Institute of Oceanic Research and Development, Tokai University, Shizuoka, Japan.
NODAI Genome Research Center, Tokyo University of Agriculture, Tokyo, Japan.
J Biol Chem. 2023 Aug;299(8):105069. doi: 10.1016/j.jbc.2023.105069. Epub 2023 Jul 17.
Mn is an essential nutrient whose concentration is tightly controlled in bacteria. In Bacillus subtilis, the Mn-activated transcription factor MntR controls Mn transporter genes. However, factors regulating intracellular Mn concentration are incompletely understood. Here, we found that glucose addition induces an increase in intracellular Mn concentration. We determined this upshift was mediated by glucose induction of the major Mn importer gene mntH by the transcription factor AhrC, which is known to be involved in arginine metabolism and to be indirectly induced by glucose. In addition, we identified novel AhrC-regulated genes encoding the Mn importer YcsG and the ABC-type exporter YknUV. We found the expression of these genes was also regulated by glucose and contributes to the glucose induction of Mn concentrations. ycsG expression is regulated by MntR as well. Furthermore, we analyzed the interaction of AhrC and MntR with the promoter driving ycsG expression and examined the Mn-dependent induction of this promoter to identify the transcription factors responsible for the Mn induction. RNA-Seq revealed that disruption of ahrC and mntR affected the expression of 502 and 478 genes, respectively (false discovery rate, <0.001, log[fold change] ≥ |2|. The AhrC- and/or MntR-dependent expression of twenty promoters was confirmed by LacZ analysis, and AhrC or MntR binding to some of these promoters was observed via EMSA. The finding that glucose promotes an increase in intracellular Mn levels without changes in extracellular Mn concentrations is reasonable for the bacterium, as intracellular Mn is required for enzymes and pathways mediating glucose metabolism.
锰是一种必需的营养物质，其浓度在细菌中受到严格控制。在枯草芽孢杆菌中，锰激活转录因子 MntR 控制锰转运基因。然而，调节细胞内锰浓度的因素尚未完全了解。在这里，我们发现葡萄糖的添加会导致细胞内锰浓度增加。我们确定这种上调是由转录因子 AhrC 介导的，葡萄糖诱导主要的锰进口基因 mntH 的表达引起的，AhrC 已知参与精氨酸代谢，并间接受葡萄糖诱导。此外，我们还鉴定了新型 AhrC 调节的基因，编码锰进口器 YcsG 和 ABC 型出口器 YknUV。我们发现这些基因的表达也受到葡萄糖的调节，有助于葡萄糖诱导锰浓度的增加。ycsG 的表达也受 MntR 调节。此外，我们分析了 AhrC 和 MntR 与驱动 ycsG 表达的启动子的相互作用，并检查了该启动子对 Mn 的依赖性诱导，以确定负责 Mn 诱导的转录因子。RNA-Seq 显示，ahrC 和 mntR 的缺失分别影响了 502 和 478 个基因的表达（错误发现率，<0.001，log[fold change]≥|2|）。通过 LacZ 分析证实了 AhrC 和/或 MntR 对二十个启动子的依赖表达，并且通过 EMSA 观察到 AhrC 或 MntR 与其中一些启动子的结合。葡萄糖促进细胞内锰水平增加而细胞外锰浓度不变的发现对细菌来说是合理的，因为细胞内锰是参与葡萄糖代谢的酶和途径所必需的。
