Structure and Function of an Irreversible Agonist-β2 Adrenoceptor complex

By D. Rosenbaum, Cheng Zhang, J. Lyons, Ralph Holl, D. Aragão, Daniel H Arlow, S. Rasmussen, Hee-Jung Choi, Brian T DeVree, R. Sunahara and 8 more. Nature, 2011

766 citations recorded by the source corpus.

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 (β2AR) as a guide, we designed a β2AR agonist that can be covalently tethered to a specific site on the receptor through a disulphide bond. The covalent β2AR-agonist complex forms efficiently, and is capable of activating a heterotrimeric G protein. We crystallized a covalent agonist-bound β2AR–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 μs) 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.

Subfields: Cellular and Molecular Neuroscience, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/43976fcbbd908bc3df9498784031d76081960938

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Citations in the corpus

A combined activation mechanism for the glucagon receptor (2020, background): “While binding of agonists promotes preactivation, full shift of the population to the active state is dependent on interaction of G proteins or G-protein mimetics with the intracellular side of the receptor (38, 39).”
Multiple conformational states in retrospective virtual screening – homology models vs. crystal structures: beta-2 adrenergic receptor case study (2015, background): “The drop in MCC, observed after adding the last two conformations (3P0G [12] and 3PDS [13]), is a consequence of the crystals being agonist bound.”
Structural insights into the dynamic process of β2-adrenergic receptor signaling (2015, unknown): “Additionally, molecular dynamics simulations of active, agonist-bound b2AR in the absence of Nb80 or Gs demonstrate a rapid transition of the receptor to the inactive state (Rosenbaum et al., 2011).”
Lifting the lid on GPCRs: the role of extracellular loops (2011, methodology): “…crystal structures of active b2AR have been published; one using an irreversible agonist (FAUC50) disulfide- bonded to an [H93C]b2AR-T4L mutant construct (Rosenbaum et al., 2011) and a b2AR-T4L:high affinity agonist (BI-167107) complex stabilized by a bound nanobody (Rasmussen et al., 2011a).”
Molecular Mechanism of β-Arrestin-Biased Agonism at Seven-Transmembrane Receptors (2011, background): “Although there are only subtle changes in the binding pocket, a relatively large outward movement of the cytoplasmic end of TM6 and a substantial rearrangement of TM5 and TM7 are seen (50, 51).”