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

高致病性耶尔森菌岛编码铁载体耶尔森吸收蛋白铁获取系统。建立了两个进化HPI谱系：鼠疫杆菌/鼠疫杆菌；假结核（Yps HPI）和小肠结肠炎耶氏菌1B （Yen HPI）。后者仅限于Y小肠结肠炎生物群1B菌株，而Yps HPI广泛分布于肠杆菌科。Yps HPI长36521 bp，除了yersiniabactin基因外，还含有负责其重组功能的其他基因。这些基因是：整合酶，由int-HPI编码；定向因子，orf2或xis，在Yps HPI的可变AT-rich部分编码；重组中识别的两个重组位点，attL和attR。Yps HPI能够转移到细菌基因组中任何自由的asn TDNA识别位点。我们想要揭示的关键因素参与调节的流动性的Yps HPI。我们将特别关注在HPI重组中发挥调控作用的Orf5。环境信号（如应力条件，sos响应等）在切除调制中的作用将被研究。整合宿主因子（integrative host factor， IHF）等细菌因子对hpi促进的整合/特异性重组的影响将被评估。重组整合酶和切除酶与重组复合体中识别DNA位点的相互作用将采用分子生物学方法进行分析。完整的Yps HPI将在一个具有广泛宿主范围的tdna呈递的共轭质粒RP4的帮助下被动员。这种协整可以通过偶联的方式高效转移到新的细菌宿主上，从而研究HPI编码的功能及其与细菌细胞的串扰。我们将建立一种由呈递靶标的共轭质粒转移致病性岛的通用模型。该方法可用于调动其他致病性岛屿，研究其在发病机制中的作用。

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.