Citrate utilization under anaerobic environment in Escherichia coli is under direct control of Fnr and indirect control of ArcA and Fnr via CitA-CitB system
Citrate utilization under anaerobic environment in Escherichia coli is under direct control of Fnr and indirect control of ArcA and Fnr via CitA-CitB system
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DOI：
10.1111/1462-2920.15357
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发表时间：
2020-12-22
影响因子：
5.1
通讯作者：
Li, Ganwu
中科院分区：
文献类型：
--
作者：
Jiang, Fengwei;Huang, Xinxin;Li, Ganwu
大多数大肠杆菌菌株不会引起疾病，它们自然生活在肠道的下部，并通过粪便排出到环境中。大肠杆菌可以在厌氧条件下利用柠檬酸盐，但不能在好氧条件下利用柠檬酸盐。然而，人们对潜在的监管机制知之甚少。在这项研究中，我们探索了在厌氧条件下，全局调节子Arca和FNR对柠檬酸发酵基因的调控机制。凝胶迁移率改变分析表明，调节蛋白Arca和FNR结合到位于citAB和citCDEFXGT操纵子之间的启动子区域。随后的实验证实，Arca通过调控CITA-CITB系统间接调控柠檬酸发酵基因的表达，而FNR通过调控CITA-CITB系统直接调控但也间接调控柠檬酸发酵基因的表达。在以柠檬酸为碳源的M9培养基中，ArcA和FNR基因的缺失显著抑制了大肠杆菌的生长。我们认为，Arca和FNR都可以通过CITA-CITB系统间接调控柠檬酸的利用，而FNR也可以直接调控厌氧条件下大肠杆菌中柠檬酸发酵基因的表达。
Most Escherichia coli (E. coli) strains do not cause disease, naturally living in the lower intestine and is expelled into the environment within faecal matter. Escherichia coli can utilize citrate under anaerobic conditions but not aerobic conditions. However, the underlying regulatory mechanisms are poorly understood. In this study, we explored regulatory mechanisms of citrate fermentation genes by global regulators ArcA and Fnr under anaerobic conditions. A gel mobility shift assay showed that the regulator proteins ArcA and Fnr binded to the promoter region localized between the citAB and citCDEFXGT operons. Subsequent assays confirmed that ArcA indirectly controled the expression of citrate fermentation genes via regulating CitA-CitB system, while Fnr directly regulated but also indirectly modulated citrate fermentation genes via controling CitA-CitB system. Deletions of arcA and fnr significantly reduced the growth of Escherichia coli in M9 medium with a citrate carbon source. We conclude that both ArcA and Fnr can indirectly control the citrate utilization via CitA-CitB system, while Fnr can also directly regulate the expression of citrate fermentation genes in E. coli under anaerobic conditions.