Yersinia pestis High-Pathogenity Island: Mechanisms and Structures responsible for its Dissemination

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The Yersinia high-pathogenicity island encodes siderophore yersiniabactin iron acquisiton system. Two evolutionary HPI lineages were established, Y. pestis/Y. pseudotuberculosis (Yps HPI) and Y. enterocolitica 1B (Yen HPI). The latter is restricted to strains of Y enterocolitica biogroup 1B, while the Yps HPI is widely disseminated in Enterobacteriaceae. The Yps HPI is 36521 bp large and besides yersiniabactin genes contains additional genes resporisible for its recombination functions. These genes are: the integrase, encoded by int-HPI, the directionality factor, orf2 or xis, encoded in the variable AT-rich part of the Yps HPI and two recombination sites recognized in recombination, attL and attR. The Yps HPI is able to translocate to any free asn TDNA recognition site in the bacterial genome. We would like to uncover the key elements involved in regulation of mobility of the Yps HPI. Special interest will be addressed to Orf5 supposed to play a regulatory function in HPI recombination. Role of environmental signals (like stress conditions, SOS-response, etc) in excision modulation will be investigated. Influence of bacterial factors like integrative host factor (IHF) on HPI-promoted integrative/excisive recombination will be estimated. Interaction of the recombinant integrase and the excisionase with the recognition DNA sites in recombination complex will be analysed using molecular biological approaches. The complete Yps HPI will be mobilized with the help of asn tDNA-presenting conjugative plasmid RP4 with a wide host range. Such cointegrate could be transferred with high efficiency by conjugation to new bacterial hosts to study the functions encoded by the HPI and its cross talk with the bacterial cell. A general model for transfer of pathogenicity islands by target-presenting conjugative plasmids will be developed. Such approach would be applied to mobilize other pathogenicity islands to study their role in pathogenesis.