Staphylococcus aureus is an opportunistic human and animal pathogen with an arsenal of virulence factors that are tightly regulated during bacterial infection. The latter is achieved through a sophisticated network of regulatory proteins and regulatory RNAs. Here, we describe the involvement of a novel prophage-carried small regulatory S. aureus RNA, SprY, in the control of virulence genes. An MS2-affinity purification assay reveals that SprY forms a complex in vivo with RNAIII, a major regulator of S. aureus virulence genes. SprY binds to the 13th stem-loop of RNAIII, a key functional region involved in the repression of multiple mRNA targets. mRNAs encoding the repressor of toxins Rot and the extracellular complement binding protein Ecb are among the targets whose expression is increased by SprY binding to RNAIII. Moreover, SprY decreases S. aureus hemolytic activity and virulence. Our results indicate that SprY titrates RNAIII activity by targeting a specific stem loop. Thus, we demonstrate that a prophage-encoded sRNA reduces the pathogenicity of S. aureus through RNA sponge activity.

中文翻译：

---

一种小的调节 RNA 通过滴定 RNAIII 活性来改变金黄色葡萄球菌的毒力

金黄色葡萄球菌是一种机会性人类和动物病原体，具有在细菌感染期间受到严格调节的毒力因子库。后者是通过复杂的调节蛋白和调节 RNA 网络实现的。在这里，我们描述了一种新的携带前噬菌体的小型调控金黄色葡萄球菌 RNA，SprY，参与毒力基因的控制。MS2 亲和纯化分析表明，SprY 在体内与 RNAIII 形成复合物，RNAIII 是金黄色葡萄球菌毒力基因的主要调节剂。SprY 与 RNAIII 的第 13 个茎环结合，这是一个参与抑制多个 mRNA 靶标的关键功能区域。编码毒素 Rot 阻遏物和胞外补体结合蛋白 Ecb 的 mRNA 是通过 SprY 与 RNAIII 结合而增加其表达的靶标之一。此外，SprY 降低了 S。金黄色葡萄球菌的溶血活性和毒力。我们的结果表明，SprY 通过靶向特定的茎环来滴定 RNAIII 活性。因此，我们证明了前噬菌体编码的 sRNA 通过 RNA 海绵活性降低了金黄色葡萄球菌的致病性。