1
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Montgomery D, Campbell A, Sullivan HJ, Wu C. Molecular dynamics simulation of biased agonists at the dopamine D2 receptor suggests the mechanism of receptor functional selectivity. J Biomol Struct Dyn 2018; 37:3206-3225. [PMID: 30124143 DOI: 10.1080/07391102.2018.1513378] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The dopamine D2 receptor (D2R) is the primary target for antipsychotic drugs. Besides schizophrenia, this receptor is linked to dementia, Parkinson's disease, and depression. Recent studies have shown that β-arrestin biased agonists at this receptor treat schizophrenia with less side effects. Although the high resolution structure of this receptor exists, the mechanism of biased agonism at the receptor is unknown. In this study, dopamine, the endogenous unbiased G-protein agonist, MLS1547, a G-protein biased agonist, and UNC9975, a G-protein antagonist and a β-arrestin biased agonist, were docked to a homology model of the whole D2R including all flexible loops, and molecular dynamics simulations were conducted to study the potential mechanisms of biased agonism. Our thorough analysis on the protein-ligand interaction, secondary structure, tertiary structure, structure dynamics, and molecular switches of all three systems indicates that ligand binding to transmembrane 3 might be essential for G-protein recruitment, while ligand binding to transmembrane 6 might be essential for β-arrestin recruitment. Our analysis also suggests changes in both the secondary and the tertiary structures of TM5 and TM7, molecular switches and ICL3 flexibility are important in biased signaling. Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- David Montgomery
- a College of Science and Mathematics , Rowan University , Glassboro , NJ , USA
| | - Alexandra Campbell
- a College of Science and Mathematics , Rowan University , Glassboro , NJ , USA
| | - Holli-Joi Sullivan
- a College of Science and Mathematics , Rowan University , Glassboro , NJ , USA
| | - Chun Wu
- a College of Science and Mathematics , Rowan University , Glassboro , NJ , USA
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2
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Salmas RE, Seeman P, Stein M, Durdagi S. Structural Investigation of the Dopamine-2 Receptor Agonist Bromocriptine Binding to Dimeric D2 HighR and D2 LowR States. J Chem Inf Model 2018. [PMID: 29537837 DOI: 10.1021/acs.jcim.7b00722] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The active (D2HighR) and inactive (D2LowR) states of dimeric dopamine D2 receptor (D2R) models were investigated to clarify the binding mechanisms of the dopamine agonist bromocriptine, using Molecular Dynamics (MD) simulation. The aim of this comprehensive study was to investigate the critical effects of bromocriptine binding on each distinct receptor conformation. The different binding modes of the bromocriptine ligand in the active and inactive states have a significant effect on the conformational changes of the receptor. Based on the MM/GBSA approach, the calculated binding enthalpies of bromocriptine demonstrated selectivity toward the D2HighR active state. There is good agreement between the calculated and experimentally measured D2HighR selectivity. In the ligand-binding site, the key amino acids identified for D2HighR were Asp114(3.32) and Glu95(2.65), and for D2LowR, it was Ser193(5.42). Moreover, analysis of replicate MD trajectories demonstrated that the bromocriptine structure was more rigid at the D2HighR state and more flexible at the D2LowR state. However, the side chains of the ligand-receptor complex of D2HighR showed larger variations relative to the corresponding regions of D2LowR. The present study is part of an ongoing research program to study D2R conformational changes during ligand activation and to evaluate the conformational state selectivity for ligand binding.
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Affiliation(s)
- Ramin Ekhteiari Salmas
- Computational Biology and Molecular Simulations Laboratory, Department of Biophysics, School of Medicine , Bahcesehir University , Istanbul 34349 , Turkey
| | - Philip Seeman
- Departments of Pharmacology and Psychiatry , University of Toronto , 260 Heath Street West, Unit 605 , M5P 3L6 Toronto , Ontario , Canada
| | - Matthias Stein
- Molecular Simulations and Design Group , Max Planck Institute for Dynamics of Complex Technical Systems , Sandtorstrasse 1 , 39106 Magdeburg , Germany
| | - Serdar Durdagi
- Computational Biology and Molecular Simulations Laboratory, Department of Biophysics, School of Medicine , Bahcesehir University , Istanbul 34349 , Turkey.,Neuroscience Program, Graduate School of Health Sciences , Bahcesehir University , Istanbul 34349 , Turkey
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3
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Draper-Joyce CJ, Michino M, Verma RK, Klein Herenbrink C, Shonberg J, Kopinathan A, Scammells PJ, Capuano B, Thal DM, Javitch JA, Christopoulos A, Shi L, Lane JR. The structural determinants of the bitopic binding mode of a negative allosteric modulator of the dopamine D 2 receptor. Biochem Pharmacol 2018; 148:315-328. [PMID: 29325769 DOI: 10.1016/j.bcp.2018.01.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/02/2018] [Indexed: 01/11/2023]
Abstract
SB269652 is a negative allosteric modulator of the dopamine D2 receptor (D2R) yet possesses structural similarity to ligands with a competitive mode of interaction. In this study, we aimed to understand the ligand-receptor interactions that confer its allosteric action. We combined site-directed mutagenesis with molecular dynamics simulations using both SB269652 and derivatives from our previous structure activity studies. We identify residues within the conserved orthosteric binding site (OBS) and a secondary binding pocket (SBP) that determine affinity and cooperativity. Our results indicate that interaction with the SBP is a requirement for allosteric pharmacology, but that both competitive and allosteric derivatives of SB269652 can display sensitivity to the mutation of a glutamate residue (E952.65) within the SBP. Our findings provide the molecular basis for the differences in affinity between SB269652 derivatives, and reveal how changes to interactions made by the primary pharmacophore of SB269652 in the orthosteric pocket can confer changes in the interactions made by the secondary pharmacophore in the SBP. Our insights provide a structure-activity framework towards rational optimization of bitopic ligands for D2R with tailored competitive versus allosteric properties.
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Affiliation(s)
- Christopher J Draper-Joyce
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville campus), 399 Royal Parade, Parkville, VIC 3052, Australia
| | - Mayako Michino
- Computational Chemistry and Molecular Biophysics Unit, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD 21224, United States
| | - Ravi Kumar Verma
- Computational Chemistry and Molecular Biophysics Unit, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD 21224, United States
| | - Carmen Klein Herenbrink
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville campus), 399 Royal Parade, Parkville, VIC 3052, Australia
| | - Jeremy Shonberg
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville campus), 399 Royal Parade, Parkville, VIC 3052, Australia
| | - Anitha Kopinathan
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville campus), 399 Royal Parade, Parkville, VIC 3052, Australia
| | - Peter J Scammells
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville campus), 399 Royal Parade, Parkville, VIC 3052, Australia
| | - Ben Capuano
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville campus), 399 Royal Parade, Parkville, VIC 3052, Australia
| | - David M Thal
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville campus), 399 Royal Parade, Parkville, VIC 3052, Australia
| | - Jonathan A Javitch
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York State Psychiatric Institute, New York, NY 10032, United States; Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York State Psychiatric Institute, New York, NY 10032, United States; Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY 10032, United States
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville campus), 399 Royal Parade, Parkville, VIC 3052, Australia
| | - Lei Shi
- Computational Chemistry and Molecular Biophysics Unit, National Institute on Drug Abuse Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD 21224, United States.
| | - J Robert Lane
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville campus), 399 Royal Parade, Parkville, VIC 3052, Australia.
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4
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Salmas RE, Seeman P, Aksoydan B, Erol I, Kantarcioglu I, Stein M, Yurtsever M, Durdagi S. Analysis of the Glutamate Agonist LY404,039 Binding to Nonstatic Dopamine Receptor D2 Dimer Structures and Consensus Docking. ACS Chem Neurosci 2017; 8:1404-1415. [PMID: 28272861 DOI: 10.1021/acschemneuro.7b00070] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Dopamine receptor D2 (D2R) plays an important role in the human central nervous system and is a focal target of antipsychotic agents. The D2HighR and D2LowR dimeric models previously developed by our group are used to investigate the prediction of binding affinity of the LY404,039 ligand and its binding mechanism within the catalytic domain. The computational data obtained using molecular dynamics simulations fit well with the experimental results. The calculated binding affinities of LY404,039 using MM/PBSA for the D2HighR and D2LowR targets were -12.04 and -9.11 kcal/mol, respectively. The experimental results suggest that LY404,039 binds to D2HighR and D2LowR with binding affinities (Ki) of 8.2 and 1640 nM, respectively. The high binding affinity of LY404,039 in terms of binding to [3H]domperidone was inhibited by the presence of a guanine nucleotide, indicating an agonist action of the drug at D2HighR. The interaction analysis demonstrated that while Asp114 was among the most critical amino acids for D2HighR binding, residues Ser193 and Ser197 were significantly more important within the binding cavity of D2LowR. Molecular modeling analyses are extended to ensemble docking as well as structure-based pharmacophore model (E-pharmacophore) development using the bioactive conformation of LY404,039 at the binding pocket as a template and screening of small-molecule databases with derived pharmacophore models.
