Radiation Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup, Korea.
J Microbiol Biotechnol. 2011 Mar;21(3):252-5.
Both Escherichia coli (E. coli) and Salmonella enterica serovar Typhimurium (S. Typhimurium) have a tdc operon that encodes enzymes involved in a metabolic pathway for the degradation of L-serine and L-threonine. However, S. Typhimurium does not have the tdcR gene, which is a positive regulator in E. coli. In the present study, transcriptional analysis revealed that tdcA expression in E. coli is higher under anaerobic than aerobic growth conditions, but the opposite is true in S. Typhimurium. Interestingly, a tdcR mutant strain of E. coli showed a similar expression pattern to that observed in S. Typhimurium and was also induced by anaerobic shock. These results suggest that the induction of tdcA expression by anaerobic conditions is observable when tdcA expression is low owing to the absence of TdcR.
大肠杆菌（Escherichia coli）和鼠伤寒沙门氏菌血清型 Typhimurium（S. Typhimurium）都有一个 tdc 操纵子，该操纵子编码参与 L-丝氨酸和 L-苏氨酸降解代谢途径的酶。然而，鼠伤寒沙门氏菌没有 tdcR 基因，而该基因是大肠杆菌中的一个正调控因子。在本研究中，转录分析表明，大肠杆菌中 tdcA 的表达在厌氧生长条件下高于需氧生长条件，而在鼠伤寒沙门氏菌中则相反。有趣的是，大肠杆菌的 tdcR 突变株表现出与鼠伤寒沙门氏菌相似的表达模式，并且也能被厌氧冲击诱导。这些结果表明，当 tdcR 缺失导致 tdcA 表达水平较低时，厌氧条件可以诱导 tdcA 的表达。
