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Isu UH, Polasa A, Moradi M. Differential Behavior of Conformational Dynamics in Active and Inactive States of Cannabinoid Receptor 1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.17.589939. [PMID: 38659869 PMCID: PMC11042334 DOI: 10.1101/2024.04.17.589939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The cannabinoid receptor CB1 is a G protein-coupled receptor that regulates critical physiological processes including pain, appetite, and cognition. Understanding the conformational dynamics of CB1 associated with transitions between inactive and active signaling states is imperative for developing targeted modulators. Using microsecond-level all-atom molecular dynamics simulations, we identified marked differences in the conformational ensembles of inactive and active CB1 states in apo conditions. The inactive state exhibited substantially increased structural heterogeneity and plasticity compared to the more rigidified active state in the absence of stabilizing ligands. Transmembrane helices TM3 and TM7 were identified as distinguishing factors modulating the state-dependent dynamics. TM7 displayed amplified fluctuations selectively in the inactive state simulations attributed to disruption of conserved electrostatic contacts anchoring it to surrounding helices in the active state. Additionally, we identified significant reorganization of key salt bridge and hydrogen bond networks known to control CB1 activation between states. For instance, a conserved D213-Y224 hydrogen bond and D184-K192 salt bridge interactions showed marked rearrangements between the states. Collectively, these findings reveal the specialized role of TM7 in directing state-dependent CB1 dynamics through electrostatic switch mechanisms. By elucidating the intrinsic enhanced flexibility of inactive CB1, this study provides valuable insights into the conformational landscape enabling functional transitions. Our perspective advances understanding of CB1 activation mechanisms and offers opportunities for structure-based drug discovery targeting the state-specific conformational dynamics of this receptor.
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Pawnikar S, Akhter S, Miao Y. Structural dynamics of chemokine receptors. VITAMINS AND HORMONES 2023; 123:645-662. [PMID: 37718001 DOI: 10.1016/bs.vh.2023.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Membrane proteins such as G protein-coupled receptors (GPCRs) are involved in awide range of physiological and pathological cellular processes. Binding of extracellular signals to GPCRs, including hormones, neurotransmitters, peptides and proteins, can activate intracellular signaling cascades via G protein interaction. Chemokine receptors are key GPCRs implicated in cancers, immune responses, cell migration and inflammation. Specifically, the CCR5 and CXCR4 chemokine receptors serve as important therapeutic targets against Human Immunodeficiency virus (HIV) entry into human cells. Maraviroc and Vicriviroc, two clinically used HIV entry inhibitors, are antagonists of the CCR5 receptor. These drugs block HIV entry, but ultimately resistance develops, due to emergence of viruses that can utilize the CXCR4 co-receptor. Unfortunately, development of chemokine receptor antagonists as selective drugs of HIV infection has been greatly hindered as their target orthosteric site is conserved among different receptor subtypes. Accordingly, it is important to understand the structural dynamics of these receptors to develop more effective therapeutics. In this chapter, we describe the latest advances in studies of these two key chemokine receptors with respect to their structures, dynamics and function.
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Affiliation(s)
- Shristi Pawnikar
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS, United States
| | - Sana Akhter
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS, United States
| | - Yinglong Miao
- Center for Computational Biology and Department of Molecular Biosciences, University of Kansas, Lawrence, KS, United States.
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Abstract
Homology modeling is a computational approach to generate three-dimensional structures of protein targets when experimental data about similar proteins are available. Although experimental methods such as X-ray crystallography and nuclear magnetic resonance spectroscopy successfully solved the structures of nearly 150,000 macromolecules, there is still a gap in our structural knowledge. We can fulfill this gap with computational methodologies. Our goal in this chapter is to explain how to perform homology modeling of protein targets for drug development. We choose as a homology modeling tool the program MODELLER. To illustrate its use, we describe how to model the structure of human cyclin-dependent kinase 3 using MODELLER. We explain the modeling procedure of CDK3 apoenzyme and the structure of this enzyme in complex with roscovitine.
