Systems biology approach reveals that overflow metabolism of acetate in Escherichia coli is triggered by carbon catabolite repression of acetyl-CoA synthetase.
Systems biology approach reveals that overflow metabolism of acetate in Escherichia coli is triggered by carbon catabolite repression of acetyl-CoA synthetase.
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DOI：
10.1186/1752-0509-4-166
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发表时间：
2010-12-01
影响因子：
--
通讯作者：
Vilu R
中科院分区：
文献类型：
--
作者：
Valgepea K;Adamberg K;Nahku R;Lahtvee PJ;Arike L;Vilu R
生物技术工业已经广泛地利用大肠杆菌来生产重组蛋白、生物燃料等。大肠杆菌培养伴随着乙酸盐排泄，即溢流代谢，这是有害的，因为它抑制生长，从生物质形成中转移有价值的碳，并且对目标产物合成是有害的。虽然溢流代谢已经研究了几十年，但其调节机制仍然不清楚。本工作研究了E.使用先进的连续培养方法（A-stat和D-stat）连续监测大肠杆菌。乙酸溢出转换的第一步（μ = 0.27 ± 0.02 h-1）是由碳分解代谢物阻遏触发的乙酰辅酶A合成酶（Acs）活性的阻遏，导致磷酸转乙酰酶（Pta）产生的乙酸同化减少，以及PTA-ACS结的破坏。这通过乙酸合成途径PTA-ACKA和POXB组分表达在μ = 0.27 ± 0.02 h-1的溢出转换之前下调以及同时5倍更强的乙酸消耗Acs抑制来指示。这反过来表明Acs活性不足以消耗Pta产生的所有乙酸盐，导致PTA-ACS节点中乙酸盐循环过程的破坏，其中恒定的乙酰磷酸或乙酸盐再生对E.大肠杆菌的趋化性、蛋白水解、致病性等调控。此外，双底物A-stat和D-stat实验表明，E. coli中Acs的表达在溢流代谢开始前急剧下降。溢出转换的第二步是在μ = 0.45 h-1时cAMP产量急剧下降，导致总Acs抑制和乙酸盐快速积累。这项研究是一个例子，如何系统生物学方法允许提出一个新的调控机制，溢流代谢在E。大肠杆菌的蛋白质组学、转录组学和代谢组学研究表明，乙酸积累过程分为两个阶段：Acs下调导致PTA产生的乙酸同化减少，PTA-ACS结被破坏。
The biotechnology industry has extensively exploited Escherichia coli for producing recombinant proteins, biofuels etc. However, high growth rate aerobic E. coli cultivations are accompanied by acetate excretion i.e. overflow metabolism which is harmful as it inhibits growth, diverts valuable carbon from biomass formation and is detrimental for target product synthesis. Although overflow metabolism has been studied for decades, its regulation mechanisms still remain unclear. In the current work, growth rate dependent acetate overflow metabolism of E. coli was continuously monitored using advanced continuous cultivation methods (A-stat and D-stat). The first step in acetate overflow switch (at μ = 0.27 ± 0.02 h-1) is the repression of acetyl-CoA synthethase (Acs) activity triggered by carbon catabolite repression resulting in decreased assimilation of acetate produced by phosphotransacetylase (Pta), and disruption of the PTA-ACS node. This was indicated by acetate synthesis pathways PTA-ACKA and POXB component expression down-regulation before the overflow switch at μ = 0.27 ± 0.02 h-1 with concurrent 5-fold stronger repression of acetate-consuming Acs. This in turn suggests insufficient Acs activity for consuming all the acetate produced by Pta, leading to disruption of the acetate cycling process in PTA-ACS node where constant acetyl phosphate or acetate regeneration is essential for E. coli chemotaxis, proteolysis, pathogenesis etc. regulation. In addition, two-substrate A-stat and D-stat experiments showed that acetate consumption capability of E. coli decreased drastically, just as Acs expression, before the start of overflow metabolism. The second step in overflow switch is the sharp decline in cAMP production at μ = 0.45 h-1 leading to total Acs inhibition and fast accumulation of acetate. This study is an example of how a systems biology approach allowed to propose a new regulation mechanism for overflow metabolism in E. coli shown by proteomic, transcriptomic and metabolomic levels coupled to two-phase acetate accumulation: acetate overflow metabolism in E. coli is triggered by Acs down-regulation resulting in decreased assimilation of acetic acid produced by Pta, and disruption of the PTA-ACS node.
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影响因子：
56.9
作者：
Ishii, Nobuyoshi;Nakahigashi, Kenji;Tomita, Masaru
通讯作者：
Tomita, Masaru
影响因子：
3.2
作者：
Barak, R;Abouhamad, WN;Eisenbach, M
通讯作者：
Eisenbach, M
影响因子：
3.2
作者：
Klein, Adam H.;Shulla, Ana;Wolfe, Alan J.
通讯作者：
Wolfe, Alan J.
影响因子：
3.5
作者：
Da Re, SS;Deville-Bonne, D;Stock, JB
通讯作者：
Stock, JB
影响因子：
4.4
作者：
Farmer, WR;Liao, JC
通讯作者：
Liao, JC