Structure and function of an irreversible agonist-β2 adrenoceptor complex

Daniel M. Rosenbaum, Cheng Zhang, Joseph A. Lyons, Ralph Holl, David Aragao, Daniel H. Arlow, Sã̧ren G F 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

Research output: Contribution to journalArticlepeer-review

596 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)236-242
Number of pages7
JournalNature
Volume469
Issue number7329
DOIs
StatePublished - Jan 13 2011

ASJC Scopus subject areas

  • General

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