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The 2.7‐Å crystal structure of Gα12 in complex with a regulator of G protein signaling homology (RH) domain (843.1)
Author(s) -
Kreutz Barry,
Chanthavong Dara,
Santarsiero Bernard,
Kozasa Tohru
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.843.1
Subject(s) - heterotrimeric g protein , rhoa , gtpase , pleckstrin homology domain , g protein , biology , microbiology and biotechnology , gtpase activating protein , regulator of g protein signaling , regulator , biochemistry , phosphorylation , signal transduction , gene
Heterotrimeric G proteins Gα12 and Gα13 parse signals from G protein‐coupled receptors at the cell surface to activation of RhoA through a subset of RhoA‐specific exchange factors (RhoGEFs), including human proteins p115 RhoGEF, PDZ‐RhoGEF, and leukemia‐associated RhoGEF/LARG. Each of these proteins share a well‐conserved regulator of G protein signaling homology (RH) domain which binds with high affinity and specificity to active forms of Gα12 and Gα13. Concurrent with their activation as effectors, p115 RhoGEF and LARG were shown to function as GTPase‐activating proteins (GAPs) to downregulate Gα13, and to a lesser extent, Gα12, through direct stimulation of their rates of GTP hydrolysis. To identify the structural determinants of interaction between Gα12 and RH domain‐containing RhoGEFs, we purified and crystallized a 1:1 complex of an activated Gα i/12 chimera and the RH domain of p115 RhoGEF. The 2.7‐Å crystal structure of this complex was solved by molecular replacement. Detailed comparisons were made between the refined model and previously‐reported crystal structures of Gα13 in complex with the RH domain of either p115 RhoGEF or PDZ‐RhoGEF. The interaction surface of Gα12 and the p115 RhoGEF RH domain is bipartite and highly similar to that seen in Gα13:p115 RH domain complex structures. We are currently testing the hypothesis that the engagement of p115 RhoGEF by either Gα12 or Gα13 is differentially transmitted to residues involved in the mechanism of GTP hydrolysis, and this effect is primarily responsible for measured differences in GAP activity toward Gα12 and Gα13. Grant Funding Source : Supported by a grant from the National Institutes of Health GM061454 (to T.K.).