Structural flexibility of the G alpha s alpha-helical domain in the beta2-adrenoceptor Gs complex.

TitleStructural flexibility of the G alpha s alpha-helical domain in the beta2-adrenoceptor Gs complex.
Publication TypeJournal Article
Year of Publication2011
AuthorsWestfield, G. H., S. G. F. Rasmussen, M. Su, S. Dutta, B. T. Devree, K. Young Chung, D. Calinski, G. Velez-Ruiz, A. N. Oleskie, E. Pardon, P. Seok Chae, T. Liu, S. Li, V. L. Woods, J. Steyaert, B. K. Kobilka, R. K. Sunahara, and G. Skiniotis
JournalProc Natl Acad Sci U S A
Volume108
Issue38
Pagination16086-91
Date Published2011 Sep 20
ISSN1091-6490
KeywordsAnimals, Crystallization, Crystallography, X-Ray, GTP-Binding Protein alpha Subunits, Gs, Guanosine 5'-O-(3-Thiotriphosphate), Guanosine Diphosphate, Guanosine Triphosphate, Microscopy, Electron, Models, Molecular, Protein Binding, Protein Conformation, Protein Structure, Secondary, Protein Structure, Tertiary, Receptors, Adrenergic, beta-2
Abstract

The active-state complex between an agonist-bound receptor and a guanine nucleotide-free G protein represents the fundamental signaling assembly for the majority of hormone and neurotransmitter signaling. We applied single-particle electron microscopy (EM) analysis to examine the architecture of agonist-occupied β(2)-adrenoceptor (β(2)AR) in complex with the heterotrimeric G protein Gs (Gαsβγ). EM 2D averages and 3D reconstructions of the detergent-solubilized complex reveal an overall architecture that is in very good agreement with the crystal structure of the active-state ternary complex. Strikingly however, the α-helical domain of Gαs appears highly flexible in the absence of nucleotide. In contrast, the presence of the pyrophosphate mimic foscarnet (phosphonoformate), and also the presence of GDP, favor the stabilization of the α-helical domain on the Ras-like domain of Gαs. Molecular modeling of the α-helical domain in the 3D EM maps suggests that in its stabilized form it assumes a conformation reminiscent to the one observed in the crystal structure of Gαs-GTPγS. These data argue that the α-helical domain undergoes a nucleotide-dependent transition from a flexible to a conformationally stabilized state.

DOI10.1073/pnas.1113645108
Alternate JournalProc. Natl. Acad. Sci. U.S.A.
PubMed ID21914848
PubMed Central IDPMC3179071
Grant ListAI076961 / AI / NIAID NIH HHS / United States
AI08192 / AI / NIAID NIH HHS / United States
AI2008031 / AI / NIAID NIH HHS / United States
CA118595 / CA / NCI NIH HHS / United States
GM008270 / GM / NIGMS NIH HHS / United States
GM066170 / GM / NIGMS NIH HHS / United States
GM093325 / GM / NIGMS NIH HHS / United States
GM20501 / GM / NIGMS NIH HHS / United States
P60DK-20572 / DK / NIDDK NIH HHS / United States
R01 GM020501-36 / GM / NIGMS NIH HHS / United States
R01 GM068603 / GM / NIGMS NIH HHS / United States
R01-DK090165 / DK / NIDDK NIH HHS / United States
R01-GM068603 / GM / NIGMS NIH HHS / United States
R01-GM083118 / GM / NIGMS NIH HHS / United States
R01-NS28471 / NS / NINDS NIH HHS / United States
RR029388 / RR / NCRR NIH HHS / United States
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