Figure 2

The Pseudomonas aeruginosa genome and type III secretion regulon and toxin genes. The genomic DNA of P. aeruginosa strain PAO1 was completely sequenced by the Pseudomonas Genome Project in 2000. Within the 6.3-Mb region, 5,570 open reading frames were found. The type III secretion regulatory region (25.5 kb) was found as a gene cluster and named the exoenzyme S regulon. It comprised five operons, including 36 genes for transcription (exsA-exsD), secretion apparatus (pscB-pscU), and translocation (pcrGVHpopBD). The genes of the type III secretory toxins exoS, exoT, and exoY, but not exoU, were scattered throughout the genome. The exoU gene was found to be located in an insertional pathogenic gene cluster named P. aeruginosa pathogenicity island-2 (PAPI-2) discovered in the virulent clinical strain PA14.