Open AccessInactivation of small Rho GTPases by the multifunctional RTX toxin from Vibrio cholerae
Author(s) -
Sheahan KerriLynn,
Fullner Satchell Karla J.
Publication year - 2007
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2006.00876.x
Subject(s) - gtpase , vibrio cholerae , microbiology and biotechnology , biology , clostridium difficile toxin b , cytoskeleton , actin , actin cytoskeleton , cdc42 , cholera toxin , toxin , rhoa , clostridium difficile toxin a , biochemistry , cell , signal transduction , bacteria , genetics , clostridium difficile , antibiotics
Summary Many bacterial toxins target small Rho GTPases in order to manipulate the actin cytoskeleton. The depolymerization of the actin cytoskeleton by the Vibrio cholerae RTX toxin was previously identified to be due to the unique mechanism of covalent actin cross‐linking. However, identification and subsequent deletion of the actin cross‐linking domain within the RTX toxin revealed that this toxin has an additional cell rounding activity. In this study, we identified that the multifunctional RTX toxin also disrupts the actin cytoskeleton by causing the inactivation of small Rho GTPases, Rho, Rac and Cdc42. Inactivation of Rho by RTX was reversible in the presence of cycloheximide and by treatment of cells with CNF1 to constitutively activate Rho. These data suggest that RTX targets Rho GTPase regulation rather than affecting Rho GTPase directly. A novel 548‐amino‐acid region of RTX was identified to be responsible for the toxin‐induced inactivation of the Rho GTPases. This domain did not carry GAP or phosphatase activities. Overall, these data show that the RTX toxin reversibly inactivates Rho GTPases by a mechanism distinct from other Rho‐modifying bacterial toxins.