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Affiliation(s)
- Ramin Ekhteiari Salmas
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, 34349 Istanbul, Turkey
| | - Philip Seeman
- Departments
of Pharmacology and Psychiatry, University of Toronto, 260 Heath
Street West, Unit 605, Toronto, Ontario M5P 3L6, Canada
| | - Busecan Aksoydan
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, 34349 Istanbul, Turkey
| | - Ismail Erol
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, 34349 Istanbul, Turkey
- Department
of Chemistry, Gebze Technical University, 41400, Kocaeli, Turkey
| | - Isik Kantarcioglu
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, 34349 Istanbul, Turkey
| | - Matthias Stein
- Max-Planck Institute for Dynamics of Complex Technical Systems, Molecular Simulations and Design Group, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Mine Yurtsever
- Department
of Chemistry, Istanbul Technical University, 34469 Istanbul, Turkey
| | - Serdar Durdagi
- Computational
Biology and Molecular Simulations Laboratory, Department of Biophysics,
School of Medicine, Bahcesehir University, 34349 Istanbul, Turkey
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5
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Salmas RE, Stein M, Yurtsever M, Seeman P, Erol I, Mestanoglu M, Durdagi S. The signaling pathway of dopamine D2 receptor (D2R) activation using normal mode analysis (NMA) and the construction of pharmacophore models for D2R ligands. J Biomol Struct Dyn 2016; 35:2040-2048. [PMID: 27367058 DOI: 10.1080/07391102.2016.1206487] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
G-protein-coupled receptors (GPCRs) are targets of more than 30% of marketed drugs. Investigation on the GPCRs may shed light on upcoming drug design studies. In the present study, we performed a combination of receptor- and ligand-based analysis targeting the dopamine D2 receptor (D2R). The signaling pathway of D2R activation and the construction of universal pharmacophore models for D2R ligands were also studied. The key amino acids, which contributed to the regular activation of the D2R, were in detail investigated by means of normal mode analysis (NMA). A derived cross-correlation matrix provided us an understanding of the degree of pair residue correlations. Although negative correlations were not observed in the case of the inactive D2R state, a high degree of correlation appeared between the residues in the active state. NMA results showed that the cytoplasmic side of the TM5 plays a significant role in promoting of residue-residue correlations in the active state of D2R. Tracing motions of the amino acids Arg219, Arg220, Val223, Asn224, Lys226, and Ser228 in the position of the TM5 are found to be critical in signal transduction. Complementing the receptor-based modeling, ligand-based modeling was also performed using known D2R ligands. The top-scored pharmacophore models were found as 5-sited (AADPR.671, AADRR.1398, AAPRR.3900, and ADHRR.2864) hypotheses from PHASE modeling from a pool consisting of more than 100 initial candidates. The constructed models using 38 D2R ligands (in the training set) were validated with 15 additional test set compounds. The resulting model correctly predicted the pIC50 values of an additional test set compounds as true unknowns.
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Affiliation(s)
- Ramin Ekhteiari Salmas
- a Department of Biophysics , School of Medicine, Bahcesehir University , Istanbul , Turkey
| | - Matthias Stein
- b Molecular Simulations and Design Group , Max Planck Institute for Dynamics of Complex Technical System , Sandtorstrasse 1, 39106 Magdeburg , Germany
| | - Mine Yurtsever
- c Department of Chemistry , Istanbul Technical University , Istanbul , Turkey
| | - Philip Seeman
- d Department of Pharmacology and Psychiatry , University of Toronto , 260 Heath Street West, Unit 605, M5P 3L6 Toronto , Ontario , Canada
| | - Ismail Erol
- a Department of Biophysics , School of Medicine, Bahcesehir University , Istanbul , Turkey.,e Department of Chemistry , Gebze Technical University , Gebze , Turkey
| | - Mert Mestanoglu
- a Department of Biophysics , School of Medicine, Bahcesehir University , Istanbul , Turkey
| | - Serdar Durdagi
- a Department of Biophysics , School of Medicine, Bahcesehir University , Istanbul , Turkey
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6
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Penjišević JZ, Šukalović VV, Andrić DB, Roglić GM, Šoškić V, Kostić-Rajačić SV. Synthesis, Biological, and Computational Evaluation of Substituted 1-(2-Methoxyphenyl)-4-(1-phenethylpiperidin-4-yl)piperazines and 1-(2-Methoxyphenyl)-4-[(1-phenethylpiperidin-4-yl)methyl]piperazines as Dopaminergic Ligands. Arch Pharm (Weinheim) 2016; 349:614-26. [PMID: 27335270 DOI: 10.1002/ardp.201600081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Revised: 06/03/2016] [Accepted: 06/06/2016] [Indexed: 11/05/2022]
Abstract
Sixteen new 1-(2-methoxyphenyl)-4-(1-phenethylpiperidin-4-yl)piperazines and 1-(2-methoxyphenyl)-4-[(1-phenethylpiperidin-4-yl)methyl]piperazines were synthesized to be used as probes for mapping the dopamine D2 receptor (D2 DAR) arylpiperazine binding site. All compounds were evaluated for their affinity toward D2 DAR in an in vitro competitive displacement assay. The most active one was 1-(2-methoxyphenyl)-4-{[1-(3-nitrophenethyl)piperidin-4-yl]methyl}piperazine (25) with an affinity of Ki = 54 nM. Docking analysis was conducted on all herein described compounds, whereas molecular dynamic simulation was performed on ligand 25 to establish its mode of interaction with D2 DAR. Two possible docking orientations are proposed; the one with a salt bridge between the piperidine moiety and Asp114 of D2 DAR is more stable.
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Affiliation(s)
| | | | - Deana B Andrić
- Faculty of Chemistry, University of Belgrade, Belgrade, Serbia
| | - Goran M Roglić
- Faculty of Chemistry, University of Belgrade, Belgrade, Serbia
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7
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Salmas RE, Yurtsever M, Durdagi S. Atomistic molecular dynamics simulations of typical and atypical antipsychotic drugs at the dopamine D2 receptor (D2R) elucidates their inhibition mechanism. J Biomol Struct Dyn 2016; 35:738-754. [DOI: 10.1080/07391102.2016.1159986] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
| | - Mine Yurtsever
- Department of Chemistry, Istanbul Technical University, Istanbul, Turkey
| | - Serdar Durdagi
- Department of Biophysics, School of Medicine, Bahcesehir University, Istanbul, Turkey
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8
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Weichert D, Gmeiner P. Covalent molecular probes for class A G protein-coupled receptors: advances and applications. ACS Chem Biol 2015; 10:1376-86. [PMID: 25860503 DOI: 10.1021/acschembio.5b00070] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Covalent modification of G protein-coupled receptors (GPCRs) by employing specific molecular probes has for decades provided a successful strategy to facilitate the elucidation of the structure and function of this pharmacologically important class of membrane proteins. The ligands typically comprise a pharmacophore that generates affinity for a given GPCR and contain a reactive functionality that may form a covalent bond with a suitably positioned amino acid residue. Covalent ligands have been successfully applied to circumvent poor affinity of compounds when stable labeling of receptor populations was required, and they have been used in the isolation, purification, and pharmacological characterization of specific subtypes of GPCRs. Recently, structural studies have demonstrated that covalent molecular probes are effective at stabilizing GPCRs to obtain X-ray crystal structures, thus providing valuable insights for the development of novel therapeutics. Herein, we review covalently binding molecular probes for class A GPCRs with a focus on ligands comprising cross-linking groups that do not require photoactivation and further highlight their significant and diverse applications.
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Affiliation(s)
- Dietmar Weichert
- Department
of Chemistry and
Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany
| | - Peter Gmeiner
- Department
of Chemistry and
Pharmacy, Medicinal Chemistry, Emil Fischer Center, Friedrich Alexander University, Schuhstraße 19, 91052 Erlangen, Germany
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9
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Salmas RE, Yurtsever M, Stein M, Durdagi S. Modeling and protein engineering studies of active and inactive states of human dopamine D2 receptor (D2R) and investigation of drug/receptor interactions. Mol Divers 2015; 19:321-32. [DOI: 10.1007/s11030-015-9569-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 01/11/2015] [Indexed: 01/11/2023]
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10
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Mondal S, Khelashvili G, Johner N, Weinstein H. How the dynamic properties and functional mechanisms of GPCRs are modulated by their coupling to the membrane environment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 796:55-74. [PMID: 24158801 DOI: 10.1007/978-94-007-7423-0_4] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Experimental observations of the dependence of function and organization of G protein-coupled receptors (GPCRs) on their lipid environment have stimulated new quantitative studies of the coupling between the proteins and the membrane. It is important to develop such a quantitative understanding at the molecular level because the effects of the coupling are seen to be physiologically and clinically significant. Here we review findings that offer insight into how membrane-GPCR coupling is connected to the structural characteristics of the GPCR, from sequence to 3D structural detail, and how this coupling is involved in the actions of ligands on the receptor. The application of a recently developed computational approach designed for quantitative evaluation of membrane remodeling and the energetics of membrane-protein interactions brings to light the importance of the radial asymmetry of the membrane-facing surface of GPCRs in their interaction with the surrounding membrane. As the radial asymmetry creates adjacencies of hydrophobic and polar residues at specific sites of the GPCR, the ability of membrane remodeling to achieve complete hydrophobic matching is limited, and the residual mismatch carries a significant energy cost. The adjacencies are shown to be affected by ligand-induced conformational changes. Thus, functionally important organization of GPCRs in the cell membrane can depend both on ligand-determined properties and on the lipid composition of various membrane regions with different remodeling capacities. That this functionally important reorganization can be driven by oligomerization patterns that reduce the energy cost of the residual mismatch, suggests a new perspective on GPCR dimerization and ligand-GPCR interactions. The relation between the modulatory effects on GPCRs from the binding of specific cell-membrane components, e.g., cholesterol, and those produced by the non-local energetics of hydrophobic mismatch are discussed in this context.
