Acetate overflow metabolism regulates a major metabolic shift after glucose depletion in Escherichia coli,FEBS Letters

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Acetate overflow metabolism regulates a major metabolic shift after glucose depletion in Escherichia coli
FEBS Letters ( IF 3.0 ) Pub Date : 2021-06-14 , DOI: 10.1002/1873-3468.14151
Tomohiro Shimada ₁ , Kohta Nakazawa _{1,

2} , Tomoyuki Tachikawa _{1,

2} , Natsumi Saito _{3,

4} , Tatsuya Niwa ₅ , Hideki Taguchi ₅ , Kan Tanaka ₁

Affiliation

Acetate overflow refers to the metabolism by which a large part of carbon incorporated as glucose into Escherichia coli cells is catabolized and excreted as acetate into the medium. We previously found that mutants for the acetate overflow pathway enzymes phosphoacetyltransferase (Pta) and acetate kinase (AckA) showed significant diauxic growth after glucose depletion in E. coli. Here, we analyzed the underlying mechanism in the pta mutant. Proteomic and other analyses revealed an increase in pyruvate dehydrogenase complex subunits and a decrease in glyoxylate shunt enzymes, which resulted from pyruvate accumulation. Since restoration of these enzyme levels by overexpressing PdhR (pyruvate-sensing transcription factor) or deleting iclR (gene encoding a pyruvate- and glyoxylate-sensing transcription factor) alleviated the growth lag of the pta mutant after glucose depletion, these changes were considered as the reason for the phenotype. Given the evidence for decreased coenzyme A (HS-CoA) levels in the pta mutant, the growth inhibition after glucose depletion was partly explained by limited availability of HS-CoA in the cell. The findings provide insights into the role of acetate overflow in metabolic regulation, which may be useful for biotechnological applications.

中文翻译：

醋酸溢出代谢调节大肠杆菌葡萄糖消耗后的主要代谢转变

乙酸盐溢出是指以葡萄糖形式掺入大肠杆菌细胞中的大部分碳被分解代谢并以乙酸盐形式排泄到培养基中的代谢。我们以前发现醋酸溢出途径酶磷酸乙酰转移酶 (Pta) 和醋酸激酶 (AckA) 的突变体在大肠杆菌中葡萄糖耗尽后显示出显着的双生长。在这里，我们分析了 pta 突变体的潜在机制。蛋白质组学和其他分析表明，丙酮酸脱氢酶复合体亚基增加，乙醛酸分流酶减少，这是由丙酮酸积累引起的。由于通过过表达 PdhR（丙酮酸感应转录因子）或删除iclR 来恢复这些酶水平（编码丙酮酸和乙醛酸感应转录因子的基因）减轻了葡萄糖耗尽后pta突变体的生长滞后，这些变化被认为是表型的原因。鉴于pta突变体中辅酶 A (HS-CoA) 水平降低的证据，葡萄糖耗尽后的生长抑制部分解释为细胞中 HS-CoA 的可用性有限。这些发现提供了对醋酸盐溢出在代谢调节中的作用的见解，这可能对生物技术应用有用。

更新日期：2021-08-09

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