101
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Direct Molecular Evolution of Detergent-Stable G Protein-Coupled Receptors Using Polymer Encapsulated Cells. J Mol Biol 2013; 425:662-77. [DOI: 10.1016/j.jmb.2012.11.015] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 11/05/2012] [Accepted: 11/06/2012] [Indexed: 11/18/2022]
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102
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Characterization of the dynamic events of GPCRs by automated computational simulations. Biochem Soc Trans 2013; 41:205-12. [DOI: 10.1042/bst20120287] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The recent advances in membrane protein crystallography have provided extremely valuable structural information of the superfamily of GPCRs (G-protein-coupled receptors). This has been particularly true for a few receptors whose structure was solved several times under different biochemical conditions. It follows that the mechanisms of receptor conformational equilibrium and related dynamic events can be explored by computational simulations. In the present article, we summarize our recent understanding of several dynamic features of GPCRs, accomplished through the use of MD (molecular dynamics) simulations. Our pipeline for the MD simulations of GPCRs, implemented in the web service http://gpcr.usc.es, is updated in the present paper and illustrated by recent applications. Special emphasis is put on the A2A adenosine receptor, one of the selected cases where crystal structures in several conformations and conditions exist, and on the dimerization process of the CXCR4 (CXC chemokine receptor 4).
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103
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Shibata Y, Gvozdenovic-Jeremic J, Love J, Kloss B, White JF, Grisshammer R, Tate CG. Optimising the combination of thermostabilising mutations in the neurotensin receptor for structure determination. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1293-301. [PMID: 23337476 DOI: 10.1016/j.bbamem.2013.01.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 01/07/2013] [Accepted: 01/09/2013] [Indexed: 10/27/2022]
Abstract
Conformational thermostabilisation of G protein-coupled receptors is a successful approach for their structure determination. We have recently determined the structure of a thermostabilised neurotensin receptor NTS1 in complex with its peptide agonist and here we describe the strategy for the identification and combination of the 6 thermostabilising mutations essential for crystallisation. First, thermostability assays were performed on a panel of 340 detergent-solubilised Ala/Leu NTS1 mutants and the best 16 thermostabilising mutations were identified. These mutations were combined pair-wise in nearly all combinations (119 out of a possible 120 combinations) and each mutant was expressed and its thermostability was experimentally determined. A theoretical stability score was calculated from the sum of the stabilities measured for each double mutant and applied to develop 24 triple mutants, which in turn led to the construction of 14 quadruple mutants. Use of the thermostability data for the double mutants to predict further mutant combinations resulted in a greater percentage of the triple and quadruple mutants showing improved thermostability than if only the thermostability data for the single mutations was considered. The best quadruple mutant (NTS1-Nag36k) was further improved by including an additional 2 mutations (resulting in NTS1-GW5) that were identified from a complete Ala/Leu scan of Nag36k by testing the thermostability of the mutants in situ in whole bacteria. NTS1-GW5 had excellent stability in short chain detergents and could be readily purified as a homogenous sample that ultimately allowed crystallisation and structure determination.
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Affiliation(s)
- Yoko Shibata
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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104
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Knepp AM, Sakmar TP, Huber T. Homogeneous time-resolved fluorescence assay to probe folded G protein-coupled receptors. Methods Enzymol 2013; 522:169-89. [PMID: 23374186 DOI: 10.1016/b978-0-12-407865-9.00010-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
Continued advances in G protein-coupled receptor (GPCR) structural biology and biochemistry depend in part on strategies to stabilize these polytopic membrane proteins in purified systems. New methods to measure properly folded GPCRs are needed to facilitate the identification of suitable conditions and ensure sample quality. Most GPCRs do not contain an intrinsic reporter on their functionality, so probes must be introduced. Here, we describe a fluorescence-based approach to quantitatively measure the chemokine receptor CCR5 with labeled antibodies. The assay is exceptionally sensitive and high-throughput. We detail procedures to label antibodies, characterize the system, and process data. We also describe several useful applications, including optimization of incorporation into nanoscale apolipoprotein bound bilayers (NABBs or nanodiscs), measurement of receptor stability, and competition binding assays.
