title: Transcriptional regulation of Mn-superoxide dismutase gene (sodA) of Escherichia coli is stimulated by DNA gyrase inhibitors.
abstract: The expression of manganese-containing superoxide dismutase (sodA) in Escherichia coli using sodA::lacZ gene fusion was found to be stimulated by DNA gyrase inhibitors, nalidixic acid, or coumermycin A1. Aerobically, the gyrase inhibitors increased the expression of sodA::lacZ in the presence or absence of either paraquat or the iron chelator 2,2'-dipyridyl. The concentrations of the inhibitors used were found to reduce DNA supercoiling. Treatment of wild-type cells (sodA+) with nalidixic acid increased the transcription of MnSOD mRNA. Anaerobically, the expression of sodA::lacZ in wild-type cells was not affected by nalidixic acid. However, nalidixic acid had a stimulatory effect on the anaerobic expression of sodA::lacZ in cells preinduced by the iron chelator as well as in mutants derepressed in sodA expression by virtue of their lacking the trans-acting repressor proteins or the cis-acting regulatory elements needed for sodA regulation. The results indicate that the effect of DNA gyrase inhibitors is secondary to the cis- and trans-regulatory elements of sodA and suggest that changes in DNA topology may affect transcriptional regulation of sodA.
authors.affiliation: Department of Biochemistry, North Carolina State University, Raleigh 27695-7622.
authors.forename: L W
authors.initials: LW
authors.lastname: Schrum
authors.forename: H M
authors.initials: HM
authors.lastname: Hassan
mesh_terms: D015082:2,2'-Dipyridyl / Q000494:pharmacology; D049933:Aminocoumarins; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003001:Cloning, Molecular; D003374:Coumarins / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D007700:Kinetics; D010269:Paraquat / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012974:Sodium Iodide / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000235:genetics* / Q000378:metabolism; D059005:Topoisomerase II Inhibitors; D014158:Transcription, Genetic / Q000187:drug effects; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D049933:Aminocoumarins; D000900:Anti-Bacterial Agents; D003374:Coumarins; D011993:Recombinant Fusion Proteins; D059005:Topoisomerase II Inhibitors; D015082:2,2'-Dipyridyl; D013482:Superoxide Dismutase; D001616:beta-Galactosidase; D012974:Sodium Iodide; C004628:coumermycin; D010269:Paraquat