Analyses of the GlnR- and AmtR- dependent nitrogen regulatory network of Mycobacterium smegmatis.

Total transcriptome analyses were carried out to investigate changes in transcript patterns in the Mycobacterium smegmatis wild type strain SMR5 due to nitrogen starvation and to expand the knowledge about the role of the two transcriptional regulators of nitrogen metabolism, namely GlnR and AmtR, in these processes. A first experiment revealed enhanced transcript levels of 284 genes and reduced transcripts of 231 genes in the wild type under nitrogen starvation compared to nitrogen surplus. When glnR deletion strain MH1 was compared to the wild type under nitrogen starvation, decreased transcript levels of 125 genes were detected, indicating that these are activated by GlnR due to nitrogen limitation. Comparing amtR deletion strain YL1 to the wild type under nitrogen starvation, enhanced transcript levels of 2 genes were found, indicating that they are repressed by AmtR under nitrogen surplus. A comparison of YL1 and wild type under surplus, as well as a comparison of YL1 under nitrogen surplus and starvation and of MH1 under nitrogen surplus and starvation were carried out as additional control experiments. It can be concluded that GlnR is the master regulator of nitrogen control in M. smegmatis and that AmtR fulfills only a small, subordinate role in the regulation of an operon. This SuperSeries is composed of the SubSeries listed below. Refer to individual Series

本研究通过全转录组分析，探究耻垢分枝杆菌（Mycobacterium smegmatis）野生型菌株SMR5在氮饥饿条件下的转录组模式变化，并拓展对两种氮代谢转录调控因子——GlnR与AmtR在该过程中作用的认知。首轮实验结果显示，与氮充足条件相比，野生型菌株在氮饥饿状态下，有284个基因的转录本水平上调，231个基因的转录本水平下调。在氮饥饿条件下将glnR缺失菌株MH1与野生型菌株进行比对时，检测到125个基因的转录本水平显著下调，这表明在氮限制环境中，GlnR可激活这些基因的转录。在氮饥饿条件下将amtR缺失菌株YL1与野生型菌株比对时，发现有2个基因的转录本水平显著上调，这表明在氮充足条件下，AmtR会抑制这两个基因的转录。此外，本研究还开展了多项对照实验：包括氮充足条件下YL1菌株与野生型菌株的比对、YL1菌株在氮充足与氮饥饿条件下的转录组比对，以及MH1菌株在氮充足与氮饥饿条件下的转录组比对。综上可得出结论：GlnR是耻垢分枝杆菌氮代谢调控的核心调控因子，而AmtR仅在操纵子调控中发挥微小的从属作用。本超级数据集由以下子数据集构成，具体信息请参见各独立数据集条目。