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Affiliation(s)
- Adam M Knepp
- Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University, New York, New York, USA
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105
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Andrews SP, Tehan B. Stabilised G protein-coupled receptors in structure-based drug design: a case study with adenosine A2A receptor. MEDCHEMCOMM 2013. [DOI: 10.1039/c2md20164j] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The first example of structure-based drug design with stabilised GPCRs has enabled the identification of a preclinical candidate for the treatment of Parkinson's disease.
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Affiliation(s)
| | - Benjamin Tehan
- Heptares Therapeutics Limited
- BioPark
- Welwyn Garden City
- UK
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106
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Chen D, Errey JC, Heitman LH, Marshall FH, IJzerman AP, Siegal G. Fragment screening of GPCRs using biophysical methods: identification of ligands of the adenosine A(2A) receptor with novel biological activity. ACS Chem Biol 2012; 7:2064-73. [PMID: 23013674 DOI: 10.1021/cb300436c] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Fragment-based drug discovery (FBDD) has proven a powerful method to develop novel drugs with excellent oral bioavailability against challenging pharmaceutical targets such as protein-protein interaction targets. Very recently the underlying biophysical techniques have begun to be successfully applied to membrane proteins. Here we show that novel, ligand efficient small molecules with a variety of biological activities can be found by screening a small fragment library using thermostabilized (StaR) G protein-coupled receptors (GPCRs) and target immobilized NMR screening (TINS). Detergent-solubilized StaR adenosine A(2A) receptor was immobilized with retention of functionality, and a screen of 531 fragments was performed. Hits from the screen were thoroughly characterized for biochemical activity using the wild-type receptor. Both orthosteric and allosteric modulatory activity has been demonstrated in biochemical validation assays. Allosteric activity was confirmed in cell-based functional assays. The validated fragment hits make excellent starting points for a subsequent hit-to-lead elaboration program.
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Affiliation(s)
- Dan Chen
- ZoBio BV, Leiden 2300RA, The Netherlands
| | - James C. Errey
- Heptares Therapeutics Limited, BioPark, Broadwater Road, Welwyn Garden City,
Hertfordshire AL7 3AX, U.K
| | | | - Fiona H. Marshall
- Heptares Therapeutics Limited, BioPark, Broadwater Road, Welwyn Garden City,
Hertfordshire AL7 3AX, U.K
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107
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Stabilization of functional recombinant cannabinoid receptor CB(2) in detergent micelles and lipid bilayers. PLoS One 2012; 7:e46290. [PMID: 23056277 PMCID: PMC3463599 DOI: 10.1371/journal.pone.0046290] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 08/28/2012] [Indexed: 11/19/2022] Open
Abstract
Elucidation of the molecular mechanisms of activation of G protein-coupled receptors (GPCRs) is among the most challenging tasks for modern membrane biology. For studies by high resolution analytical methods, these integral membrane receptors have to be expressed in large quantities, solubilized from cell membranes and purified in detergent micelles, which may result in a severe destabilization and a loss of function. Here, we report insights into differential effects of detergents, lipids and cannabinoid ligands on stability of the recombinant cannabinoid receptor CB2, and provide guidelines for preparation and handling of the fully functional receptor suitable for a wide array of downstream applications. While we previously described the expression in Escherichia coli, purification and liposome-reconstitution of multi-milligram quantities of CB2, here we report an efficient stabilization of the recombinant receptor in micelles - crucial for functional and structural characterization. The effects of detergents, lipids and specific ligands on structural stability of CB2 were assessed by studying activation of G proteins by the purified receptor reconstituted into liposomes. Functional structure of the ligand binding pocket of the receptor was confirmed by binding of 2H-labeled ligand measured by solid-state NMR. We demonstrate that a concerted action of an anionic cholesterol derivative, cholesteryl hemisuccinate (CHS) and high affinity cannabinoid ligands CP-55,940 or SR-144,528 are required for efficient stabilization of the functional fold of CB2 in dodecyl maltoside (DDM)/CHAPS detergent solutions. Similar to CHS, the negatively charged phospholipids with the serine headgroup (PS) exerted significant stabilizing effects in micelles while uncharged phospholipids were not effective. The purified CB2 reconstituted into lipid bilayers retained functionality for up to several weeks enabling high resolution structural studies of this GPCR at physiologically relevant conditions.