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Affiliation(s)
- Sayan Mondal
- Department of Physiology and Biophysics, Weill Cornell Medical College, Cornell University, Room E-509, 1300 York Avenue, 10065, New York City, NY, USA
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11
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Michino M, Donthamsetti P, Beuming T, Banala A, Duan L, Roux T, Han Y, Trinquet E, Newman AH, Javitch JA, Shi L. A single glycine in extracellular loop 1 is the critical determinant for pharmacological specificity of dopamine D2 and D3 receptors. Mol Pharmacol 2013; 84:854-64. [PMID: 24061855 DOI: 10.1124/mol.113.087833] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Subtype-selective agents for the dopamine D3 receptor (D3R) have been considered as potential medications for drug addiction and other neuropsychiatric disorders. Medicinal chemistry efforts have led to the discovery of 4-phenylpiperazine derivatives that are >100-fold selective for the dopamine D3 receptor over dopamine D2 receptor (D2R), despite high sequence identity (78% in the transmembrane domain). Based on the recent crystal structure of D3R, we demonstrated that the 4-phenylpiperazine moiety in this class of D3R-selective compounds binds to the conserved orthosteric binding site, whereas the extended aryl amide moiety is oriented toward a divergent secondary binding pocket (SBP). In an effort to further characterize molecular determinants of the selectivity of these compounds, we modeled their binding modes in D3R and D2R by comparative ligand docking and molecular dynamics simulations. We found that the aryl amide moiety in the SBP differentially induces conformational changes in transmembrane segment 2 and extracellular loop 1 (EL1), which amplify the divergence of the SBP in D3R and D2R. Receptor chimera and site-directed mutagenesis studies were used to validate these binding modes and to identify a divergent glycine in EL1 as critical to D3R over D2R subtype selectivity. A better understanding of drug-dependent receptor conformations such as these is key to the rational design of compounds targeting a specific receptor among closely related homologs, and may also lead to discovery of novel chemotypes that exploit subtle differences in protein conformations.
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Affiliation(s)
- Mayako Michino
- Department of Physiology and Biophysics, Institute for Computational Biomedicine, Weill Medical College of Cornell University, New York, New York (M.M., L.S.); Departments of Psychiatry and Pharmacology, Columbia University College of Physicians and Surgeons, New York, New York (P.D., L.D., Y.H., J.A.J.); Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, New York (P.D., L.D., Y.H., J.A.J.); Schrödinger, Inc., New York, New York (T.B.); Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, Intramural Research Program of the National Institutes of Health National Institute on Drug Abuse, Baltimore, Maryland (A.B., A.H.N.); and Cisbio Bioassays, Codolet, France (T.R., E.T.)
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12
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Rathmann D, Pedragosa-Badia X, Beck-Sickinger AG. In vitro modification of substituted cysteines as tool to study receptor functionality and structure-activity relationships. Anal Biochem 2013; 439:173-83. [PMID: 23624320 DOI: 10.1016/j.ab.2013.04.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 04/11/2013] [Accepted: 04/16/2013] [Indexed: 12/11/2022]
Abstract
Mutagenic investigations of expressed membrane proteins are routine, but the variety of modifications is limited by the twenty canonical amino acids. We describe an easy and effective cysteine substitution mutagenesis method to modify and investigate distinct amino acids in vitro. The approach combines the substituted cysteine accessibility method (SCAM) with a functional signal transduction readout system using different thiol-specific reagents. We applied this approach to the prolactin-releasing peptide receptor (PrRPR) to facilitate biochemical structure-activity relationship studies of eight crucial positions. Especially for D(6.59)C, the treatment with the positively charged methanethiosulfonate (MTS) ethylammonium led to an induced basal activity, whereas the coupling of the negatively charged MTS ethylsulfonate nearly reconstituted full activity, obviously by mimicking the wild-type charged side chain. At E(5.26)C, W(5.28)C, Y(5.38)C, and Q(7.35)C, accessibility was observed but hindered transfer into the active receptor conformation. Accordingly, the combination of SCAM and signaling assay is feasible and can be adapted to other G-protein-coupled receptors (GPCRs). This method circumvents the laborious way of inserting non-proteinogenic amino acids to investigate activity and ligand binding, with rising numbers of MTS reagents allowing selective side chain modification. This method pinpoints to residues being accessible but also presents potential molecular positions to investigate the global conformation.
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Affiliation(s)
- Daniel Rathmann
- Institute of Biochemistry, Faculty of Biosciences, Pharmacy and Psychology, Leipzig University, D-04103 Leipzig, Germany
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13
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Soriano-Ursúa MA, Ocampo-López JO, Ocampo-Mendoza K, Trujillo-Ferrara JG, Correa-Basurto J. Theoretical study of 3-D molecular similarity and ligand binding modes of orthologous human and rat D2 dopamine receptors. Comput Biol Med 2011; 41:537-45. [PMID: 21621758 DOI: 10.1016/j.compbiomed.2011.04.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 04/27/2011] [Accepted: 04/29/2011] [Indexed: 02/07/2023]
Abstract
The D(2) dopamine receptor (D(2)DR) is an important target for the treatment of some central nervous system disorders, such as Parkinson disease, schizophrenia and drug-dependence. In this work, we built 3-D models of the long form of human and rat D(2)DRs by considering data from the crystallized D3 dopamine receptor, β2 adrenoceptor and A2a adenosine receptor as templates. Then, docking was performed with ligand and protein residue flexibility. These results were used to analyze ligand recognition and estimate binding affinity. Our results show that the predicted ligand affinity correlates with experimental data, and binding modes are very similar between the D(2)DRs of these two species.
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Affiliation(s)
- Marvin A Soriano-Ursúa
- Departamento de Bioquímica, Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón, 11340 México, Mexico
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14
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Zhao Y, Lu X, Yang CY, Huang Z, Fu W, Hou T, Zhang J. Computational modeling toward understanding agonist binding on dopamine 3. J Chem Inf Model 2011; 50:1633-43. [PMID: 20695484 DOI: 10.1021/ci1002119] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dopamine 3 (D3) receptor is a promising therapeutic target for the treatment of nervous system disorders, such as Parkinson's disease, and current research interests primarily focus on the discovery/design of potent D3 agonists. Herein, a well-designed computational protocol, which combines pharmacophore identification, homology modeling, molecular docking, and molecular dynamics (MD) simulations, was employed to understand the agonist binding on D3 aiming to provide insights into the development of novel potent D3 agonists. We (1) identified the chemical features required in effective D3 agonists by pharmacophore modeling based upon 18 known diverse D3 agonists; (2) constructed the three-dimensional (3D) structure of D3 based on homology modeling and the pharmacophore hypothesis; (3) identified the binding modes of the agonists to D3 by the correlation between the predicted binding free energies and the experimental values; and (4) investigated the induced fit of D3 upon agonist binding through MD simulations. The pharmacophore models of the D3 agonists and the 3D structure of D3 can be used for either ligand- or receptor-based drug design. Furthermore, the MD simulations further give the insight that the long and flexible EL2 acts as a "door" for agonist binding, and the "ionic lock" at the bottom of TM3 and TM6 is essential to transduce the activation signal.
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Affiliation(s)
- Yaxue Zhao
- Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, China
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15
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Abstract
G protein-coupled receptors (GPCRs) comprise a large class of transmembrane proteins that play critical roles in both normal physiology and pathophysiology. These critical roles offer targets for therapeutic intervention, as exemplified by the substantial fraction of current pharmaceutical agents that target members of this family. Tremendous contributions to our understanding of GPCR structure and dynamics have come from both indirect and direct structural characterization techniques. Key features of GPCR conformations derived from both types of characterization techniques are reviewed.
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Affiliation(s)
- Abby L. Parrill
- Department of Chemistry, The University of Memphis, Memphis, TN 38152, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-901-678-2638; Fax: +1-901-678-3447
| | - Debra L. Bautista
- Christian Brothers High School, 5900 Walnut Grove Road, Memphis, TN 38120, USA; E-Mail: (D.L.B.)
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16
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Ortore G, Tuccinardi T, Orlandini E, Martinelli A. Different Binding Modes of Structurally Diverse Ligands for Human D3DAR. J Chem Inf Model 2010; 50:2162-75. [DOI: 10.1021/ci100290f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gabriella Ortore
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Tiziano Tuccinardi
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Elisabetta Orlandini
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy
| | - Adriano Martinelli
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy
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17
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Tehan BG, Lloyd EJ, Wong MG, Chalmers DK. Analysis of agonism by dopamine at the dopaminergic D 2 G-protein coupled receptor based on comparative modelling of rhodopsin. MOLECULAR SIMULATION 2010. [DOI: 10.1080/0892702021000002548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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18
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McRobb FM, Capuano B, Crosby IT, Chalmers DK, Yuriev E. Homology Modeling and Docking Evaluation of Aminergic G Protein-Coupled Receptors. J Chem Inf Model 2010; 50:626-37. [DOI: 10.1021/ci900444q] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Fiona M. McRobb
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - Ben Capuano
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - Ian T. Crosby
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - David K. Chalmers
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
| | - Elizabeth Yuriev
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 381 Royal Parade, Parkville, VIC 3052 Australia
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19
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Katritch V, Reynolds KA, Cherezov V, Hanson MA, Roth CB, Yeager M, Abagyan R. Analysis of full and partial agonists binding to beta2-adrenergic receptor suggests a role of transmembrane helix V in agonist-specific conformational changes. J Mol Recognit 2009; 22:307-18. [PMID: 19353579 DOI: 10.1002/jmr.949] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The 2.4 A crystal structure of the beta(2)-adrenergic receptor (beta(2)AR) in complex with the high-affinity inverse agonist (-)-carazolol provides a detailed structural framework for the analysis of ligand recognition by adrenergic receptors. Insights into agonist binding and the corresponding conformational changes triggering G-protein coupled receptor (GPCR) activation mechanism are of special interest. Here we show that while the carazolol pocket captured in the beta(2)AR crystal structure accommodates (-)-isoproterenol and other agonists without steric clashes, a finite movement of the flexible extracellular part of TM-V helix (TM-Ve) obtained by receptor optimization in the presence of docked ligand can further improve the calculated binding affinities for agonist compounds. Tilting of TM-Ve towards the receptor axis provides a more complete description of polar receptor-ligand interactions for full and partial agonists, by enabling optimal engagement of agonists with two experimentally identified anchor sites, formed by Asp113/Asn312 and Ser203/Ser204/Ser207 side chains. Further, receptor models incorporating a flexible TM-V backbone allow reliable prediction of binding affinities for a set of diverse ligands, suggesting potential utility of this approach to design of effective and subtype-specific agonists for adrenergic receptors. Systematic differences in capacity of partial, full and inverse agonists to induce TM-V helix tilt in the beta(2)AR model suggest potential role of TM-V as a conformational "rheostat" involved in the whole spectrum of beta(2)AR responses to small molecule signals.
