Activation of Rho through a cross-link with polyamines catalyzed by Bordetella dermonecrotizing toxin

• Published in: The EMBO journal Vol. 19; no. 4; pp. 521 - 530
• Main Authors: Masuda, Minako, Betancourt, Lazaro, Matsuzawa, Takeshi, Kashimoto, Takashige, Takao, Toshifumi, Shimonishi, Yasutsugu, Horiguchi, Yasuhiko
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 15.02.2000; Blackwell Publishing Ltd; Oxford University Press
• Subjects: 3T3 Cells; Actins - metabolism; Animals; Bacterial Toxins; Base Sequence; Bordetella; Bordetella bronchiseptica; Bordetella dermonecrotizing toxin; Cross-Linking Reagents; dermonecrotizing toxin; DNA Primers - genetics; Enzyme Activation; Fibers; Intracellular Signaling Peptides and Proteins; Mice; Models, Biological; polyamine; Polyamines - chemistry; Polyamines - metabolism; Protein Serine-Threonine Kinases - chemistry; Protein Serine-Threonine Kinases - genetics; Protein Serine-Threonine Kinases - metabolism; putrescine; Rho; rho GTP-Binding Proteins - chemistry; rho GTP-Binding Proteins - metabolism; Rho protein; rho-Associated Kinases; rhoA GTP-Binding Protein - chemistry; rhoA GTP-Binding Protein - metabolism; Rocks; spermidine; spermine; Toxins; transglutaminase; Transglutaminases; Virulence Factors, Bordetella
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1093/emboj/19.4.521

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.