title: Regulatory roles of Fnr, Fur, and Arc in expression of manganese-containing superoxide dismutase in Escherichia coli.
abstract: Transcriptional regulation of the sodA gene, encoding the manganese superoxide dismutase (superoxide: superoxide oxidoreductase, EC 1.15.1.1) of Escherichia coli, was studied by monitoring expression of sodA-lacZ in different genetic backgrounds and under different growth conditions. Mutations in the fnr gene were found to affect aerobic and anaerobic expression of sodA-lacZ. Potential Fnr-binding sites were identified in the promoter region of sodA. Strains harboring simultaneous mutations in arcA/B and fur expressed sodA-lacZ under anaerobic growth conditions but were still inducible by iron chelators. However, in the triple mutants (fnr fur arcA/B) sodA-lacZ was fully expressed under anaerobiosis and was not further induced by the presence of 2,2'-dipyridyl, nitrate, or oxidants. On the other hand, aerobic expression of sodA-lacZ from a Fur-strain was approximately 3.8-fold higher than that from the wild-type strain but was diminished by introducing mutations in fnr or arcA/B. In conclusion, Fnr, Arc, and Fur act as anaerobic repressors of sodA. Furthermore, the regulation of sodA by Fur (ferric uptake regulation protein), Arc (aerobic respiratory control), and Fnr (fumarate nitrate reduction/regulator of anaerobic respiration) is independent of the superoxide response regulon SoxRS.
authors.affiliation: Department of Biochemistry, North Carolina State University, Raleigh 27695-7622.
authors.forename: H M
authors.initials: HM
authors.lastname: Hassan
authors.forename: H C
authors.initials: HC
authors.lastname: Sun
mesh_terms: D015082:2,2'-Dipyridyl / Q000494:pharmacology; D000332:Aerobiosis; D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005798:Genes, Bacterial; D005838:Genotype; D007506:Iron-Sulfur Proteins; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics*; D008345:Manganese / Q000378:metabolism*; D008969:Molecular Sequence Data; D009566:Nitrates / Q000494:pharmacology; D009838:Oligodeoxyribonucleotides; D016877:Oxidants / Q000494:pharmacology; D010269:Paraquat / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis*; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C060704:FNR protein, E coli; D007506:Iron-Sulfur Proteins; D007527:Isoenzymes; D009566:Nitrates; D009838:Oligodeoxyribonucleotides; D016877:Oxidants; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C068477:ferric uptake regulating proteins, bacterial; C016649:phage repressor proteins; D008345:Manganese; D015082:2,2'-Dipyridyl; D013482:Superoxide Dismutase; D001616:beta-Galactosidase; D010269:Paraquat