Conformational changes in the G protein Gs induced by the β2 adrenergic receptor

TY - JOUR

T1 - Conformational changes in the G protein Gs induced by the β2 adrenergic receptor

AU - Chung, Ka Young

AU - Rasmussen, Søren Gøgsig Faarup

AU - Liu, Tong

AU - Li, Sheng

AU - DeVree, Brian T

AU - Chae, Pil Seok

AU - Calinski, Diane

AU - Kobilka, Brian K

AU - Woods, Virgil L

AU - Sunahara, Roger K

N1 - © 2011 Macmillan Publishers Limited. All rights reserved

PY - 2011/9/29

Y1 - 2011/9/29

N2 - G protein-coupled receptors represent the largest family of membrane receptors that instigate signalling through nucleotide exchange on heterotrimeric G proteins. Nucleotide exchange, or more precisely, GDP dissociation from the G protein α-subunit, is the key step towards G protein activation and initiation of downstream signalling cascades. Despite a wealth of biochemical and biophysical studies on inactive and active conformations of several heterotrimeric G proteins, the molecular underpinnings of G protein activation remain elusive. To characterize this mechanism, we applied peptide amide hydrogen-deuterium exchange mass spectrometry to probe changes in the structure of the heterotrimeric bovine G protein, Gs (the stimulatory G protein for adenylyl cyclase) on formation of a complex with agonist-bound human β(2) adrenergic receptor (β(2)AR). Here we report structural links between the receptor-binding surface and the nucleotide-binding pocket of Gs that undergo higher levels of hydrogen-deuterium exchange than would be predicted from the crystal structure of the β(2)AR-Gs complex. Together with X-ray crystallographic and electron microscopic data of the β(2)AR-Gs complex (from refs 2, 3), we provide a rationale for a mechanism of nucleotide exchange, whereby the receptor perturbs the structure of the amino-terminal region of the α-subunit of Gs and consequently alters the 'P-loop' that binds the β-phosphate in GDP. As with the Ras family of small-molecular-weight G proteins, P-loop stabilization and β-phosphate coordination are key determinants of GDP (and GTP) binding affinity.

AB - G protein-coupled receptors represent the largest family of membrane receptors that instigate signalling through nucleotide exchange on heterotrimeric G proteins. Nucleotide exchange, or more precisely, GDP dissociation from the G protein α-subunit, is the key step towards G protein activation and initiation of downstream signalling cascades. Despite a wealth of biochemical and biophysical studies on inactive and active conformations of several heterotrimeric G proteins, the molecular underpinnings of G protein activation remain elusive. To characterize this mechanism, we applied peptide amide hydrogen-deuterium exchange mass spectrometry to probe changes in the structure of the heterotrimeric bovine G protein, Gs (the stimulatory G protein for adenylyl cyclase) on formation of a complex with agonist-bound human β(2) adrenergic receptor (β(2)AR). Here we report structural links between the receptor-binding surface and the nucleotide-binding pocket of Gs that undergo higher levels of hydrogen-deuterium exchange than would be predicted from the crystal structure of the β(2)AR-Gs complex. Together with X-ray crystallographic and electron microscopic data of the β(2)AR-Gs complex (from refs 2, 3), we provide a rationale for a mechanism of nucleotide exchange, whereby the receptor perturbs the structure of the amino-terminal region of the α-subunit of Gs and consequently alters the 'P-loop' that binds the β-phosphate in GDP. As with the Ras family of small-molecular-weight G proteins, P-loop stabilization and β-phosphate coordination are key determinants of GDP (and GTP) binding affinity.

KW - Adrenergic beta-2 Receptor Agonists

KW - Animals

KW - Biocatalysis

KW - Catalytic Domain

KW - Cattle

KW - Crystallography, X-Ray

KW - Deuterium Exchange Measurement

KW - GTP-Binding Protein alpha Subunits, Gs

KW - Guanosine Diphosphate

KW - Guanosine Triphosphate

KW - Humans

KW - Models, Molecular

KW - Protein Binding

KW - Protein Conformation

KW - Receptors, Adrenergic, beta-2

U2 - 10.1038/nature10488

DO - 10.1038/nature10488

M3 - Journal article

C2 - 21956331

SN - 0028-0836

VL - 477

SP - 611

EP - 615

JO - Nature

JF - Nature

IS - 7366

ER -