Department of Microbiology, University of Illinois, Urbana, Illinois, USA.
J Bacteriol. 2024 Aug 22;206(8):e0004924. doi: 10.1128/jb.00049-24. Epub 2024 Jul 9.
The small RNA (sRNA) RydC strongly activates , which encodes the cyclopropane fatty acid synthase. Previous work demonstrated that RydC activation of increases the conversion of unsaturated fatty acids to cyclopropanated fatty acids in membrane lipids and changes the biophysical properties of membranes, making cells more resistant to acid stress. The regulators that control RydC synthesis had not previously been identified. In this study, we identify a GntR-family transcription factor, YieP, that represses transcription. YieP positively autoregulates its own transcription and indirectly regulates through RydC. We further identify additional sRNA regulatory inputs that contribute to the control of RydC and . The translation of is repressed by the Fnr-dependent sRNA, FnrS, making FnrS an indirect activator of and . Conversely, RydC activity on is antagonized by the OmpR-dependent sRNA OmrB. Altogether, this work illuminates a complex regulatory network involving transcriptional and post-transcriptional inputs that link the control of membrane biophysical properties to multiple environmental signals.
Bacteria experience many environmental stresses that challenge their membrane integrity. To withstand these challenges, bacteria sense what stress is occurring and mount a response that protects membranes. Previous work documented the important roles of small RNA (sRNA) regulators in membrane stress responses. One sRNA, RydC, helps cells cope with membrane-disrupting stresses by promoting changes in the types of lipids incorporated into membranes. In this study, we identified a regulator, YieP, that controls when RydC is produced and additional sRNA regulators that modulate YieP levels and RydC activity. These findings illuminate a complex regulatory network that helps bacteria sense and respond to membrane stress.
小分子 RNA（sRNA）RydC 强烈激活 ，它编码环丙烷脂肪酸合酶。先前的工作表明，RydC 对 的激活增加了膜脂中环丙烷脂肪酸的不饱和脂肪酸转化，并改变了膜的生物物理性质，使细胞更能抵抗酸应激。以前尚未确定控制 RydC 合成的调节剂。在这项研究中，我们鉴定了一种 GntR 家族转录因子 YieP，它抑制 转录。YieP 自身转录呈正调控，并通过 RydC 间接调节 。我们进一步鉴定了其他 sRNA 调节输入，这些输入有助于控制 RydC 和 。 的翻译受到 Fnr 依赖性 sRNA FnrS 的抑制，这使得 FnrS 成为 和 的间接激活剂。相反，RydC 对 的活性受到 OmpR 依赖性 sRNA OmrB 的拮抗。总之，这项工作阐明了一个涉及转录和转录后输入的复杂调控网络，该网络将膜生物物理性质的控制与多种环境信号联系起来。
细菌经历许多挑战其膜完整性的环境压力。为了承受这些挑战，细菌感知到正在发生的压力，并做出反应来保护膜。先前的工作记录了小分子 RNA（sRNA）调节剂在膜应激反应中的重要作用。一种 sRNA，RydC，通过促进整合到膜中的脂质类型的变化来帮助细胞应对破坏膜的应激。在这项研究中，我们确定了一种调节剂 YieP，它控制 RydC 的产生，以及其他调节 YieP 水平和 RydC 活性的 sRNA 调节剂。这些发现阐明了一个复杂的调控网络，帮助细菌感知和应对膜应激。
