Conformational plasticity of the intracellular cavity of GPCR−G-protein complexes leads to G-protein promiscuity and selectivity

Manbir Sandhu, Anja M. Touma, Matthew Dysthe, Fredrik Sadler, Sivaraj Sivaramakrishnan, Nagarajan Vaidehi

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

While the dynamics of the intracellular surface in agonist-stimulated GPCRs is well studied, the impact of GPCR dynamics on G-protein selectivity remains unclear. Here, we combine molecular dynamics simulations with live-cell FRET and secondary messenger measurements, for 21 GPCR−G-protein combinations, to advance a dynamic model of the GPCR−G-protein interface. Our data show C terminus peptides of Gαs, Gαi, and Gαq proteins assume a small ensemble of unique orientations when coupled to their cognate GPCRs, similar to the variations observed in 3D structures of GPCR−G-protein complexes. The noncognate G proteins interface with latent intracellular GPCR cavities but dissociate due to weak and unstable interactions. Three predicted mutations in β2-adrenergic receptor stabilize binding of noncognate Gαq protein in its latent cavity, allowing promiscuous signaling through both Gαs and Gαq in a dose-dependent manner. This demonstrates that latent GPCR cavities can be evolved, by design or nature, to tune G-protein selectivity, giving insights to pluridimensional GPCR signaling.

Original languageEnglish (US)
Pages (from-to)11956-11965
Number of pages10
JournalProceedings of the National Academy of Sciences of the United States of America
Volume116
Issue number24
DOIs
StatePublished - Jun 11 2019

Bibliographical note

Funding Information:
Research in this publication is supported by Grant NIH-R01GM117923 (to N.V. and S.S.) and Maximizing Investigator Research Award Grant NIH-R35GM126940 (to S.S.).

Funding Information:
ACKNOWLEDGMENTS. Research in this publication is supported by Grant NIH-R01GM117923 (to N.V. and S.S.) and Maximizing Investigator Research Award Grant NIH-R35GM126940 (to S.S.).

Publisher Copyright:
© 2019 National Academy of Sciences. All rights reserved.

Keywords

  • G-protein−coupled receptor
  • GPCR
  • dynamics
  • functional selectivity
  • structural plasticity

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