title: Activation of MeIQ (2-amino-3,4-dimethylimidazo- [4,5-f]quinoline) by sequence variants of recombinant human cytochrome P450 1A2.
abstract: Understanding the relationships between the sequences and catalytic activities of P450 enzymes that catalyze the bioactivation of mutagens and carcinogens is an important goal in mutation research. Escherichia coli strain DJ4309 expresses recombinant human P450 1A2 and activates promutagens such as MeIQ (2-amino-3, 4-dimethylimidazo[4,5-f]quinoline), as measured by induction of reverse mutations detected as lacZ(+) colonies on minimal lactose (ML) plates. Pools of P450 1A2 mutants were constructed by polymerase chain reaction (PCR) mutagenesis of putative substrate recognition sites (SRSs). Cultures of individual clones were patched onto MeIQ/ML plates and the growth of revertant microcolonies within each patch was inspected after 2 days of incubation. Beginning with a pool of several thousand clones, we identified 25 distinct P450 1A2 SRS variants with altered activities. In this study, the MeIQ dose-responses of all the variants are reported. The implications of the results are considered with reference to published models of the protein's structure.
authors.affiliation: Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry and Biochemistry, University of Guelph, Guelph, Ontario, Canada. josephy@chembio.uoguelph.ca
authors.forename: P D
authors.initials: PD
authors.lastname: Josephy
authors.forename: K L
authors.initials: KL
authors.lastname: Bibeau
authors.forename: D H
authors.initials: DH
authors.lastname: Evans
mesh_terms: D001711:Biotransformation; D002273:Carcinogens / Q000493:pharmacokinetics*; D019388:Cytochrome P-450 CYP1A2 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016296:Mutagenesis; D009152:Mutagenicity Tests; D011804:Quinolines / Q000493:pharmacokinetics*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D002273:Carcinogens; D011804:Quinolines; D011994:Recombinant Proteins; D019388:Cytochrome P-450 CYP1A2; C036989:2-amino-3,4-dimethylimidazo(4,5-f)quinoline