Virulence role and regulation of Shigella suf genes

说明(申请人提供)：志贺氏菌是志贺氏菌病的病原体，每年导致约60万人死亡。传播通常通过受污染的食物或水，或通过人与人之间的接触。旨在确定志贺氏菌用于适应人类宿主的基因的基础研究将有助于设计有效的治疗方法和疫苗。此外，由于志贺氏菌的毒力在很大程度上取决于它在人类结肠细胞内的生存能力，因此完全了解志贺氏菌在细胞内环境中生存和繁殖的机制将有助于更好地了解细胞内病原体的生活方式。长期的研究目标是阐明志贺氏菌在真核细胞中生存和繁殖所使用的代谢和生理过程。实现这一目标的一种方法是表征志贺氏菌在真核细胞质中诱导的基因。一个对真核细胞内环境做出反应而诱导的特定基因座(Suf)与一个提高植物病原菌欧文氏杆菌毒力和氧化胁迫生存能力的基因座同源。六个suf基因中的三个被预测为介导铁-硫簇的合成。这导致了一种假设，即志贺氏菌suf基因可能通过增强铁-硫簇代谢和/或氧化应激生存来介导对真核细胞质的适应。本项目的目标是确定志贺氏菌suf基因的特征，特别是suf基因的调控和suf系统在志贺氏菌适应真核细胞质中的作用。具体目的1是确定在体外和体内调节suf表达的元件。因为Sufa基因是在志贺氏菌处于真核细胞质中时被诱导的，所以特定的目的2是评估志贺菌Suf蛋白是否在真核细胞内环境中生存和/或增殖所必需的。志贺氏菌suf基因的特征将提供有关志贺氏菌处于细胞内环境时suf基因的重要性的信息，并将提供更好的理解志贺菌如何感知和适应真核细胞内环境的信息。

DESCRIPTION (provided by applicant): Shigella species are the causative agents of shigellosis, which results in approximately 600,000 deaths per year. Transmission usually occurs via contaminated food or water, or through person-to-person contact. Basic research aimed at characterizing the genes that Shigella uses to adapt to the human host will be useful in designing effective therapies and vaccines. Furthermore, since Shigella virulence depends largely on its ability to live inside human colon cells, a complete understanding of the mechanisms that Shigella uses to survive and multiply in the intracellular environment will provide better insight into the lifestyles of intracellular pathogens. The long-term research goal is to elucidate the metabolic and physiological processes that Shigella employs to survive and multiply the eukaryotic cell. An approach to accomplishing this goal was to characterize Shigella genes that are induced when Shigella is in the eukaryotic cytoplasm. One particular locus (suf) that is induced in response to the eukaryotic intracellular environment is homologous to a locus that enhances virulence and oxidative stress survival in the plant pathogen Erwinia chrysanthemi. Three of the six suf genes are predicted to mediate iron-sulfur cluster synthesis. This led to the hypothesis that the Shigella suf genes mediate adaptation to the eukaryotic cytoplasm, possibly through enhanced iron-sulfur cluster metabolism and/or oxidative stress survival. The goal of this project is to characterize the S. flexneri suf locus, specifically the regulation of the suf genes and the contribution of the Suf system to Shigella adaptation to the eukaryotic cytoplasm. Specific aim 1 is to identify the elements that regulate suf expression in vitro and in vivo. Because the sufA gene is induced when Shigella is in the eukaryotic cytoplasm, specific aim 2 is to assess whether the Shigella Suf proteins are required for survival and/or multiplication in the eukaryotic intracellular environment. Characterization of the Shigella suf genes will provide information about the importance of the suf genes when Shigella is in the intracellular environment and will provide a better understanding of how Shigella senses and adapts to the eukaryotic intracellular environment.