1 Department of Molecular Reproduction, Development and Genetics Indian Institute of Science, Bangalore 560012, India.
Microbiology (Reading). 2019 Jun;165(6):683-696. doi: 10.1099/mic.0.000806. Epub 2019 May 7.
Regulators encoded by the beta-glucoside (bgl) operon of Escherichia coli are known to influence the expression of downstream target genes that confer a fitness advantage in stationary phase. We have examined the role of bglG in the regulation of ridA that encodes an enamine/imine deaminase essential for the elimination of reactive intermediates generated during the catabolism of amino acids such as serine. We report here that ridA is positively regulated by leucine responsive regulatory protein (Lrp) and leucine antagonizes the activation by Lrp. We also show that Lrp itself is under the indirect regulation of BglG, which brings about the overexpression of ridA in Bgl strains during stationary phase. Loss of ridA function in a Bgl background results in a significant growth retardation in serine-containing media compared to that in a Bgl background. We propose that overexpression of ridA in Bgl background during stationary phase is physiologically relevant to eliminate toxic metabolites generated by the catabolism of serine-containing peptides as a result of elevated levels of their uptake.
大肠杆菌的β-葡萄糖苷（bgl）操纵子编码的调控因子已知会影响下游靶基因的表达，这些靶基因在静止期赋予了适应性优势。我们研究了 bglG 在调节编码烯胺/亚胺脱氨酶的 ridA 中的作用，该脱氨酶对于消除氨基酸如丝氨酸代谢过程中产生的反应中间体是必不可少的。我们在这里报告说，ridA 受到亮氨酸反应调节蛋白（Lrp）的正调控，亮氨酸拮抗 Lrp 的激活。我们还表明，Lrp 本身受到 BglG 的间接调控，这导致 Bgl 菌株在静止期过度表达 ridA。与 Bgl 背景相比，Bgl 背景中 ridA 功能缺失会导致在含有丝氨酸的培养基中生长明显迟缓。我们提出，在静止期 Bgl 背景中过度表达 ridA 与消除由丝氨酸肽代谢产生的有毒代谢物有关，这是由于其摄取水平升高的结果。
