Use of heterologously-expressed cytochrome P450 and glutathione transferase enzymes in toxicity assays.

Guengerich FP, Wheeler JB, Chun YJ, Kim D, Shimada T, Aryal P, Oda Y, Gillam EM
Toxicology. 2002 181-182: 261-4

PMID: 12505322 · DOI:10.1016/s0300-483x(02)00293-7

Our groups have had a long-term interest in utilizing bacterial systems in the characterization of bioactivation and detoxication reactions catalyzed by cytochrome P450 (P450) and glutathione transferase (GST) enzymes. Bacterial systems remain the first choice for initial screens with new chemicals and have advantages, including high-throughput capability. Most human P450s of interest in toxicology have been readily expressed in Escherichia coli with only minor sequence modification. These enzymes can be readily purified and used in assays of activation of chemicals. Bicistronic systems have been developed in order to provide the auxiliary NADPH-P450 reductase. Alternative systems involve these enzymes expressed together within bacteria. In one approach, a lac selection system is used with E. coli and has been applied to the characterization of inhibitors of P450s 1A2 and 1B1, as well as in basic studies involving random mutagenesis. Another approach utilizes induction of the SOS (umu) response in Salmonella typhimurium, and systems have now been developed with human P450s 1A1, 1A2, 1B1, 2C9, 2D6, 2E1, and 3A4, which have been used to report responses from heterocyclic amines. S. typhimurium his reporter systems have also been used with GSTs, first to demonstrate the role of rat GST 5-5 in the activation of dihalomethanes. These systems have been used to compare these GSTs with regard to activation of dihaloalkanes and potential toxicity.

MeSH Terms (11)

Anticarcinogenic Agents Bacteria Cytochrome P-450 Enzyme System DNA DNA, Complementary Escherichia coli Glutathione Transferase Humans Mutagens Salmonella typhimurium Toxicology

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