Cardiac disease remains the leading cause of morbidity and mortality worldwide. The β1-adrenergic receptor (β1-AR) is a major regulator of cardiac functions and is downregulated in the majority of heart failure cases. A key physiological process is the activation of heterotrimeric G-protein Gs by β1-ARs, leading to increased heart rate and contractility. Here, we use cryo-electron microscopy and functional studies to investigate the molecular mechanism by which β1-AR activates Gs. We find that the tilting of α5-helix breaks a hydrogen bond between the sidechain of His373 in the C-terminal α5-helix and the backbone carbonyl of Arg38 in the N-terminal αN-helix of Gαs. Together with the disruption of another interacting network involving Gln59 in the α1-helix, Ala352 in the β6-α5 loop, and Thr355 in the α5-helix, these conformational changes might lead to the deformation of the GDP-binding pocket. Our data provide molecular insights into the activation of G-proteins by G-protein-coupled receptors.
Bibliographical noteFunding Information:
We thank members of our research groups for helpful discussion and comments on the manuscript. This work was supported by NIH grant HL130478 (X.-Y.H.), the Josie Robertson Investigators Program (R.K.H.), the Searle Scholars Program (R.K.H.), the Canada Excellence Research Chairs Program (O.P.E.), and CIHR grant 159464 (O.P.E.). The Simons Electron Microscopy Center and the National Resource for Automated Molecular Microscopy located at the New York Structural Biology Center are supported by grants from the NIH National Institute of General Medical Sciences ( GM103310 ), NYSTAR , and the Simons Foundation ( SF349247 ).
© 2020 Elsevier Inc.
- G-protein-coupled receptor
- activation of G-proteins
- cardiac disease
- cryo-electron microscopy
- signal transduction
- structural biology
- β1-adrenergic receptor
PubMed: MeSH publication types
- Journal Article
- Research Support, N.I.H., Extramural
- Research Support, Non-U.S. Gov't
- Research Support, U.S. Gov't, Non-P.H.S.