Acetate Metabolism in Escherichia coli Strains Lacking Phosphoenolpyruvate: Carbohydrate Phosphotransferase System; Evidence of Carbon Recycling Strategies and Futile Cycles
Acetate Metabolism in Escherichia coli Strains Lacking Phosphoenolpyruvate: Carbohydrate Phosphotransferase System; Evidence of Carbon Recycling Strategies and Futile Cycles
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DOI：
10.1159/000151219
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发表时间：
2009-01-01
影响因子：
1.2
通讯作者：
Bolivar, Francisco
中科院分区：
文献类型：
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作者：
Carlos Sigala, Juan;Flores, Salvador;Bolivar, Francisco
从大肠杆菌野生型JM 101中删除ptsHlcrr操纵子以产生菌株PB 11（PTS-）。在通过适应性进化过程部分恢复其在葡萄糖上的生长能力的衍生自PB 11的突变体（PB 12，PTS-Glc（+））中，葡萄糖转运中未使用的磷酸烯醇丙酮酸的一部分已被用于芳香族化合物的合成。在该报告中，显示了在乙酸盐作为碳源时，PB 11显示出比生长速率（mu）高于PB 12（分别为0.21和0.13 h（-1）），而JM 101的mu为0.28 h（-1）。为了了解这些生长差异乙酸，我们比较了中央代谢基因的表达谱的RT-PCR分析。获得的数据显示，与JM 101相比，两种PTS菌株中的一些糖异生基因均下调，而与PB 11和JM 101相比，PB 12中的大多数糖酵解基因均上调。此外，致突变基因（如ppsA、sfcA和maeB）以及编码丙酮酸氧化酶的poxB基因的失活对这些菌株的乙酸盐代谢具有不同的影响。结果表明，PTS-衍生物中乙酸盐的生长差异是由于潜在的碳循环策略，主要是在PB 11中，和无效的碳循环，特别是在PB 12中。版权所有（C）2008 S. Karger AG，巴塞尔
The ptsHlcrr operon was deleted from Escherichia coli wildtype JM101 to generate strain PB11 (PTS-). In a mutant derived from PB11 that partially recovered its growth capacity on glucose by an adaptive evolution process (PB12, PTS- Glc(+)), part of the phosphoenolpyruvate not used in glucose transport has been utilized for the synthesis of aromatic compounds. In this report, it is shown that on acetate as a carbon source, PB11 displayed a specific growth rate (mu) higher than PB12 (0.21 and 0.13 h(-1), respectively) while JM101 had a mu of 0.28 h(-1). To understand these growth differences on acetate, we compared the expression profiles of central metabolic genes by RT-PCR analysis. Obtained data revealed that some gluconeogenic genes were downregulated in both PTS- strains as compared to JM101, while most glycolytic genes were upregulated in PB12 in contrast to PB11 and JM101. Furthermore, inactivation of gluconeogenic genes, like ppsA, sfcA, and maeB, and poxB gene that codes for pyruvate oxidase, has differential impacts in the acetate metabolism of these strains. Results indicate that growth differences on acetate in the PTS- derivatives are due to potential carbon recycling strategies, mainly in PB11, and futile carbon cycles, especially in PB12. Copyright (C) 2008 S. Karger AG, Basel