title: Activation of rho through a cross-link with polyamines catalyzed by Bordetella dermonecrotizing toxin.
abstract: The small GTPase Rho, which regulates a variety of cell functions, also serves as a specific substrate for bacterial toxins. Here we demonstrate that Bordetella dermonecrotizing toxin (DNT) catalyzes cross-linking of Rho with ubiquitous polyamines such as putrescine, spermidine and spermine. Mass spectrometric analyses revealed that the cross-link occurred at Gln63, which had been reported to be deamidated by DNT in the absence of polyamines. Rac1 and Cdc42, other members of the Rho family GTPases, were also polyaminated by DNT. The polyamination, like the deamidation, markedly reduced the GTPase activity of Rho without affecting its GTP-binding activity, indicating that polyaminated Rho behaves as a constitutively active analog. Moreover, polyamine-linked Rho, even in the GDP-bound form, associated more effectively with its effector ROCK than deamidated Rho in the GTP-bound form and, when microinjected into cells, induced the anomalous formation of stress fibers indistinguishable from those seen in DNT-treated cells. The results imply that the polyamine-linked Rho, transducing signals to downstream ROCK in a novel GTP-independent manner, plays an important role in DNT cell toxicity.
authors.affiliation: Project Research for Molecular Bacteriology, Research Institute for Microbial Diseases, Osaka University, Yamada-oka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Masuda
authors.forename: L
authors.initials: L
authors.lastname: Betancourt
authors.forename: T
authors.initials: T
authors.lastname: Matsuzawa
authors.forename: T
authors.initials: T
authors.lastname: Kashimoto
authors.forename: T
authors.initials: T
authors.lastname: Takao
authors.forename: Y
authors.initials: Y
authors.lastname: Shimonishi
authors.forename: Y
authors.initials: Y
authors.lastname: Horiguchi
mesh_terms: D016475:3T3 Cells; D000199:Actins / Q000378:metabolism; D000818:Animals; D001427:Bacterial Toxins; D001483:Base Sequence; D016950:Bordetella bronchiseptica; D003432:Cross-Linking Reagents; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008954:Models, Biological; D011073:Polyamines / Q000737:chemistry / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011503:Transglutaminases; D010566:Virulence Factors, Bordetella; D020741:rho GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000737:chemistry / Q000378:metabolism
chemical_list: D000199:Actins; D001427:Bacterial Toxins; D003432:Cross-Linking Reagents; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D011073:Polyamines; D010566:Virulence Factors, Bordetella; C060969:dermonecrotic toxin, Bordetella; D011503:Transglutaminases; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein