Abstract
Escherichia coli cells from strain fpr, deficient in the soxRS-induced ferredoxin (flavodoxin)-NADP(H) reductase (FPR), display abnormal sensitivity to the bactericidal effects of the superoxide-generating reagent methyl viologen (MV). Neither bacteriostatic effects nor inactivation of oxidant-sensitive hydrolyases could be detected in fpr cells exposed to MV. FPR inactivation did not affect the MV-driven soxRS response, whereas FPR overexpression led to enhanced stimulation of the regulon, with concomitant oxidation of the NADPH pool. Accumulation of a site-directed FPR mutant that uses NAD(H) instead of NADP(H) had no effect on soxRS induction and failed to protect fpr cells from MV toxicity, suggesting that FPR contributes to NADP(H) homeostasis in stressed bacteria.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Escherichia coli / enzymology*
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Escherichia coli / genetics
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Escherichia coli / growth & development
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Escherichia coli Proteins*
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Gene Expression Regulation, Bacterial*
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Herbicides / pharmacology
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Homeostasis
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NADH, NADPH Oxidoreductases / genetics
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NADH, NADPH Oxidoreductases / metabolism*
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NADP / metabolism*
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Oxidative Stress
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Paraquat / pharmacology
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Trans-Activators*
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Transcription Factors / genetics
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Transcription Factors / metabolism*
Substances
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Bacterial Proteins
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Escherichia coli Proteins
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Herbicides
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Trans-Activators
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Transcription Factors
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SoxR protein, Bacteria
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SoxS protein, E coli
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NADP
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NADH, NADPH Oxidoreductases
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flavodoxin NADPH oxidoreductase
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Paraquat