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

Daniel M Rosenbaum, Cheng Zhang, Joseph A Lyons, Ralph Holl, David Aragao, Daniel H Arlow, Søren Gøgsig Faarup Rasmussen, Hee-Jung Choi, Brian T Devree, Roger K Sunahara, Pil Seok Chae, Samuel H Gellman, Ron O Dror, David E Shaw, William I Weis, Martin Caffrey, Peter Gmeiner, Brian K Kobilka

612 Citationer (Scopus)

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 β2 adrenergic receptor (β2 AR) as a guide, we designed a β2 AR agonist that can be covalently tethered to a specific site on the receptor through a disulphide bond. The covalent β2 AR-agonist complex forms efficiently, and is capable of activating a heterotrimeric G protein. We crystallized a covalent agonist-bound β2 ARg-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 30μs) 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.

OriginalsprogEngelsk
TidsskriftNature
Vol/bind469
Udgave nummer7329
Sider (fra-til)236-40
Antal sider5
ISSN0028-0836
DOI
StatusUdgivet - 13 jan. 2011

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