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Affiliation(s)
- Vsevolod Katritch
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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20
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Domazet I, Martin SS, Holleran BJ, Morin ME, Lacasse P, Lavigne P, Escher E, Leduc R, Guillemette G. The fifth transmembrane domain of angiotensin II Type 1 receptor participates in the formation of the ligand-binding pocket and undergoes a counterclockwise rotation upon receptor activation. J Biol Chem 2009; 284:31953-61. [PMID: 19773549 DOI: 10.1074/jbc.m109.051839] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The octapeptide hormone angiotensin II exerts a wide variety of cardiovascular effects through the activation of the angiotensin II Type 1 (AT(1)) receptor, which belongs to the G protein-coupled receptor superfamily. Like other G protein- coupled receptors, the AT(1) receptor possesses seven transmembrane domains that provide structural support for the formation of the ligand-binding pocket. The role of the fifth transmembrane domain (TMD5) was investigated using the substituted cysteine accessibility method. All of the residues within Thr-190 to Leu-217 region were mutated one at a time to cysteine, and after expression in COS-7 cells, the mutant receptors were treated with the sulfhydryl-specific alkylating agent methanethiosulfonate-ethylammonium (MTSEA). MTSEA reacts selectively with water-accessible, free sulfhydryl groups of endogenous or introduced point mutation cysteines. If a cysteine is found in the binding pocket, the covalent modification will affect the binding kinetics of the ligand. MTSEA substantially decreased the binding affinity of L197C-AT(1), N200C-AT(1), I201C-AT(1), G203C-AT(1), and F204C-AT(1) mutant receptors, which suggests that these residues orient themselves within the water-accessible binding pocket of the AT(1) receptor. Interestingly, this pattern of acquired MTSEA sensitivity was altered for TMD5 reporter cysteines engineered in a constitutively active N111G-AT(1) receptor background. Indeed, mutant I201C-N111G-AT(1) became more sensitive to MTSEA, whereas mutant G203C-N111G-AT(1) lost some sensitivity. Our results suggest that constitutive activation of AT(1) receptor causes an apparent counterclockwise rotation of TMD5 as viewed from the extracellular side.
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Affiliation(s)
- Ivana Domazet
- Department of Pharmacology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
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21
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Ahuja S, Hornak V, Yan ECY, Syrett N, Goncalves JA, Hirshfeld A, Ziliox M, Sakmar TP, Sheves M, Reeves PJ, Smith SO, Eilers M. Helix movement is coupled to displacement of the second extracellular loop in rhodopsin activation. Nat Struct Mol Biol 2009; 16:168-75. [PMID: 19182802 PMCID: PMC2705779 DOI: 10.1038/nsmb.1549] [Citation(s) in RCA: 183] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2008] [Accepted: 01/02/2009] [Indexed: 11/30/2022]
Abstract
The second extracellular loop (EL2) of rhodopsin forms a cap over the binding site of its photoreactive 11-cis retinylidene chromophore. A critical question has been whether EL2 forms a reversible gate that opens upon activation or acts as a rigid barrier. Distance measurements using solid-state 13C NMR spectroscopy between the retinal chromophore and the β4 strand of EL2 show the loop is displaced from the retinal binding site upon activation, and there is a rearrangement in the hydrogen-bonding networks connecting EL2 with the extracellular ends of transmembrane helices H4, H5 and H6. NMR measurements further reveal that structural changes in EL2 are coupled to the motion of helix H5 and breaking of the ionic lock that regulates activation. These results provide a comprehensive view of how retinal isomerization triggers helix motion and activation in this prototypical G protein-coupled receptor.
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Affiliation(s)
- Shivani Ahuja
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-5215, USA
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22
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Ahuja S, Crocker E, Eilers M, Hornak V, Hirshfeld A, Ziliox M, Syrett N, Reeves PJ, Khorana HG, Sheves M, Smith SO. Location of the retinal chromophore in the activated state of rhodopsin*. J Biol Chem 2009; 284:10190-201. [PMID: 19176531 DOI: 10.1074/jbc.m805725200] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Rhodopsin is a highly specialized G protein-coupled receptor (GPCR) that is activated by the rapid photochemical isomerization of its covalently bound 11-cis-retinal chromophore. Using two-dimensional solid-state NMR spectroscopy, we defined the position of the retinal in the active metarhodopsin II intermediate. Distance constraints were obtained between amino acids in the retinal binding site and specific (13)C-labeled sites located on the beta-ionone ring, polyene chain, and Schiff base end of the retinal. We show that the retinal C20 methyl group rotates toward the second extracellular loop (EL2), which forms a cap on the retinal binding site in the inactive receptor. Despite the trajectory of the methyl group, we observed an increase in the C20-Gly(188) (EL2) distance consistent with an increase in separation between the retinal and EL2 upon activation. NMR distance constraints showed that the beta-ionone ring moves to a position between Met(207) and Phe(208) on transmembrane helix H5. Movement of the ring toward H5 was also reflected in increased separation between the Cepsilon carbons of Lys(296) (H7) and Met(44) (H1) and between Gly(121) (H3) and the retinal C18 methyl group. Helix-helix interactions involving the H3-H5 and H4-H5 interfaces were also found to change in the formation of metarhodopsin II reflecting increased retinal-protein interactions in the region of Glu(122) (H3) and His(211) (H5). We discuss the location of the retinal in metarhodopsin II and its interaction with sequence motifs, which are highly conserved across the pharmaceutically important class A GPCR family, with respect to the mechanism of receptor activation.
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Affiliation(s)
- Shivani Ahuja
- Departments of Physics & Astronomy and Biochemistry & Cell Biology, Stony Brook University, Stony Brook, New York 11794-5215
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23
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Nebane NM, Hurst DP, Carrasquer CA, Qiao Z, Reggio PH, Song ZH. Residues accessible in the binding-site crevice of transmembrane helix 6 of the CB2 cannabinoid receptor. Biochemistry 2009; 47:13811-21. [PMID: 19053233 DOI: 10.1021/bi8007802] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We have used the substituted-cysteine accessibility method (SCAM) to map the residues in the sixth membrane-spanning segment of the CB2 cannabinoid receptor that contribute to the surface of the water-accessible binding-site crevice. Using a background of the mutant C2.59S which is relatively insensitive to the methanethiosulfonate (MTS) reagents, we mutated to cysteine, one at a time, 34 consecutive residues in TMH6 of the CB2 receptor. These mutant receptors were then expressed in HEK293 cells. By incubating HEK293 cells stably transfected with CB2 receptors with the small, charged, hydrophilic, thiol-specific reagent methanethiosulfonate ethylammonium (MTSEA), [(3)H]CP55940 binding was significantly inhibited for six mutant receptors. All six of the mutants that reacted with MTSEA were protected from the reaction when pretreated with the cannabinoid agonist WIN55212-2, suggesting that MTSEA modification occurred within the binding crevice. Therefore, the side chains of the residues at these reactive loci (V6.51, L6.52, L6.54, M6.55, L6.59, and T6.62) are on the water-accessible surface of the binding-site crevice. These residues are extracellular to the TMH6 CWXP hinge motif. The pattern of accessibility is consistent with a alpha-helical conformation for this segment of TMH6. Molecular modeling studies performed in the context of the CB2 model show that V6.51, L6.52, L6.54, M6.55, L6.59, and T6.62 face into the CB2 binding pocket, further confirming our SCAM results. These results are similar to the accessibility patterns determined by SCAM studies of TMH6 in the opioid and dopamine D2 receptors.
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Affiliation(s)
- Ntsang M Nebane
- Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Louisville, Kentucky 40292, USA
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24
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Roth CB, Hanson MA, Stevens RC. Stabilization of the human beta2-adrenergic receptor TM4-TM3-TM5 helix interface by mutagenesis of Glu122(3.41), a critical residue in GPCR structure. J Mol Biol 2007; 376:1305-19. [PMID: 18222471 DOI: 10.1016/j.jmb.2007.12.028] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2007] [Revised: 12/07/2007] [Accepted: 12/12/2007] [Indexed: 11/26/2022]
Abstract
G protein-coupled receptor (GPCR) instability represents one of the most profound obstacles in the structural study of GPCRs that bind diffusible ligands. The introduction of targeted mutations at nonconserved residues that lie proximal to helix interfaces has the potential to enhance the fold stability of the receptor helix bundle while maintaining wild-type receptor function. To test this hypothesis, we studied the effect of amino acid substitutions at Glu122(3.41) in the well-studied beta(2)-adrenergic receptor (beta(2)AR), which was predicted from sequence conservation to lie at a position equivalent to a tryptophan residue in rhodopsin at the 3,4,5 helix interface among transmembrane (TM) domains 3, 4, and 5. Replacement of Glu122(3.41) with bulky hydrophobic residues, such as tryptophan, tyrosine, and phenylalanine, increases the yield of functionally folded beta(2)AR by as much as 5-fold. Receptor stability in detergent solution was studied by isothermal denaturation, and it was found that the E122W and E122Y mutations enhanced the beta(2)AR thermal half-life by 9.3- and 6.7-fold, respectively, at 37 degrees C. The beta(1)AR was also stabilized by the introduction of tryptophan at Glu147(3.41), and the effect on protein behavior was similar to the rescue of the unstable wild-type receptor by the antagonist propranolol. Molecular modeling of the E122W and E122Y mutants revealed that the tryptophan ring edge and tyrosine hydroxyl are positioned proximal to the helical break in TM5 introduced by the conserved Pro211(5.50) and may stabilize the helix by interacting favorably with the unpaired carbonyl oxygen of Val206(5.45). Conformational flexibility of TM5 is likely to be a general property of class A GPCRs; therefore, engineering of the TM4-TM3-TM5 interface at the 3.41 position may provide a general strategy for the stabilization of other receptors.
