Rainbow trout cytochrome P450s: purification, molecular aspects, metabolicactivity, induction and role in environmental monitoring

Cytochromes P450 (P450s or CYPs) constitute a superfamily of heme-thiolate proteins that play important roles in oxidative metabolism of endogenous an d exogenous compounds. This review provides some limited history but addres ses mainly the research progress on the cytochrome P450s in rainbow trout ( Oncorhynchus mykiss), their purification, structures at the primary level, role in metabolism, responses to chemicals and environmental pollutants, ap plication to biomonitoring and the effect of various factors on their expre ssion or activities. Information obtained to date suggests that the rainbow trout P450 systems are as complex as those seen in mammals. Fourteen P450s have been purified from liver or trunk kidney to relatively high specific content. cDNAs belonging to seven different P450 families have been documen ted from trout liver, kidney and ovary. Two CYP1A genes, nine cDNAs contain ing open reading frames, and a cDNA fragment were entered into GenBank. Amo ng them, CYP2K1, CYP2K3, CYP2K4, CYP2M1, CYP3A27 and CYP4T1 are the most re cently described forms. CYP2K1, CYP2M1 and CYP4T1 represent newly identifie d P450 subfamilies first described in the rainbow trout. In many cases, the cloned rainbow trout P450s have subsequently been expressed in heterologou s expressions systems such as COS-7 cells, yeast and baculovirus infected i nsect cells. Some of the overexpressed P450 isoforms have been partially ch aracterized. Potential future research directions are discussed. (C) 1998 E lsevier Science Inc. All rights reserved.