Invasin production by Yersinia pestis is abolished by insertion of an IS200-like element within the inv gene.

The two enteropathogens Yersinia pseudotuberculosis and Yersinia enterocolitica penetrate eukaryotic cells in vitro through invasin, a surface-exposed protein. In contrast, Yersinia pestis, the causative agent of plague, is unable to enter mammalian cell lines, although the inv gene is present on its chromosome. Although 99.3% identical to the inv gene of Y. pseudotuberculosis, the Y. pestis inv gene was disrupted in its central region by a 708-bp IS200-like element. Multiple copies of this insertion sequence element were found within the genome of the plague bacillus.