Recombinant enzymes overexpressed in bacteria show broad catalytic specificity of human cytochrome P450 2W1 and limited activity of human cytochrome P450 2S1.
Human cytochromes P450 2S1 and 2W1 have received only limited attention with regard to characterization of function. Both cytochromes P450 have been reported to be overexpressed in human tumors, and cytochrome P450 2S1 is induced by carcinogenic polycyclic hydrocarbons. We report methods for high-level expression and purification of both cytochromes P450 from Escherichia coli, with the goal of establishing function. The level of expression of human cytochrome P450 2W1 achieved using codon optimization for E. coli was 1800 nmol of cytochrome P450 per liter of culture, the highest level achieved in this laboratory to date. Assays with a number of the typical cytochrome P450 substrates showed no detectable activity, including some for which qualitative reports have appeared in the literature. Cytochrome P450 2W1 catalyzed benzphetamine N-demethylation (k(cat), 3.8/min) and arachidonic acid oxidation, albeit at a very low rate (approximately 0.05/min). In a umu genotoxicity screen, cytochrome P450 2W1 catalyzed the activation of several procarcinogens, particularly polycyclic hydrocarbon diols, but cytochrome P450 2S1 did not. The bioactivation of procarcinogens by cytochrome P450 2W1 may be of significance in the context of reports of preferential expression of the enzyme in tumors, in that activation of procarcinogens could lead to the accumulation of mutations and enhance the carcinogenic process.
Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, 638 Robinson Research Building, 23rd and Pierce Avenues, Nashville, TN 37232-0146, USA.
Zhong-Liu
ZL
Wu
Christal D
CD
Sohl
Tsutomu
T
Shimada
F Peter
FP
Guengerich
D000595:Amino Acid Sequence; D001483:Base Sequence; D002384:Catalysis; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D000072467:Cytochrome P450 Family 2; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006899:Mixed Function Oxygenases / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification
D011994:Recombinant Proteins; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C422564:CYP2S1 protein, human; C509336:CYP2W1 protein, human; D000072467:Cytochrome P450 Family 2