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Burger WAC, Gentry PR, Berizzi AE, Vuckovic Z, van der Westhuizen ET, Thompson G, Yeasmin M, Lindsley CW, Sexton PM, Langmead CJ, Tobin AB, Christopoulos A, Valant C, Thal DM. Identification of a Novel Allosteric Site at the M 5 Muscarinic Acetylcholine Receptor. ACS Chem Neurosci 2021; 12:3112-3123. [PMID: 34351123 DOI: 10.1021/acschemneuro.1c00383] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The M5 muscarinic acetylcholine receptor (mAChR) has emerged as an exciting therapeutic target for the treatment of addiction and behavioral disorders. This has been in part due to promising preclinical studies with the M5 mAChR selective negative allosteric modulator (NAM), ML375. The binding site of ML375 remains unknown, however, making it difficult to develop improved M5 mAChR selective modulators. To determine the possible location of the ML375 binding site, we used radioligand binding and functional assays to show that ML375 does not interact with the well-characterized "common" mAChR allosteric site located in the receptor's extracellular vestibule, nor a previously proposed second allosteric site recognized by the modulator, amiodarone. Molecular docking was used to predict potential allosteric sites within the transmembrane (TM) domain of the M5 mAChR. These predicted sites were assessed using M5-M2 mAChR receptor chimeras and further targeted with site-directed mutagenesis, which enabled the identification of a putative binding site for ML375 at the interface of TMs 2-4. Collectively, these results identify a third allosteric site at the M5 mAChR and highlight the ability of allosteric modulators to selectively target highly conserved proteins.
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Affiliation(s)
- Wessel A. C. Burger
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Patrick R. Gentry
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Alice E. Berizzi
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Ziva Vuckovic
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Emma T. van der Westhuizen
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Geoff Thompson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Mahmuda Yeasmin
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Craig W. Lindsley
- Department of Pharmacology, Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
- Department of Chemistry, Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Patrick M. Sexton
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Christopher J. Langmead
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Andrew B. Tobin
- The Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Arthur Christopoulos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Celine Valant
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - David M. Thal
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
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2
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Okimoto R, Ino K, Ishizu K, Takamatsu H, Sakamoto K, Yuyama H, Fuji H, Someya A, Ohtake A, Ishigami T, Masuda N, Takeda M, Kajioka S, Yoshimura N. Potentiation of muscarinic M3 receptor activation through a new allosteric site with a nove l positive allosteric modulator ASP8302. J Pharmacol Exp Ther 2021; 379:64-73. [PMID: 34244231 DOI: 10.1124/jpet.121.000709] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 07/06/2021] [Indexed: 11/22/2022] Open
Abstract
Muscarinic M3 (M3) receptors mediate a wide range of acetylcholine (ACh)-induced functions, including visceral smooth muscle contraction and glandular secretion. Positive allosteric modulators (PAMs) can avoid various side effects of muscarinic agonists with their spatiotemporal receptor activation control and potentially better subtype selectivity. However, the mechanism of allosteric modulation of M3 receptors is not fully understood, presumably due to the lack of a potent and selective PAM. In this study, we investigated the pharmacological profile of ASP8302, a novel PAM of M3 receptors, and explored the principal site of amino acid sequences in the human M3 receptor required for the potentiation of receptor activation. In cells expressing human M3 and M5 receptors, ASP8302 shifted the concentration-response curve (CRC) for carbachol to the lower concentrations with no significant effects on other subtypes. In a binding study with M3 receptor-expressing membrane, ASP8302 also shifted the CRC for ACh without affecting the binding of orthosteric agonists. Similar shifts in the CRC of contractions by multiple stimulants were also confirmed in isolated human bladder strips. Mutagenesis analysis indicated no interaction between ASP8302 and previously reported allosteric sites; however, identified threonine 230 as the amino acid essential for the PAM effect of ASP8302. These results demonstrate that ASP8302 enhances the activation of human M3 receptors by interacting with a single amino acid distinct from the reported allosteric sites. Our findings suggest not only a novel allosteric site of M3 receptors but also the potential application of ASP8302 to diseases caused by insufficient M3 receptor activation. Significance Statement The significance of this study is that the novel M3 receptor positive allosteric modulator ASP8302 enhances the activation of human M3 receptor by interacting with a residue distinct from the reported allosteric sites. The finding of Thr230 as a novel amino acid involved in the allosteric modulation of M3 receptors provides significant insight into further research of the mechanism of allosteric modulation of M3 and other muscarinic receptors.
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Affiliation(s)
- Risa Okimoto
- Drug Discovery Research, Astellas Pharma Inc., Japan
| | | | | | | | - Kazuyuki Sakamoto
- Research Program Management Office, Drug Discovery Research, Astellas Pharma Inc., Japan
| | | | | | | | | | | | | | | | - Shunichi Kajioka
- Department of Pharmaceutical Sciences, International University of Health and Welfare, Japan
| | - Naoki Yoshimura
- Department of Urology, University of Pittsburgh School of Medicine, United States
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3
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Skiba MA, Kruse AC. Autoantibodies as Endogenous Modulators of GPCR Signaling. Trends Pharmacol Sci 2020; 42:135-150. [PMID: 33358695 DOI: 10.1016/j.tips.2020.11.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/24/2020] [Accepted: 11/28/2020] [Indexed: 02/06/2023]
Abstract
Endogenous self-reactive autoantibodies (AAs) recognize a range of G-protein-coupled receptors (GPCRs). They are frequently associated with cardiovascular, neurological, and autoimmune disorders, and in some cases directly impact disease progression. Many GPCR AAs modulate receptor signaling, but molecular details of their modulatory activity are not well understood. Technological advances have provided insight into GPCR biology, which now facilitates deeper understanding of GPCR AA function at the molecular level. Most GPCR AAs are allosteric modulators and exhibit a broad range of pharmacological properties, altering both receptor signaling and trafficking. Understanding GPCR AAs is not only important for defining how these unusual GPCR modulators function in disease, but also provides insight into the potential use and limitations of using therapeutic antibodies to modulate GPCR signaling.
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Affiliation(s)
- Meredith A Skiba
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Andrew C Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA.
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4
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Abstract
The 5 subtypes of the muscarinic acetylcholine receptors (mAChRs) are expressed throughout the central and peripheral nervous system where they play a vital role in physiology and pathologies. Recently, the M5 mAChR subtype has emerged as an exciting drug target for the treatment of drug addiction. We have determined the atomic structure of the M5 mAChR bound to the clinically used inverse agonist tiotropium. The M5 mAChR structure now allows for a full comparison of all 5 mAChR subtypes and reveals that small differences in the extracellular loop regions can mediate orthosteric and allosteric ligand selectivity. Together, these findings open the door for future structure-based design of selective drugs that target this therapeutically important class of receptors. The human M5 muscarinic acetylcholine receptor (mAChR) has recently emerged as an exciting therapeutic target for treating a range of disorders, including drug addiction. However, a lack of structural information for this receptor subtype has limited further drug development and validation. Here we report a high-resolution crystal structure of the human M5 mAChR bound to the clinically used inverse agonist, tiotropium. This structure allowed for a comparison across all 5 mAChR family members that revealed important differences in both orthosteric and allosteric sites that could inform the rational design of selective ligands. These structural studies, together with chimeric swaps between the extracellular regions of the M2 and M5 mAChRs, provided structural insight into kinetic selectivity, where ligands show differential residency times between related family members. Collectively, our study provides important insights into the nature of orthosteric and allosteric ligand interaction across the mAChR family that could be exploited for the design of selective drugs.
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5
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Dreher J, Scheiber J, Stiefl N, Baumann K. xMaP-An Interpretable Alignment-Free Four-Dimensional Quantitative Structure-Activity Relationship Technique Based on Molecular Surface Properties and Conformer Ensembles. J Chem Inf Model 2018; 58:165-181. [PMID: 29172519 DOI: 10.1021/acs.jcim.7b00419] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel alignment-free molecular descriptor called xMaP (flexible MaP descriptor) is introduced. The descriptor is the advancement of the previously published translationally and rotationally invariant three-dimensional (3D) descriptor MaP (mapping property distributions onto the molecular surface) to the fourth dimension (4D). In addition to MaP, xMaP is independent of the chosen starting conformation of the encoded molecules and is therefore entirely alignment-free. This is achieved by using ensembles of conformers, which are generated by conformational searches. This step of the procedure is similar to Hopfinger's 4D quantitative structure-activity relationship (QSAR). A five-step procedure is used to compute the xMaP descriptor. First, a conformational search for each molecule is carried out. Next, for each of the conformers an approximation to the molecular surface with equally distributed surface points is computed. Third, molecular properties are projected onto this surface. Fourth, areas of identical properties are clustered to so-called patches. Fifth, the spatial distribution of the patches is converted into an alignment-free descriptor that is based on the entire conformer ensemble. The resulting descriptor can be interpreted by superimposing the most important descriptor variables and the molecules of the data set. The most important descriptor variables are identified with chemometric regression tools. The novel descriptor was applied to several benchmark data sets and was compared to other descriptors and QSAR techniques comprising a binary fingerprint, a topological pharmacophore descriptor (Cats2D), and the field-based 3D-QSAR technique GRID/PLS which is alignment-dependent. The use of conformer ensembles renders xMaP very robust. It turns out that xMaP performs very well on (almost) all data sets and that the statistical results are comparable to GRID/PLS. In addition to that, xMaP can also be used to efficiently visualize the derived quantitative structure-activity relationships.
