Mechanism of NADPH Oxidase Activation by the Rac/Rho-GDI Complex

• DOI: 10.1021/bi010289c
• Publication Date: 2002-07-26T04:51:48Z
• Authors: Nicolas Di-Poï; Julien Fauré; Sylvestre Grizot; Gergely Molnár; Edgar Pick; Marie-Claire Dagher
• Keywords: Rac GTP-Binding Proteins; Small GTPase; GTP-binding protein regulators

The low molecular weight GTP binding protein Rac is essential to the activation of NADPH oxidase complex, involved in pathogen killing during phagocytosis. In resting cells, exists as a heterodimeric complex with Rho GDP dissociation inhibitor (Rho-GDI). Two types interactions exist between and Rho-GDI: protein−lipid interaction, implicating polyisoprene GTPase, well protein−protein interactions. Using two-hybrid system, we show that nonprenylated Rac1 interacts very weakly Rho-GDI, pointing predominant role protein−isoprene interaction formation. absence this strong demonstrate three sites Arg66Rac-Leu67Rac, His103Rac, C-terminal polybasic region Arg183Rac−Lys188Rac, are cooperate When mutants prenylated by expression insect they all interact Rho-GDI. Rho-GDI able exert an inhibitory effect on GDP/GTP exchange reaction except which has deletion (Arg183Rac−Lys188Rac). This is, most likely, held together through only. Although function GTPases, failed also activate cell-free assay after loading GTP. Mutant Leu119RacGln could both oxidase. Rac1/Rho-GDI Rac1(Leu119Gln)/Rho-GDI complexes, GTPases were bound GDP, found efficiently. These data suggest stabilizes active conformation, even GDP-bound state, presents it its effector, p67phox component