8UNR

CryoEM structure of beta-2-adrenergic receptor in complex with GTP-bound Gs heterotrimer (Class G)

Summary for 8UNR

• Entry DOI: 10.2210/pdb8unr/pdb
• EMDB information: 42414
• Descriptor: Guanine nucleotide-binding protein G(s) subunit alpha isoforms short, Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1, Guanine nucleotide-binding protein G(I)/G(S)/G(O) subunit gamma-2, ... (7 entities in total)
• Functional Keywords: gpcr, adrenergic, receptor, g protein, signaling protein
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 4
• Total formula weight: 142260.95

Authors

Papasergi-Scott, M.M.,Skiniotis, G. (deposition date: 2023-10-19, release date: 2024-03-06, Last modification date: 2024-10-23)

Primary citation

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.
Time-resolved cryo-EM of G-protein activation by a GPCR.
Nature, 629:1182-1191, 2024

PubMed Abstract: G-protein-coupled receptors (GPCRs) activate heterotrimeric G proteins by stimulating guanine nucleotide exchange in the Gα subunit. 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 protein in complex with the β-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.

PubMed: 38480881
DOI: 10.1038/s41586-024-07153-1

Experimental method

ELECTRON MICROSCOPY (3.4 Å)