Transcript Profiling and Inference of Escherichia coli K-12 ArcA Activity across the Range of Physiologically Relevant Oxygen Concentrations
Transcript Profiling and Inference of Escherichia coli K-12 ArcA Activity across the Range of Physiologically Relevant Oxygen Concentrations
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DOI：
10.1074/jbc.m110.211144
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发表时间：
2011-03-25
影响因子：
4.8
通讯作者：
Green, Jeffrey
中科院分区：
文献类型：
--
作者：
Rolfe, Matthew D.;Ter Beek, Alex;Green, Jeffrey
氧气的可获得性是决定大肠杆菌代谢模式的主要因素。虽然人们对完全好氧和厌氧条件下的大肠杆菌基因表达和新陈代谢已有很多了解，但在自然生态位中遇到的中等氧分压还没有得到充分的研究。在这里，首次描述了大肠杆菌K-12在生理上显著的氧气可利用性范围内的转录谱。这表明，随着氧气供应的增加，细胞逐渐转向有氧呼吸代谢和细胞膜的重塑。转录反应与细胞色素bd、bo‘和外膜蛋白OmpW丰度的变化一致。观察到的转录本和蛋白质图谱是由于对氧气本身或对氧气可获得性敏感的代谢和环境信号做出反应的调节器活动的变化(有氧代谢)。一个概率模型(TFInfer)被用来预测间接氧气传感双组分系统ArcBA在有氧代谢范围内的活性。该模型表明，调节子Arca的活性与有氧代谢有关，但与泛醌池的氧化还原状态无关，挑战了Arca活性被氧化的泛醌抑制的观点。磷酸化Arca的量与预测的Arca活性和好氧作用相关，表明在本文所用的条件下，发酵产物介导的ArcB磷酸酶活性的抑制是调节Arca活性的主要机制。
Oxygen availability is the major determinant of the metabolic modes adopted by Escherichia coli. Although much is known about E. coli gene expression and metabolism under fully aerobic and anaerobic conditions, the intermediate oxygen tensions that are encountered in natural niches are understudied. Here, for the first time, the transcript profiles of E. coli K-12 across the physiologically significant range of oxygen availabilities are described. These suggested a progressive switch to aerobic respiratory metabolism and a remodeling of the cell envelope as oxygen availability increased. The transcriptional responses were consistent with changes in the abundance of cytochrome bd and bo' and the outer membrane protein OmpW. The observed transcript and protein profiles result from changes in the activities of regulators that respond to oxygen itself or to metabolic and environmental signals that are sensitive to oxygen availability (aerobiosis). A probabilistic model (TFInfer) was used to predict the activity of the indirect oxygen-sensing two-component system ArcBA across the aerobiosis range. The model implied that the activity of the regulator ArcA correlated with aerobiosis but not with the redox state of the ubiquinone pool, challenging the idea that ArcA activity is inhibited by oxidized ubiquinone. The amount of phosphorylated ArcA correlated with the predicted ArcA activities and with aerobiosis, suggesting that fermentation product-mediated inhibition of ArcB phosphatase activity is the dominant mechanism for regulating ArcA activity under the conditions used here.