Structural diversity in the RGS domain and its interaction with heterotrimeric G protein alpha-subunits

Meera Soundararajan, Francis S. Willard, Adam J. Kimple, Andrew P. Turnbull, Linda J. Ball, Guillaume A. Schoch, Carina Gileadi, Oleg Y. Fedorov, Elizabeth F. Dowler, Victoria A. Higman, Stephanie Q. Hutsell, Michael Sundstrom, Declan A. Doyle, David P. Siderovski*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

115 Citations (Scopus)

Abstract

Regulator of G protein signaling (RGS) proteins accelerate GTP hydrolysis by G alpha subunits and thus facilitate termination of signaling initiated by G protein-coupled receptors (GPCRs). RGS proteins hold great promise as disease intervention points, given their signature role as negative regulators of GPCRs-receptors to which the largest fraction of approved medications are currently directed. RGS proteins share a hallmark RGS domain that interacts most avidly with G alpha when in its transition state for GTP hydrolysis; by binding and stabilizing switch regions I and II of G alpha, RGS domain binding consequently accelerates G alpha-mediated GTP hydrolysis. The human genome encodes more than three dozen RGS domain-containing proteins with varied G alpha substrate specificities. To facilitate their exploitation as drug-discovery targets, we have taken a systematic structural biology approach toward cataloging the structural diversity present among RGS domains and identifying molecular determinants of their differential G alpha selectivities. Here, we determined 14 structures derived from NMR and x-ray crystallography of members of the R4, R7, R12, and RZ subfamilies of RGS proteins, including 10 uncomplexed RGS domains and 4 RGS domain/G alpha complexes. Heterogeneity observed in the structural architecture of the RGS domain, as well as in engagement of switch III and the all-helical domain of the G alpha substrate, suggests that unique structural determinants specific to particular RGS protein/G alpha pairings exist and could be used to achieve selective inhibition by small molecules.

Original languageEnglish
Pages (from-to)6457-6462
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume105
Issue number17
DOIs
Publication statusPublished - 29 Apr 2008

Keywords

  • BINDING
  • GTPase-accelerating proteins
  • REGULATOR
  • PHOSPHORYLATION
  • RGS proteins
  • x-ray crystallography
  • NMR structure
  • COMPLEX
  • DETERMINANTS
  • MEMBRANE
  • GTPASE-ACTIVATING PROTEIN
  • ANXIETY
  • SUGGESTS
  • INHIBITION

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