RaoN is a Salmonella-specific small RNA that is encoded in the cspH-envE intergenic region on Salmonella pathogenicity island-11. We previously reported that RaoN is induced under conditions of acid and oxidative stress combined with nutrient limitation, contributing to the intramacrophage growth of Salmonella enterica serovar Typhimurium. However, the role of RaoN in nitrosative stress response and virulence has not yet been elucidated. Here we show that the raoN mutant strain has increased susceptibility to nitrosative stress by using a nitric oxide generating acidified nitrite. Extending previous research on the role of RaoN in oxidative stress resistance, we found that NADPH oxidase inhibition restores the growth of the raoN mutant in LPS-treated J774A.1 macrophages. Flow cytometry analysis further revealed that the inactivation of raoN leads to an increase in the intracellular level of reactive oxygen species (ROS) in Salmonella-infected macrophages, suggesting that RaoN is involved in the inhibition of NADPH oxidase-mediated ROS production by mechanisms not yet resolved. Moreover, we evaluated the effect of raoN mutation on the virulence in murine systemic infection and determined that the raoN mutant is less virulent than the wild-type strain following oral inoculation. In conclusion, small regulatory RNA RaoN controls nitrosative-oxidative stress resistance and is required for virulence of Salmonella in mice.

中文翻译：

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小 RNA RaoN 对鼠伤寒沙门氏菌亚硝化氧化应激抗性和毒力的影响。

RaoN 是一种沙门氏菌特异性小 RNA，编码在沙门氏菌致病性岛 11上的cspH - envE基因间区域。我们之前曾报道，RaoN 在酸和氧化应激以及营养限制的条件下被诱导，有助于鼠伤寒沙门氏菌的巨噬细胞内生长。然而，RaoN 在亚硝化应激反应和毒力中的作用尚未阐明。在这里我们表明raoN突变菌株通过使用产生酸化亚硝酸盐的一氧化氮增加了对亚硝化胁迫的易感性。扩展先前关于 RaoN 在抗氧化应激中的作用的研究，我们发现 NADPH 氧化酶抑制可恢复LPS 处理的 J774A.1 巨噬细胞中raoN突变体的生长。流式细胞术分析进一步表明，raoN的失活导致沙门氏菌感染的巨噬细胞中活性氧 (ROS) 的细胞内水平升高，表明 RaoN 参与抑制 NADPH 氧化酶介导的 ROS 产生的机制尚不明确解决。此外，我们评估了raoN的效果小鼠全身感染毒力的突变，并确定raoN突变体的毒性低于口服接种后的野生型菌株。总之，小的调节性 RNA RaoN 控制亚硝化氧化应激抵抗力，并且是小鼠沙门氏菌毒力所必需的。