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Affiliation(s)
- Gabriela Bitencourt-Ferreira
- Escola de Ciências da Saúde, Pontifícia Universidade Católica do Rio Grande do Sul-PUCRS, Porto Alegre, RS, Brazil
| | - Walter Filgueira de Azevedo
- Escola de Ciências da Saúde, Pontifícia Universidade Católica do Rio Grande do Sul-PUCRS, Porto Alegre, RS, Brazil.
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García-Cuesta EM, Santiago CA, Vallejo-Díaz J, Juarranz Y, Rodríguez-Frade JM, Mellado M. The Role of the CXCL12/CXCR4/ACKR3 Axis in Autoimmune Diseases. Front Endocrinol (Lausanne) 2019; 10:585. [PMID: 31507535 PMCID: PMC6718456 DOI: 10.3389/fendo.2019.00585] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 08/09/2019] [Indexed: 12/19/2022] Open
Abstract
Chemokine receptors are members of the G protein-coupled receptor superfamily. These receptors are intimately involved in cell movement, and thus play a critical role in several physiological and pathological situations that require the precise regulation of cell positioning. CXCR4 is one of the most studied chemokine receptors and is involved in many functions beyond leukocyte recruitment. During embryogenesis, it plays essential roles in vascular development, hematopoiesis, cardiogenesis, and nervous system organization. It has been also implicated in tumor progression and autoimmune diseases and, together with CD4, is one of the co-receptors used by the HIV-1 virus to infect immune cells. In contrast to other chemokine receptors that are characterized by ligand promiscuity, CXCR4 has a unique ligand-stromal cell-derived factor-1 (SDF1, CXCL12). However, this ligand also binds ACKR3, an atypical chemokine receptor that modulates CXCR4 functions and is overexpressed in multiple cancer types. The CXCL12/CXCR4/ACKR3 axis constitutes a potential therapeutic target for a wide variety of inflammatory diseases, not only by interfering with cell migration but also by modulating immune responses. Thus far, only one antagonist directed against the ligand-binding site of CXCR4, AMD3100, has demonstrated clinical relevance. Here, we review the role of this ligand and its receptors in different autoimmune diseases.
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Affiliation(s)
- Eva M. García-Cuesta
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - César A. Santiago
- Macromolecular X-Ray Crystallography Unit, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - Jesús Vallejo-Díaz
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
| | - Yasmina Juarranz
- Department Cell Biology, Research Institute Hospital 12 de Octubre (i+12), Complutense University of Madrid, Madrid, Spain
| | | | - Mario Mellado
- Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, Madrid, Spain
- *Correspondence: Mario Mellado
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5
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A3 adenosine receptor: Homology modeling and 3D-QSAR studies. J Mol Graph Model 2013; 42:60-72. [DOI: 10.1016/j.jmgm.2013.03.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 02/01/2013] [Accepted: 03/07/2013] [Indexed: 11/21/2022]
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Rodríguez D, Gutiérrez-de-Terán H. Characterization of the homodimerization interface and functional hotspots of the CXCR4 chemokine receptor. Proteins 2012; 80:1919-28. [PMID: 22513895 DOI: 10.1002/prot.24099] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 04/03/2012] [Accepted: 04/13/2012] [Indexed: 01/11/2023]
Abstract
The recent crystallographic structures of the human chemokine CXC Receptor 4 (CXCR4) provide experimental evidence of a human G Protein-Coupled Receptor (GPCR) dimer in atomic detail. The CXCR4 homodimers reveal an unexpected dimerization mode involving transmembrane helices TM5 and TM6, which is examined here using all-atom molecular dynamics (MD) simulations in the physiological environment of a lipid bilayer. The bacteriophage T4 lysozyme (T4L), which was fused to the crystallized protein but absent in our simulations, is found to slightly affect the observed relative position of the protomers in the two dimers studied here, and consequently some rearrangements of the dimerization interface are proposed. In addition, the simulations provide further evidence about the role of the two stabilizing single point mutations introduced to crystallize the receptor. Finally, this work analyzes the structural and dynamic role of key residues involved both in ligand binding and in the infection process of HIV. In particular, the different side chain conformations of His113(3.39) are found to influence the dynamics of the surrounding functional hotspot region being evaluated both in the presence and in the absence of the co-crystallized ligand IT1t. The analysis reported here adds valuable knowledge for future structure-based drug design (SBDD) efforts on this pharmacological target.