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Affiliation(s)
- Jan Dreher
- Institute of Medicinal and Pharmaceutical Chemistry, University of Technology Braunschweig , Beethovenstrasse 55, D 38106 Braunschweig, Germany
| | - Josef Scheiber
- Institute of Medicinal and Pharmaceutical Chemistry, University of Technology Braunschweig , Beethovenstrasse 55, D 38106 Braunschweig, Germany
| | - Nikolaus Stiefl
- Institute of Medicinal and Pharmaceutical Chemistry, University of Technology Braunschweig , Beethovenstrasse 55, D 38106 Braunschweig, Germany
| | - Knut Baumann
- Institute of Medicinal and Pharmaceutical Chemistry, University of Technology Braunschweig , Beethovenstrasse 55, D 38106 Braunschweig, Germany
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6
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She X, Pegoli A, Mayr J, Hübner H, Bernhardt G, Gmeiner P, Keller M. Heterodimerization of Dibenzodiazepinone-Type Muscarinic Acetylcholine Receptor Ligands Leads to Increased M 2R Affinity and Selectivity. ACS OMEGA 2017; 2:6741-6754. [PMID: 30023530 PMCID: PMC6044897 DOI: 10.1021/acsomega.7b01085] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 09/05/2017] [Indexed: 05/13/2023]
Abstract
In search for selective ligands for the muscarinic acetylcholine receptor (MR) subtype M2, the dimeric ligand approach, that is combining two pharmacophores in one and the same molecule, was pursued. Different types (agonists, antagonists, orthosteric, and allosteric) of monomeric MR ligands were combined by various linkers with a dibenzodiazepinone-type MR antagonist, affording five types of heterodimeric compounds ("DIBA-xanomeline," "DIBA-TBPB," "DIBA-77-LH-28-1," "DIBA-propantheline," and "DIBA-4-DAMP"), which showed high M2R affinities (pKi > 8.3). The heterodimeric ligand UR-SK75 (46) exhibited the highest M2R affinity and selectivity [pKi (M1R-M5R): 8.84, 10.14, 7.88, 8.59, and 7.47]. Two tritium-labeled dimeric derivatives ("DIBA-xanomeline"-type: [3H]UR-SK71 ([3H]44) and "DIBA-TBPB"-type: [3H]UR-SK59 ([3H]64)) were prepared to investigate their binding modes at hM2R. Saturation-binding experiments showed that these compounds address the orthosteric binding site of the M2R. The investigation of the effect of various allosteric MR modulators [gallamine (13), W84 (14), and LY2119620 (15)] on the equilibrium (13-15) or saturation (14) binding of [3H]64 suggested a competitive mechanism between [3H]64 and the investigated allosteric ligands, and consequently a dualsteric binding mode of 64 at the M2R.
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Affiliation(s)
- Xueke She
- Institute
of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Andrea Pegoli
- Institute
of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Judith Mayr
- Institute
of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Harald Hübner
- Department
of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Schuhstr. 19, D-91052 Erlangen, Germany
| | - Günther Bernhardt
- Institute
of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
| | - Peter Gmeiner
- Department
of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Schuhstr. 19, D-91052 Erlangen, Germany
| | - Max Keller
- Institute
of Pharmacy, Faculty of Chemistry and Pharmacy, University of Regensburg, Universitätsstr. 31, D-93053 Regensburg, Germany
- E-mail: . Phone: (+49)941-9433329.
Fax: (+49)941-9434820 (M.K.)
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7
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De Min A, Matera C, Bock A, Holze J, Kloeckner J, Muth M, Traenkle C, De Amici M, Kenakin T, Holzgrabe U, Dallanoce C, Kostenis E, Mohr K, Schrage R. A New Molecular Mechanism To Engineer Protean Agonism at a G Protein–Coupled Receptor. Mol Pharmacol 2017; 91:348-356. [DOI: 10.1124/mol.116.107276] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 02/02/2017] [Indexed: 12/22/2022] Open
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8
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Binding of N-methylscopolamine to the extracellular domain of muscarinic acetylcholine receptors. Sci Rep 2017; 7:40381. [PMID: 28091608 PMCID: PMC5238504 DOI: 10.1038/srep40381] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 12/06/2016] [Indexed: 01/07/2023] Open
Abstract
Interaction of orthosteric ligands with extracellular domain was described at several aminergic G protein-coupled receptors, including muscarinic acetylcholine receptors. The orthosteric antagonists quinuclidinyl benzilate (QNB) and N-methylscopolamine (NMS) bind to the binding pocket of the muscarinic acetylcholine receptor formed by transmembrane α-helices. We show that high concentrations of either QNB or NMS slow down dissociation of their radiolabeled species from all five subtypes of muscarinic acetylcholine receptors, suggesting allosteric binding. The affinity of NMS at the allosteric site is in the micromolar range for all receptor subtypes. Using molecular modelling of the M2 receptor we found that E172 and E175 in the second extracellular loop and N419 in the third extracellular loop are involved in allosteric binding of NMS. Mutation of these amino acids to alanine decreased affinity of NMS for the allosteric binding site confirming results of molecular modelling. The allosteric binding site of NMS overlaps with the binding site of some allosteric, ectopic and bitopic ligands. Understanding of interactions of NMS at the allosteric binding site is essential for correct analysis of binding and action of these ligands.
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9
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Nguyen ATN, Vecchio EA, Thomas T, Nguyen TD, Aurelio L, Scammells PJ, White PJ, Sexton PM, Gregory KJ, May LT, Christopoulos A. Role of the Second Extracellular Loop of the Adenosine A1 Receptor on Allosteric Modulator Binding, Signaling, and Cooperativity. Mol Pharmacol 2016; 90:715-725. [PMID: 27683013 DOI: 10.1124/mol.116.105015] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 09/27/2016] [Indexed: 02/05/2023] Open
Abstract
Allosteric modulation of adenosine A1 receptors (A1ARs) offers a novel therapeutic approach for the treatment of numerous central and peripheral disorders; however, despite decades of research, there is a relative paucity of structural information regarding the A1AR allosteric site and mechanisms governing cooperativity with orthosteric ligands. We combined alanine-scanning mutagenesis of the A1AR second extracellular loop (ECL2) with radioligand binding and functional interaction assays to quantify effects on allosteric ligand affinity, cooperativity, and efficacy. Docking and molecular dynamics (MD) simulations were performed using an A1AR homology model based on an agonist-bound A2AAR structure. Substitution of E172ECL2 for alanine reduced the affinity of the allosteric modulators PD81723 and VCP171 for the unoccupied A1AR. Residues involved in cooperativity with the orthosteric agonist NECA were different in PD81723 and VCP171; positive cooperativity between PD81723 and NECA was reduced on alanine substitution of a number of ECL2 residues, including E170ECL2 and K173ECL2, whereas mutation of W146ECL2 and W156ECL2 decreased VCP171 cooperativity with NECA. Molecular modeling localized a likely allosteric pocket for both modulators to an extracellular vestibule that overlaps with a region used by orthosteric ligands as they transit into the canonical A1AR orthosteric site. MD simulations confirmed a key interaction between E172ECL2 and both modulators. Bound PD81723 is flanked by another residue, E170ECL2, which forms hydrogen bonds with adjacent K168ECL2 and K173ECL2. Collectively, our data suggest E172ECL2 is a key allosteric ligand-binding determinant, whereas hydrogen-bonding networks within the extracellular vestibule may facilitate the transmission of cooperativity between orthosteric and allosteric sites.
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Affiliation(s)
- Anh T N Nguyen
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
| | - Elizabeth A Vecchio
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
| | - Trayder Thomas
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
| | - Toan D Nguyen
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
| | - Luigi Aurelio
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
| | - Peter J Scammells
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
| | - Paul J White
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
| | - Patrick M Sexton
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
| | - Karen J Gregory
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
| | - Lauren T May
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
| | - Arthur Christopoulos
- Monash Institute of Pharmaceutical Sciences (A.T.N.N., E.A.V., T.T., L.A., P.J.S., P.J.W., P.M.S., K.J.G., L.T.M., A.C.), Monash e-Research Centre (T.D.N.), and Department of Pharmacology (A.T.N.N., E.A.V., P.M.S., K.J.G., L.T.M., A.C), Monash University, Victoria, Australia
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10
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Bock A, Bermudez M, Krebs F, Matera C, Chirinda B, Sydow D, Dallanoce C, Holzgrabe U, De Amici M, Lohse MJ, Wolber G, Mohr K. Ligand Binding Ensembles Determine Graded Agonist Efficacies at a G Protein-coupled Receptor. J Biol Chem 2016; 291:16375-89. [PMID: 27298318 PMCID: PMC4965584 DOI: 10.1074/jbc.m116.735431] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 06/07/2016] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors constitute the largest family of membrane receptors and modulate almost every physiological process in humans. Binding of agonists to G protein-coupled receptors induces a shift from inactive to active receptor conformations. Biophysical studies of the dynamic equilibrium of receptors suggest that a portion of receptors can remain in inactive states even in the presence of saturating concentrations of agonist and G protein mimetic. However, the molecular details of agonist-bound inactive receptors are poorly understood. Here we use the model of bitopic orthosteric/allosteric (i.e. dualsteric) agonists for muscarinic M2 receptors to demonstrate the existence and function of such inactive agonist·receptor complexes on a molecular level. Using all-atom molecular dynamics simulations, dynophores (i.e. a combination of static three-dimensional pharmacophores and molecular dynamics-based conformational sampling), ligand design, and receptor mutagenesis, we show that inactive agonist·receptor complexes can result from agonist binding to the allosteric vestibule alone, whereas the dualsteric binding mode produces active receptors. Each agonist forms a distinct ligand binding ensemble, and different agonist efficacies depend on the fraction of purely allosteric (i.e. inactive) versus dualsteric (i.e. active) binding modes. We propose that this concept may explain why agonist·receptor complexes can be inactive and that adopting multiple binding modes may be generalized also to small agonists where binding modes will be only subtly different and confined to only one binding site.