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108
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Langmead CJ. Ligand properties and behaviours in an allosteric age. Trends Pharmacol Sci 2012; 33:621-2. [PMID: 23021944 DOI: 10.1016/j.tips.2012.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 09/05/2012] [Indexed: 11/16/2022]
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109
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A crystal clear solution for determining G-protein-coupled receptor structures. Trends Biochem Sci 2012; 37:343-52. [PMID: 22784935 DOI: 10.1016/j.tibs.2012.06.003] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 05/31/2012] [Accepted: 06/05/2012] [Indexed: 11/21/2022]
Abstract
G-protein-coupled receptors (GPCRs) are medically important membrane proteins that are targeted by over 30% of small molecule drugs. At the time of writing, 15 unique GPCR structures have been determined, with 77 structures deposited in the PDB database, which offers new opportunities for drug development and for understanding the molecular mechanisms of GPCR activation. Many different factors have contributed to this success, but if there is one single factor that can be singled out as the foundation for producing well-diffracting GPCR crystals, it is the stabilisation of the detergent-solubilised receptor-ligand complex. This review will focus predominantly on one of the successful strategies for the stabilisation of GPCRs, namely the thermostabilisation of GPCRs using systematic mutagenesis coupled with thermostability assays. Structures of thermostabilised GPCRs bound to a wide variety of ligands have been determined, which has led to an understanding of ligand specificity; why some ligands act as agonists as opposed to partial or inverse agonists; and the structural basis for receptor activation.
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110
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Mason JS, Bortolato A, Congreve M, Marshall FH. New insights from structural biology into the druggability of G protein-coupled receptors. Trends Pharmacol Sci 2012; 33:249-60. [DOI: 10.1016/j.tips.2012.02.005] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 02/27/2012] [Accepted: 02/27/2012] [Indexed: 11/28/2022]
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111
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Emerging role of surface plasmon resonance in fragment-based drug discovery. Future Med Chem 2012; 3:1809-20. [PMID: 22004086 DOI: 10.4155/fmc.11.128] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Surface plasmon resonance (SPR) offers a method of biophysical fragment screening that is fast, efficient, cost effective and accurate. SPR is increasingly being adopted as a secondary assay to validate fragment hits. Recently, technical advances have resulted in the emergence of SPR as a primary screening methodology for fragment-based drug discovery. Moreover, SPR biosensor assays can be developed for a wide range of proteins, including membrane proteins, such as G-protein-coupled receptors. In this review, we discuss the advantages and limitations of SPR fragment screening including experimental consideration of reducing false positive and false negative rates to a minimum. We discuss how ligand efficiency can be used both as a method to eliminate false positives and to understand which fragments in a library may be a source of false negatives.
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112
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Herr DR. Potential use of G protein-coupled receptor-blocking monoclonal antibodies as therapeutic agents for cancers. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 297:45-81. [PMID: 22608557 DOI: 10.1016/b978-0-12-394308-8.00002-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The therapeutic use of monoclonal antibodies (mAbs) is the fastest growing area of pharmaceutical development and has enjoyed significant clinical success since approval of the first mAb drug in1984. However, despite significant effort, there are still no approved therapeutic mAbs directed against the largest and most attractive family of drug targets: G protein-coupled receptors (GPCRs). GPCRs regulate essentially all cellular processes, including those that are fundamental to cancer pathology, such as proliferation, survival/drug resistance, migration, differentiation, tissue invasion, and angiogenesis. Many different GPCR isoforms are enhanced or dysregulated in multiple tumor types, and several GPCRs have known oncogenic activity. With approximately 350 distinct GPCRs in the genome, these receptors provide a rich landscape for the design of effective, targeted therapies for cancer, a uniquely heterogeneous disease family. While the generation of selective, efficacious mAbs has been problematic for these structurally complex integral membrane proteins, progress in the development of immunotherapeutics has been made by several independent groups. This chapter provides an overview of the roles of GPCRs in cancer and describes the current state of the art of GPCR-targeted mAb drugs.
