University of Würzburg, Institute of Molecular Infection Biology, Department of Molecular Infection Biology II, 97080, Würzburg, Germany.
The Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology and Immunology, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, 200031, China.
Nat Commun. 2024 Jun 19;15(1):5240. doi: 10.1038/s41467-024-48986-8.
Like for many bacteria, flagella are crucial for Campylobacter jejuni motility and virulence. Biogenesis of the flagellar machinery requires hierarchical transcription of early, middle (RpoN-dependent), and late (FliA-dependent) genes. However, little is known about post-transcriptional regulation of flagellar biogenesis by small RNAs (sRNAs). Here, we characterized two sRNAs with opposing effects on C. jejuni filament assembly and motility. We demonstrate that CJnc230 sRNA (FlmE), encoded downstream of the flagellar hook protein, is processed from the RpoN-dependent flgE mRNA by RNase III, RNase Y, and PNPase. We identify mRNAs encoding a flagella-interaction regulator and the anti-sigma factor FlgM as direct targets of CJnc230 repression. CJnc230 overexpression upregulates late genes, including the flagellin flaA, culminating in longer flagella and increased motility. In contrast, overexpression of the FliA-dependent sRNA CJnc170 (FlmR) reduces flagellar length and motility. Overall, our study demonstrates how the interplay of two sRNAs post-transcriptionally fine-tunes flagellar biogenesis through balancing of the hierarchically-expressed components.
与许多细菌一样，鞭毛对于空肠弯曲菌的运动性和毒力至关重要。鞭毛机器的生物发生需要早期、中期（依赖 RpoN）和晚期（依赖 FliA）基因的分层转录。然而，关于小 RNA（sRNA）对鞭毛生物发生的转录后调控知之甚少。在这里，我们描述了两种对空肠弯曲菌丝状组装和运动具有相反影响的 sRNA。我们证明了编码在鞭毛钩蛋白下游的 CJnc230 sRNA（FlmE）由 RNase III、RNase Y 和 PNPase 从依赖 RpoN 的 flgE mRNA 中加工而来。我们确定了编码一个鞭毛相互作用调节剂和反西格玛因子 FlgM 的 mRNA 是 CJnc230 抑制的直接靶标。CJnc230 的过表达上调了晚期基因，包括鞭毛蛋白 flaA，导致更长的鞭毛和更高的运动性。相比之下，依赖 FliA 的 sRNA CJnc170（FlmR）的过表达会降低鞭毛长度和运动性。总的来说，我们的研究表明，两种 sRNA 如何通过平衡分层表达的成分来实现对鞭毛生物发生的转录后微调。