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Affiliation(s)
- Andreas Bock
- From the Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, 97078 Würzburg, Germany,
| | - Marcel Bermudez
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Strasse 2 und 4, 14195 Berlin, Germany,
| | - Fabian Krebs
- Pharmacology and Toxicology Section, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Strasse 3, 53121 Bonn, Germany
| | - Carlo Matera
- Dipartimento di Scienze Farmaceutiche, Sezione di Chimica Farmaceutica "Pietro Pratesi," Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milan, Italy, and
| | - Brian Chirinda
- Pharmacology and Toxicology Section, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Strasse 3, 53121 Bonn, Germany
| | - Dominique Sydow
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Strasse 2 und 4, 14195 Berlin, Germany
| | - Clelia Dallanoce
- Dipartimento di Scienze Farmaceutiche, Sezione di Chimica Farmaceutica "Pietro Pratesi," Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milan, Italy, and
| | - Ulrike Holzgrabe
- Institute of Pharmacy, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Marco De Amici
- Dipartimento di Scienze Farmaceutiche, Sezione di Chimica Farmaceutica "Pietro Pratesi," Università degli Studi di Milano, Via Mangiagalli 25, 20133 Milan, Italy, and
| | - Martin J Lohse
- From the Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Strasse 9, 97078 Würzburg, Germany
| | - Gerhard Wolber
- Institute of Pharmacy, Freie Universität Berlin, Königin-Luise-Strasse 2 und 4, 14195 Berlin, Germany
| | - Klaus Mohr
- Pharmacology and Toxicology Section, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Strasse 3, 53121 Bonn, Germany,
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11
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Hui WQ, Cheng Q, Liu TY, Ouyang Q. Homology modeling, docking, and molecular dynamics simulation of the receptor GALR2 and its interactions with galanin and a positive allosteric modulator. J Mol Model 2016; 22:90. [PMID: 27021209 DOI: 10.1007/s00894-016-2944-x] [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] [Received: 12/30/2015] [Accepted: 02/22/2016] [Indexed: 12/17/2022]
Abstract
Galanin receptor type 2 (GALR2) is a class A G-protein-coupled receptor (GPCR), and it has been reported that orthosteric ligands and positive allosteric modulators (PAMs) of GALR2 could potentially be used to treat epilepsy. So far, the X-ray structure of this receptor has not been resolved, and knowledge of the 3D structure of GALR2 may prove informative in attempts to design novel ligands and to explore the mechanism for the allosteric modulation of this receptor. In this study, homology modeling was used to obtain several GALR2 models using known templates. ProSA-web Z-scores and Ramachandran plots as well as pre-screening against a test dataset of known compounds were all utilized to select the best model of GALR2. Molecular dockings of galanin (a peptide) and a nonpeptide ligand were carried out to choose the (GALR2 model)-galanin complex that showed the closest agreement with the corresponding experimental data. Finally, a 50-ns MD simulation was performed to study the interactions between the GALR2 model and the synthetic and endogenous ligands. The results from docking and MD simulation showed that, besides the reported residues, Tyr160(4.60), Ile105(3.32), Ala274(7.35), and Tyr163(ECL2) also appear to play important roles in the binding of galanin. The potential allosteric binding pockets in the GALR2 model were then investigated via MD simulation. The results indicated that the mechanism for the allosteric modulation caused by PAMs is the binding of the PAM at pocket III, which is formed by galanin, ECL2, TM2, TM3, and ECL1; this results in the disruption of the Na(+)-binding site and/or the Na(+) ion pathway, leading to GALR2 agonism.
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Affiliation(s)
- Wen-Qi Hui
- College of Pharmacy, Third Military Medical University, No. 30 Gaotanyan Street, Chongqing, 400038, China
| | - Qi Cheng
- College of Pharmacy, Third Military Medical University, No. 30 Gaotanyan Street, Chongqing, 400038, China
| | - Tian-Yu Liu
- College of Pharmacy, Third Military Medical University, No. 30 Gaotanyan Street, Chongqing, 400038, China.
| | - Qin Ouyang
- College of Pharmacy, Third Military Medical University, No. 30 Gaotanyan Street, Chongqing, 400038, China.
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12
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13
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The experimental power of FR900359 to study Gq-regulated biological processes. Nat Commun 2015; 6:10156. [PMID: 26658454 PMCID: PMC4682109 DOI: 10.1038/ncomms10156] [Citation(s) in RCA: 244] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 11/06/2015] [Indexed: 12/13/2022] Open
Abstract
Despite the discovery of heterotrimeric αβγ G proteins ∼25 years ago, their selective perturbation by cell-permeable inhibitors remains a fundamental challenge. Here we report that the plant-derived depsipeptide FR900359 (FR) is ideally suited to this task. Using a multifaceted approach we systematically characterize FR as a selective inhibitor of Gq/11/14 over all other mammalian Gα isoforms and elaborate its molecular mechanism of action. We also use FR to investigate whether inhibition of Gq proteins is an effective post-receptor strategy to target oncogenic signalling, using melanoma as a model system. FR suppresses many of the hallmark features that are central to the malignancy of melanoma cells, thereby providing new opportunities for therapeutic intervention. Just as pertussis toxin is used extensively to probe and inhibit the signalling of Gi/o proteins, we anticipate that FR will at least be its equivalent for investigating the biological relevance of Gq.
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14
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Hutchings CJ, Cseke G, Osborne G, Woolard J, Zhukov A, Koglin M, Jazayeri A, Pandya-Pathak J, Langmead CJ, Hill SJ, Weir M, Marshall FH. Monoclonal anti-β1-adrenergic receptor antibodies activate G protein signaling in the absence of β-arrestin recruitment. MAbs 2014; 6:246-61. [PMID: 24253107 DOI: 10.4161/mabs.27226] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Thermostabilized G protein-coupled receptors used as antigens for in vivo immunization have resulted in the generation of functional agonistic anti-β1-adrenergic (β1AR) receptor monoclonal antibodies (mAbs). The focus of this study was to examine the pharmacology of these antibodies to evaluate their mechanistic activity at β1AR. Immunization with the β1AR stabilized receptor yielded five stable hybridoma clones, four of which expressed functional IgG, as determined in cell-based assays used to evaluate cAMP stimulation. The antibodies bind diverse epitopes associated with low nanomolar agonist activity at β1AR, and they appeared to show some degree of biased signaling as they were inactive in an assay measuring signaling through β-arrestin. In vitro characterization also verified different antibody receptor interactions reflecting the different epitopes on the extracellular surface of β1AR to which the mAbs bind. The anti-β1AR mAbs only demonstrated agonist activity when in dimeric antibody format, but not as the monomeric Fab format, suggesting that agonist activation may be mediated through promoting receptor dimerization. Finally, we have also shown that at least one of these antibodies exhibits in vivo functional activity at a therapeutically-relevant dose producing an increase in heart rate consistent with β1AR agonism.
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15
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Schmitz J, van der Mey D, Bermudez M, Klöckner J, Schrage R, Kostenis E, Tränkle C, Wolber G, Mohr K, Holzgrabe U. Dualsteric Muscarinic Antagonists–Orthosteric Binding Pose Controls Allosteric Subtype Selectivity. J Med Chem 2014; 57:6739-50. [DOI: 10.1021/jm500790x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Jens Schmitz
- Institute
of Pharmacy and Food Chemistry, University of Würzburg, Am
Hubland, D-97074 Würzburg, Germany
| | - Dorina van der Mey
- Pharmacology
and Toxicology, Institute of Pharmacy, Gerhard-Domagk-Straße 3,D-53121 Bonn, Germany
| | - Marcel Bermudez
- Institute
for Pharmacy, Free University Berlin, Königin-Luise-Straße
2 und 4, D-14195 Berlin, Germany
| | - Jessica Klöckner
- Institute
of Pharmacy and Food Chemistry, University of Würzburg, Am
Hubland, D-97074 Würzburg, Germany
| | - Ramona Schrage
- Pharmacology
and Toxicology, Institute of Pharmacy, Gerhard-Domagk-Straße 3,D-53121 Bonn, Germany
| | - Evi Kostenis
- Institute
of Pharmaceutical Biology, Molecular-, Cellular-, and Pharmacobiology
Section, University of Bonn, Nussallee 6, D-53115 Bonn, Germany
| | - Christian Tränkle
- Pharmacology
and Toxicology, Institute of Pharmacy, Gerhard-Domagk-Straße 3,D-53121 Bonn, Germany
| | - Gerhard Wolber
- Institute
for Pharmacy, Free University Berlin, Königin-Luise-Straße
2 und 4, D-14195 Berlin, Germany
| | - Klaus Mohr
- Pharmacology
and Toxicology, Institute of Pharmacy, Gerhard-Domagk-Straße 3,D-53121 Bonn, Germany
| | - Ulrike Holzgrabe
- Institute
of Pharmacy and Food Chemistry, University of Würzburg, Am
Hubland, D-97074 Würzburg, Germany
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16
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Keov P, López L, Devine SM, Valant C, Lane JR, Scammells PJ, Sexton PM, Christopoulos A. Molecular mechanisms of bitopic ligand engagement with the M1 muscarinic acetylcholine receptor. J Biol Chem 2014; 289:23817-37. [PMID: 25006252 DOI: 10.1074/jbc.m114.582874] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
TBPB and 77-LH-28-1 are selective agonists of the M1 muscarinic acetylcholine receptor (mAChR) that may gain their selectivity through a bitopic mechanism, interacting concomitantly with the orthosteric site and part of an allosteric site. The current study combined site-directed mutagenesis, analytical pharmacology,and molecular modeling to gain further insights into the structural basis underlying binding and signaling by these agonists. Mutations within the orthosteric binding site caused similar reductions in affinity and signaling efficacy for both selective and prototypical orthosteric ligands. In contrast, the mutation of residues within transmembrane helix (TM) 2 and the second extracellular loop (ECL2) discriminated between the different classes of ligand. In particular, ECL2 appears to be involved in the selective binding of bitopic ligands and in coordinating biased agonism between intracellular calcium mobilization and ERK1/2 phosphorylation. Molecular modeling of the interaction between TBPB and the M1 mAChR revealed a binding pose predicted to extend from the orthosteric site up toward a putative allosteric site bordered by TM2, TM3, and TM7, thus consistent with a bitopic mode of binding. Overall, these findings provide valuable structural and mechanistic insights into bitopic ligand actions and receptor activation and support a role for ECL2 in dictating the active states that can be adopted by a G protein-coupled receptor. This may enable greater selective ligand design and development for mAChRs and facilitate improved identification of bitopic ligands.
