The PhoPR two-component system, a highly conserved system in corynebacteria and mycobacteria, is involved in the cellular response to environmental stress. When analysing the transcriptomic data of Corynebacterium glutamicum strains under different dissolved oxygen (DO) levels, PhoPR was found to be the most responsive two-component system to DO changes. Here, we systematically investigated the expression of PhoPR in response to different DO levels and its impact on genes related to global regulation and energy metabolism. Using Green fluorescent protein as a reporter, we confirmed that PhoPR was significantly upregulated upon decrease of DO. Through real-time quantitative PCR and electrophoretic mobility shift assay, we found that the effector protein PhoP directly activated glxR (encoding a global regulator), pfk and gapA (encoding the glycolytic enzymes) and ctaD (encoding cytochrome c in the electron transport chain), while downregulated aceE and gltA (encoding the TCA cycle enzymes). Overexpression of phoP or phoR resulted in a decreased intracellular NAD+/NADH ratio and increased intracellular ATP level, consistent with the gene expression changes regulated by PhoP. These results reveal the PhoPR system respond to oxygen deficiency and is responsible for the regulation of pathways involved in the sustainability of the energy levels required under low oxygen conditions. Our findings in this study not only provide new insights into the adaptation pathways of C. glutamicum in response to low oxygen conditions but also identify new possible genetic targets for the construction of the new cell factories aimed toward industrial applications.

PhoPR 双组分系统是棒状杆菌和分枝杆菌中高度保守的系统，参与细胞对环境压力的反应。在分析不同溶解氧 (DO) 水平下谷氨酸棒杆菌菌株的转录组数据时，发现 PhoPR 是对 DO 变化最敏感的双组分系统。在这里，我们系统地研究了 PhoPR 响应不同 DO 水平的表达及其对与全局调节和能量代谢相关的基因的影响。使用绿色荧光蛋白作为报告基因，我们证实 PhoPR 在 DO 降低时显着上调。通过实时定量 PCR 和电泳迁移率变化分析，我们发现效应蛋白 PhoP 直接激活了glxR（编码全局调节器）、pfk和gapA（编码糖酵解酶）和ctaD（编码电子传递链中的细胞色素 c），同时下调aceE和gltA（编码 TCA 循环酶）。phoP或phoR 的过度表达导致细胞内 NAD+/NADH 比率降低和细胞内 ATP 水平增加，这与 PhoP 调控的基因表达变化一致。这些结果揭示了 PhoPR 系统对缺氧做出反应，并负责调节参与低氧条件下所需能量水平可持续性的途径。我们在这项研究中的发现不仅为谷氨酸棒杆菌响应低氧条件的适应途径提供了新的见解，而且还为构建面向工业应用的新细胞工厂确定了新的可能的遗传目标。