducing mutations in distant sites that alter the activation state equilibrium of the AT1R. Differential accessibility of reporter cysteines introduced at four conformation-sensitive sites in ECL2 of these mutants was measured. Binding of the agonist angiotensin II (AngII) and inverse agonist losartan in wild-type AT1R changed the accessibility of reporter cysteines, and the pattern was consistent with ligand-specific "lid" conformations of ECL2. Without agonist stimulation, the ECL2 in the gain of function mutant N111G assumed a lid conformation similar to AngII-bound wild-type AT1R. In the presence of inverse agonists, the conformation of ECL2 in the N111G mutant was similar to the inactive state of wild-type AT1R. In contrast, AngII did not induce a lid conformation in ECL2 in the loss of function D281A mutant, which is consistent with the reduced AngII binding affinity in this mutant. However, a lid conformation was induced by [Sar(1),Gln(2),Ile(8)] AngII, a specific analog that binds to the D281A mutant with better affinity than AngII. These results provide evidence for the emerging paradigm of domain coupling facilitated by long range interactions at distant sites on the same receptor.
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Affiliation(s)
- Hamiyet Unal
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
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Natarajan C, Hata AN, Hamm HE, Zent R, Breyer RM. Extracellular loop II modulates GTP sensitivity of the prostaglandin EP3 receptor. Mol Pharmacol 2012; 83:206-16. [PMID: 23087260 DOI: 10.1124/mol.112.080473] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Unlike the majority of G protein-coupled receptors, the prostaglandin E(2) (PGE(2)) E-prostanoid 3 (EP3) receptor binds agonist with high affinity that is insensitive to the presence of guanosine 5[prime]-O-(3-thio)triphosphate (GTPγS). We report the identification of mutations that confer GTPγS sensitivity to agonist binding. Seven point mutations were introduced into the conserved motif in the second extracellular loop (ECII) of EP3, resulting in acquisition of GTP-sensitive agonist binding. One receptor mutation W203A was studied in detail. Loss of agonist binding was observed on intact human embryonic kidney 293 cells expressing the W203A receptor, conditions where high GTP levels are present; however, high affinity binding [(3)H]PGE(2) was observed in broken cell preparations washed free of GTP. The [(3)H]PGE(2) binding of W203A in broken cell membrane fractions was inhibited by addition of GTPγS (IC(50) 21 ± 1.8 nM). Taken together, these results suggest that the wild-type EP3 receptor displays unusual characteristics of the complex coupled equilibria between agonist-receptor and receptor-G protein interaction. Moreover, mutation of ECII can alter this coupled equilibrium from GTP-insensitive agonist binding to more conventional GTP-sensitive binding. This suggests that for the mutant receptors, ECII plays a critical role in linking the agonist bound receptor conformation to the G protein nucleotide bound state.
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Affiliation(s)
- Chandramohan Natarajan
- Division of Nephrology, Vanderbilt University School of Medicine, S3223 MCN, 1161 21st Avenue, Nashville, TN 37232-2372, USA
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Dupakuntla M, Pathak B, Roy BS, Mahale SD. Extracellular loop 2 in the FSH receptor is crucial for ligand mediated receptor activation. Mol Cell Endocrinol 2012; 362:60-8. [PMID: 22641019 DOI: 10.1016/j.mce.2012.05.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 05/17/2012] [Accepted: 05/18/2012] [Indexed: 10/28/2022]
Abstract
The present study aims to determine the role of the specific residues of the extracellular loops (ELs) of the FSH receptor (FSHR) in hormone binding and receptor activation. By substituting the sequences of each of the ELs of human FSHR with those of the luteinizing hormone/choriogonadotropin receptor (LH/CGR), we generated three mutant constructs where the three ELs were individually replaced. A fourth construct had all the three substituted ELs. The receptor expression and hormone binding ability of the mutants were comparable to that of the wild type. Hormone-induced signaling and internalization were lower in the EL2 substitution mutant (EL2M). In this mutant, the EL2 of FSHR was substituted with the corresponding loop of LH/CGR. Interestingly, homology modeling revealed a change in the orientation of EL2 in the mutant receptor. Thus, disruption of EL2 affected overall receptor function, suggesting the role of FSHR specific residues of the loop in ligand mediated signaling.
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Affiliation(s)
- Madhavi Dupakuntla
- Division of Structural Biology, National Institute for Research in Reproductive Health (Indian Council of Medical Research), Parel, Mumbai 400 012, India
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Zhang L, Shih AY, Yang XV, Kuei C, Wu J, Deng X, Mani NS, Mirzadegan T, Sun S, Lovenberg TW, Liu C. Identification of structural motifs critical for epstein-barr virus-induced molecule 2 function and homology modeling of the ligand docking site. Mol Pharmacol 2012; 82:1094-103. [PMID: 22930711 DOI: 10.1124/mol.112.080275] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Epstein-Barr virus-induced molecule 2 (EBI2) (also known as G-protein-coupled receptor 183) is a G-protein-coupled receptor (GPCR) that is best known for its role in B cell migration and localization. Our recent deorphanization effort led to the discovery of 7α,25-dihydroxycholesterol (7α,25-OHC) as the endogenous ligand for EBI2, which provides a tool for mechanistic studies of EBI2 function. Because EBI2 is the first GPCR known to bind and to be activated by an oxysterol, the goal of this study was to understand the molecular and structural bases for its ligand-dependent activation; this was achieved by identifying structural moieties in EBI2 or in 7α,25-OHC that might affect receptor-ligand interactions. By using a series of chemically related OHC analogs, we demonstrated that all three hydroxyl groups in 7α,25-OHC contributed to ligand-induced activation of the receptor. To determine the location and composition of the ligand binding domain in EBI2, we used a site-directed mutagenesis approach and generated mutant receptors with single amino acid substitutions at selected positions of interest. Biochemical and pharmacological profiling of these mutant receptors allowed for structure-function analyses and revealed critical motifs that likely interact with 7α,25-OHC. By using a hybrid β(2)-adrenergic receptor-C-X-C chemokine receptor type 4 structure as a template, we created a homology model for EBI2 and optimized the docking of 7α,25-OHC into the putative ligand binding site, so that the hydroxyl groups interact with residues Arg87, Asn114, and Glu183. This model of ligand docking yields important structural insight into the molecular mechanisms mediating EBI2 function and may facilitate future efforts to design novel therapeutic agents that target EBI2.
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Affiliation(s)
- Li Zhang
- Janssen Pharmaceutical Research and Development, San Diego, California, USA
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