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Affiliation(s)
- Peter Keov
- From the Drug Discovery Biology Theme and Department of Pharmacology and
| | - Laura López
- From the Drug Discovery Biology Theme and Department of Pharmacology and
| | - Shane M Devine
- the Medicinal Chemistry Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Celine Valant
- From the Drug Discovery Biology Theme and Department of Pharmacology and
| | - J Robert Lane
- From the Drug Discovery Biology Theme and Department of Pharmacology and
| | - Peter J Scammells
- the Medicinal Chemistry Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Patrick M Sexton
- From the Drug Discovery Biology Theme and Department of Pharmacology and
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17
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Bock A, Mohr K. Dualsteric GPCR targeting and functional selectivity: the paradigmatic M(2) muscarinic acetylcholine receptor. DRUG DISCOVERY TODAY. TECHNOLOGIES 2014; 10:e245-52. [PMID: 24050275 DOI: 10.1016/j.ddtec.2012.12.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Muscarinic acetylcholine receptors belong to Class Aseven transmembrane helical receptors and serve as important drug targets in the treatment of various diseases such as chronic obstructive pulmonary disease, overactive bladder, bronchial asthma and glaucoma. Despite intensive research the discovery of experimental ligands which activate or block specific muscarinic receptor subtypes has only been successful for the M1 and M4 subtypes but remains a challenging task at the other subtypes. In recent years, ligands have been introduced which bind simultaneously to the acetylcholine binding site, that is, the orthosteric site, and to an allosteric binding site. These so-called dualsteric ligands display M2 subtype preference due to the addressing of the allosteric binding site. As proven recently, dualsteric receptor activation goes along with a pronounced signaling bias which follows clear structure–bias-relationships. Dualsteric receptor targeting might represent a common strategy to generate functional selectivity.
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18
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Evaluation of 1,2,5-thiadiazoles as modulators of M1/M5 muscarinic receptor subtypes. Bioorg Med Chem 2014; 22:1838-44. [DOI: 10.1016/j.bmc.2014.01.049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/20/2014] [Accepted: 01/30/2014] [Indexed: 11/21/2022]
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19
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Kennedy DP, McRobb FM, Leonhardt SA, Purdy M, Figler H, Marshall MA, Chordia M, Figler R, Linden J, Abagyan R, Yeager M. The second extracellular loop of the adenosine A1 receptor mediates activity of allosteric enhancers. Mol Pharmacol 2014; 85:301-9. [PMID: 24217444 PMCID: PMC3913357 DOI: 10.1124/mol.113.088682] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 11/11/2013] [Indexed: 01/26/2023] Open
Abstract
Allosteric enhancers of the adenosine A1 receptor amplify signaling by orthosteric agonists. Allosteric enhancers are appealing drug candidates because their activity requires that the orthosteric site be occupied by an agonist, thereby conferring specificity to stressed or injured tissues that produce adenosine. To explore the mechanism of allosteric enhancer activity, we examined their action on several A1 receptor constructs, including (1) species variants, (2) species chimeras, (3) alanine scanning mutants, and (4) site-specific mutants. These findings were combined with homology modeling of the A1 receptor and in silico screening of an allosteric enhancer library. The binding modes of known docked allosteric enhancers correlated with the known structure-activity relationship, suggesting that these allosteric enhancers bind to a pocket formed by the second extracellular loop, flanked by residues S150 and M162. We propose a model in which this vestibule controls the entry and efflux of agonists from the orthosteric site and agonist binding elicits a conformational change that enables allosteric enhancer binding. This model provides a mechanism for the observations that allosteric enhancers slow the dissociation of orthosteric agonists but not antagonists.
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Affiliation(s)
- Dylan P Kennedy
- Department of Pharmacology (D.P.K.), Department of Molecular Physiology and Biological Physics (S.A.L., M.P., H.F., M.C., R.F., M.Y.), Cardiovascular Research Center (M.A.M., R.F., M.Y.), Center for Membrane Biology (M.Y.), and Department of Medicine, Division of Cardiovascular Medicine (M.Y.), University of Virginia School of Medicine, Charlottesville, Virginia; the Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California (F.M.M., R.A.); and the La Jolla Institute for Allergy and Immunology (J.L.), La Jolla, California
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20
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Abdul-Ridha A, López L, Keov P, Thal DM, Mistry SN, Sexton PM, Lane JR, Canals M, Christopoulos A. Molecular determinants of allosteric modulation at the M1 muscarinic acetylcholine receptor. J Biol Chem 2014; 289:6067-79. [PMID: 24443568 DOI: 10.1074/jbc.m113.539080] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Benzylquinolone carboxylic acid (BQCA) is an unprecedented example of a selective positive allosteric modulator of acetylcholine at the M1 muscarinic acetylcholine receptor (mAChR). To probe the structural basis underlying its selectivity, we utilized site-directed mutagenesis, analytical modeling, and molecular dynamics to delineate regions of the M1 mAChR that govern modulator binding and transmission of cooperativity. We identified Tyr-85(2.64) in transmembrane domain 2 (TMII), Tyr-179 and Phe-182 in the second extracellular loop (ECL2), and Glu-397(7.32) and Trp-400(7.35) in TMVII as residues that contribute to the BQCA binding pocket at the M1 mAChR, as well as to the transmission of cooperativity with the orthosteric agonist carbachol. As such, the BQCA binding pocket partially overlaps with the previously described "common" allosteric site in the extracellular vestibule of the M1 mAChR, suggesting that its high subtype selectivity derives from either additional contacts outside this region or through a subtype-specific cooperativity mechanism. Mutation of amino acid residues that form the orthosteric binding pocket caused a loss of carbachol response that could be rescued by BQCA. Two of these residues (Leu-102(3.29) and Asp-105(3.32)) were also identified as indirect contributors to the binding affinity of the modulator. This new insight into the structural basis of binding and function of BQCA can guide the design of new allosteric ligands with tailored pharmacological properties.
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21
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Structural basis for modulation of a G-protein-coupled receptor by allosteric drugs. Nature 2013; 503:295-9. [DOI: 10.1038/nature12595] [Citation(s) in RCA: 319] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Accepted: 08/15/2013] [Indexed: 12/18/2022]
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22
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Muscarinic acetylcholine receptor modulators derived from natural toxins and diverse interaction modes. Sci China Chem 2013. [DOI: 10.1007/s11426-013-4958-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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23
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Jakubík J, Randáková A, Doležal V. On homology modeling of the M₂ muscarinic acetylcholine receptor subtype. J Comput Aided Mol Des 2013; 27:525-38. [PMID: 23812908 PMCID: PMC3717152 DOI: 10.1007/s10822-013-9660-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 06/19/2013] [Indexed: 01/20/2023]
Abstract
Twelve homology models of the human M2 muscarinic receptor using different sets of templates have been designed using the Prime program or the modeller program and compared to crystallographic structure (PDB:3UON). The best models were obtained using single template of the closest published structure, the M3 muscarinic receptor (PDB:4DAJ). Adding more (structurally distant) templates led to worse models. Data document a key role of the template in homology modeling. The models differ substantially. The quality checks built into the programs do not correlate with the RMSDs to the crystallographic structure and cannot be used to select the best model. Re-docking of the antagonists present in crystallographic structure and relative binding energy estimation by calculating MM/GBSA in Prime and the binding energy function in YASARA suggested it could be possible to evaluate the quality of the orthosteric binding site based on the prediction of relative binding energies. Although estimation of relative binding energies distinguishes between relatively good and bad models it does not indicate the best one. On the other hand, visual inspection of the models for known features and knowledge-based analysis of the intramolecular interactions allows an experimenter to select overall best models manually.
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Affiliation(s)
- Jan Jakubík
- Department of Neurochemistry, Institute of Physiology v.v.i., Academy of Sciences of the Czech Republic, Prague 14200, Czech Republic.
