Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands.
Top Institute Food and Nutrition (TIFN), Wageningen, The Netherlands.
PLoS One. 2019 Jun 20;14(6):e0218508. doi: 10.1371/journal.pone.0218508. eCollection 2019.
Small regulatory RNAs (sRNAs) and their enormous potential and versatility have provided us with an astounding insight in the complexity of bacterial transcriptomes. sRNAs have been shown to be involved in a variety of cellular processes that range from stress to general metabolism. Here we report that the gene encoding the transcriptional regulator ArgR is immediately followed by the gene of the small regulatory RNA ArgX. The latter is transcribed from its own promoter. The production of ArgX is induced by increasing arginine concentrations and repressed by CcpA. Previously, ArgR was shown to act as a transcriptional repressor of the catabolic arginine deiminase pathway (arc operon) by binding in the promoter region of arcA. Here we demonstrate that ArgX downregulates arc mRNA levels. Furthermore, ArgX putatively blocks the translation of one of the genes in the operon, arcC1, a process that would redirect an intermediate in arginine degradation, carbamoyl phosphate, towards pyrimidine synthesis. Our findings exemplify, for the first time, the combinatorial power of a transcription factor and a small regulatory RNA derived from the 3'-UTR region. The regulators ArgR and ArgX share a common target, but act on transcription and on RNA level, respectively.
小调控 RNA（sRNAs）及其巨大的潜力和多功能性为我们提供了对细菌转录组复杂性的惊人洞察。sRNAs 已被证明参与各种细胞过程，从应激到一般代谢。在这里，我们报告编码转录调节因子 ArgR 的基因紧接着是小调控 RNA ArgX 的基因。后者从自己的启动子转录。ArgX 的产生受增加精氨酸浓度诱导，并受 CcpA 抑制。先前，ArgR 通过结合 arcA 启动子区域被证明作为分解代谢精氨酸脱亚氨酶途径（arc 操纵子）的转录抑制剂。在这里，我们证明 ArgX 下调 arc mRNA 水平。此外，ArgX 推测会阻止操纵子中一个基因 arcC1 的翻译，这一过程将使精氨酸降解的中间体碳酰磷酸重新定向用于嘧啶合成。我们的发现首次例证了来自 3'-UTR 区域的转录因子和小调控 RNA 的组合能力。调节因子 ArgR 和 ArgX 具有共同的靶标，但分别作用于转录和 RNA 水平。
