NADPH inhibits transcription of the Escherichia coli manganese superoxide dismutase gene (sodA) in vitro.
We have previously reported that the thiols glutathione, dithiothreitol, and beta-mercaptoethanol suppress transcription of the Escherichia coli manganese-containing superoxide dismutase gene (sodA) in an in vitro coupled transcription plus translation system (Gardner, P. R., and Fridovich, I. (1987) J. Biol. Chem. 262, 17591-17595). We now report that NADPH, but not NADH, selectively decreases transcription of sodA in vitro and that an NADPH generating system utilizing glucose 6-phosphate and the corresponding dehydrogenase markedly augments this suppressive effect. A redox buffer containing various ratios of oxidized and reduced glutathione also modulated transcription of sodA thus demonstrating the existence of a redox-sensitive mechanism controlling sodA transcription. Fusion of a 120-base pair fragment, containing 90 base pairs of DNA upstream of the sodA transcription initiation site, to a promoterless galactokinase gene (galK) conferred redox-sensitivity to GalK synthesis. We propose that these redox effects act through a redox-sensitive regulator of sodA and that the anabolic reduction charge, [NADPH]/([NADPH]+[NADP+]), is one cellular signal controlling sodA transcription.
Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.
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Gardner
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Fridovich
D001483:Base Sequence; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D005686:Galactokinase / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005798:Genes, Bacterial; D005978:Glutathione / Q000031:analogs & derivatives / Q000494:pharmacology; D019803:Glutathione Disulfide; D007700:Kinetics; D008969:Molecular Sequence Data; D009243:NAD / Q000494:pharmacology; D009249:NADP / Q000494:pharmacology*; D010084:Oxidation-Reduction; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics*; D014158:Transcription, Genetic / Q000187:drug effects*
D012333:RNA, Messenger; D009243:NAD; D009249:NADP; D013482:Superoxide Dismutase; D005686:Galactokinase; D005978:Glutathione; D019803:Glutathione Disulfide