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24
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Bock A, Merten N, Schrage R, Dallanoce C, Bätz J, Klöckner J, Schmitz J, Matera C, Simon K, Kebig A, Peters L, Müller A, Schrobang-Ley J, Tränkle C, Hoffmann C, De Amici M, Holzgrabe U, Kostenis E, Mohr K. The allosteric vestibule of a seven transmembrane helical receptor controls G-protein coupling. Nat Commun 2013; 3:1044. [PMID: 22948826 PMCID: PMC3658004 DOI: 10.1038/ncomms2028] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 07/30/2012] [Indexed: 12/16/2022] Open
Abstract
Seven transmembrane helical receptors (7TMRs) modulate cell function via different types of G proteins, often in a ligand-specific manner. Class A 7TMRs harbour allosteric vestibules in the entrance of their ligand-binding cavities, which are in the focus of current drug discovery. However, their biological function remains enigmatic. Here we present a new strategy for probing and manipulating conformational transitions in the allosteric vestibule of label-free 7TMRs using the M2 acetylcholine receptor as a paradigm. We designed dualsteric agonists as 'tailor-made' chemical probes to trigger graded receptor activation from the acetylcholine-binding site while simultaneously restricting spatial flexibility of the receptor's allosteric vestibule. Our findings reveal for the first time that a 7TMR's allosteric vestibule controls the extent of receptor movement to govern a hierarchical order of G-protein coupling. This is a new concept assigning a biological role to the allosteric vestibule for controlling fidelity of 7TMR signalling. Class A seven transmembrane helical receptors harbour vestibules at the entrance to the ligand-binding domain. Here, Bock et al. use probes to monitor the conformation of the M2 muscarinic receptor and show that the vestibule alters the extent of receptor movement.
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Affiliation(s)
- Andreas Bock
- Pharmacology and Toxicology Section, Institute of Pharmacy, University of Bonn, Gerhard-Domagk-Straße 3, 53121 Bonn, Germany
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25
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Mohr K, Schmitz J, Schrage R, Tränkle C, Holzgrabe U. Molecular Alliance-From Orthosteric and Allosteric Ligands to Dualsteric/Bitopic Agonists at G Protein Coupled Receptors. Angew Chem Int Ed Engl 2012; 52:508-16. [DOI: 10.1002/anie.201205315] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Indexed: 11/09/2022]
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26
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Mohr K, Schmitz J, Schrage R, Tränkle C, Holzgrabe U. Molekulare Allianz - von orthosterischen und allosterischen Liganden zu dualsterischen/bitopischen Agonisten G-Protein-gekoppelter Rezeptoren. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201205315] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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27
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Ragnarsson L, Wang CIA, Andersson Å, Fajarningsih D, Monks T, Brust A, Rosengren KJ, Lewis RJ. Conopeptide ρ-TIA defines a new allosteric site on the extracellular surface of the α1B-adrenoceptor. J Biol Chem 2012. [PMID: 23184947 DOI: 10.1074/jbc.m112.430785] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The G protein-coupled receptor (GPCR) superfamily is an important drug target that includes over 1000 membrane receptors that functionally couple extracellular stimuli to intracellular effectors. Despite the potential of extracellular surface (ECS) residues in GPCRs to interact with subtype-specific allosteric modulators, few ECS pharmacophores for class A receptors have been identified. Using the turkey β(1)-adrenergic receptor crystal structure, we modeled the α(1B)-adrenoceptor (α(1B)-AR) to help identify the allosteric site for ρ-conopeptide TIA, an inverse agonist at this receptor. Combining mutational radioligand binding and inositol 1-phosphate signaling studies, together with molecular docking simulations using a refined NMR structure of ρ-TIA, we identified 14 residues on the ECS of the α(1B)-AR that influenced ρ-TIA binding. Double mutant cycle analysis and docking confirmed that ρ-TIA binding was dominated by a salt bridge and cation-π between Arg-4-ρ-TIA and Asp-327 and Phe-330, respectively, and a T-stacking-π interaction between Trp-3-ρ-TIA and Phe-330. Water-bridging hydrogen bonds between Asn-2-ρ-TIA and Val-197, Trp-3-ρ-TIA and Ser-318, and the positively charged N terminus and Glu-186, were also identified. These interactions reveal that peptide binding to the ECS on transmembrane helix 6 (TMH6) and TMH7 at the base of extracellular loop 3 (ECL3) is sufficient to allosterically inhibit agonist signaling at a GPCR. The ligand-accessible ECS residues identified provide the first view of an allosteric inhibitor pharmacophore for α(1)-adrenoceptors and mechanistic insight and a new set of structural constraints for the design of allosteric antagonists at related GPCRs.
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Affiliation(s)
- Lotten Ragnarsson
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
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28
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Mitchelson FJ. The pharmacology of McN-A-343. Pharmacol Ther 2012; 135:216-45. [DOI: 10.1016/j.pharmthera.2012.05.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 05/07/2012] [Indexed: 01/01/2023]
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29
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Allosteric modulators of rhodopsin-like G protein-coupled receptors: opportunities in drug development. Pharmacol Ther 2012; 135:292-315. [PMID: 22728155 DOI: 10.1016/j.pharmthera.2012.06.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 06/07/2012] [Indexed: 11/21/2022]
Abstract
Rhodopsin-like (class A) G protein-coupled receptors (GPCRs) are one of the most important classes of drug targets. The discovery that these GPCRs can be allosterically modulated by small drug molecules has opened up new opportunities in drug development. It will allow the drugability of "difficult targets", such as GPCRs activated by large (glyco)proteins, or by very polar or highly lipophilic physiological agonists. Receptor subtype selectivity should be more easily achievable with allosteric than with orthosteric ligands. Allosteric modulation will allow a broad spectrum of pharmacological effects largely expanding that of orthosteric ligands. Furthermore, allosteric modulators may show an improved safety profile as compared to orthosteric ligands. Only recently, the explicit search for allosteric modulators has been started for only a few rhodopsin-like GPCRs. The first negative allosteric modulators (allosteric antagonists) of chemokine receptors, maraviroc (CCR5 receptor), used in HIV therapy, and plerixafor (CXCR4 receptor) for stem cell mobilization, have been approved as drugs. The development of allosteric modulators for rhodopsin-like GPCRs as novel drugs is still at an early stage; it appears highly promising.
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30
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Abstract
The physiological role of muscarinic receptors is highly complex and, although not completely understood, has become clearer over the last decade. Recent pharmacological evidence with novel compounds, together with data from transgenic mice, suggests that all five subtypes have defined functions in the nervous system as well as mediating the non neuronal, hormonal actions of acetylcholine. Numerous novel agonists, allosteric regulators, and antagonists have now been identified with authentic subtype specificity in vitro and in vivo. These compounds provide additional pharmacological opportunities for selective subtype modulation as well as a new generation of muscarinic receptor-based therapeutics.
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Affiliation(s)
- Richard M Eglen
- Corning Life Sciences, 900 Chelmsford St., MA 01851, Lowell, USA.
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31
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Niessen KV, Tattersall JEH, Timperley CM, Bird M, Green C, Thiermann H, Worek F. Competition radioligand binding assays for the investigation of bispyridinium compound affinities to the human muscarinic acetylcholine receptor subtype 5 (hM5). Drug Test Anal 2012; 4:292-7. [DOI: 10.1002/dta.410] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 12/02/2011] [Accepted: 12/02/2011] [Indexed: 11/08/2022]
Affiliation(s)
- K. V. Niessen
- Bundeswehr Institute of Pharmacology and Toxicology; Munich; Germany
| | | | | | - M. Bird
- Detection Department; Dstl Porton Down; Salisbury; UK
| | - C. Green
- Biomedical Sciences Department; Dstl Porton Down; Salisbury; UK
| | - H. Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology; Munich; Germany
| | - F. Worek
- Bundeswehr Institute of Pharmacology and Toxicology; Munich; Germany
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Abstract
There has been great interest in the structure-function relationships of the muscarinic acetylcholine receptors (mAChRs) because these prototypical Family A/class 1 G protein-coupled receptors (GPCRs) are attractive therapeutic targets for both peripheral and central nervous system disorders. A multitude of drugs that act at the mAChRs have been identified over the years, but many of these show minimal selectivity for any one of the five mAChR subtypes over the others, which has hampered their development into therapeutics due to adverse side effects. The lack of drug specificity is primarily due to high sequence similarity in this family of receptor, especially in the orthosteric binding pocket. Thus, there remains an ongoing need for a molecular understanding of how mAChRs bind their ligands, and how selectivity in binding and activation can be achieved. Unfortunately, there remains a paucity of solved high-resolution structures of GPCRs, including the mAChRs, and thus most of our knowledge of structure-function mechanisms related to this receptor family to date has been obtained indirectly through approaches such as mutagenesis. Nonetheless, such studies have revealed a wealth of information that has led to novel insights and may be used to guide future rational drug design campaigns.
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Marquer C, Fruchart-Gaillard C, Letellier G, Marcon E, Mourier G, Zinn-Justin S, Ménez A, Servent D, Gilquin B. Structural model of ligand-G protein-coupled receptor (GPCR) complex based on experimental double mutant cycle data: MT7 snake toxin bound to dimeric hM1 muscarinic receptor. J Biol Chem 2011; 286:31661-75. [PMID: 21685390 DOI: 10.1074/jbc.m111.261404] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The snake toxin MT7 is a potent and specific allosteric modulator of the human M1 muscarinic receptor (hM1). We previously characterized by mutagenesis experiments the functional determinants of the MT7-hM1 receptor interaction (Fruchart-Gaillard, C., Mourier, G., Marquer, C., Stura, E., Birdsall, N. J., and Servent, D. (2008) Mol. Pharmacol. 74, 1554-1563) and more recently collected evidence indicating that MT7 may bind to a dimeric form of hM1 (Marquer, C., Fruchart-Gaillard, C., Mourier, G., Grandjean, O., Girard, E., le Maire, M., Brown, S., and Servent, D. (2010) Biol. Cell 102, 409-420). To structurally characterize the MT7-hM1 complex, we adopted a strategy combining double mutant cycle experiments and molecular modeling calculations. First, thirty-three ligand-receptor proximities were identified from the analysis of sixty-one double mutant binding affinities. Several toxin residues that are more than 25 Å apart still contact the same residues on the receptor. As a consequence, attempts to satisfy all the restraints by docking the toxin onto a single receptor failed. The toxin was then positioned onto two receptors during five independent flexible docking simulations. The different possible ligand and receptor extracellular loop conformations were described by performing simulations in explicit solvent. All the docking calculations converged to the same conformation of the MT7-hM1 dimer complex, satisfying the experimental restraints and in which (i) the toxin interacts with the extracellular side of the receptor, (ii) the tips of MT7 loops II and III contact one hM1 protomer, whereas the tip of loop I binds to the other protomer, and (iii) the hM1 dimeric interface involves the transmembrane helices TM6 and TM7. These results structurally support the high affinity and selectivity of the MT7-hM1 interaction and highlight the atypical mode of interaction of this allosteric ligand on its G protein-coupled receptor target.