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Affiliation(s)
- Deron R Herr
- Expression Drug Designs, LLC, San Marcos, California, USA
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113
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Doré AS, Robertson N, Errey JC, Ng I, Hollenstein K, Tehan B, Hurrell E, Bennett K, Congreve M, Magnani F, Tate CG, Weir M, Marshall FH. Structure of the adenosine A(2A) receptor in complex with ZM241385 and the xanthines XAC and caffeine. Structure 2011; 19:1283-93. [PMID: 21885291 DOI: 10.1016/j.str.2011.06.014] [Citation(s) in RCA: 438] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 06/08/2011] [Accepted: 06/13/2011] [Indexed: 02/01/2023]
Abstract
Methylxanthines, including caffeine and theophylline, are among the most widely consumed stimulant drugs in the world. These effects are mediated primarily via blockade of adenosine receptors. Xanthine analogs with improved properties have been developed as potential treatments for diseases such as Parkinson's disease. Here we report the structures of a thermostabilized adenosine A(2A) receptor in complex with the xanthines xanthine amine congener and caffeine, as well as the A(2A) selective inverse agonist ZM241385. The receptor is crystallized in the inactive state conformation as defined by the presence of a salt bridge known as the ionic lock. The complete third intracellular loop, responsible for G protein coupling, is visible consisting of extended helices 5 and 6. The structures provide new insight into the features that define the ligand binding pocket of the adenosine receptor for ligands of diverse chemotypes as well as the cytoplasmic regions that interact with signal transduction proteins.
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Affiliation(s)
- Andrew S Doré
- Heptares Therapeutics Ltd, BioPark, Welwyn Garden City, Herts, AL7 3AX, UK
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114
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The orexin OX(1) receptor exists predominantly as a homodimer in the basal state: potential regulation of receptor organization by both agonist and antagonist ligands. Biochem J 2011; 439:171-83. [PMID: 21770891 DOI: 10.1042/bj20110230] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
It is unclear what proportion of a G-protein-coupled receptor is present in cells as dimers or oligomers. Saturation bioluminescence resonance energy transfer studies demonstrated the orexin OX(1) receptor to be present in such complexes. Forms of this receptor containing a minimal epitope tag, with the C-terminus linked to yellow fluorescent protein or modified at the N-terminus to incorporate a SNAP tag, migrated in SDS/PAGE gels as monomers, indicating a lack of covalent interactions. Solubilization with dodecylmaltoside, followed by Blue native-PAGE, indicated that the receptor constructs migrated predominantly as anticipated for dimeric species with evidence for further, higher-order, complexes, and this was true over a wide range of expression levels. Addition of SDS prior to separation by Blue native-PAGE resulted in much of the previously dimeric, and all of the higher-order, complexes being dissociated and now migrating at the size predicted for monomeric species. Expression of forms of the OX(1) receptor capable of generating enzyme complementation confirmed that solubilization itself did not result in interaction artefacts. Addition of the endogenous agonist orexin A enhanced the proportion of higher-order OX(1) receptor complexes, whereas selective OX(1) antagonists increased the proportion the OX(1) receptor migrating in Blue native-PAGE as a monomer. The antagonist effects were produced in a concentration-dependent manner, consistent with the affinity of the ligands for the receptor. Homogeneous time-resolved fluorescence resonance energy transfer studies using Tag-Lite™ reagents on cells expressing the SNAP-tagged OX(1) receptor identified cell-surface OX(1) homomers. Predominantly at low receptor expression levels, orexin A increased such fluorescence resonance energy transfer signals, also consistent with ligand-induced reorganization of the homomeric complex.
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115
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Miller JL, Tate CG. Engineering an ultra-thermostable β(1)-adrenoceptor. J Mol Biol 2011; 413:628-38. [PMID: 21907721 DOI: 10.1016/j.jmb.2011.08.057] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 08/26/2011] [Accepted: 08/29/2011] [Indexed: 02/04/2023]
Abstract
Conformational thermostabilisation of G-protein-coupled receptors is a successful strategy for their structure determination. The thermostable mutants tolerate short-chain detergents, such as octylglucoside and nonylglucoside, which are ideal for crystallography, and in addition, the receptors are preferentially in a single conformational state. The first thermostabilised receptor to have its structure determined was the β(1)-adrenoceptor mutant β(1)AR-m23 bound to the antagonist cyanopindolol, and recently, additional structures have been determined with agonist bound. Here, we describe further stabilisation of β(1)AR-m23 by the addition of three thermostabilising mutations (I129V, D322K, and Y343L) to make a mutant receptor that is 31 °C more thermostable than the wild-type receptor in dodecylmaltoside and is 13 °C more thermostable than β(1)AR-m23 in nonylglucoside. Although a number of thermostabilisation methods were tried, including rational design of disulfide bonds and engineered zinc bridges, the two most successful strategies to improve the thermostability of β(1)AR-m23 were an engineered salt bridge and leucine scanning mutagenesis. The three additional thermostabilising mutations did not significantly affect the pharmacological properties of β(1)AR-m23, but the new mutant receptor was significantly more stable in short-chain detergents such as heptylthioglucoside and denaturing detergents such as SDS.
