Role of pyruvate oxidase in Escherichia coli strains lacking the phosphoenolpyruvate:: carbohydrate phosphotransferase system
Role of pyruvate oxidase in Escherichia coli strains lacking the phosphoenolpyruvate:: carbohydrate phosphotransferase system
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DOI：
10.1159/000086702
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发表时间：
2004-01-01
影响因子：
1.2
通讯作者：
Bolivar, F
中科院分区：
文献类型：
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作者：
Flores, N;de Anda, R;Bolivar, F
我们报告了一项研究，以确定丙酮酸氧化酶的作用，大肠杆菌等基因菌株与活跃和不活跃的磷酸烯醇丙酮酸：碳水化合物磷酸转移酶系统（PTS）。在葡萄糖基本培养基中显示0.1 h（-1）的比生长速率（mu）的菌株PB 11是野生型JM 101的ptsHI，crr操纵子缺失衍生物（显示0.70 h（-1）的mu）。菌株PB 12是从PB 11中筛选得到的一个自发突变株，其在葡萄糖上的生长能力为0.40 h（-1）。在补充有葡萄糖加乙酸盐的基本培养基培养物中，菌株JM 101显示优先消耗葡萄糖，而菌株PB 11和PB 12不显示葡萄糖分解代谢抑制乙酸盐消耗。当在含有葡萄糖或葡萄糖加乙酸盐的培养基的发酵罐中生长时，poxB的灭活导致菌株PB 11的生长速率严重降低，而在相同条件下，poxB衍生菌株JM 101和PB 12不受影响。使用RT-PCR确定了与poxB转录调节和中枢代谢相关的29个基因的相对转录水平。该分析显示，与JM 101相比，菌株PB 11中编码丙酮酸脱氢酶复合物（Pdh）亚基的基因的转录水平低2倍，菌株PB 11和PB 12中poxB的转录水平高4至6倍。此外，在PTS（-）菌株中，检测到poxB转录因子rpoS、soxS和marA的上调。结果表明，在菌株PB 11中，AcCoA主要由丙酮酸氧化酶产生的乙酸合成，而在菌株JM 101和PB 12中，AcCoA优先由Pdh产生的丙酮酸合成。版权所有（C）2004 S. Karger AG，巴塞尔。
We report a study to determine the role of pyruvate oxidase among Escherichia coli isogenic strains with active and inactive phosphoenolpyruvate: carbohydrate phosphotransferase system (PTS). Strain PB11, displaying a specific growth rate (mu) in glucose minimal medium of 0.1 h(-1) is a ptsHI, crr operon deletion derivative of wildtype JM101 ( displaying a mu of 0.70 h(-1)). Strain PB12 is a spontaneous mutant obtained from PB11 after selection for its capacity to grow on glucose with a mu of 0.40 h(-1). In minimal medium cultures supplemented with glucose plus acetate, strain JM101 displayed preferential consumption of glucose, whereas strains PB11 and PB12 did not display glucose catabolic repression of acetate consumption. Inactivation of poxB caused a severe reduction in growth rate in strain PB11 when grown in the fermentor with medium containing glucose or glucose plus acetate, whereas under the same conditions poxB derivative strains of JM101 and PB12 were not affected. Relative transcript levels for 29 genes related to poxB transcriptional regulation and central metabolism were determined using RT-PCR. This analysis revealed 2-fold lower transcript levels for genes encoding subunits of the pyruvate dehydrogenase complex (Pdh) in strain PB11 and 4- to 6-fold higher transcript levels for poxB in strains PB11 and PB12, when compared to JM101. In addition, in the PTS(-) strains, upregulation of the poxB transcription factors rpoS, soxS and marA, was detected. The results presented here strongly suggest that AcCoA is mainly synthesized from acetate produced by pyruvate oxidase in strain PB11, whereas in strains JM101 and PB12, AcCoA is synthesized preferentially from pyruvate by Pdh. Copyright (C) 2004 S. Karger AG, Basel.