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Affiliation(s)
- Catherine Marquer
- Laboratoire de Biologie Structurale et Radiobiologie, Service de Bioénergétique, Biologie Structurale et Mécanismes (SB2SM), CNRS Unité de Recherche Associée 2096, Gif sur Yvette F-91191, France
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Leach K, Davey AE, Felder CC, Sexton PM, Christopoulos A. The Role of Transmembrane Domain 3 in the Actions of Orthosteric, Allosteric, and Atypical Agonists of the M4Muscarinic Acetylcholine Receptor. Mol Pharmacol 2011; 79:855-65. [DOI: 10.1124/mol.111.070938] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Jakubík J, El-Fakahany EE. Allosteric Modulation of Muscarinic Acetylcholine Receptors. Pharmaceuticals (Basel) 2010; 3:2838-2860. [PMID: 27713379 PMCID: PMC4034100 DOI: 10.3390/ph3092838] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 08/17/2010] [Accepted: 08/18/2010] [Indexed: 11/16/2022] Open
Abstract
An allosteric modulator is a ligand that binds to an allosteric site on the receptor and changes receptor conformation to produce increase (positive cooperativity) or decrease (negative cooperativity) in the binding or action of an orthosteric agonist (e.g., acetylcholine). Since the identification of gallamine as the first allosteric modulator of muscarinic receptors in 1976, this unique mode of receptor modulation has been intensively studied by many groups. This review summarizes over 30 years of research on the molecular mechanisms of allosteric interactions of drugs with the receptor and for new allosteric modulators of muscarinic receptors with potential therapeutic use. Identification of positive modulators of acetylcholine binding and function that enhance neurotransmission and the discovery of highly selective allosteric modulators are mile-stones on the way to novel therapeutic agents for the treatment of schizophrenia, Alzheimer’s disease and other disorders involving impaired cognitive function.
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Affiliation(s)
- Jan Jakubík
- Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 00 Praha, Czech Republic.
| | - Esam E El-Fakahany
- Division of Neuroscience Research in Psychiatry, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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Jacobson MA, Kreatsoulas C, Pascarella DM, O'Brien JA, Sur C. The M1 muscarinic receptor allosteric agonists AC-42 and 1-[1'-(2-methylbenzyl)-1,4'-bipiperidin-4-yl]-1,3-dihydro-2H-benzimidazol-2-one bind to a unique site distinct from the acetylcholine orthosteric site. Mol Pharmacol 2010; 78:648-57. [PMID: 20660086 DOI: 10.1124/mol.110.065771] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of M1 muscarinic receptors occurs through orthosteric and allosteric binding sites. To identify critical residues, site-directed mutagenesis and chimeric receptors were evaluated in functional calcium mobilization assays to compare orthosteric agonists, acetylcholine and xanomeline, M1 allosteric agonists AC-42 (4-n-butyl-1-[4-(2-methylphenyl)-4-oxo-1-butyl]-piperidine hydrogen chloride), TBPB (1-[1'-(2-methylbenzyl)-1,4'-bipiperidin-4-yl]-1,3-dihydro-2H-benzimidazol-2-one), and the clozapine metabolite N-desmethylclozapine. A minimal epitope has been defined for AC-42 that comprises the first 45 amino acids, the third extracellular loop, and seventh transmembrane domain (Mol Pharmacol 61:1297-1302, 2002). Using chimeric M1 and M3 receptor constructs, the AC-42 minimal epitope has been extended to also include transmembrane II. Phe77 was identified as a critical residue for maintenance of AC-42 and TBPB agonist activity. In contrast, the functional activity of N-desmethylclozapine did not require Phe77. To further map the binding site of AC-42, TBPB, and N-desmethylclozapine, point mutations previously reported to affect activities of M1 orthosteric agonists and antagonists were studied. Docking into an M1 receptor homology model revealed that AC-42 and TBPB share a similar binding pocket adjacent to the orthosteric binding site at the opposite face of Trp101. In contrast, the activity of N-desmethylclozapine was generally unaffected by the point mutations studied, and the docking indicated that N-desmethylclozapine bound to a site distinct from AC-42 and TBPB overlapping with the orthosteric site. These results suggest that structurally diverse allosteric agonists AC-42, TBPB, and N-desmethylclozapine may interact with different subsets of residues, supporting the hypothesis that M1 receptor activation can occur through at least three different binding domains.
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Affiliation(s)
- Marlene A Jacobson
- Merck Research Labs, Schizophrenia Research, WP26-265, West Point, PA 19486, USA.
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De Amici M, Dallanoce C, Holzgrabe U, Tränkle C, Mohr K. Allosteric ligands for G protein-coupled receptors: a novel strategy with attractive therapeutic opportunities. Med Res Rev 2010; 30:463-549. [PMID: 19557759 DOI: 10.1002/med.20166] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Allosteric receptor ligands bind to a recognition site that is distinct from the binding site of the endogenous messenger molecule. As a consequence, allosteric agents may attach to receptors that are already transmitter-bound. Ternary complex formation opens an avenue to qualitatively new drug actions at G protein-coupled receptors (GPCRs), in particular receptor subtype selective potentiation of endogenous transmitter action. Consequently, suitable exploitation of allosteric recognition sites as alternative molecular targets could pave the way to a drug discovery paradigm different from those aimed at mimicking or blocking the effects of endogenous (orthosteric) receptor activators. The number of allosteric ligands reported to modulate GPCR function is steadily increasing and some have already reached routine clinical use. This review aims at introducing into this fascinating field of drug discovery and at providing an overview about the achievements that have already been made. Various case examples will be discussed in the framework of GPCR classification (family A, B, and C receptors). In addition, the behavior at muscarinic receptors of hybrid derivatives incorporating both an allosteric and an orthosteric fragment in a common molecular skeleton will be illustrated.
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Affiliation(s)
- Marco De Amici
- Department of Pharmaceutical Sciences Pietro Pratesi, University of Milan, via Mangiagalli 25, 20133 Milano, Italy.
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van der Horst E, Peironcely JE, Ijzerman AP, Beukers MW, Lane JR, van Vlijmen HWT, Emmerich MTM, Okuno Y, Bender A. A novel chemogenomics analysis of G protein-coupled receptors (GPCRs) and their ligands: a potential strategy for receptor de-orphanization. BMC Bioinformatics 2010; 11:316. [PMID: 20537162 PMCID: PMC2897831 DOI: 10.1186/1471-2105-11-316] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Accepted: 06/10/2010] [Indexed: 02/03/2023] Open
Abstract
Background G protein-coupled receptors (GPCRs) represent a family of well-characterized drug targets with significant therapeutic value. Phylogenetic classifications may help to understand the characteristics of individual GPCRs and their subtypes. Previous phylogenetic classifications were all based on the sequences of receptors, adding only minor information about the ligand binding properties of the receptors. In this work, we compare a sequence-based classification of receptors to a ligand-based classification of the same group of receptors, and evaluate the potential to use sequence relatedness as a predictor for ligand interactions thus aiding the quest for ligands of orphan receptors. Results We present a classification of GPCRs that is purely based on their ligands, complementing sequence-based phylogenetic classifications of these receptors. Targets were hierarchically classified into phylogenetic trees, for both sequence space and ligand (substructure) space. The overall organization of the sequence-based tree and substructure-based tree was similar; in particular, the adenosine receptors cluster together as well as most peptide receptor subtypes (e.g. opioid, somatostatin) and adrenoceptor subtypes. In ligand space, the prostanoid and cannabinoid receptors are more distant from the other targets, whereas the tachykinin receptors, the oxytocin receptor, and serotonin receptors are closer to the other targets, which is indicative for ligand promiscuity. In 93% of the receptors studied, de-orphanization of a simulated orphan receptor using the ligands of related receptors performed better than random (AUC > 0.5) and for 35% of receptors de-orphanization performance was good (AUC > 0.7). Conclusions We constructed a phylogenetic classification of GPCRs that is solely based on the ligands of these receptors. The similarities and differences with traditional sequence-based classifications were investigated: our ligand-based classification uncovers relationships among GPCRs that are not apparent from the sequence-based classification. This will shed light on potential cross-reactivity of GPCR ligands and will aid the design of new ligands with the desired activity profiles. In addition, we linked the ligand-based classification with a ligand-focused sequence-based classification described in literature and proved the potential of this method for de-orphanization of GPCRs.
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Affiliation(s)
- Eelke van der Horst
- Division of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, 2333CC, The Netherlands.