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116
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Robichaud AJ, Engers DW, Lindsley CW, Hopkins CR. Recent progress on the identification of metabotropic glutamate 4 receptor ligands and their potential utility as CNS therapeutics. ACS Chem Neurosci 2011; 2:433-49. [PMID: 22860170 DOI: 10.1021/cn200043e] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 06/14/2011] [Indexed: 11/28/2022] Open
Abstract
This Review describes recent activity in the advancement of ligands for the metabotropic glutamate 4 receptor subtype and their potential utility as central nervous system (CNS) therapeutics. Until recently, there was a paucity of compounds with suitable selectivity and druglike properties to elucidate the value of this target. The search for selective entities has led several groups to the investigation of allosteric modulators as a path to optimization of potential ligands. Recent efforts, discussed here, have afforded a variety of derivatives with improvements in potency, solubility, and pharmacokinetic properties that garner support for continued investigation and optimization.
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Affiliation(s)
- Albert J. Robichaud
- Chemical & Pharmacokinetic Sciences, Lundbeck Research USA, 215 College Road, Paramus, New Jersey 07652, United States
| | - Darren W. Engers
- Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (MLPCN), Nashville, Tennessee 37232, United States
| | - Craig W. Lindsley
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (MLPCN), Nashville, Tennessee 37232, United States
| | - Corey R. Hopkins
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
- Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (MLPCN), Nashville, Tennessee 37232, United States
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117
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Congreve M, Langmead CJ, Mason JS, Marshall FH. Progress in structure based drug design for G protein-coupled receptors. J Med Chem 2011; 54:4283-311. [PMID: 21615150 PMCID: PMC3308205 DOI: 10.1021/jm200371q] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Indexed: 12/12/2022]
Affiliation(s)
- Miles Congreve
- Heptares Therapeutics Limited, BioPark, Welwyn Garden City, Hertfordshire, UK.
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118
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Navratilova I, Besnard J, Hopkins AL. Screening for GPCR Ligands Using Surface Plasmon Resonance. ACS Med Chem Lett 2011; 2:549-554. [PMID: 21765967 PMCID: PMC3137231 DOI: 10.1021/ml2000017] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2011] [Accepted: 05/16/2011] [Indexed: 11/30/2022] Open
Abstract
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G-protein coupled receptors (GPCRs) are a class of drug targets of primary importance. However, receptor assays are based on measurement of either ligand displacement or downstream functional responses, rather than direct observation of ligand binding. Issues of allosteric modulation, probe dependence, and functional selectivity create challenges in selecting suitable assays formats. Therefore, a method that directly measures GPCR–ligand interactions, independent of binding site, probe, and signaling pathway would be a useful primary and orthogonal screening method. We have developed a GPCR biosensor assay protocol that offers the opportunity for high-throughput label-free screening that directly measures GPCR–ligand interactions. The biosensor-based direct screening method identifies the interaction of both orthosteric and allosteric ligands with solubilized, native GPCRs, in a label-free and cell-free environment, thus overcoming the limitations of indirect and displacement assay methods. We exemplify the method by the discovery of novel ligands for the chemokine receptor, CCR5, that are ligand efficient fragments.
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Affiliation(s)
- Iva Navratilova
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, United Kingdom
| | - Jérémy Besnard
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, United Kingdom
| | - Andrew L. Hopkins
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, United Kingdom
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119
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Zhukov A, Andrews SP, Errey JC, Robertson N, Tehan B, Mason JS, Marshall FH, Weir M, Congreve M. Biophysical mapping of the adenosine A2A receptor. J Med Chem 2011; 54:4312-23. [PMID: 21661720 PMCID: PMC3308198 DOI: 10.1021/jm2003798] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A new approach to generating information on ligand receptor interactions within the binding pocket of G protein-coupled receptors has been developed, called Biophysical Mapping (BPM). Starting from a stabilized receptor (StaR), minimally engineered for thermostability, additional single mutations are then added at positions that could be involved in small molecule interactions. The StaR and a panel of binding site mutants are captured onto Biacore chips to enable characterization of the binding of small molecule ligands using surface plasmon resonance (SPR) measurement. A matrix of binding data for a set of ligands versus each active site mutation is then generated, providing specific affinity and kinetic information (K(D), k(on), and k(off)) of receptor-ligand interactions. This data set, in combination with molecular modeling and docking, is used to map the small molecule binding site for each class of compounds. Taken together, the many constraints provided by these data identify key protein-ligand interactions and allow the shape of the site to be refined to produce a high quality three-dimensional picture of ligand binding, thereby facilitating structure based drug design. Results of biophysical mapping of the adenosine A(2A) receptor are presented.
