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

TY - JOUR

T1 - Structural flexibility of the G alpha s alpha-helical domain in the beta2-adrenoceptor Gs complex

AU - Westfield, Gerwin H

AU - Rasmussen, Søren Gøgsig Faarup

AU - Su, Min

AU - Dutta, Somnath

AU - DeVree, Brian T

AU - Chung, Ka Young

AU - Calinski, Diane

AU - Velez-Ruiz, Gisselle

AU - Oleskie, Austin N

AU - Pardon, Els

AU - Chae, Pil Seok

AU - Liu, Tong

AU - Li, Sheng

AU - Woods, Virgil L

AU - Steyaert, Jan

AU - Kobilka, Brian K

AU - Sunahara, Roger K

AU - Skiniotis, Georgios

PY - 2011/10/20

Y1 - 2011/10/20

N2 - 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.

AB - 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.

KW - Animals

KW - Crystallization

KW - Crystallography, X-Ray

KW - GTP-Binding Protein alpha Subunits, Gs

KW - Guanosine 5'-O-(3-Thiotriphosphate)

KW - Guanosine Diphosphate

KW - Guanosine Triphosphate

KW - Microscopy, Electron

KW - Models, Molecular

KW - Protein Binding

KW - Protein Conformation

KW - Protein Structure, Secondary

KW - Protein Structure, Tertiary

KW - Receptors, Adrenergic, beta-2

U2 - 10.1073/pnas.1113645108

DO - 10.1073/pnas.1113645108

M3 - Journal article

C2 - 21914848

SN - 0027-8424

VL - 108

SP - 16086

EP - 16091

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

IS - 38

ER -