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Affiliation(s)
- Christopher B Roth
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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25
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Al-Fulaij MA, Ren Y, Beinborn M, Kopin AS. Identification of amino acid determinants of dopamine 2 receptor synthetic agonist function. J Pharmacol Exp Ther 2007; 321:298-307. [PMID: 17204745 DOI: 10.1124/jpet.106.116384] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human dopamine 2 receptor (hD2R) modulates locomotor activity, hormone secretion, and neuropsychiatric function. Current knowledge of the hD2R structure is in large part derived from mutagenesis studies and molecular pharmacologic analysis together with homology modeling using bovine rhodopsin as a template. In this study, we utilized comparison of the Drosophila D2-like receptor (DD2R) with the hD2R as a novel approach for identifying candidate amino acids that are determinants of ligand potency and/or efficacy. We focused our studies on four dopaminergic ligands that are used in the treatment of Parkinson's disease: bromocriptine, pergolide, piribedil, and ropinirole. All four ligands are potent agonists at the wild-type hD2R, whereas only bromocriptine shows comparable function at the DD2R. We performed site-directed mutagenesis to replace hD2R amino acids (modeled to project into the ligand binding pocket) with corresponding fly residues, and vice versa. Substitution of three amino acids in the hD2R with the homologous DD2R residues (V91A, C118S, and L170I) led to a pronounced loss of pergolide potency and efficacy. A converse triple amino acid substitution of human residues into the fly receptor (DD2R-A133V/S160C/I211L) markedly enhanced pergolide efficacy and potency at the mutant DD2R. The same substitutions also converted piribedil and ropinirole, which lacked appreciable activity on the DD2R, to partial agonists. These findings show the important role of these three residues in drug-receptor interactions. Our study illustrates that comparison of a mammalian receptor with an invertebrate homolog complements previously described strategies for defining G protein-coupled receptor structure-function relationships.
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Affiliation(s)
- Munya A Al-Fulaij
- Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA
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26
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Abaffy T, Malhotra A, Luetje CW. The Molecular Basis for Ligand Specificity in a Mouse Olfactory Receptor. J Biol Chem 2007; 282:1216-24. [PMID: 17114180 DOI: 10.1074/jbc.m609355200] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sequence differences between members of the mouse olfac-tory receptor MOR42 subfamily (MOR42-3 and MOR42-1) are likely to be the basis for variation in ligand binding preference among these receptors. We investigated the specificity of MOR42-3 for a variety of dicarboxylic acids. We used site-directed mutagenesis, guided by homology modeling and ligand docking studies, to locate functionally important residues. Receptors were expressed in Xenopus oocytes and assayed using high throughput electrophysiology. The importance of the Val-113 residue, located deep within the receptor, was analyzed in the context of interhelical interactions. We also screened additional residues predicted to be involved in ligand binding site, based on comparison of ortholog/paralog pairs from the mouse and human olfactory receptor genomes (Man, O., Gilad, Y., and Lancet, D. (2004) Protein Sci. 13, 240-254). A network of 8 residues in transmembrane domains III, V, and VI was identified. These residues form part of the ligand binding pocket of MOR42-3. C12 dicarboxylic acid did not activate the receptor in our functional assay, yet our docking simulations predicted its binding site in MOR42-3. Binding without activation implied that C12 dicarboxylic acid might act as an antagonist. In our functional assay, C12 dicarboxylic acid did indeed act as an antagonist of MOR42-3, in agreement with molecular docking studies. Our results demonstrate a powerful approach based on the synergy between computational predictions and physiological assays.
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Affiliation(s)
- Tatjana Abaffy
- Department of Molecular and Cellular Pharmacology, University of Miami, Miami, Florida 33101, USA.
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27
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Chen L, Durkin KA, Casida JE. Spontaneous mobility of GABAA receptor M2 extracellular half relative to noncompetitive antagonist action. J Biol Chem 2006; 281:38871-8. [PMID: 17050528 DOI: 10.1074/jbc.m608301200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The gamma-aminobutyric acid type A receptor beta(3) homopentamer is spontaneously open and highly sensitive to many noncompetitive antagonists(NCAs) and Zn(2+). Our earlier study of the M2 cytoplasmic half (-1' to 10') established a model in which NCAs bind at pore-lining residues Ala(2)', Thr(6)', and Leu(9)'. To further define transmembrane 2 (M2) structure relative to NCA action, we extended the Cys scanning to the extra cellular half of the beta(3) homopentamer (11' to 20'). Spontaneous disulfides formed with T13'C, L18'C, and E20'C from M2/M2 cross-linking and with I14'C (weak), H17'C, and R19'Con bridging M2/M3 intersubunits, based on single (M2 Cys only) and dual (M2 Cys plus M3 C289S) mutations. Induced disulfides also formed with T16'C, but there were few or none with M11'C, T12'C, and N15'C. These findings show conformational flexibility/mobility in the M2 extracellular half 17' to 20' region interpreted as a deformed beta-like conformation in the open channel. The NCA radioligands used were [(3)H]1-(4-ethynylphenyl)-4-n-propyl-2,6,7-trioxabicyclo[2.2.2]octane ([(3)H]EBOB) and [(3)H]3,3-bis-trifluoromethylbicyclo[2.2.1]heptane-2,2-dicarbonitrile with essentially the same results. NCA binding was disrupted by individual Cys substitutions at 13',14',16',17', and 19'. The inactivity of T13'C/T13'S may have been due to disturbance of the channel gate; I14'S and T16'S showed much better binding activity than their Cys counterparts, and the low activities of H17'C and R19'C were reversed by dithiothreitol. Zn(2+) potency for inhibition of [(3)H]EBOB binding was lowered 346-fold by the mutation H17'A. We propose that NCAs enter their binding site both directly, through the channel pore, and indirectly, through the water cavity of adjacent subunits.
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Affiliation(s)
- Ligong Chen
- Environmental Chemistry and Toxicology Laboratory, Department of Environmental Science, Policy, and Management, College of Chemistry, University of California-Berkeley, CA 94720, USA
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28
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Hobrath JV, Wang S. Computational elucidation of the structural basis of ligand binding to the dopamine 3 receptor through docking and homology modeling. J Med Chem 2006; 49:4470-6. [PMID: 16854052 DOI: 10.1021/jm0501634] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The dopamine subtype 3 receptor (D3) is a promising therapeutic target for the treatment of cocaine addiction, schizophrenia, Parkinson's disease, and other disorders, but little is known about the binding of ligands to D3 at the atomic level. In the present study, binding of 29 known ligands to the D3 receptor was modeled computationally using four D3 receptor models which were obtained from homology modeling. The predicted binding models were validated with experimental data from site-directed mutagenesis, structure-activity relationship studies, and affinity labeling studies. Docking scores calculated for these 29 ligands correlate reasonably well with the experimentally determined binding affinities. A pharmacophore model is proposed that describes the binding of ligands at a single D3 receptor binding site and offers insights into the binding of structurally diverse D3 ligands to this receptor.
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Affiliation(s)
- Judith Varady Hobrath
- Department of Internal Medicine, University of Michigan, 1500 E. Medical Center Drive, Ann Arbor, Michigan 48109-0934, USA
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29
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Boeckler F, Gmeiner P. The structural evolution of dopamine D3 receptor ligands: structure-activity relationships and selected neuropharmacological aspects. Pharmacol Ther 2006; 112:281-333. [PMID: 16905195 DOI: 10.1016/j.pharmthera.2006.04.007] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Accepted: 04/13/2006] [Indexed: 01/13/2023]
Abstract
"Evolution consists largely of molecular tinkering."-Following the famous concept of the molecular geneticist and medicine Nobel laureate François Jacob, in this review we describe the structural evolution of dopamine D3 receptor ligands from the natural agonist dopamine (DA) to highly potent and subtype selective new agents by bioisosteric tinkering with well-established and privileged or novel and fancy chemical functionalities and scaffolds. Some of the more than 200 ligands presented herein have already achieved therapeutic or scientific value up to now, some will most likely achieve it in the future. Hence, great importance is not only attached to the relationship between structure and activity of the ligands, but also to their utility as pharmacological tools in animal models or as therapeutics in patients with neurological diseases or other disorders.
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Affiliation(s)
- Frank Boeckler
- Department of Medicinal Chemistry, Emil Fischer Center, Friedrich-Alexander University Erlangen-Nürnberg, Schuhstrasse 19, 91052 Erlangen, Germany.
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30
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Xhaard H, Rantanen VV, Nyrönen T, Johnson MS. Molecular evolution of adrenoceptors and dopamine receptors: implications for the binding of catecholamines. J Med Chem 2006; 49:1706-19. [PMID: 16509586 DOI: 10.1021/jm0511031] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We derived homology models for all human catecholamine-binding GPCRs (CABRs; the alpha-1, alpha-2, and beta-adrenoceptors and the D1-type and D2-type dopamine receptor) using the bovine rhodopsin-11-cis-retinal X-ray structure. Interactions were predicted from the endogenous ligands norepinephrine or dopamine and from the binding site and were used to optimize receptor-ligand interactions. Similar binding modes in the complexes agree with a large "binding core" conserved across the CABRs, that is, D3.32, V(I)3.33, T3.37, S5.42, S(A/C)5.43, S5.46, F6.51, F6.52, and W6.48. Model structures and docking simulations suggest that extracellular loop 2 could provide a common attachment point for the ligands' beta-hydroxyl via a hydrogen bond donated by the main-chain NH group of residue xl2.52. The modeled CABRs and docking modes are in good agreement with published experimental studies. Complementarity between the ligand and the binding site suggests that the bovine rhodopsin structure is a suitable template for modeling agonist-bound CABRs.
