title: Requirement of ArcA for redox regulation in Escherichia coli under microaerobic but not anaerobic or aerobic conditions.
abstract: 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.
authors.affiliation: Laboratory for Microbiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018WV Amsterdam, The Netherlands.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Alexeeva
authors.forename: Klaas J
authors.initials: KJ
authors.lastname: Hellingwerf
authors.forename: M Joost
authors.initials: MJ
authors.lastname: Teixeira de Mattos
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D000332:Aerobiosis; D000693:Anaerobiosis; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D002952:Citric Acid Cycle; D003470:Culture Media; D003576:Electron Transport Complex IV / Q000378:metabolism; D004926:Escherichia coli / Q000254:growth & development* / Q000502:physiology; D029968:Escherichia coli Proteins; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000494:pharmacology; D010101:Oxygen Consumption; D011768:Pyruvate Dehydrogenase Complex / Q000378:metabolism; D012097:Repressor Proteins
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D011768:Pyruvate Dehydrogenase Complex; D012097:Repressor Proteins; C041610:arcA protein, E coli; D003576:Electron Transport Complex IV; D000123:Acetyltransferases; C022560:formate C-acetyltransferase; D005947:Glucose; D010100:Oxygen