Independent acquisition and insertion into different chromosomal locationsof the same pathogenicity island in Yersinia pestis and Yersinia pseudotuberculosis

We show that Yersinia pestis and pesticin-sensitive isolates of Y. pseudotu berculosis possess a common 34 kbp DNA region that has all the hallmarks of a pathogenicity island and is inserted into different asparaginyl tRNA gen es at different chromosomal locations in each species. This pathogenicity i sland (YP-HPI) is marked by IS100, has a G + C content different from its h ost, is flanked by 24 bp direct repeats, encodes a putative, P4-like integr ase and contains the iron uptake virulence genes from the pgm locus of Y. p estis. These findings indicate independent horizontal acquisition of this i sland by Y. pestis and Y. pseudotuberculosis. The two YP-HPI locations and their possession of an integrase gene support a model of site-specific inte gration of the YP-HPI into these bacteria.