Functional co-expression of human oxidoreductase and cytochrome P450 1A1 in Saccharomyces cerevisiae results in increased EROD activity.
A cDNA coding for human oxidoreductase (NADPH-cytochrome P450 reductase) was expressed in S. cerevisiae on a high copy plasmid under control of a constitutive promoter. Microsomes from a transformed strain lacking endogenous oxidoreductase exhibited cytochrome c reductase activity. An apparent Km of 7.3 microM for the substrate NADPH was determined. Expression of human oxidoreductase complemented a mutation in the yeast oxidoreductase gene CPR1 and fully reversed the ketoconazole sensitive phenotype of the respective strain. The 7-ethoxyresorufin-O-deethylase activity of yeast cells expressing human cytochrome P450 1A1 was increased by more than sixteen-fold upon coexpression of human oxidoreductase. These results strongly suggest that a more efficient coupling between the human enzymes might be responsible for the increase in enzyme activity.
Eugster
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Institute of Toxicology, Swiss Federal Institute of Technology, Schwerzenbach.
Bärtsch
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Würgler
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Sengstag
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D001483:Base Sequence; D003001:Cloning, Molecular; D019363:Cytochrome P-450 CYP1A1; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005816:Genetic Complementation Test; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009251:NADPH-Ferrihemoprotein Reductase / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010088:Oxidoreductases / Q000378:metabolism*; D011994:Recombinant Proteins; D012441:Saccharomyces cerevisiae; D013045:Species Specificity; D014162:Transfection
D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D019363:Cytochrome P-450 CYP1A1; D009251:NADPH-Ferrihemoprotein Reductase