EMD-29953

Single-particle
3.3 Å
EMD-29953 Deposition: 06/03/2023
Map released: 06/03/2024
Last modified: 13/11/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-29953

CryoEM structure of beta-2-adrenergic receptor in complex with nucleotide-free Gs heterotrimer (#3 of 20)

EMD-29953

Single-particle
3.3 Å
EMD-29953 Deposition: 06/03/2023
Map released: 06/03/2024
Last modified: 13/11/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Homo sapiens
Sample: Complex of beta-2 adrenergic receptor and Gs G protein heterotrimer
Fitted models: 8ge2 (Avg. Q-score: 0.51)
Raw data: EMPIAR-11855

Deposition Authors: Papasergi-Scott MM , Skiniotis G
Time-resolved cryo-EM of G-protein activation by a GPCR.
PUBMED: 38480881
DOI: doi:10.1038/s41586-024-07153-1
ISSN: 1476-4687
ASTM: NATUAS
Abstract:
G-protein-coupled receptors (GPCRs) activate heterotrimeric G proteins by stimulating guanine nucleotide exchange in the Gα subunit1. To visualize this mechanism, we developed a time-resolved cryo-EM approach that examines the progression of ensembles of pre-steady-state intermediates of a GPCR-G-protein complex. By monitoring the transitions of the stimulatory Gs protein in complex with the β2-adrenergic receptor at short sequential time points after GTP addition, we identified the conformational trajectory underlying G-protein activation and functional dissociation from the receptor. Twenty structures generated from sequential overlapping particle subsets along this trajectory, compared to control structures, provide a high-resolution description of the order of main events driving G-protein activation in response to GTP binding. Structural changes propagate from the nucleotide-binding pocket and extend through the GTPase domain, enacting alterations to Gα switch regions and the α5 helix that weaken the G-protein-receptor interface. Molecular dynamics simulations with late structures in the cryo-EM trajectory support that enhanced ordering of GTP on closure of the α-helical domain against the nucleotide-bound Ras-homology domain correlates with α5 helix destabilization and eventual dissociation of the G protein from the GPCR. These findings also highlight the potential of time-resolved cryo-EM as a tool for mechanistic dissection of GPCR signalling events.