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首页> 外文期刊>Journal of bacteriology >Requirement of ArcA for Redox Regulation in Escherichia coli under Microaerobic but Not Anaerobic or Aerobic Conditions
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Requirement of ArcA for Redox Regulation in Escherichia coli under Microaerobic but Not Anaerobic or Aerobic Conditions

机译：在微需氧条件下，而非厌氧或需氧条件下，ArcA对大肠杆菌中氧化还原调节的要求

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In Escherichia coli, the two-component regulatory ArcAB system functions as a major control system for the regulation of expression of genes encoding enzymes involved in both aerobic and anaerobic catabolic pathways. Previously, we have described the physiological response of wild-type E. coli to changes in oxygen availability through the complete range from anaerobiosis to full aerobiosis (S. Alexeeva, B. de Kort, G. Sawers, K. J. Hellingwerf, and M. J. Teixeira de Mattos, J. Bacteriol. 182:4934-4940, 2000, and S. Alexeeva, K. J. Hellingwerf, and M. J. Teixeira de Mattos, J. Bacteriol. 184:1402-1406, 2002). Here, we address the question of the contribution of the ArcAB-dependent transcriptional regulation to this response. Wild-type E. coli and a mutant lacking the ArcA regulator were grown in glucose-limited chemostat cultures at controlled levels of oxygen availability ranging from full aerobiosis to complete anaerobiosis. A flux analysis of the distribution of catabolic fluxes over parallel pathways was carried out, and the intracellular redox state (as reflected by the NADH/NAD ratio) was monitored for all steady states. Deletion of ArcA neither significantly altered the in vivo activity of the pyruvate dehydrogenase complex and pyruvate formate lyase nor significantly affected catabolism under fully aerobic and fully anaerobic conditions. In contrast, profound effects of the absence of ArcA were seen under conditions of oxygen-restricted growth: increased respiration, an altered electron flux distribution over the cytochrome o- and d-terminal oxidases, and a significant change in the intracellular redox state were observed. Thus, the ArcA regulator was found to exert major control on flux distribution, and it is concluded that the ArcAB system should be considered a microaerobic redox regulator.
机译：在大肠埃希氏菌中，两组分调节性ArcAB系统充当主要控制系统，可调节有氧和厌氧分解代谢途径中涉及的酶编码基因的表达。以前，我们已经描述了野生型 E的生理反应。大肠杆菌从整个厌氧菌到完全需氧菌的整个过程中的氧气利用率变化（S. Alexeeva，B。de Kort，G。Sawers，KJ Hellingwerf和MJ Teixeira de Mattos，J。Bacteriol。182：4934- 4940，2000，和S. Alexeeva，KJ Hellingwerf，和MJ Teixeira de Mattos，J。Bacteriol。184：1402-1406，2002）。在这里，我们解决了ArcAB依赖的转录调控对此反应的贡献问题。野生型 E。大肠杆菌和缺少ArcA调节剂的突变体在葡萄糖受限的恒化器培养物中生长，其受控氧水平从完全需氧量到完全厌氧量不等。对分解代谢通量在平行路径上的分布进行通量分析，并监测所有稳态的细胞内氧化还原状态（如NADH / NAD比所反映）。在完全有氧和完全厌氧条件下，ArcA的缺失既不会显着改变丙酮酸脱氢酶复合物和丙酮酸甲酸酯裂解酶的体内活性，也不会显着影响分解代谢。相反，在氧气限制的生长条件下，没有ArcA会产生深远的影响：呼吸增加，细胞色素 o -和 d -上电子通量分布发生变化末端氧化酶，并观察到细胞内氧化还原状态的重大变化。因此，发现ArcA调节剂可对通量分布起主要控制作用，并得出结论认为ArcAB系统应被视为微氧氧化还原调节剂。

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