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Ligand-dependent perturbation of the conformational ensemble for the GPCR ?2 adrenergic receptor revealed by HDX.

ABSTRACT: Mechanism of G protein-coupled receptor (GPCR) activation and their modulation by functionally distinct ligands remains elusive. Using the technique of amide hydrogen/deuterium exchange coupled with mass spectrometry, we examined the ligand-induced changes in conformational states and stability within the beta-2-adrenergic receptor (?(2)AR). Differential HDX reveals ligand-specific alterations in the energy landscape of the receptor's conformational ensemble. The inverse agonists timolol and carazolol were found to be most stabilizing even compared with the antagonist alprenolol, notably in intracellular regions where G proteins are proposed to bind, while the agonist isoproterenol induced the largest degree of conformational mobility. The partial agonist clenbuterol displayed conformational effects found in both the inverse agonists and the agonist. This study highlights the regional plasticity of the receptor and characterizes unique conformations spanning the entire receptor sequence stabilized by functionally selective ligands, all of which differ from the profile for the apo receptor.

SUBMITTER: West GM

PROVIDER: S-EPMC3196059 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature

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Ligand-dependent perturbation of the conformational ensemble for the GPCR β2 adrenergic receptor revealed by HDX.

West Graham M GM Chien Ellen Y T EY Katritch Vsevolod V Gatchalian Jovylyn J Chalmers Michael J MJ Stevens Raymond C RC Griffin Patrick R PR

Structure (London, England : 1993) 20110901 10

Mechanism of G protein-coupled receptor (GPCR) activation and their modulation by functionally distinct ligands remains elusive. Using the technique of amide hydrogen/deuterium exchange coupled with mass spectrometry, we examined the ligand-induced changes in conformational states and stability within the beta-2-adrenergic receptor (β(2)AR). Differential HDX reveals ligand-specific alterations in the energy landscape of the receptor's conformational ensemble. The inverse agonists timolol and car ...[more]

PMID: 21889352

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Project description:PURPOSE:G protein-coupled receptors (GPCRs) are a superfamily of membrane proteins of vast pharmaceutical interest. Here, we describe a graph theory-based analysis of the structure of the ?2 adrenergic receptor (?2 AR), a prototypical GPCR. In particular, we illustrate the network of direct and indirect interactions that link each amino acid residue to any other residue of the receptor. METHODS:Networks of interconnected amino acid residues in proteins are analogous to social networks of interconnected people. Hence, they can be studied through the same analysis tools typically employed to analyze social networks - or networks in general - to reveal patterns of connectivity, influential members, and dynamicity. We focused on the analysis of closeness-centrality, which is a measure of the overall connectivity distance of the member of a network to all other members. RESULTS:The residues endowed with the highest closeness-centrality are located in the middle of the seven transmembrane domains (TMs). In particular, they are mostly located in the middle of TM2, TM3, TM6 or TM7, while fewer of them are located in the middle of TM1, TM4 or TM5. At the cytosolic end of TM6, the centrality detected for the active structure is markedly lower than that detected for the corresponding residues in the inactive structures. Moreover, several residues acquire centrality when the structures are analyzed in the presence of ligands. Strikingly, there is little overlap between the residues that acquire centrality in the presence of the ligand in the blocker-bound structures and the agonist-bound structures. CONCLUSIONS:Our results reflect the fact that the receptor resembles a bow tie, with a rather tight knot of closely interconnected residues and two ends that fan out in two opposite directions: one toward the extracellular space, which hosts the ligand binding cavity, and one toward the cytosol, which hosts the G protein binding cavity. Moreover, they underscore how interaction network is by the conformational rearrangements concomitant with the activation of the receptor and by the presence of agonists or blockers.

Dataset Information

Ligand-dependent perturbation of the conformational ensemble for the GPCR ?2 adrenergic receptor revealed by HDX.

Publications

Ligand-dependent perturbation of the conformational ensemble for the GPCR β2 adrenergic receptor revealed by HDX.

Similar Datasets

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