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Affiliation(s)
- David Rodríguez
- Fundación Pública Galega de Medicina Xenómica, Hospital Clínico Universitario de Santiago, Santiago de Compostela, Spain
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7
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Seddon G, Lounnas V, McGuire R, van den Bergh T, Bywater RP, Oliveira L, Vriend G. Drug design for ever, from hype to hope. J Comput Aided Mol Des 2012; 26:137-50. [PMID: 22252446 PMCID: PMC3268973 DOI: 10.1007/s10822-011-9519-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 12/05/2011] [Indexed: 01/28/2023]
Abstract
In its first 25 years JCAMD has been disseminating a large number of techniques aimed at finding better medicines faster. These include genetic algorithms, COMFA, QSAR, structure based techniques, homology modelling, high throughput screening, combichem, and dozens more that were a hype in their time and that now are just a useful addition to the drug-designers toolbox. Despite massive efforts throughout academic and industrial drug design research departments, the number of FDA-approved new molecular entities per year stagnates, and the pharmaceutical industry is reorganising accordingly. The recent spate of industrial consolidations and the concomitant move towards outsourcing of research activities requires better integration of all activities along the chain from bench to bedside. The next 25 years will undoubtedly show a series of translational science activities that are aimed at a better communication between all parties involved, from quantum chemistry to bedside and from academia to industry. This will above all include understanding the underlying biological problem and optimal use of all available data.
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Affiliation(s)
- G Seddon
- Adelard Institute, Manchester, UK
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8
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Fanelli F, De Benedetti PG. Update 1 of: computational modeling approaches to structure-function analysis of G protein-coupled receptors. Chem Rev 2011; 111:PR438-535. [PMID: 22165845 DOI: 10.1021/cr100437t] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute, University of Modena and Reggio Emilia, via Campi 183, 41125 Modena, Italy.
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9
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Ghosh A, Sonavane U, Andhirka SK, Aradhyam GK, Joshi R. Structural insights into human GPCR protein OA1: a computational perspective. J Mol Model 2011; 18:2117-33. [DOI: 10.1007/s00894-011-1228-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 08/18/2011] [Indexed: 11/24/2022]
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Simpson LM, Wall ID, Blaney FE, Reynolds CA. Modeling GPCR active state conformations: the β(2)-adrenergic receptor. Proteins 2011; 79:1441-57. [PMID: 21337626 DOI: 10.1002/prot.22974] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 11/13/2010] [Accepted: 12/02/2010] [Indexed: 01/28/2023]
Abstract
The recent publication of several G protein-coupled receptor (GPCR) structures has increased the information available for homology modeling inactive class A GPCRs. Moreover, the opsin crystal structure shows some active features. We have therefore combined information from these two sources to generate an extensively validated model of the active conformation of the β(2)-adrenergic receptor. Experimental information on fully active GPCRs from zinc binding studies, site-directed spin labeling, and other spectroscopic techniques has been used in molecular dynamics simulations. The observed conformational changes reside mainly in transmembrane helix 6 (TM6), with additional small but significant changes in TM5 and TM7. The active model has been validated by manual docking and is in agreement with a large amount of experimental work, including site-directed mutagenesis information. Virtual screening experiments show that the models are selective for β-adrenergic agonists over other GPCR ligands, for (R)- over (S)-β-hydroxy agonists and for β(2)-selective agonists over β(1)-selective agonists. The virtual screens reproduce interactions similar to those generated by manual docking. The C-terminal peptide from a model of the stimulatory G protein, readily docks into the active model in a similar manner to which the C-terminal peptide from transducin, docks into opsin, as shown in a recent opsin crystal structure. This GPCR-G protein model has been used to explain site-directed mutagenesis data on activation. The agreement with experiment suggests a robust model of an active state of the β(2)-adrenergic receptor has been produced. The methodology used here should be transferable to modeling the active state of other GPCRs.
