Pseudomonas aeruginosa ExoU, a Toxin Transported by the Type III Secretion System, Kills Saccharomyces cerevisiae

ExoU, a protein transported by the type III secretion system of Pseudomonas aeruginosa, is an important cytotoxin, though its mechanism of action is unclear. Here we show that the intracellular expression of ExoU is cytotoxic to Saccharomyces cerevisiae. Furthermore, internal amino- and carboxyl-terminal deletions confirmed that regions of ExoU previously shown to be essential for killing mammalian cells were also required for killing yeast cells. These findings indicate that S. cerevisiae is a useful model organism for the study of ExoU.