Identification of Critical Residues in Gα13 for Stimulation of p115RhoGEF Activity and the Structure of the Gα13-p115RhoGEF Regulator of G Protein Signaling Homology (RH) Domain Complex

• Published in: The Journal of biological chemistry Vol. 286; no. 23; pp. 20625 - 20636
• Main Authors: Hajicek, Nicole, Kukimoto-Niino, Mutsuko, Mishima-Tsumagari, Chiemi, Chow, Christina R., Shirouzu, Mikako, Terada, Takaho, Patel, Maulik, Yokoyama, Shigeyuki, Kozasa, Tohru
• Format: Journal Article
• Language: English
• Published: 9650 Rockville Pike, Bethesda, MD 20814, U.S.A Elsevier Inc 10-06-2011; American Society for Biochemistry and Molecular Biology
• Subjects: Crystal Structure; G Proteins; Guanine Nucleotide Exchange Factor; Protein Conformation; RGS Domain; Rho; Signal Transduction; Crystal Structure; Signal Transduction; RGS Domain; G Proteins; Rho; Protein Conformation; Guanine Nucleotide Exchange Factor
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.201392

RH-RhoGEFs are a family of guanine nucleotide exchange factors that contain a regulator of G protein signaling homology (RH) domain. The heterotrimeric G protein Gα13 stimulates the guanine nucleotide exchange factor (GEF) activity of RH-RhoGEFs, leading to activation of RhoA. The mechanism by which Gα13 stimulates the GEF activity of RH-RhoGEFs, such as p115RhoGEF, has not yet been fully elucidated. Here, specific residues in Gα13 that mediate activation of p115RhoGEF are identified. Mutation of these residues significantly impairs binding of Gα13 to p115RhoGEF as well as stimulation of GEF activity. These data suggest that the exchange activity of p115RhoGEF is stimulated allosterically by Gα13 and not through its interaction with a secondary binding site. A crystal structure of Gα13 bound to the RH domain of p115RhoGEF is also presented, which differs from a previously crystallized complex with a Gα13-Gαi1 chimera. Taken together, these data provide new insight into the mechanism by which p115RhoGEF is activated by Gα13.