sRNAs in EHEC virulence

项目摘要 细菌快速感知和响应环境变化的能力是根本 殖民和生存的关键这对于胃肠道病原体尤其重要， 有效地与微生物群竞争营养，并精确地协调基因表达， 以确定感染小RNA（sRNA）正在成为使高效的生物降解成为可能的重要因素。 响应于特定代谢物的可用性的基因的时空表达和/或 环境线索，因此在发病机制中发挥核心作用。细菌病原体 肠出血性大肠杆菌O 157：H7（EHEC）定殖于人类结肠并引起 出血性结肠炎和溶血性尿毒综合征（HUS），这可能是致命的。EHEC编码 几种重要的毒力因子，包括导致HUS的强效滋贺毒素和三型 分泌系统（T3 SS）和附着和消除（AE）病变形成所必需的效应物， 肠细胞肠出血性大肠杆菌的感染剂量非常低，这表明肠出血性大肠杆菌已经进化出了一种机制， 利用宿主中的营养物质，精确控制毒力基因的表达， 合适的宿主壁龛我们的研究强调了sRNAs在细菌毒力中的重要性， 表明两种sRNA，DicF和MavR，在调节EHEC毒力中起重要作用。 DicF影响T3 SS的表达，并且是AE损伤形成所需的。DicF还调节 编码滋贺毒素、转录调节因子和粘附素的基因的表达。MavR调节 肠出血性大肠杆菌代谢以及应激反应，是必不可少的强大的殖民化的 哺乳动物胃肠道。此外，我们的数据表明，这些sRNA调节靶基因， 通过不寻常的机制表达。在本申请中，我们将研究分子机制 DicF和MavR依赖的基因调控，并全面鉴定DicF的直接靶点 和MavR。拟议的研究不仅将阐明EHEC的毒力，而且还将阐明sRNA- 依赖性调节机制可能对不同细菌中基因调节重要， 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.