Modulation of host signaling by a bacterial mimic: structure of the Salmonella effector SptP bound to Rac1.
Stebbins, C.E., Galan, J.E.(2000) Mol Cell 6: 1449-1460
- PubMed: 11163217 
- DOI: https://doi.org/10.1016/s1097-2765(00)00141-6
- Primary Citation of Related Structures:  
1G4U, 1G4W - PubMed Abstract: 
Salmonella spp. utilize a specialized protein secretion system to deliver a battery of effector proteins into host cells. Several of these effectors stimulate Cdc42- and Rac1-dependent cytoskeletal changes that promote bacterial internalization. These potentially cytotoxic alterations are rapidly reversed by the effector SptP, a tyrosine phosphatase and GTPase activating protein (GAP) that targets Cdc42 and Rac1. The 2.3 A resolution crystal structure of an SptP-Rac1 transition state complex reveals an unusual GAP architecture that mimics host functional homologs. The phosphatase domain possesses a conserved active site but distinct surface properties. Binding to Rac1 induces a dramatic stabilization in SptP of a four-helix bundle that makes extensive contacts with the Switch I and Switch II regions of the GTPase.
Organizational Affiliation: 
Section of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale School of Medicine, New Haven, CT 06536, USA.