NADPH: ferredoxin oxidoreductase acts as a paraquat diaphorase and is a member of the soxRS regulon.
Soluble extracts of Escherichia coli contain four NADPH:paraquat diaphorases that were separable by anion-exchange HPLC over Mono Q. One of these was induced when the cells were exposed to paraquat. This was the case in a soxRS-competent strain but not in a soxRS-null strain, while a soxRS-constitutive strain overexpressed this diaphorase without the stimulus of exposure to paraquat. This NADPH:paraquat diaphorase could use cytochrome c or nitroblue tetrazolium as an electron acceptor, whereas O2 was a relatively poor acceptor. This diaphorase was identified as the NADPH:ferredoxin reductase. A role for reduced ferredoxin and flavodoxin in the adaptive soxRS response to oxidative stress and in the regulation of the redox status of soxR is discussed.
Liochev
S I
SI
Department of Biochemistry, Duke University Medical Center, Durham, NC 27710.
Hausladen
A
A
Beyer
W F
WF
Fridovich
I
I
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D008058:Dihydrolipoamide Dehydrogenase / Q000378:metabolism; D004790:Enzyme Induction; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D005287:Ferredoxin-NADP Reductase / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010269:Paraquat / Q000378:metabolism*; D018085:Regulon / Q000235:genetics*; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C070724:SoxR protein, Bacteria; C070725:SoxS protein, E coli; D005287:Ferredoxin-NADP Reductase; D009247:NADH, NADPH Oxidoreductases; C085915:paraquat diaphorase; D008058:Dihydrolipoamide Dehydrogenase; D010269:Paraquat