Kargeti Manika, Venkatesh K V
Department of Chemical Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai - 400076, India.
Mol Biosyst. 2017 Jun 27;13(7):1388-1398. doi: 10.1039/c6mb00721j.
Global transcription factors are known to regulate the anaerobic growth of Escherichia coli on glucose. These transcription factors help the organism to sense oxygen and accordingly regulate the synthesis of mixed acid producing enzymes. Five global transcription factors, namely ArcA, Fnr, IhfA-B, Crp and Fis, are known to play an important role in the growth phenotype of the organism in the transition from anaerobic to aerobic conditions. The effect of deletion of most of these global transcription factors on the growth phenotype has not been characterized under strict anaerobic fermentation conditions. In order to enumerate the role of global transcription factors in central carbon metabolism, experiments were performed using single deletion mutants of the above mentioned global transcription regulators. The mutants demonstrated lower growth rates, ranging from 3-75% lower growth as compared to the wild-type strain along with varying glucose uptake rates. Global transcription regulators help in lowering formate and acetate synthesis, thereby effectively channeling the carbon towards redox balance (through ethanol formation) and biomass synthesis. Flux analysis of mutant strains indicated that deletion of a single transcription factor alone does not play a significant role in the normalized flux distribution of the central carbon metabolism.
已知全局转录因子可调节大肠杆菌在葡萄糖上的厌氧生长。这些转录因子帮助生物体感知氧气，并相应地调节产生混合酸的酶的合成。已知五个全局转录因子，即ArcA、Fnr、IhfA - B、Crp和Fis，在生物体从厌氧条件转变为需氧条件的生长表型中起重要作用。在严格的厌氧发酵条件下，尚未对这些全局转录因子中大多数缺失对生长表型的影响进行表征。为了阐明全局转录因子在中心碳代谢中的作用，使用上述全局转录调节因子的单缺失突变体进行了实验。与野生型菌株相比，突变体的生长速率较低，生长降低幅度为3% - 75%，同时葡萄糖摄取率也有所不同。全局转录调节因子有助于降低甲酸和乙酸的合成，从而有效地将碳导向氧化还原平衡（通过乙醇形成）和生物量合成。突变体菌株的通量分析表明，单独缺失单个转录因子在中心碳代谢的标准化通量分布中不起显著作用。
