Lack of redox control of the anaerobically-induced nirB+ gene of Escherichia coli K-12.
Operon fusion strains of Escherichia coli K-12 have been used to demonstrate that transcription of the structural gene for NADH-dependent nitrite reductase is regulated by oxygen repression and induction by its substrate, nitrite. This two-stage regulation of nirB is totally dependent upon a functional Fnr protein. Unlike the Fnr-dependent fumarate reductase operon, nirB transcription is not repressed by nitrate. These results suggest that the Fnr protein is simply a positive control protein essential for the derepression of some, but not all, anaerobically-induced operons rather than a more general redox-sensitive regulator, as suggested by the redox control hypothesis for the regulation of gene expression in facultatively anaerobic bacteria.
D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D004790:Enzyme Induction; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D005561:Formates / Q000378:metabolism / Q000494:pharmacology; D005786:Gene Expression Regulation; D005796:Genes; D005798:Genes, Bacterial; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics*; D009566:Nitrates / Q000378:metabolism / Q000494:pharmacology; D050898:Nitrite Reductase (NAD(P)H); D009572:Nitrite Reductases / Q000096:biosynthesis / Q000235:genetics*; D009573:Nitrites / Q000378:metabolism / Q000494:pharmacology; D010084:Oxidation-Reduction; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D005561:Formates; D009566:Nitrates; D009573:Nitrites; C030544:formic acid; D009247:NADH, NADPH Oxidoreductases; D009572:Nitrite Reductases; D050898:Nitrite Reductase (NAD(P)H)