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Affiliation(s)
- Henri Xhaard
- Department of Biochemistry and Pharmacy, Abo Akademi University, FI-20520 Turku, Finland
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31
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Schwartz TW, Frimurer TM, Holst B, Rosenkilde MM, Elling CE. Molecular mechanism of 7TM receptor activation--a global toggle switch model. Annu Rev Pharmacol Toxicol 2006; 46:481-519. [PMID: 16402913 DOI: 10.1146/annurev.pharmtox.46.120604.141218] [Citation(s) in RCA: 316] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The multitude of chemically highly different agonists for 7TM receptors apparently do not share a common binding mode or active site but nevertheless act through induction of a common molecular activation mechanism. A global toggle switch model is proposed for this activation mechanism to reconcile the accumulated biophysical data supporting an outward rigid-body movement of the intracellular segments, as well as the recent data derived from activating metal ion sites and tethered ligands, which suggests an opposite, inward movement of the extracellular segments of the transmembrane helices. According to this model, a vertical see-saw movement of TM-VI-and to some degree TM-VII-around a pivot corresponding to the highly conserved prolines will occur during receptor activation, which may involve the outer segment of TM-V in an as yet unclear fashion. Small-molecule agonists can stabilize such a proposed active conformation, where the extracellular segments of TM-VI and -VII are bent inward toward TM-III, by acting as molecular glue deep in the main ligand-binding pocket between the helices, whereas larger agonists, peptides, and proteins can stabilize a similar active conformation by acting as Velcro at the extracellular ends of the helices and the connecting loops.
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Affiliation(s)
- Thue W Schwartz
- Laboratory for Molecular Pharmacology, The Panum Institute, University of Copenhagen, and 7TM Pharma A/S, Hørsholm, Denmark.
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32
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Ortore G, Tuccinardi T, Bertini S, Martinelli A. A theoretical study to investigate D2DAR/D4DAR selectivity: receptor modeling and molecular docking of dopaminergic ligands. J Med Chem 2006; 49:1397-407. [PMID: 16480275 DOI: 10.1021/jm051046b] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular modeling methods have been applied to construct three-dimensional models for dopaminergic ligand complexes with D2 and D4 receptor subtypes (D2DAR and D4DAR), using the bovine rhodopsin crystal structure as a template for the modeling study. Different dopaminergic ligands, in particular the N-n-propyl-substituted 3-aryl- and 3-cyclohexylpiperidines, were docked into the D2DAR and the D4DAR, to evaluate the agreement between theoretical and experimental results as regards their D2/D4 selectivity. The different position of an aromatic region in the two receptors might explain the structural basis of this biological property.
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Affiliation(s)
- Gabriella Ortore
- Dipartimento di Scienze Farmaceutiche, Università di Pisa, via Bonanno 6, 56126 Pisa, Italy
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33
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Lan H, Durand CJ, Teeter MM, Neve KA. Structural Determinants of Pharmacological Specificity Between D1and D2Dopamine Receptors. Mol Pharmacol 2005; 69:185-94. [PMID: 16236817 DOI: 10.1124/mol.105.017244] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To test the hypothesis that pharmacological differentiation between D(1) and D(2) dopamine receptors results from interactions of selective ligands with nonconserved residues lining the binding pocket, we mutated amino acid residues in the D(2) receptor to the corresponding aligned residues in the D(1) receptor and vice versa and expressed the receptors in human embryonic kidney 293 cells. Determinations of the affinity of the 14 mutant D(2) receptors and 11 mutant D(1) receptors for D(1)- and D(2)-selective antagonists, and rhodopsin-based homology models of the two receptors, identified two residues whose direct interactions with certain ligands probably contribute to ligand selectivity. The D(1) receptor mutant W99(3.28)F showed dramatically increased affinity for several D(2)-selective antagonists, particularly spiperone (225-fold), whereas the D(2) receptor mutant Y417(7.43)W had greatly decreased affinity for benzamide ligands such as raclopride (200-fold) and sulpiride (125-fold). The binding of the D(1)-selective ligand R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine (SCH23390) was unaffected, indicating that SCH23390 makes little contact with these ancillary pocket residues. Mutation of A/V(5.39) caused modest but consistent and reciprocal changes in affinity of the receptors for D(1) and D(2)-selective ligands, perhaps reflecting altered packing of the interface of helices 5 and 6. We also obtained some evidence that residues in the second extracellular loop contribute to ligand binding. We conclude that additional determinants of D(1)/D(2) receptor-selective binding are located either in that loop or in the transmembrane helices but, like residue 5.39, indirectly influence the interactions of selective ligands with conserved residues by altering the shape of the primary and ancillary binding pockets.
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Affiliation(s)
- Hongxiang Lan
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon, USA
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34
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Floresca CZ, Schetz JA. Dopamine receptor microdomains involved in molecular recognition and the regulation of drug affinity and function. J Recept Signal Transduct Res 2005; 24:207-39. [PMID: 15521362 DOI: 10.1081/rrs-200032088] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A cationic protonatable amine moiety on dopaminergic ligands forms a high affinity reinforced ionic bond with an anionic aspartic acid at position 3.32 of dopamine receptors. When present, catechol hydroxyls of the ligands form hydrogen bonds with serines at position 5.42, 5.43, and 5.46, and this network of hydrogen bonds serves to orient ligands in the binding-site crevice and increase their binding affinity. A steric clash between aromatic moieties of the ligands and aromatic amino acids of the receptor (e.g., H6.55, F6.52 or F6.51 and W6.48) is likely to be propagated in domino-like fashion along the length of TM6, which is believed to trigger activation of the receptor. Specifically, it is the change in the conformation of W6.48 from an orientation perpendicular to the plane of the lipid membrane to one that is parallel that is believed to result in activation. Molecular determinants that mediate the D4/D2-selectivity of many extremely D4-selective 1,4-DAP ligands, include a nonconserved cluster of bulky amino acids at the TM2/TM3 interface (positions 2.61, 3.28 and 3.29).
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Affiliation(s)
- Christina Z Floresca
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas 76107-2699, USA
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35
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Lavecchia A, Cosconati S, Novellino E. Architecture of the Human Urotensin II Receptor: Comparison of the Binding Domains of Peptide and Non-Peptide Urotensin II Agonists. J Med Chem 2005; 48:2480-92. [PMID: 15801838 DOI: 10.1021/jm049110x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The human urotensin II receptor (h-UTR) is a member of the family of rhodopsin-like G-protein-coupled receptors (GPCRs) involved in the modulation of the functionality of many tissues and organs. Recently the urotensin-II (UII) neuropeptide, which is a potent vasoconstrictor in mammals and it is postulated to play a central role in cardiovascular homeostasis, has been identified as an agonist of the UII receptor. To elucidate the receptor's molecular recognition, a h-UTR model was constructed by homology modeling using the 2.6 A crystal structure of bovine rhodopsin as a template and subsequently refined by molecular dynamics simulations. The molecular recognition of h-UTR was probed by automated docking of P5U, a potent UII peptide agonist, as well as of the non-peptide compounds 1-4. We believe that this new model of the h-UTR provides the means for understanding the ligand's potency and for facilitating the design of novel and more potent UII ligands.
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Affiliation(s)
- Antonio Lavecchia
- Dipartimento di Chimica Farmaceutica e Tossicologica, Università di Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy.
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36
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Evers A, Klabunde T. Structure-based Drug Discovery Using GPCR Homology Modeling: Successful Virtual Screening for Antagonists of the Alpha1A Adrenergic Receptor. J Med Chem 2005; 48:1088-97. [PMID: 15715476 DOI: 10.1021/jm0491804] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In this paper, we describe homology modeling of the alpha1A receptor based on the X-ray structure of bovine rhodopsin. The protein model has been generated by applying ligand-supported homology modeling, using mutational and ligand SAR data to guide the protein modeling procedure. We performed a virtual screening of the company's compound collection to test how well this model is suited to identify alpha1A antagonists. We applied a hierarchical virtual screening procedure guided by 2D filters and three-dimensional pharmacophore models. The ca. 23,000 filtered compounds were docked into the alpha1A homology model with GOLD and scored with PMF. From the top-ranked compounds, 80 diverse compounds were tested in a radioligand displacement assay. 37 compounds revealed K(i) values better than 10 microM; the most active compound binds with 1.4 nM to the alpha1A receptor. Our findings suggest that rhodopsin-based homology models may be used as the structural basis for GPCR lead finding and compound optimization.
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Affiliation(s)
- Andreas Evers
- Aventis Pharma Deutschland GmBH, Ein Unternehmen der Sanofi-Aventis Gruppe, DI&A Chemistry, Computational Chemistry, Industriepark Höchst, Building G838, D-65926 Frankfurt am Main, Germany.
