Variability of the Structure of the Melibiose Operon and the High Pathogenicity Island in Yersinia pseudotuberculosis Strains

The features of the melibiose operon and high pathogenicity island organization were studied in Yersinia pseudotuberculosis strains of different origin, including 14 first time studied strains from Central Asia and Mongolia. Eight strains were identified that are not capable of fermenting melibiose. The melR, melB, and more than 70% of the melA genes have been found to be deletified in the structure of their melibiose operon, caused by the transposition of an island of high pathogenicity. In non-melibiose-fermenting strains, the island of high pathogenicity is shortened by 12 kb compared to the reference strain, which led to the loss of the fyuA gene and some ybt-region genes participating in the siderophore-dependent iron uptake system. According to the results of phylogenetic analysis, these strains are included in the same branch with the O:3 serotype strains, which are found in many regions of the world. The results from this work broaden the understanding of the genetic diversity of the ubiquitous bacterium Y. pseudotuberculosis, pathogenic variants of which can cause cases and outbreaks of pseudotuberculosis, as well as causing lethal yersiniosis in animals.