Download MendeleyTime-resolved cryo-EM of G-protein activation by a GPCR.
Papasergi-Scott, M.M., Perez-Hernandez, G., Batebi, H., Gao, Y., Eskici, G., Seven, A.B., Panova, O., Hilger, D., Casiraghi, M., He, F., Maul, L., Gmeiner, P., Kobilka, B.K., Hildebrand, P.W., Skiniotis, G.(2024) Nature 629: 1182-1191
- PubMed: 38480881 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1038/s41586-024-07153-1
- PubMed Abstract:
G-protein-coupled receptors (GPCRs) activate heterotrimeric G proteins by stimulating guanine nucleotide exchange in the Gα subunit 1 . 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 G s protein in complex with the β 2 -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.
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.
Organizational Affiliation:
