Identification of mammalian proteins that collaborate with type III secretion system function: involvement of a chemokine receptor in supporting translocon activity.

Unlabelled: The type III secretion system (T3SS) is a highly conserved protein delivery system found in multiple Gram-negative pathogens, including Yersinia pseudotuberculosis. Most studies of Yersinia species type III intoxication of host cells have focused on the bacterial determinants that promote assembly and function of the secretion system. In this study, we performed a pooled RNA interference (RNAi) screen to identify mammalian host proteins required for the cytotoxic effects associated with the Yersinia translocated substrate YopE, a GTPase-activating protein (GAP) that inactivates the small Rho GTPases.

Genetic determination of essential residues of the Vibrio cholerae actin cross-linking domain reveals functional similarity with glutamine synthetases.

Actin cross-linking domains (ACDs) are distinct domains found in several bacterial toxins, including the Vibrio cholerae MARTX toxin. The ACD of V. cholerae (ACD(Vc)) catalyses the formation of an irreversible iso-peptide bond between lysine 50 and glutamic acid 270 on two actin molecules in an ATP- and Mg/Mn(2+)-dependent manner.

Inactivation of small Rho GTPases by the multifunctional RTX toxin from Vibrio cholerae.

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.

Autoprocessing of the Vibrio cholerae RTX toxin by the cysteine protease domain.

Vibrio cholerae RTX is a large multifunctional bacterial toxin that causes actin crosslinking. Due to its size, it was predicted to undergo proteolytic cleavage during translocation into host cells to deliver activity domains to the cytosol. In this study, we identified a domain within the RTX toxin that is conserved in large clostridial glucosylating toxins TcdB, TcdA, TcnA, and TcsL; putative toxins from V.

Identification of a domain within the multifunctional Vibrio cholerae RTX toxin that covalently cross-links actin.

The Gram-negative pathogen Vibrio cholerae causes diarrheal disease through the export of enterotoxins. The V. cholerae RTX toxin was previously identified and characterized by its ability to round human laryngeal epithelial (HEp-2) cells.

FAK blunts adenosine-homocysteine-induced endothelial cell apoptosis: requirement for PI 3-kinase.

Treatment of cultured bovine pulmonary endothelial cells (BPAEC) with adenosine (Ado) alone or in combination with homocysteine (Hc) leads to disruption of focal adhesion complexes, caspase-dependent degradation of components of focal adhesion complexes, and subsequent apoptosis. Endothelial cells transiently overexpressing paxillin or p130(Cas) cDNAs underwent Ado-Hc-induced apoptosis to an extent similar to that of cells transfected with vector alone. However, overexpression of focal adhesion kinase (FAK) cDNA blunted Ado-Hc-induced apoptosis.