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Structure and function of an irreversible agonist-?(2) adrenoceptor complex.

ABSTRACT: G-protein-coupled receptors (GPCRs) are eukaryotic integral membrane proteins that modulate biological function by initiating cellular signalling in response to chemically diverse agonists. Despite recent progress in the structural biology of GPCRs, the molecular basis for agonist binding and allosteric modulation of these proteins is poorly understood. Structural knowledge of agonist-bound states is essential for deciphering the mechanism of receptor activation, and for structure-guided design and optimization of ligands. However, the crystallization of agonist-bound GPCRs has been hampered by modest affinities and rapid off-rates of available agonists. Using the inactive structure of the human ?(2) adrenergic receptor (?(2)AR) as a guide, we designed a ?(2)AR agonist that can be covalently tethered to a specific site on the receptor through a disulphide bond. The covalent ?(2)AR-agonist complex forms efficiently, and is capable of activating a heterotrimeric G protein. We crystallized a covalent agonist-bound ?(2)AR-T4L fusion protein in lipid bilayers through the use of the lipidic mesophase method, and determined its structure at 3.5?Å resolution. A comparison to the inactive structure and an antibody-stabilized active structure (companion paper) shows how binding events at both the extracellular and intracellular surfaces are required to stabilize an active conformation of the receptor. The structures are in agreement with long-timescale (up to 30??s) molecular dynamics simulations showing that an agonist-bound active conformation spontaneously relaxes to an inactive-like conformation in the absence of a G protein or stabilizing antibody.

SUBMITTER: Rosenbaum DM

PROVIDER: S-EPMC3074335 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Structure and function of an irreversible agonist-β(2) adrenoceptor complex.

Rosenbaum Daniel M DM Zhang Cheng C Lyons Joseph A JA Holl Ralph R Aragao David D Arlow Daniel H DH Rasmussen Søren G F SG Choi Hee-Jung HJ Devree Brian T BT Sunahara Roger K RK Chae Pil Seok PS Gellman Samuel H SH Dror Ron O RO Shaw David E DE Weis William I WI Caffrey Martin M Gmeiner Peter P Kobilka Brian K BK

Nature 20110101 7329

G-protein-coupled receptors (GPCRs) are eukaryotic integral membrane proteins that modulate biological function by initiating cellular signalling in response to chemically diverse agonists. Despite recent progress in the structural biology of GPCRs, the molecular basis for agonist binding and allosteric modulation of these proteins is poorly understood. Structural knowledge of agonist-bound states is essential for deciphering the mechanism of receptor activation, and for structure-guided design ...[more]

PMID: 21228876

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Structure and function of an irreversible agonist-?(2) adrenoceptor complex.

Publications

Structure and function of an irreversible agonist-β(2) adrenoceptor complex.

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