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Kaszuba K, Róg T, Bryl K, Vattulainen I, Karttunen M. Molecular Dynamics Simulations Reveal Fundamental Role of Water As Factor Determining Affinity of Binding of β-Blocker Nebivolol to β2-Adrenergic Receptor. J Phys Chem B 2010; 114:8374-86. [DOI: 10.1021/jp909971f] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Karol Kaszuba
- Department of Physics, Tampere University of Technology, Tampere, Finland, Department of Physics and Biophysics, University of Warmia and Mazury, Olsztyn, Poland, University of Southern Denmark, Odensee, Denmark, Department of Applied Physics, Aalto University School of Science and Technology, Aalto, Finland, and Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada
| | - Tomasz Róg
- Department of Physics, Tampere University of Technology, Tampere, Finland, Department of Physics and Biophysics, University of Warmia and Mazury, Olsztyn, Poland, University of Southern Denmark, Odensee, Denmark, Department of Applied Physics, Aalto University School of Science and Technology, Aalto, Finland, and Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada
| | - Krzysztof Bryl
- Department of Physics, Tampere University of Technology, Tampere, Finland, Department of Physics and Biophysics, University of Warmia and Mazury, Olsztyn, Poland, University of Southern Denmark, Odensee, Denmark, Department of Applied Physics, Aalto University School of Science and Technology, Aalto, Finland, and Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada
| | - Ilpo Vattulainen
- Department of Physics, Tampere University of Technology, Tampere, Finland, Department of Physics and Biophysics, University of Warmia and Mazury, Olsztyn, Poland, University of Southern Denmark, Odensee, Denmark, Department of Applied Physics, Aalto University School of Science and Technology, Aalto, Finland, and Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada
| | - Mikko Karttunen
- Department of Physics, Tampere University of Technology, Tampere, Finland, Department of Physics and Biophysics, University of Warmia and Mazury, Olsztyn, Poland, University of Southern Denmark, Odensee, Denmark, Department of Applied Physics, Aalto University School of Science and Technology, Aalto, Finland, and Department of Applied Mathematics, The University of Western Ontario, London (ON), Canada
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40
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Stahl E, Ellis J. Novel allosteric effects of amiodarone at the muscarinic M5 receptor. J Pharmacol Exp Ther 2010; 334:214-22. [PMID: 20348203 DOI: 10.1124/jpet.109.165316] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Allosteric sites on muscarinic receptors may present superior therapeutic targets for several central nervous system disorders, due to the potential of allosteric ligands to provide more selective modulation and to preserve the spatiotemporal patterning that is characteristic of synaptic transmission. We have found that the antiarrhythmic drug amiodarone interacts allosterically with M(1) and M(5) muscarinic receptors. At both M(1) and M(5), amiodarone was only able to partially inhibit the binding of the orthosteric antagonist [(3)H]N-methylscopolamine (NMS). In addition, amiodarone was able to alter the rate of dissociation of [(3)H]NMS from M(1) and M(5) receptors. These findings suggest that NMS and amiodarone are able to bind to the receptor simultaneously. The pharmacology of the effect on NMS dissociation demonstrated that amiodarone was not interacting at the "common" site at which gallamine, obidoxime, and many other muscarinic allosteric ligands are known to bind. In functional studies, amiodarone enhanced the ability of acetylcholine (at EC(20)) to activate the M(5) receptor; however, under the same conditions, amiodarone did not enhance M(1) activation. More detailed studies at M(5) found that the effect of amiodarone was to enhance the efficacy of acetylcholine, without increasing its potency. This report describes the first demonstration of allosteric enhancement of efficacy at the M(5) receptor, and the first demonstration of enhancement of efficacy but not potency at any muscarinic receptor. In summary, amiodarone has been shown to be a novel positive allosteric modulator of muscarinic receptors that is selective for the M(5) subtype, relative to M(1).
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Affiliation(s)
- Edward Stahl
- Department of Psychiatry, Penn State University College of Medicine, Hershey, PA 17033, USA
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41
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Gregory KJ, Hall NE, Tobin AB, Sexton PM, Christopoulos A. Identification of orthosteric and allosteric site mutations in M2 muscarinic acetylcholine receptors that contribute to ligand-selective signaling bias. J Biol Chem 2010; 285:7459-74. [PMID: 20051519 PMCID: PMC2844194 DOI: 10.1074/jbc.m109.094011] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Indexed: 11/06/2022] Open
Abstract
Muscarinic acetylcholine receptors contain at least one allosteric site that is topographically distinct from the acetylcholine, orthosteric binding site. Although studies have investigated the basis of allosteric modulation at these receptors, less is known about putative allosteric ligands that activate the receptor in their own right. We generated M(2) muscarinic acetylcholine receptor mutations in either the orthosteric site in transmembrane helices 3 and 6 (TM3 and -6) or part of an allosteric site involving the top of TM2, the second extracellular (E2) loop, and the top of TM7 and investigated their effects on the binding and function of the novel selective (putative allosteric) agonists (AC-42 (4-n-butyl-1-(4-(2-methylphenyl)-4-oxo-1-butyl)piperidine HCl), 77-LH-28-1 (1-(3-(4-butyl-1-piperidinyl)propyl)-3,3-dihydro-2(1H)-quinolinone), and N-desmethylclozapine) as well as the bitopic orthosteric/allosteric ligand, McN-A-343 (4-(m-chlorophenyl-carbamoyloxy)-2-butynyltrimethylammonium). Four classes of agonists were identified, depending on their response to the mutations, suggesting multiple, distinct modes of agonist-receptor interaction. Interestingly, with the exception of 77-LH-28-1, allosteric site mutations had no effect on the affinity of any of the agonists tested, but some mutations in the E2 loop influenced the efficacy of both orthosteric and novel selective agonists, highlighting a role for this region of the receptor in modulating activation status. Two point mutations (Y104(3.33)A (Ballesteros and Weinstein numbers in superscript) in the orthosteric and Y177A in the allosteric site) unmasked ligand-selective and signaling pathway-selective effects, providing evidence for the existence of pathway-specific receptor conformations. Molecular modeling of 77-LH-28-1 and N-desmethylclozapine yielded novel binding poses consistent with the possibility that the functional selectivity of such agents may arise from a bitopic mechanism.
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Affiliation(s)
- Karen J. Gregory
- From the Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia and
| | - Nathan E. Hall
- From the Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia and
| | - Andrew B. Tobin
- the Department of Cell Physiology and Pharmacology, University of Leicester, Leicester LE1 9HN, United Kingdom
| | - Patrick M. Sexton
- From the Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia and
| | - Arthur Christopoulos
- From the Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia and
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42
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Molecular mechanisms of action and in vivo validation of an M4 muscarinic acetylcholine receptor allosteric modulator with potential antipsychotic properties. Neuropsychopharmacology 2010; 35:855-69. [PMID: 19940843 PMCID: PMC3055367 DOI: 10.1038/npp.2009.194] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We recently identified LY2033298 as a novel allosteric potentiator of acetylcholine (ACh) at the M(4) muscarinic acetylcholine receptor (mAChR). This study characterized the molecular mode of action of this modulator in both recombinant and native systems. Radioligand-binding studies revealed that LY2033298 displayed a preference for the active state of the M(4) mAChR, manifested as a potentiation in the binding affinity of ACh (but not antagonists) and an increase in the proportion of high-affinity agonist-receptor complexes. This property accounted for the robust allosteric agonism displayed by the modulator in recombinant cells in assays of [(35)S]GTPgammaS binding, extracellular regulated kinase 1/2 phosphorylation, glycogen synthase kinase 3beta phosphorylation, and receptor internalization. We also found that the extent of modulation by LY2033298 differed depending on the signaling pathway, indicating that LY2033298 engenders functional selectivity in the actions of ACh. This property was retained in NG108-15 cells, which natively express rodent M(4) mAChRs. Functional interaction studies between LY2033298 and various orthosteric and allosteric ligands revealed that its site of action overlaps with the allosteric site used by prototypical mAChR modulators. Importantly, LY2033298 reduced [(3)H]ACh release from rat striatal slices, indicating retention of its ability to allosterically potentiate endogenous ACh in situ. Moreover, its ability to potentiate oxotremorine-mediated inhibition of condition avoidance responding in rodents was significantly attenuated in M(4) mAChR knockout mice, validating the M(4) mAChR as a key target of action of this novel allosteric ligand.
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Mohr K, Tränkle C, Kostenis E, Barocelli E, De Amici M, Holzgrabe U. Rational design of dualsteric GPCR ligands: quests and promise. Br J Pharmacol 2010; 159:997-1008. [PMID: 20136835 DOI: 10.1111/j.1476-5381.2009.00601.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Dualsteric ligands represent a novel mode of targeting G protein-coupled receptors (GPCRs). These compounds attach simultaneously to both, the orthosteric transmitter binding site and an additional allosteric binding area of a receptor protein. This approach allows the exploitation of favourable characteristics of the orthosteric and the allosteric site by a single ligand molecule. The orthosteric interaction provides high affinity binding and activation of receptors. The allosteric interaction yields receptor subtype-selectivity and, in addition, may modulate both, efficacy and intracellular signalling pathway activation. Insight into the spatial arrangement of the orthosteric and the allosteric site is far advanced in the muscarinic acetylcholine receptor, and the design of dualsteric muscarinic agonists has now been accomplished. Using the muscarinic receptor as a paradigm, this review summarizes the way from suggestive evidence for an orthosteric/allosteric overlap binding to the rational design and experimental validation of dualsteric ligands. As allosteric interactions are increasingly described for GPCRs and as insight into the spatial geometry of ligand/GPCR-complexes is growing impressively, the rational design of dualsteric drugs is a promising new approach to achieve fine-tuned GPCR-modulation.
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Affiliation(s)
- Klaus Mohr
- Institute of Pharmacy, Rheinische Friedrich-Wilhelms-University, Bonn, Germany.
