sRNAs in EHEC virulence

项目总结 细菌快速感知并对环境变化做出反应的能力是基本的 为殖民和生存干杯。这与胃肠道病原体尤其相关，必须 有效地与微生物区系争夺营养，并精确协调基因表达 以确定感染情况。小RNA(SRNA)正在成为使高效 基因的时空表达对特定代谢物和/或可用性的响应 环境因素，因此在发病机制中起着核心作用。细菌病原体 肠出血性大肠埃希菌O157：H7(EHEC)在人结肠定植并引起 出血性结肠炎和溶血性尿毒症综合征(HUS)，可能是致命的。EHEC编码 几个重要的毒力因子，包括引起HUS的强效志贺毒素和一种3型 分泌系统(T3SS)和附着和消除(AE)损伤形成所必需的效应器 肠道细胞。EHEC的感染量非常低，这表明EHEC已经进化出了 利用寄主中的营养物质，精确控制毒力基因的表达 合适的主人位置。我们的研究强调了sRNA在细菌毒力中的重要性 证明了DicF和MavR这两个sRNAs在调节EHEC毒力方面起着重要作用。 DicF影响T3SS的表达，是AE病变形成所必需的。DicF还调制 志贺毒素、转录调节因子和粘附素编码基因的表达。MavR调节 EHEC的新陈代谢和应激反应，对于强健的定殖性是必不可少的 哺乳动物的胃肠道。此外，我们的数据表明，这些srna调控靶基因。 通过不寻常的机制表达。在这一应用中，我们将研究分子机制 DicF和MavR依赖的基因调控及全面鉴定DicF的直接靶点 和MavR.拟议的研究不仅将揭示EHEC的毒力，还将揭示SRNA- 依赖的调控机制，可能对不同细菌的基因调控很重要 病原体。

PROJECT SUMMARY The ability of bacteria to rapidly sense and respond to changes in the environment is fundamental to colonization and survival. This is especially relevant for gastrointestinal pathogens that must effectively compete for nutrients with the microbiota as well as precisely coordinate gene expression to establish infection. Small RNAs (sRNAs) are emerging as important factors that enable efficient spatiotemporal expression of genes in response to the availability of a specific metabolite and/or environmental cues, and thus play a central role in pathogenesis. The bacterial pathogen enterohemorrhagic Escherichia coli O157:H7 (EHEC) colonizes the human colon and causes hemorrhagic colitis and hemolytic uremic syndrome (HUS), which can be fatal. EHEC encodes several important virulence factors, including the potent Shiga toxin that causes HUS and a type three secretion system (T3SS) and effectors necessary for attaching and effacing (AE) lesion formation on enterocytes. EHEC has a very low infectious dose, suggesting that EHEC has evolved mechanisms to exploit nutrients in the host and precisely control virulence gene expression to occur within appropriate host niches. Our studies underscore the importance of sRNAs in bacterial virulence by demonstrating that two sRNAs, DicF and MavR, play important roles in modulating EHEC virulence. DicF influences expression of the T3SS and is required for AE lesion formation. DicF also modulates expression of genes encoding Shiga toxin, transcriptional regulators, and adhesins. MavR regulates EHEC metabolism as well as stress responses and is essential for robust colonization of the mammalian gastrointestinal tract. Moreover, our data indicate that these sRNAs regulate target gene expression via unusual mechanisms. In this application, we will investigate the molecular mechanisms of DicF- and MavR-dependent gene regulation and comprehensively identify direct targets of DicF and MavR. The proposed studies will shed light not only on EHEC virulence but also on sRNA- dependent regulatory mechanisms that may be important for gene regulation in diverse bacterial pathogens.