Activated RhoA Binds to the Pleckstrin Homology (PH) Domain of PDZ-RhoGEF, a Potential Site for Autoregulation

作者：Chen Zhe^*; Medina Frank; Liu Mu Ya; Thomas Celestine; Sprang Stephen R; Sternweis Paul C

来源：JOURNAL OF BIOLOGICAL CHEMISTRY, 2010, 285(27): 21070-21081.

DOI：10.1074/jbc.M110.122549

Guanine nucleotide exchange factors (GEFs) catalyze exchange of GDP for GTP by stabilizing the nucleotide-free state of the small GTPases through their Dbl homology/pleckstrin homology (DH.PH) domains. Unconventionally, PDZ-RhoGEF (PRG), a member of the RGS-RhoGEFs, binds tightly to both nucleotide-free and activated RhoA (RhoA.GTP). We have characterized the interaction between PRG and activated RhoA and determined the structure of the PRG-DH.PH-RhoA.GTP gamma S (guanosine 5'-O-[gamma-thio]triphosphate) complex. The interface bears striking similarity to a GTPase-effector interface and involves the switch regions in RhoA and a hydrophobic patch in PRG-PH that is conserved among all Lbc RhoGEFs. The two surfaces that bind activated and nucleotide-free RhoA on PRG-DH.PH do not overlap, and a ternary complex of PRG-DH.PH bound to both forms of RhoA can be isolated by size-exclusion chromatography. This novel interaction between activated RhoA and PH could play a key role in regulation of RhoGEF activity in vivo.

• 出版日期2010-7-2