RNA Biology Laboratory, Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA.
J Biochem. 2022 Mar 3;171(3):277-285. doi: 10.1093/jb/mvab142.
Bacterial small RNAs (sRNAs) play a pivotal role in post-transcriptional regulation of gene expression and participate in many physiological circuits. An ~80-nt-long RyjB was earlier identified as a novel sRNA, which appeared to be accumulated in all phases of growth in Escherichia coli. We have taken a comprehensive approach in the current study to understand the regulation of ryjB expression under normal and pH stress conditions. RpoS was not necessary for ryjB expression neither at normal condition nor under acid stress. Hfq also emerged to be unnecessary for RyjB accumulation. Interestingly, RyjB was detected as a novel acid stress induced sRNA. A DNA binding protein PhoP, a component of PhoP/Q regulon, was found to regulate ryjB expression at low pH, as the elimination of phoP allele in the chromosome exhibited a basal level of RyjB expression under acid stress. Ectopic expression of PhoP in ΔphoP cells restored the overabundance of RyjB in the cell. Overexpression of RyjB increased the abundance of sgcA transcripts, with which RyjB shares a 4-nt overlap. The current study increases our knowledge substantially regarding the regulation of ryjB expression in E. coli cell.
细菌小 RNA（sRNA）在基因表达的转录后调控中发挥着关键作用，并参与许多生理回路。早先鉴定出一种约 80nt 长的 RyjB 是一种新的 sRNA，它似乎在大肠杆菌的所有生长阶段都积累。在当前的研究中，我们采用了一种综合的方法来了解 RyjB 在正常和 pH 应激条件下的表达调控。RpoS 在正常条件下和酸应激下都不是 ryjB 表达所必需的。Hfq 也似乎不需要 RyjB 的积累。有趣的是，RyjB 被检测为一种新的酸应激诱导的 sRNA。PhoP/Q 调控子的一个组成部分 DNA 结合蛋白 PhoP 被发现可以在低 pH 值下调节 ryjB 的表达，因为染色体中 phoP 等位基因的缺失在酸应激下表现出 RyjB 的基础水平表达。PhoP 在 ΔphoP 细胞中的异位表达恢复了细胞中 RyjB 的过度丰度。RyjB 的过表达增加了 sgcA 转录本的丰度，RyjB 与 sgcA 转录本共享 4nt 重叠。本研究大大增加了我们对大肠杆菌细胞中 ryjB 表达调控的认识。
