ISSN:
1365-2958
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Medicine
Notes:
Pseudomonas aeruginosa delivers exoenzyme S (ExoS) into the intracellular compartment of eukaryotic cells via a type III secretion pathway. Intracellular delivery of ExoS is cytotoxic for eukaryotic cells and has been shown to ADP-ribosylate Ras in vivo and uncouple a Ras-mediated signal transduction pathway. Functional mapping has localized the FAS-dependent ADP-ribosyltransferase domain to the carboxyl-terminus of ExoS. A transient transfection system was used to examine cellular responses to the amino-terminal 234 amino acids of ExoS (ΔC234). Intracellular expression of ΔC234 elicited the rounding of Chinese hamster ovary (CHO) cells and the disruption of actin filaments in a dose-dependent manner. Expression of ΔC234 did not inhibit the expression of two independent reporter proteins, GFP and luciferase, or induce trypan blue uptake, which indicated that expression of ΔC234 was not cytotoxic to CHO cells. Carboxyl-terminal deletion proteins of ΔC234 were less efficient in the elicitation of CHO cell rounding than ΔC234. Cytoskeleton rearrangement elicited by ΔC234 was blocked and reversed by the addition of cytotoxic necrotizing factor 1 (CNF-1). CNF-1 catalyses the deamidation of Gln-63 of members of the Rho subfamily of small-molecular-weight GTP-binding proteins, resulting in protein activation. This implies a role for small-molecular-weight GTP-binding proteins in the disruption of actin by ΔC234. Together, these data identify ExoS as a cytotoxin that possesses two functional domains. Intracellular expression of the amino-terminal domain of ExoS elicits the disruption of actin, while expression of the carboxyl-terminal domain of ExoS possesses FAS-dependent ADP-ribosyltransferase activity and is cytotoxic to eukaryotic cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-2958.1999.01359.x