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Affiliation(s)
- Lisa M Simpson
- Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, United Kingdom
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11
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Ramos J, Cruz VL, Martínez-Salazar J, Campillo NE, Páez JA. Dissimilar interaction of CB1/CB2 with lipid bilayers as revealed by molecular dynamics simulation. Phys Chem Chem Phys 2011; 13:3660-8. [DOI: 10.1039/c0cp01456g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Wu B, Chien EY, Mol CD, Fenalti G, Liu W, Katritch V, Abagyan R, Brooun A, Wells P, Bi FC, Hamel DJ, Kuhn P, Handel TM, Cherezov V, Stevens RC. Structures of the CXCR4 chemokine GPCR with small-molecule and cyclic peptide antagonists. Science 2010; 330:1066-71. [PMID: 20929726 PMCID: PMC3074590 DOI: 10.1126/science.1194396] [Citation(s) in RCA: 1412] [Impact Index Per Article: 100.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Chemokine receptors are critical regulators of cell migration in the context of immune surveillance, inflammation, and development. The G protein-coupled chemokine receptor CXCR4 is specifically implicated in cancer metastasis and HIV-1 infection. Here we report five independent crystal structures of CXCR4 bound to an antagonist small molecule IT1t and a cyclic peptide CVX15 at 2.5 to 3.2 angstrom resolution. All structures reveal a consistent homodimer with an interface including helices V and VI that may be involved in regulating signaling. The location and shape of the ligand-binding sites differ from other G protein-coupled receptors and are closer to the extracellular surface. These structures provide new clues about the interactions between CXCR4 and its natural ligand CXCL12, and with the HIV-1 glycoprotein gp120.
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Affiliation(s)
- Beili Wu
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Ellen Y.T. Chien
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Clifford D. Mol
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Gustavo Fenalti
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Wei Liu
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Vsevolod Katritch
- University of California, San Diego, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA 92093,USA
| | - Ruben Abagyan
- University of California, San Diego, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA 92093,USA
| | - Alexei Brooun
- Pfizer Worldwide Research and Development, 10770 Science Center Drive, San Diego, CA 92121, USA
| | - Peter Wells
- Pfizer Worldwide Research and Development, 10770 Science Center Drive, San Diego, CA 92121, USA
| | - F. Christopher Bi
- Pfizer Worldwide Research and Development, 10770 Science Center Drive, San Diego, CA 92121, USA
| | - Damon J. Hamel
- University of California, San Diego, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA 92093,USA
| | - Peter Kuhn
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Tracy M. Handel
- University of California, San Diego, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA 92093,USA
| | - Vadim Cherezov
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Raymond C. Stevens
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Increasingly accurate dynamic molecular models of G-protein coupled receptor oligomers: Panacea or Pandora's box for novel drug discovery? Life Sci 2009; 86:590-7. [PMID: 19465029 DOI: 10.1016/j.lfs.2009.05.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Revised: 05/07/2009] [Accepted: 05/14/2009] [Indexed: 01/06/2023]
Abstract
For years, conventional drug design at G-protein coupled receptors (GPCRs) has mainly focused on the inhibition of a single receptor at a usually well-defined ligand-binding site. The recent discovery of more and more physiologically relevant GPCR dimers/oligomers suggests that selectively targeting these complexes or designing small molecules that inhibit receptor-receptor interactions might provide new opportunities for novel drug discovery. To uncover the fundamental mechanisms and dynamics governing GPCR dimerization/oligomerization, it is crucial to understand the dynamic process of receptor-receptor association, and to identify regions that are suitable for selective drug binding. This minireview highlights current progress in the development of increasingly accurate dynamic molecular models of GPCR oligomers based on structural, biochemical, and biophysical information that has recently appeared in the literature. In view of this new information, there has never been a more exciting time for computational research into GPCRs than at present. Information-driven modern molecular models of GPCR complexes are expected to efficiently guide the rational design of GPCR oligomer-specific drugs, possibly allowing researchers to reach for the high-hanging fruits in GPCR drug discovery, i.e. more potent and selective drugs for efficient therapeutic interventions.
