The State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China.
Microb Biotechnol. 2022 Jun;15(6):1795-1810. doi: 10.1111/1751-7915.14016. Epub 2022 Feb 11.
GlnR activates nitrogen metabolism genes under nitrogen-limited conditions, whereas MtrA represses these genes under nutrient-rich conditions in Streptomyces. In this study, we compared the transcription patterns of nitrogen metabolism genes in a double deletion mutant (ΔmtrA-glnR) lacking both mtrA and glnR and in mutants lacking either mtrA (ΔmtrA) or glnR (ΔglnR). The nitrogen metabolism genes were expressed similarly in ΔmtrA-glnR and ΔglnR under both nitrogen-limited and nutrient-rich conditions, with patterns distinctly different from that of ΔmtrA, suggesting a decisive role for GlnR in the control of nitrogen metabolism genes and further suggesting that regulation of these genes by MtrA is GlnR-dependent. MtrA and GlnR utilize the same binding sites upstream of nitrogen metabolism genes, and we showed stronger in vivo binding of MtrA to these sites under nutrient-rich conditions and of GlnR under nitrogen-limited conditions, consistent with the higher levels of MtrA or GlnR under those respective conditions. In addition, we showed that both mtrA and glnR are self-regulated. Our study provides new insights into the regulation of nitrogen metabolism genes in Streptomyces.
GlnR 在氮限制条件下激活氮代谢基因，而 MtrA 在营养丰富的条件下抑制这些基因在链霉菌中的表达。在这项研究中，我们比较了缺乏 mtrA 和 glnR 的双缺失突变体（ΔmtrA-glnR）和缺乏 mtrA（ΔmtrA）或 glnR（ΔglnR）的突变体中氮代谢基因的转录模式。在氮限制和营养丰富的条件下，ΔmtrA-glnR 和 ΔglnR 中的氮代谢基因表达相似，与 ΔmtrA 的模式明显不同，表明 GlnR 在氮代谢基因的调控中起决定性作用，并进一步表明这些基因的调控依赖于 MtrA。MtrA 和 GlnR 在氮代谢基因的上游利用相同的结合位点，我们在营养丰富的条件下显示了 MtrA 对这些位点更强的体内结合，在氮限制条件下显示了 GlnR 的结合更强，这与相应条件下 MtrA 或 GlnR 的更高水平一致。此外，我们还表明 mtrA 和 glnR 都是自我调控的。我们的研究为链霉菌中氮代谢基因的调控提供了新的见解。
