title: Pseudomonas aeruginosa ExoT acts in vivo as a GTPase-activating protein for RhoA, Rac1, and Cdc42.
abstract: The Pseudomonas aeruginosa protein ExoT is a bacterial GTPase-activating protein (GAP) that has in vitro activity toward Rho, Rac, and Cdc42 GTPases. Expression of ExoT both inhibits the internalization of strain PA103 by macrophages and epithelial cells and is associated with morphological changes (cell rounding and detachment) of infected cells. We find that expression of ExoT leads to the loss of GTP-bound RhoA, Rac1, and Cdc42 in transfected HeLa cells, demonstrating that ExoT has GAP activity in vivo toward all three GTPases. GAP activity is absolutely dependent on the presence of arginine at position 149 but is not affected by whether ExoT is expressed in the absence or presence of other P. aeruginosa type III secreted proteins. We also demonstrate that expression of ExoT in epithelial cells is sufficient to cause stress fiber disassembly by means of ExoT's GAP activity toward RhoA.
authors.affiliation: Department of Medicine, University of California, San Francisco, San Francisco, California 94143, USA.
authors.forename: B I
authors.initials: BI
authors.lastname: Kazmierczak
authors.forename: J N
authors.initials: JN
authors.lastname: Engel
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism; D003603:Cytotoxins; D004285:Dogs; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D011550:Pseudomonas aeruginosa / Q000378:metabolism / Q000472:pathogenicity*; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D000199:Actins; D001427:Bacterial Toxins; D003603:Cytotoxins; D020690:GTPase-Activating Proteins; D006160:Guanosine Triphosphate; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein