title: The N-terminal domain of Pseudomonas aeruginosa exoenzyme S is a GTPase-activating protein for Rho GTPases.
abstract: Pseudomonas aeruginosa exoenzyme S (ExoS) is a bifunctional cytotoxin. The ADP-ribosyltransferase domain is located within the C terminus part of ExoS. Recent studies showed that the N terminus part of ExoS (amino acid residues 1-234, ExoS(1-234)), which does not possess ADP-ribosyltransferase activity, stimulates cell rounding when transfected or microinjected into eukaryotic cells. Here we studied the effects of ExoS(1-234) on nucleotide binding and hydrolysis by Rho GTPases. ExoS(1-234) (100-500 nM) did not influence nucleotide exchange of Rho, Rac, and Cdc42 but increased GTP hydrolysis. A similar increase in GTPase activity was stimulated by full-length ExoS. Half-maximal stimulation of GTP hydrolysis by Rho, Rac, and Cdc42 was observed at 10-11 nM ExoS(1-234), respectively. We identified arginine 146 of ExoS to be essential for the stimulation of GTPase activity of Rho proteins. These data identify ExoS as a GTPase-activating protein for Rho GTPases.
authors.affiliation: Institut für Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany.
authors.forename: U M
authors.initials: UM
authors.lastname: Goehring
authors.forename: G
authors.initials: G
authors.lastname: Schmidt
authors.forename: K J
authors.initials: KJ
authors.lastname: Pederson
authors.forename: K
authors.initials: K
authors.lastname: Aktories
authors.forename: J T
authors.initials: JT
authors.lastname: Barbieri
mesh_terms: D036002:ADP Ribose Transferases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D020690:GTPase-Activating Proteins; D036002:ADP Ribose Transferases; C444820:exoenzyme S; D020741:rho GTP-Binding Proteins