Involvement of Ras-related Rho proteins in the mechanisms of action of Clostridium difficile toxin A and toxin B.
Toxins A and B of Clostridium difficile are responsible for pseudomembranous colitis, a disease that afflicts a substantial number of hospitalized patients treated with antibiotics. A major effect of these proteins is the disruption of the actin cytoskeleton. Recently, I. Just, G. Fritz, K. Aktories, M. Giry, M. R. Popoff, P. Boquet, S. Hegenbarth, and C. von Eichel-Streiber (J. Biol. Chem. 269:10706-10712, 1994) implicated Rho proteins as cellular targets of C. difficile toxin B, since pretreatment of cells or purified Rho with toxin prevented subsequent ADP-ribosylation of Rho by exoenzyme C3. Moreover, they showed that overexpression of Rho proteins in cells suppressed cell rounding normally associated with exposure of cells to C. difficile toxin B. Here we expand these findings by showing directly that Rho proteins are covalently modified by both C. difficile toxins A and B. In addition, we demonstrate that the stability of toxin-modified Rho in NIH 3T3 cells is dramatically reduced. Finally, we show that C. difficile toxins A and B do not have similar effects on the closely related Rac and CDC42 GTP-binding proteins.
Dillon
S T
ST
Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111.
Rubin
E J
EJ
Yakubovich
M
M
Pothoulakis
C
C
LaMont
J T
JT
Feig
L A
LA
Gilbert
R J
RJ
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000378:metabolism*; D002522:Chlorocebus aethiops; D016360:Clostridioides difficile / Q000472:pathogenicity*; D003013:Clostridium; D004768:Enterotoxins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D066298:In Vitro Techniques; D051379:Mice; D008969:Molecular Sequence Data; D020741:rho GTP-Binding Proteins
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004768:Enterotoxins; C041348:tcdA protein, Clostridium difficile; C031815:toxB protein, Clostridium difficile; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins