The flavohaemoglobin (HMP) of Escherichia coli generates superoxide in vitro and causes oxidative stress in vivo.
Purified flavohaemoglobin (HMP) of Escherichia coli reduces Fe(III) in a superoxide dismutase (SOD)-sensitive reaction, demonstrating superoxide anion generation during aerobic NADH oxidation. In vivo, sodA-lacZ fusion activity was increased 3-fold by introducing plasmid pPL341, containing the hmp gene, or by growth with paraquat. The effects were additive and SOXS-dependent. Thus HMP activity causes oxidative stress in vivo. Activities of sodA-lacZ and hmp-lacZ fusions were stimulated in a himA mutant, demonstrating repression of both promoters by integration host factor (IHF), but the effects of pPL341 on sodA-lacZ activity were not due to titration of IHF by the hmp promoter.
Membrillo-Hernández
J
J
Division of Life Sciences, King's College London, U.K.
Ioannidis
N
N
Poole
R K
RK
D000332:Aerobiosis; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D004093:Dihydropteridine Reductase; D004790:Enzyme Induction; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005290:Ferric Compounds / Q000378:metabolism; D006420:Hemeproteins / Q000235:genetics / Q000378:metabolism*; D034982:Integration Host Factors; D009247:NADH, NADPH Oxidoreductases; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology*; D010269:Paraquat / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics; D013481:Superoxides / Q000378:metabolism*; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D005290:Ferric Compounds; D006420:Hemeproteins; D034982:Integration Host Factors; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D013481:Superoxides; C070724:SoxR protein, Bacteria; C070725:SoxS protein, E coli; C025314:ferric citrate; C095500:SodA protein, Bacteria; D013482:Superoxide Dismutase; D004093:Dihydropteridine Reductase; C076538:hmp protein, E coli; D009247:NADH, NADPH Oxidoreductases; D001616:beta-Galactosidase; D010269:Paraquat