Pseudomonas aeruginosa Type III Secretory Toxin ExoU and Its Predicted Homologs.

ExoU, a type III secretory toxin and major virulence factor with patatin-like phospholipase activity, is responsible for acute lung injury and sepsis in immunocompromised patients. Through use of a recently updated bacterial genome database, protein sequences predicted to be homologous to ExoU were identified in 17 other species (, , , , , , , , , , , , , , and ) and 8 Gram-negative bacteria from three other genera (, , and ). In the alignment of the predicted primary amino acid sequences used for the phylogenetic analyses, both highly conserved and nonconserved parts of the toxin were discovered among the various species. Further comparative studies of the predicted ExoU homologs should provide us with more detailed information about the unique characteristics of the ExoU toxin.