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Affiliation(s)
- Andrei Zhukov
- Heptares Therapeutics Limited, BioPark, Welwyn Garden City, Hertfordshire, UK
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120
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Lebon G, Warne T, Edwards PC, Bennett K, Langmead CJ, Leslie AGW, Tate CG. Agonist-bound adenosine A2A receptor structures reveal common features of GPCR activation. Nature 2011; 474:521-5. [PMID: 21593763 PMCID: PMC3146096 DOI: 10.1038/nature10136] [Citation(s) in RCA: 671] [Impact Index Per Article: 51.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 04/21/2011] [Indexed: 12/18/2022]
Abstract
Adenosine receptors and β-adrenoceptors are G-protein-coupled receptors (GPCRs) that activate intracellular G proteins on binding the agonists adenosine or noradrenaline, respectively. GPCRs have similar structures consisting of seven transmembrane helices that contain well-conserved sequence motifs, indicating that they are probably activated by a common mechanism. Recent structures of β-adrenoceptors highlight residues in transmembrane region 5 that initially bind specifically to agonists rather than to antagonists, indicating that these residues have an important role in agonist-induced activation of receptors. Here we present two crystal structures of the thermostabilized human adenosine A(2A) receptor (A(2A)R-GL31) bound to its endogenous agonist adenosine and the synthetic agonist NECA. The structures represent an intermediate conformation between the inactive and active states, because they share all the features of GPCRs that are thought to be in a fully activated state, except that the cytoplasmic end of transmembrane helix 6 partially occludes the G-protein-binding site. The adenine substituent of the agonists binds in a similar fashion to the chemically related region of the inverse agonist ZM241385 (ref. 8). Both agonists contain a ribose group, not found in ZM241385, which extends deep into the ligand-binding pocket where it makes polar interactions with conserved residues in H7 (Ser 277(7.42) and His 278(7.43); superscripts refer to Ballesteros-Weinstein numbering) and non-polar interactions with residues in H3. In contrast, the inverse agonist ZM241385 does not interact with any of these residues and comparison with the agonist-bound structures indicates that ZM241385 sterically prevents the conformational change in H5 and therefore it acts as an inverse agonist. Comparison of the agonist-bound structures of A(2A)R with the agonist-bound structures of β-adrenoceptors indicates that the contraction of the ligand-binding pocket caused by the inward motion of helices 3, 5 and 7 may be a common feature in the activation of all GPCRs.
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Affiliation(s)
- Guillaume Lebon
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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121
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Lebon G, Bennett K, Jazayeri A, Tate CG. Thermostabilisation of an agonist-bound conformation of the human adenosine A(2A) receptor. J Mol Biol 2011; 409:298-310. [PMID: 21501622 PMCID: PMC3145977 DOI: 10.1016/j.jmb.2011.03.075] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 03/31/2011] [Accepted: 03/31/2011] [Indexed: 11/02/2022]
Abstract
The adenosine A(2A) receptor (A(2A)R) is a G-protein-coupled receptor that plays a key role in transmembrane signalling mediated by the agonist adenosine. The structure of A(2A)R was determined recently in an antagonist-bound conformation, which was facilitated by the T4 lysozyme fusion in cytoplasmic loop 3 and the considerable stabilisation conferred on the receptor by the bound inverse agonist ZM241385. Unfortunately, the natural agonist adenosine does not sufficiently stabilise the receptor for the formation of diffraction-quality crystals. As a first step towards determining the structure of A(2A)R bound to an agonist, the receptor was thermostabilised by systematic mutagenesis in the presence of the bound agonist [(3)H]5'-N-ethylcarboxamidoadenosine (NECA). Four thermostabilising mutations were identified that when combined to give mutant A(2A)R-GL26, conferred a greater than 200-fold decrease in its rate of unfolding compared to the wild-type receptor. Pharmacological analysis suggested that A(2A)R-GL26 is stabilised in an agonist-bound conformation because antagonists bind with up to 320-fold decreased affinity. None of the thermostabilising mutations are in the ZM241385 binding pocket, suggesting that the mutations affect ligand binding by altering the conformation of the receptor rather than through direct interactions with ligands. A(2A)R-GL26 shows considerable stability in short-chain detergents, which has allowed its purification and crystallisation.