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37
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Hjerde E, Dahl SG, Sylte I. Atypical and typical antipsychotic drug interactions with the dopamine D2 receptor. Eur J Med Chem 2005; 40:185-94. [PMID: 15694653 DOI: 10.1016/j.ejmech.2004.10.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2004] [Revised: 09/27/2004] [Accepted: 10/15/2004] [Indexed: 11/21/2022]
Abstract
A model of the dopamine D2 receptor was used to study the receptor interactions of dopamine, the typical antipsychotics haloperidol and loxapine, and the atypical antipsychotics clozapine and melperone. The atypical antipsychotics interacted with the halogen atom of the ring system in the direction of the transmembrane helices (TMHs) 2, 3 and 7, while the typical had the corresponding halogen atom in the direction of TMH5. Molecular dynamics simulations indicated that the average helical displacement upon binding increased in the order: typical < atypical < dopamine. Upon binding, the atypical induced larger displacements into TMH5 than did the typical. The typical had stronger non-bonded interactions with the receptor than had the atypical, which is in agreement with the experimental observation that the atypical antipsychotic drugs dissociate faster from the receptor than the typical antipsychotic drugs.
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Affiliation(s)
- Erik Hjerde
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway
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38
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Shacham S, Marantz Y, Bar-Haim S, Kalid O, Warshaviak D, Avisar N, Inbal B, Heifetz A, Fichman M, Topf M, Naor Z, Noiman S, Becker OM. PREDICT modeling and in-silico screening for G-protein coupled receptors. Proteins 2005; 57:51-86. [PMID: 15326594 DOI: 10.1002/prot.20195] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
G-protein coupled receptors (GPCRs) are a major group of drug targets for which only one x-ray structure is known (the nondrugable rhodopsin), limiting the application of structure-based drug discovery to GPCRs. In this paper we present the details of PREDICT, a new algorithmic approach for modeling the 3D structure of GPCRs without relying on homology to rhodopsin. PREDICT, which focuses on the transmembrane domain of GPCRs, starts from the primary sequence of the receptor, simultaneously optimizing multiple 'decoy' conformations of the protein in order to find its most stable structure, culminating in a virtual receptor-ligand complex. In this paper we present a comprehensive analysis of three PREDICT models for the dopamine D2, neurokinin NK1, and neuropeptide Y Y1 receptors. A shorter discussion of the CCR3 receptor model is also included. All models were found to be in good agreement with a large body of experimental data. The quality of the PREDICT models, at least for drug discovery purposes, was evaluated by their successful utilization in in-silico screening. Virtual screening using all three PREDICT models yielded enrichment factors 9-fold to 44-fold better than random screening. Namely, the PREDICT models can be used to identify active small-molecule ligands embedded in large compound libraries with an efficiency comparable to that obtained using crystal structures for non-GPCR targets.
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39
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Boeckler F, Lanig H, Gmeiner P. Modeling the Similarity and Divergence of Dopamine D2-like Receptors and Identification of Validated Ligand−Receptor Complexes. J Med Chem 2005; 48:694-709. [PMID: 15689154 DOI: 10.1021/jm049612a] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Focusing on the similarity and divergence of GPCR subtypes and their ligand interactions, we generated dopamine D2, D3, and D4 receptor models based on the rhodopsin crystal structure and refined these with an extensive MM/MD protocol. After validation by diagnostic experimental data, subtype-specific relative positions of TM1, 2, 6, and 7 and bending angles of TM7 were found. To sample the conformational space of the complex, we performed simulated-annealing runs of the receptor protein with the sub-nanomolar antagonist spiperone. Docking a representative set of ligands, we were able to identify one superior model for each subtype when excellent correlations between predicted energies of binding and experimental affinities (r2 = 0.72 for D2, 0.91 for D3 and 0.77 for D4) could be observed. Further analysis revealed general ligand interactions with ASP3.32 and aromatic residues in TM6/7 and individual key interactions with TM1 and TM2 residues of the D3 and D4 receptor models, respectively.
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Affiliation(s)
- Frank Boeckler
- Department of Medicinal Chemistry, Emil Fischer Center, Friedrich-Alexander University, Schuhstrasse 19, D-91052 Erlangen, Germany
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40
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Gouldson PR, Kidley NJ, Bywater RP, Psaroudakis G, Brooks HD, Diaz C, Shire D, Reynolds CA. Toward the active conformations of rhodopsin and the beta2-adrenergic receptor. Proteins 2004; 56:67-84. [PMID: 15162487 DOI: 10.1002/prot.20108] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Using sets of experimental distance restraints, which characterize active or inactive receptor conformations, and the X-ray crystal structure of the inactive form of bovine rhodopsin as a starting point, we have constructed models of both the active and inactive forms of rhodopsin and the beta2-adrenergic G-protein coupled receptors (GPCRs). The distance restraints were obtained from published data for site-directed crosslinking, engineered zinc binding, site-directed spin-labeling, IR spectroscopy, and cysteine accessibility studies conducted on class A GPCRs. Molecular dynamics simulations in the presence of either "active" or "inactive" restraints were used to generate two distinguishable receptor models. The process for generating the inactive and active models was validated by the hit rates, yields, and enrichment factors determined for the selection of antagonists in the inactive model and for the selection of agonists in the active model from a set of nonadrenergic GPCR drug-like ligands in a virtual screen using ligand docking software. The simulation results provide new insights into the relationships observed between selected biochemical data, the crystal structure of rhodopsin, and the structural rearrangements that occur during activation.
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41
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Kristiansen K. Molecular mechanisms of ligand binding, signaling, and regulation within the superfamily of G-protein-coupled receptors: molecular modeling and mutagenesis approaches to receptor structure and function. Pharmacol Ther 2004; 103:21-80. [PMID: 15251227 DOI: 10.1016/j.pharmthera.2004.05.002] [Citation(s) in RCA: 392] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The superfamily of G-protein-coupled receptors (GPCRs) could be subclassified into 7 families (A, B, large N-terminal family B-7 transmembrane helix, C, Frizzled/Smoothened, taste 2, and vomeronasal 1 receptors) among mammalian species. Cloning and functional studies of GPCRs have revealed that the superfamily of GPCRs comprises receptors for chemically diverse native ligands including (1) endogenous compounds like amines, peptides, and Wnt proteins (i.e., secreted proteins activating Frizzled receptors); (2) endogenous cell surface adhesion molecules; and (3) photons and exogenous compounds like odorants. The combined use of site-directed mutagenesis and molecular modeling approaches have provided detailed insight into molecular mechanisms of ligand binding, receptor folding, receptor activation, G-protein coupling, and regulation of GPCRs. The vast majority of family A, B, C, vomeronasal 1, and taste 2 receptors are able to transduce signals into cells through G-protein coupling. However, G-protein-independent signaling mechanisms have also been reported for many GPCRs. Specific interaction motifs in the intracellular parts of these receptors allow them to interact with scaffold proteins. Protein engineering techniques have provided information on molecular mechanisms of GPCR-accessory protein, GPCR-GPCR, and GPCR-scaffold protein interactions. Site-directed mutagenesis and molecular dynamics simulations have revealed that the inactive state conformations are stabilized by specific interhelical and intrahelical salt bridge interactions and hydrophobic-type interactions. Constitutively activating mutations or agonist binding disrupts such constraining interactions leading to receptor conformations that associates with and activate G-proteins.
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Affiliation(s)
- Kurt Kristiansen
- Department of Pharmacology, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway.
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42
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Shim JY, Welsh WJ, Howlett AC. Homology model of the CB1 cannabinoid receptor: sites critical for nonclassical cannabinoid agonist interaction. Biopolymers 2004; 71:169-89. [PMID: 12767117 DOI: 10.1002/bip.10424] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Association of cannabimimetic compounds such as cannabinoids, aminoalkylindoles (AAIs), and arachidonylethanolamide (anandamide) with the brain cannabinoid (CB(1)) receptor activates G-proteins and relays signals to regulate neuronal functions. A CB(1) receptor homology model was constructed using the published x-ray crystal structure of bovine rhodopsin (Palczewski et al., Science, 2000, Vol. 289, pp. 739-745) in the conformation most likely to represent the "high-affinity" state for agonist binding to G-protein coupled receptors (GPCRs). A molecular docking approach that combined Monte Carlo and molecular dynamics simulations was used to identify the putative binding conformations of nonclassical cannabinoid agonists, including AC-bicyclic CP47497 and CP55940, and ACD-tricyclic CP55244. Placement of these ligands was based upon the assumption of a critical hydrogen bond between the A-ring OH and the side chain N of Lys192 in transmembrane helix 3. We evaluated two alternative binding conformations, C3-in and C3-out, denoting the directionality of the ligand C3 side chain within the receptor with respect to the inside or the outside of the cell. Assuming both the C3-in or C3-out conformation, the calculated ligand-receptor binding energy (DeltaE(bind)) was correlated with the experimentally observed binding affinity (K(i)) for a series of nonclassical cannabinoid agonists. The C3-in conformation was marginally better than the alternative C3-out conformation in predicting the rank order of the tested nonclassical cannabinoid analogs. Adopting the C3-in conformation due to the greater number of receptor interactions with known pharmacophoric elements of the ligand, key residues were identified comprising the presumed hydrophobic pocket that interacts with the C3 side chain of cannabinoid agonists. Key hydrogen bonds would form between both K3.28(192) and E(258) and the A-ring OH, and between Q(261) and the C-ring C-12 hydroxypropyl. In summary, the present study represents one of the first attempts to construct a homology model of the CB(1) cannabinoid receptor based upon the published bovine rhodopsin x-ray crystal structure and to elucidate the putative ligand binding site for nonclassical cannabinoid agonists. We postulated sites of the CB(1) receptor critical for the ligand interaction, including the hydrophobic pocket interacting with the key pharmacophoric moiety, the C3 side chain. More work is needed to delineate between two alternative (and possibly other) binding conformations of the nonclassical cannabinoid ligands within the CB(1) receptor. The present study provides a consistent framework for further investigation of the CB(1) receptor-ligand interaction and for the study of CB(1) receptor activation.
