Host iron and Yersinia pathogenesis

大多数细菌病原体需要铁作为必需的营养素，哺乳动物宿主已经进化出一种铁营养素。 许多机制来螯合铁和限制入侵微生物的生长。然而，细菌在 反过来，进化出了无数的铁吸收策略以及调节蛋白质，这些蛋白质可以感知铁水平， 铁获取系统和其他对毒力至关重要的基因的表达。铁是一个重要的因素， 鼠疫病原体鼠疫耶尔森氏菌和肠道病原体Y. enterocolitica和Y. 假结核我们最近发现Y.假结核病使用铁硫簇协调 称为IscR的转录因子驱动其主要毒力因子Ysc III型分泌的表达 IscR是许多其他代谢和毒力系统（T3SS）的适当表达所必需的， 基因.我们的初步数据表明，Y需要IscR。假结核毒力和生存 血由于IscR是一种全局性转录调节因子，因此精确确定哪种IscR调节 途径对于病原体在体内的生长和存活是重要的。为了解决这个问题，在目标1中，我们将确定 Y.假结核，它是如何影响铁水平，并评估其在Y。 鼠疫菌和Y.小肠结肠炎此外，在目标2中，我们将测试Ysc T3SS的IscR控制如何影响Y。 正常和铁超载小鼠的假结核毒力。最后，在目标3中，我们将确定IscR如何 使Y。假结核在血液中的存活以及这如何影响播散性感染。在 本研究的结论是，我们将建立耶尔森氏菌IscR控制的途径，并确定 它们是如何导致发病的这项工作将有助于阐明病原体感知其 环境，以优化感染过程中的毒力因子利用。

The majority of bacterial pathogens require iron as an essential nutrient and mammalian hosts have evolved a number of mechanisms to sequester iron and limit the growth of invading microbes. However, bacteria have, in turn, evolved a myriad of iron uptake strategies as well as regulatory proteins that sense iron levels to control expression of iron acquisition systems and other genes critical for virulence. Iron is an important factor in the pathogenesis of the plague agent Yersinia pestis and the enteropathogens Y. enterocolitica and Y. pseudotuberculosis. We recently showed that Y. pseudotuberculosis uses an iron-sulfur cluster coordinating transcription factor called IscR to drive expression of its major virulence factor, the Ysc type III secretion system (T3SS), and that IscR is required for proper expression of a number of other metabolic and virulence genes. Our preliminary data show that IscR is required for Y. pseudotuberculosis virulence and for survival in blood. As IscR is a global transcriptional regulator, it is critical to determine precisely which IscR-regulated pathways are important for pathogen growth and survival in vivo. To address this, in Aim 1, we will determine the IscR regulon in Y. pseudotuberculosis, how it is influenced by iron levels, and assess its conservation in Y. pestis and Y. enterocolitica. In addition, in Aim 2, we will test how IscR control of the Ysc T3SS impacts Y. pseudotuberculosis virulence in normal and iron overloaded mice. Lastly, in Aim 3, we will determine how IscR enables Y. pseudotuberculosis survival in blood and how this influences disseminated infection. At the conclusion of this study, we will have established the pathways controlled by IscR in Yersinia and determined how they contribute to pathogenesis. This work will help to elucidate the ways in which pathogens sense their environment to optimize virulence factor utilization during infection.