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14
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Cozzini P, Kellogg GE, Spyrakis F, Abraham DJ, Costantino G, Emerson A, Fanelli F, Gohlke H, Kuhn LA, Morris GM, Orozco M, Pertinhez TA, Rizzi M, Sotriffer CA. Target flexibility: an emerging consideration in drug discovery and design. J Med Chem 2008; 51:6237-55. [PMID: 18785728 DOI: 10.1021/jm800562d] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Pietro Cozzini
- Department of General and Inorganic Chemistry, University of Parma, Via G.P. Usberti 17/A 43100, Parma,
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15
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Mobarec JC, Filizola M. Advances in the Development and Application of Computational Methodologies for Structural Modeling of G-Protein Coupled Receptors. Expert Opin Drug Discov 2008; 3:343-355. [PMID: 19672320 DOI: 10.1517/17460441.3.3.343] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND: Despite the large amount of experimental data accumulated in the past decade on G-protein coupled receptor (GPCR) structure and function, understanding of the molecular mechanisms underlying GPCR signaling is still far from being complete, thus impairing the design of effective and selective pharmaceuticals. OBJECTIVE: Understanding of GPCR function has been challenged even further by more recent experimental evidence that several of these receptors are organized in the cell membrane as homo- or hetero-oligomers, and that they may exhibit unique pharmacological properties. Given the complexity of these new signaling systems, researcher's efforts are turning increasingly to molecular modeling, bioinformatics and computational simulations for mechanistic insights of GPCR functional plasticity. METHODS: We review here current advances in the development and application of computational approaches to improve prediction of GPCR structure and dynamics, thus enhancing current understanding of GPCR signaling. RESULTS/CONCLUSIONS: Models resulting from use of these computational approaches further supported by experiments are expected to help elucidate the complex allosterism that propagates through GPCR complexes, ultimately aiming at successful structure-based rational drug design.
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Affiliation(s)
- Juan Carlos Mobarec
- Department of Structural and Chemical Biology, Mount Sinai School of Medicine, Icahn Medical Institute Building, 1425 Madison Avenue, Box 1677, New York, NY 10029-6574, Tel: 212-241-8634
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16
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Dark and photoactivated rhodopsin share common binding modes to transducin. FEBS Lett 2008; 582:991-6. [PMID: 18307992 DOI: 10.1016/j.febslet.2008.02.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2007] [Revised: 02/07/2008] [Accepted: 02/19/2008] [Indexed: 01/28/2023]
Abstract
The structure of the photoactivated deprotonated rhodopsin intermediate was compared with two different structures of dark rhodopsin. Structure comparisons relied on the computation of molecular indices and on docking simulations with heterotrimeric transducin (Gt). The results of this study provide the first evidence that dark and photoactivated rhodopsins share a common recognition mode to Gt, characterized by the docking of the Gt alpha C-tail in the proximity to the E/DRY motif of rhodopsin.
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17
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Gonzalez A, Duran LS, Araya-Secchi R, Garate JA, Pessoa-Mahana CD, Lagos CF, Perez-Acle T. Computational modeling study of functional microdomains in cannabinoid receptor type 1. Bioorg Med Chem 2008; 16:4378-89. [PMID: 18342519 DOI: 10.1016/j.bmc.2008.02.070] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 02/18/2008] [Accepted: 02/21/2008] [Indexed: 10/22/2022]
Abstract
The seven transmembrane helices (TMH) G-protein-coupled receptors (GPCRs) constitute one of the largest superfamily of signaling proteins found in mammals. Some of its members, in which the cannabinoid (CB) receptors are included, stand out because their functional states can be modulated by a broad spectrum of effector molecules. The relative ligand promiscuity exhibited by these receptors could be related with particular attributes conferred by their molecular architecture and represents a motivating issue to be explored. In this regard, this study represents an effort to investigate the cannabinoid receptor type 1 (CB1) ligand recognition plasticity, using comparative modeling, molecular dynamics (MD) simulations and docking. Our results suggest that a cooperative set of subtle structural rearrangements within the TMHs provide to the CB1 protein the plasticity to reach alternate configurations. These changes include the relaxation of intramolecular constraints, the rotations, translations and kinks of the majority of TMHs and the reorganization of the ligand binding cavities.