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Affiliation(s)
- Joong-Youn Shim
- Department of Basic Pharmaceutical Sciences, College of Pharmacy, University of South Carolina, Columbia, SC 29208, USA.
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43
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Shi L, Javitch JA. The second extracellular loop of the dopamine D2 receptor lines the binding-site crevice. Proc Natl Acad Sci U S A 2004; 101:440-5. [PMID: 14704269 PMCID: PMC327166 DOI: 10.1073/pnas.2237265100] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The binding site of the dopamine D(2) receptor (D2R), like those of homologous rhodopsin-like G protein-coupled receptors (GPCRs) that bind small molecules, is contained within a water-accessible crevice formed among its seven transmembrane segments (TMs). The high-resolution structure of bovine rhodopsin, however, revealed that the second extracellular loop (E2), which connects TM4 and TM5, folds down into the transmembrane domain and forms part of the ligand-binding surface for retinal. Whether E2 plays a related role in other rhodopsin-like GPCRs is unclear. To address this issue, we have now mutated to cysteine, one at a time, 10 consecutive residues in E2 of D2R. The reaction of five of these mutants with sulfhydryl reagents inhibited antagonist binding, and bound antagonist protected two, I184C and N186C, from reaction. The pattern of accessibility in E2 is consistent with a structure similar to that of bovine rhodopsin, in which the region C-terminal to the conserved disulfide bond is deeper in the binding-site crevice than is the N-terminal part of E2. Thus, E2 likely contributes to the binding site in the D2R and probably in other aminergic GPCRs as well. Knowledge of its detailed positioning and interactions with ligand would benefit GPCR molecular modeling and facilitate the design of novel drugs.
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Affiliation(s)
- Lei Shi
- Center for Molecular Recognition, Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032, USA
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44
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Varady J, Wu X, Fang X, Min J, Hu Z, Levant B, Wang S. Molecular Modeling of the Three-Dimensional Structure of Dopamine 3 (D3) Subtype Receptor: Discovery of Novel and Potent D3 Ligands through a Hybrid Pharmacophore- and Structure-Based Database Searching Approach. J Med Chem 2003; 46:4377-92. [PMID: 14521403 DOI: 10.1021/jm030085p] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dopamine 3 (D3) subtype receptor has been implicated in several neurological conditions, and potent and selective D3 ligands may have therapeutic potential for the treatment of drug addiction, Parkinson's disease, and schizophrenia. In this paper, we report computational homology modeling of the D3 receptor based upon the high-resolution X-ray structure of rhodopsin, extensive structural refinement in the presence of explicit lipid bilayer and water environment, and validation of the refined D3 structural models using experimental data. We further describe the development, validation, and application of a hybrid computational screening approach for the discovery of several classes of novel and potent D3 ligands. This computational approach employs stepwise pharmacophore and structure-based searching of a large three-dimensional chemical database for the identification of potential D3 ligands. The obtained hits are then subjected to structural novelty screening, and the most promising compounds are tested in a D3 binding assay. Using this approach we identified four compounds with K(i) values better than 100 nM and eight compounds with K(i) values better than 1 microM out of 20 compounds selected for testing in the D3 receptor binding assay. Our results suggest that the D3 structural models obtained from this study may be useful for the discovery and design of novel and potent D3 ligands. Furthermore, the employed hybrid approach may be more effective for lead discovery from a large chemical database than either pharmacophore-based or structure-based database screening alone.
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Affiliation(s)
- Judith Varady
- Departments of Internal Medicine and Medicinal Chemistry, University of Michigan, 3-316 CCGC Box 0934, 1500 East Medical Center Drive, Ann Arbor, MI 48109-0934, USA
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45
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McFadyen I, Metzger T, Subramanian G, Poda G, Jorvig E, Ferguson DM. Molecular modeling of opioid receptor-ligand complexes. PROGRESS IN MEDICINAL CHEMISTRY 2003; 40:107-35. [PMID: 12516524 DOI: 10.1016/s0079-6468(08)70083-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Affiliation(s)
- Iain McFadyen
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
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46
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McAllister SD, Tao Q, Barnett-Norris J, Buehner K, Hurst DP, Guarnieri F, Reggio PH, Nowell Harmon KW, Cabral GA, Abood ME. A critical role for a tyrosine residue in the cannabinoid receptors for ligand recognition. Biochem Pharmacol 2002; 63:2121-36. [PMID: 12110371 DOI: 10.1016/s0006-2952(02)01031-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Previous mutation and modeling studies have identified an aromatic cluster in the transmembrane helix (TMH) 3-4-5 region as important for ligand binding at the CB(1) and CB(2) cannabinoid receptors. Through novel mixed mode Monte Carlo/Stochastic Dynamics (MC/SD) calculations, we tested the importance of aromaticity at position 5.39(275) in CB(1). MC/SD calculations were performed on wild-type (WT) CB(1) and two mutants, Y5.39(275)F and Y5.39(275)I. Results indicated that while the CB(1) Y5.39(275)F mutant is very similar to WT, the Y5.39(275)I mutant shows pronounced topology changes in the TMH 3-4-5 region. Site-directed mutagenesis studies of tyrosine 5.39 to phenylalanine (Y-->F) or isoleucine (Y-->I) in both CB(1) and CB(2) were performed to determine the functional role of this amino acid in each receptor subtype. HEK 293 cells transfected with mutant receptor cDNAs were evaluated in radioligand binding and cyclic AMP assays. The CB(1) mutant and WT receptors were also co-expressed with G-protein-coupled inwardly rectifying channels (GIRK1 and GIRK4) in Xenopus oocytes to assess functional coupling. The Y-->F mutation resulted in cannnabinoid receptors with subtle differences in WT binding and signal transduction. In contrast, the Y-->I mutations produced receptors that could not produce signal transduction or bind to multiple cannabinoid compounds. However, immunofluorescence data indicate that the Y-->I mutation was compartmentalized and expressed at a level similar to that of the WT cannabinoid receptor. These results underscore the importance of aromaticity at position CB(1) 5.39(275) and CB(2) 5.39(191) for ligand recognition in the cannabinoid receptors.
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Affiliation(s)
- Sean D McAllister
- Forbes Norris ALS/MDA Research Center, California Pacific Medical Center, San Francisco, CA 94115, USA
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47
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Shi L, Javitch JA. The binding site of aminergic G protein-coupled receptors: the transmembrane segments and second extracellular loop. Annu Rev Pharmacol Toxicol 2002; 42:437-67. [PMID: 11807179 DOI: 10.1146/annurev.pharmtox.42.091101.144224] [Citation(s) in RCA: 270] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the current chapter, we review approaches to the identification of the residues forming the binding sites for agonists, antagonists, and allosteric modulators in the family of aminergic G protein-coupled receptors (GPCRs). We then review the structural bases for ligand binding and pharmacological specificity based on the application of these methods to muscarinic cholinergic, adrenergic, dopaminergic, serotonergic, and histaminergic receptors, using the high resolution rhodopsin structure as a template. Furthermore, we propose a critical role of the second extracellular loop in forming the binding site for small molecular weight aminergic ligands, much as this loop dives down into the binding-site crevice and contacts retinal in rhodopsin.
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Affiliation(s)
- Lei Shi
- Center for Molecular Recognition and Department of Pharmacology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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48
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Javitch JA, Shi L, Liapakis G. Use of the substituted cysteine accessibility method to study the structure and function of G protein-coupled receptors. Methods Enzymol 2002; 343:137-56. [PMID: 11665562 DOI: 10.1016/s0076-6879(02)43131-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Jonathan A Javitch
- Center for Molecular Recognition and Departments of Psychiatry and Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
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49
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Ballesteros JA, Shi L, Javitch JA. Structural Mimicry in G Protein-Coupled Receptors: Implications of the High-Resolution Structure of Rhodopsin for Structure-Function Analysis of Rhodopsin-Like Receptors. Mol Pharmacol 2001. [DOI: 10.1124/mol.60.1.1] [Citation(s) in RCA: 357] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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50
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Dawson ES, Wells JN. Determination of amino acid residues that are accessible from the ligand binding crevice in the seventh transmembrane-spanning region of the human A(1) adenosine receptor. Mol Pharmacol 2001; 59:1187-95. [PMID: 11306703 DOI: 10.1124/mol.59.5.1187] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The substituted-cysteine accessibility method (SCAM) was applied to transmembrane span seven of the human A(1) adenosine receptor (hA(1)AR) to reveal a subset of amino acids that are exposed to the ligand-binding crevice. The SCAM approach involved a systematic probe of receptor structure by individual substitutions of residues K265 (7.30) to R296 (7.61) with cysteine. In most cases, hA(1)AR substituted-cysteine mutant membranes displayed antagonist dissociation binding constants that did not differ significantly from wild-type (WT). Radioligand binding assays were used to compare cell membranes that were treated with hydrophilic, sulfhydryl-specific methanethiosulfonate derivatives with control cell membranes. Position H278 was previously reported to be required for A(1)AR ligand binding; however, that report did not establish that H278 represents a contact point for ligands. Cysteine-substitution at H278 yields membrane preparations with greatly decreased receptor density compared with WT membranes from cells in the same transfection experiment. However, H278C membranes retain a measurable fraction of antagonist binding. This observation allows for the investigation of binding-crevice accessibility at position 278 and suggests that H278 may not be required for binding of antagonist ligands. Our data reveal the binding-crevice accessibility of residues T270 (7.35), A273 (7.38), I274 (7.39), T277 (7.42), H278 (7.43), N284 (7.49), and Y288 (7.53) in the hA(1)AR. These data are consistent with the high-resolution structure of bovine rhodopsin that features three alpha-helical turns in this region that are interrupted by an elongated, nonhelical structure from positions 7.43 to 7.48 in the primary amino acid sequence.
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Affiliation(s)
- E S Dawson
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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