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Fragment Screening of Stabilized G-Protein-Coupled Receptors Using Biophysical Methods. Methods Enzymol 2011; 493:115-36. [DOI: 10.1016/b978-0-12-381274-2.00005-4] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Congreve M, Langmead C, Marshall FH. The use of GPCR structures in drug design. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2011; 62:1-36. [PMID: 21907905 DOI: 10.1016/b978-0-12-385952-5.00011-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Structure-based drug discovery is routinely applied to soluble targets such as proteases and kinases. It is only recently that multiple high-resolution X-ray structures of G protein-coupled receptors (GPCRs) have become available. Here we review the technology developments that have led to the recent plethora of GPCR structures. These include developments in protein expression and purification as well as techniques to stabilize receptors and crystallize them. We discuss the findings derived from the new structures with regard to understanding GPCR function and pharmacology. Finally, we examine the utility of structure-based drug discovery approaches including homology modeling, virtual screening, and fragment screening for GPCRs in the context of what has been learnt from other target classes.
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Affiliation(s)
- Miles Congreve
- Heptares Therapeutics, Biopark, Welwyn Garden City, Hertfordshire, United Kingdom
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Hutchings CJ, Koglin M, Marshall FH. Therapeutic antibodies directed at G protein-coupled receptors. MAbs 2010; 2:594-606. [PMID: 20864805 DOI: 10.4161/mabs.2.6.13420] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are one of the most important classes of targets for small molecule drug discovery, but many current GPCRs of interest are proving intractable to small molecule discovery and may be better approached with bio-therapeutics. GPCRs are implicated in a wide variety of diseases where antibody therapeutics are currently used. These include inflammatory diseases such as rheumatoid arthritis and Crohn disease, as well as metabolic disease and cancer. Raising antibodies to GPCRs has been difficult due to problems in obtaining suitable antigen because GPCRs are often expressed at low levels in cells and are very unstable when purified. A number of new developments in over-expressing receptors, as well as formulating stable pure protein, are contributing to the growing interest in targeting GPCRs with antibodies. This review discusses the opportunities for targeting GPCRs with antibodies using these approaches and describes the therapeutic antibodies that are currently in clinical development.
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Spedding M. Resolution of controversies in drug/receptor interactions by protein structure. Limitations and pharmacological solutions. Neuropharmacology 2010; 60:3-6. [PMID: 20709088 DOI: 10.1016/j.neuropharm.2010.08.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 08/05/2010] [Indexed: 11/29/2022]
Abstract
Structural biology offers breakthroughs for key issues in receptors, ion channels and transporters. Unfortunately, while knowledge is growing exponentially about receptors and drug targets, there is also an exponential knowledge of all the variables involved. A key issue for structure-based drug design is if there are distinct outcomes from a single structurally defined site. The ways in which drugs can interact with G-protein-coupled receptors (GPCRs) at the orthosteric site can be multiple, and ligands can also interact with allosteric sites. Receptors may exist as homo- or heterodimers, with the potential for distinct pharmacology, and NC-IUPHAR has proposed stringent criteria for recognition of heterodimers (Pin et al., 2007). Furthermore, some drugs have the capacity for activating different signalling cascades from a single receptor (Urban et al., 2007) indicating unique pharmacology. Thus although specific drugs were the main tool by which receptors were (and still can be, if appropriate precautions are taken) classified, drugs may also have distinct pharmacology at certain receptors depending on their chemical structure, showing drug-specific pharmacology rather than the specific-drug pharmacology which had been used in the past to define (and limit) drug classes. Primary structure is an essential but occasionally treacherous tool for defining receptors because distinct primary structures may evolve to perform similar function. This has immense implications in drug screening, and development - which also entails much testing, and selection, in pathophysiological situations.
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Affiliation(s)
- Michael Spedding
- Experimental Sciences, Institute of Research Servier, 11 Rue des Moulineaux, 92150 Suresnes, France.
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