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Affiliation(s)
- Angel Gonzalez
- Centre for Bioinformatics CBUC, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Portugal 49-6513492, Santiago, Chile.
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18
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Angelova K, Fanelli F, Puett D. Contributions of intracellular loops 2 and 3 of the lutropin receptor in Gs coupling. Mol Endocrinol 2007; 22:126-38. [PMID: 17872379 PMCID: PMC2194637 DOI: 10.1210/me.2007-0352] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
A number of amino acids essential for Gs coupling, i.e. hot spots, were identified after in vitro Ala-scanning mutagenesis of the cytosolic extensions of helices 3, 5, and 6 and of intracellular loops 2 and 3 (IL2 and IL3) of the human LH receptor (LHR). Consistent with the results of in vitro experiments involving ligand binding and ligand-mediated signaling in transiently transfected human embryonic kidney 293 cells, computational modeling of the isolated receptor and of the receptor-G protein complexes suggests an important role of the cytosolic extension of helix 3 and the N-terminal portion of the IL2 in Gs(alpha) interaction, whereas the contribution of IL3 is marginal. Mapping the hot spots into the computational models of LHR and the LHR-Gs complexes allowed for a distinction between receptor sites required for intramolecular structural changes (i.e. I460, T461, H466, and I549) and receptor sites more likely involved in G protein recognition (i.e. R464, T467, I468, Y470, Y550, and D564). The latter sites include the highly conserved arginine of the (E/D)R(Y/W) motif, which is therefore likely to be a receptor recognition point for Gs rather than a switch of receptor activation. The results of in vitro and in silico experiments carried out in this study represent the first comprehensive delineation of functionality of the individual residues in the intracellular domains of LHR and establish potential switches of receptor activation as well as a map of the primary receptor recognition sites for Gs. A novel way to consider constitutively active mutants was inferred from this study, i.e. receptor states with improved complementarity for the G protein compared to the wild-type receptor.
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Affiliation(s)
- Krassimira Angelova
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-7229, USA
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19
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Strasser A, Wittmann HJ. Analysis of the activation mechanism of the guinea-pig Histamine H1-receptor. J Comput Aided Mol Des 2007; 21:499-509. [PMID: 17712599 DOI: 10.1007/s10822-007-9131-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 08/06/2007] [Indexed: 01/09/2023]
Abstract
The Histamine H(1)-receptor (H1R), belonging to the amine receptor-class of family A of the G-protein coupled receptors (GPCRs) gets activated by agonists. The consequence is a conformational change of the receptor, which may involve the binding-pocket. So, for a good prediction of the binding-mode of an agonist, it is necessary to have knowledge about these conformational changes. Meanwhile some experimental data about the structural changes of GPCRs during activation exist. Based on homology modeling of the guinea-pig H1R (gpH1R), using the crystal structure of bovine rhodopsin as template, we performed several MD simulations with distance restraints in order to get an inactive and an active structure of the gpH1R. The calculations led to a Phe6.44/Trp6.48/Phe6.52-switch and linearization of the proline kinked transmembrane helix VI during receptor activation. Our calculations showed that the Trp6.48/Phe6.52-switch induces a conformational change in Phe6.44, which slides between transmembrane helices III and VI. Additionally we observed a hydrogen bond interaction of Ser3.39 with Asn7.45 in the inactive gpH1R, but because of a counterclockwise rotation of transmembrane helix III Ser3.39 establishes a water-mediated hydrogen bond to Asp2.50 in the active gpH1R. Additionally we simulated a possible mechanism for receptor activation with a modified LigPath-algorithm.
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Affiliation(s)
- Andrea Strasser
- Department of Pharmaceutical and Medicinal Chemistry, Faculty of Chemistry and Pharmacy, University of Regensburg, Regensburg, Germany.
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