Salmonella Typhimurium is an enteric pathogen that has evolved masterful strategies to enable survival under stress conditions both within and outside a host. The acid tolerance response (ATR) is one such mechanism that enhances the viability of acid adapted bacteria to lethal pH levels. While numerous studies exist on the protein coding components of this response, there is very little data on the roles of small RNAs (sRNAs). These non-coding RNA molecules have recently been shown to play roles as regulators of bacterial stress response and virulence pathways. They function through complementary base pairing interactions with target mRNAs and affect their translation and/or stability. There are also a few that directly bind to proteins by mimicking their respective targets. Here, we identify several sRNAs expressed during the ATR of S. Typhimurium and characterize one highly induced candidate, RyeC. Further, we identify ptsI as a trans-encoded target that is directly regulated by this sRNA. From a functional perspective, over-expression of RyeC in Salmonella produced a general attenuation of several in vitro phenotypes including acid survival, motility, adhesion and invasion of epithelial cell lines as well as replication within macrophages. Together, this study highlights the diverse roles played by sRNAs in acid tolerance and virulence of S. Typhimurium.

鼠伤寒沙门氏菌是一种肠内病原体，已进化出精通策略，可以在宿主体内和外部的应激条件下存活。耐酸反应（ATR）是一种这样的机制，可增强耐酸细菌对致命pH值的生存能力。尽管关于这种应答的蛋白质编码成分已有许多研究，但是关于小RNA（sRNA）的作用的数据很少。这些非编码RNA分子最近已显示出作为细菌应激反应和毒力途径的调节剂的作用。它们通过与靶标mRNA的互补碱基配对相互作用而起作用，并影响其翻译和/或稳定性。还有一些通过模仿蛋白质各自的靶标直接结合蛋白质。在这里，我们确定了在ATR期间表达的几种sRNA。鼠伤寒沙门氏菌（S. Typhimurium）并鉴定出一种高度诱导的候选基因RyeC。此外，我们将ptsI确定为直接受此sRNA调控的反式编码靶标。从功能的角度来看，沙门氏菌中RyeC的过度表达会导致几种体外表型的普遍减弱，包括酸性存活，运动性，上皮细胞系的粘附和侵袭以及巨噬细胞内的复制。总之，这项研究强调了在耐酸性和毒力的sRNA所起的不同作用S.鼠伤寒沙门氏菌。