Structure of the TPR domain of p67(phox) in complex with Rac center dot GTP

p67(phox) is an essential part of the NADPH oxidase, a multiprotein enzyme complex that produces superoxide ions in response to microbial infection. B inding of the small GTPase Rac to p67(phox) is a key step in the assembly o f the active enzyme complex. The structure of Rac GTP bound to the N-termin al TPR (tetratricopeptide repeat) domain of p67(phox) reveals a novel mode of Rho family/effector interaction and explains the basis of GTPase specifi city. Complex formation is largely mediated by an insertion between two TPR motifs, suggesting an unsuspected versatility of TPR domains in target rec ognition and in their more general role as scaffolds for the assembly of mu ltiprotein complexes.