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44
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Kebig A, Kostenis E, Mohr K, Mohr-Andrä M. An optical dynamic mass redistribution assay reveals biased signaling of dualsteric GPCR activators. J Recept Signal Transduct Res 2009; 29:140-5. [PMID: 19586284 DOI: 10.1080/10799890903047437] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Increasing attention is paid in basic science and in drug discovery to pathway selective intracellular signaling as a novel approach to achieve precise control of cell function via G protein-coupled receptors (GPCRs). With respect to signaling, GPCRs are often promiscuous in that more than one intracellular biochemical pathway is activated upon receptor stimulation by the endogenous transmitter or by exogenous drugs. We studied signaling by a novel class of GPCR activators that were designed to bind simultaneously to the orthosteric transmitter-binding site and the allosteric site of muscarinic acetylcholine receptors. An optical biosensor technique was applied to measure activation-induced dynamic mass redistribution (DMR) in CHO cells stably expressing the muscarinic receptor subtype of interest. The use of tools to modulate signaling and measuring G protein activation directly proved that DMR is a valid and comfortable approach to gain real-time insight into intracellular signaling pathway activation and to identify signaling pathway-selective drugs.
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Affiliation(s)
- Anna Kebig
- Pharmacology and Toxicology Section, Institute of Pharmacy, Rheinische Friedrich-Wilhelms-University, Bonn, Germany
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45
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Conn PJ, Christopoulos A, Lindsley CW. Allosteric modulators of GPCRs: a novel approach for the treatment of CNS disorders. Nat Rev Drug Discov 2009; 8:41-54. [PMID: 19116626 PMCID: PMC2907734 DOI: 10.1038/nrd2760] [Citation(s) in RCA: 822] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Despite G-protein-coupled receptors (GPCRs) being among the most fruitful targets for marketed drugs, intense discovery efforts for several GPCR subtypes have failed to deliver selective drug candidates. Historically, drug discovery programmes for GPCR ligands have been dominated by efforts to develop agonists and antagonists that act at orthosteric sites for endogenous ligands. However, in recent years, there have been tremendous advances in the discovery of novel ligands for GPCRs that act at allosteric sites to regulate receptor function. These compounds provide high selectivity, novel modes of efficacy and may lead to novel therapeutic agents for the treatment of multiple psychiatric and neurological human disorders.
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Affiliation(s)
- P Jeffrey Conn
- Department of Pharmacology, Vanderbilt Program in Drug Discovery, Vanderbilt Medical Center, 1215 Light Hall, Nashville, Tennessee 37232, USA.
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46
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Antony J, Kellershohn K, Mohr-Andrä M, Kebig A, Prilla S, Muth M, Heller E, Disingrini T, Dallanoce C, Bertoni S, Schrobang J, Tränkle C, Kostenis E, Christopoulos A, Höltje HD, Barocelli E, De Amici M, Holzgrabe U, Mohr K. Dualsteric GPCR targeting: a novel route to binding and signaling pathway selectivity. FASEB J 2008; 23:442-50. [PMID: 18842964 DOI: 10.1096/fj.08-114751] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Selective modulation of cell function by G protein-coupled receptor (GPCR) activation is highly desirable for basic research and therapy but difficult to achieve. We present a novel strategy toward this goal using muscarinic acetylcholine receptors as a model. The five subtypes bind their physiological transmitter in the highly conserved orthosteric site within the transmembrane domains of the receptors. Orthosteric muscarinic activators have no binding selectivity and poor signaling specificity. There is a less well conserved allosteric site at the extracellular entrance of the binding pocket. To gain subtype-selective receptor activation, we synthesized two hybrids fusing a highly potent oxotremorine-like orthosteric activator with M(2)-selective bis(ammonio)alkane-type allosteric fragments. Radioligand binding in wild-type and mutant receptors supplemented by receptor docking simulations proved M(2) selective and true allosteric/orthosteric binding. G protein activation measurements using orthosteric and allosteric blockers identified the orthosteric part of the hybrid to engender receptor activation. Hybrid-induced dynamic mass redistribution in CHO-hM(2) cells disclosed pathway-specific signaling. Selective receptor activation (M(2)>M(1)>M(3)) was verified in living tissue preparations. As allosteric sites are increasingly recognized on GPCRs, the dualsteric concept of GPCR targeting represents a new avenue toward potent agonists for selective receptor and signaling pathway activation.
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Affiliation(s)
- Johannes Antony
- Pharmacology and Toxicology Section, Institute of Pharmacy, Rheinische Friedrich-Wilhelms-University, Bonn, Germany
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47
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Warne T, Serrano-Vega MJ, Baker JG, Moukhametzianov R, Edwards PC, Henderson R, Leslie AG, Tate CG, Schertler GF. Structure of a beta1-adrenergic G-protein-coupled receptor. Nature 2008; 454:486-91. [PMID: 18594507 PMCID: PMC2923055 DOI: 10.1038/nature07101] [Citation(s) in RCA: 1188] [Impact Index Per Article: 74.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Accepted: 05/19/2008] [Indexed: 11/09/2022]
Abstract
G-protein-coupled receptors have a major role in transmembrane signalling in most eukaryotes and many are important drug targets. Here we report the 2.7 A resolution crystal structure of a beta(1)-adrenergic receptor in complex with the high-affinity antagonist cyanopindolol. The modified turkey (Meleagris gallopavo) receptor was selected to be in its antagonist conformation and its thermostability improved by earlier limited mutagenesis. The ligand-binding pocket comprises 15 side chains from amino acid residues in 4 transmembrane alpha-helices and extracellular loop 2. This loop defines the entrance of the ligand-binding pocket and is stabilized by two disulphide bonds and a sodium ion. Binding of cyanopindolol to the beta(1)-adrenergic receptor and binding of carazolol to the beta(2)-adrenergic receptor involve similar interactions. A short well-defined helix in cytoplasmic loop 2, not observed in either rhodopsin or the beta(2)-adrenergic receptor, directly interacts by means of a tyrosine with the highly conserved DRY motif at the end of helix 3 that is essential for receptor activation.
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Affiliation(s)
- Tony Warne
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | | | | | | | | | - Richard Henderson
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
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48
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Affiliation(s)
- David E Nichols
- Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences, Purdue University, West Lafayette, Indiana 47906-2091, USA.
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Ehlert FJ, Griffin MT. Two-state models and the analysis of the allosteric effect of gallamine at the M2 muscarinic receptor. J Pharmacol Exp Ther 2008; 325:1039-60. [PMID: 18305010 DOI: 10.1124/jpet.108.136960] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We measured the influence of gallamine on the functional responses and binding properties of selected agonists at the M(2) muscarinic receptor and analyzed the data within the context of the allosteric ternary complex model. Our analysis showed that gallamine modified agonist affinity without influencing efficacy. To explain this behavior, we investigated the allosteric ternary complex model at a deeper level of analysis to assess allosterism in terms of the differential affinity of gallamine for ground and active states of the receptor. Our simulations showed that two-state models based on a single orthosteric site for the agonist linked to an allosteric site for gallamine could not account for affinity-only modulation, even if multiple conformations of ground and active states were considered. We also expanded the tandem two-site model (J Biol Chem 275:18836-18844, 2000) within the context of the allosteric ternary complex model and analyzed the resulting hybrid model at the level of receptor states. This model posits that the agonist first binds to a relay site and then shuttles to the activation site to turn on the receptor. If it is assumed that allosterism occurs at the relay site and not the activation site, then this model can account for affinity-only modulation in a manner consistent with the allosteric ternary complex model.
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Affiliation(s)
- Frederick J Ehlert
- Department of Pharmacology, School of Medicine, University of California, Irvine, CA 92697-4625, USA.
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50
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Jäger D, Schmalenbach C, Prilla S, Schrobang J, Kebig A, Sennwitz M, Heller E, Tränkle C, Holzgrabe U, Höltje HD, Mohr K. Allosteric small molecules unveil a role of an extracellular E2/transmembrane helix 7 junction for G protein-coupled receptor activation. J Biol Chem 2007; 282:34968-76. [PMID: 17890226 DOI: 10.1074/jbc.m705563200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors represent the largest superfamily of cell membrane-spanning receptors. We used allosteric small molecules as a novel approach to better understand conformational changes underlying the inactive-to-active switch in native receptors. Allosteric molecules bind outside the orthosteric area for the endogenous receptor activator. The human muscarinic M(2) acetylcholine receptor is prototypal for the study of allosteric interactions. We measured receptor-mediated G protein activation, applied a series of structurally diverse muscarinic allosteric agents, and analyzed their cooperative effects with orthosteric receptor agonists. A strong negative cooperativity of receptor binding was observed with acetylcholine and other full agonists, whereas a pronounced negative cooperativity of receptor activation was observed with the partial agonist pilocarpine. Applying a newly synthesized allosteric tool, point mutated receptors, radioligand binding, and a three-dimensional receptor model, we found that the deviating allosteric/orthosteric interactions are mediated through the core region of the allosteric site. A key epitope is M(2)Trp(422) in position 7.35 that is located at the extracellular top of transmembrane helix 7 and that contacts, in the inactive receptor, the extracellular loop E2. Trp 7.35 is critically involved in the divergent allosteric/orthosteric cooperativities with acetylcholine and pilocarpine, respectively. In the absence of allosteric agents, Trp 7.35 is essential for receptor binding of the full agonist and for receptor activation by the partial agonist. This study provides first evidence for a role of an allosteric E2/transmembrane helix 7 contact region for muscarinic receptor activation by orthosteric agonists.
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Affiliation(s)
- Dorothea Jäger
- Pharmacology and Toxicology Section, Institute of Pharmacy, Rheinische Friedrich-Wilhelms-University, D-53121 Bonn, Germany
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