Identification of two Nereis virens (Annelida: Polychaeta) cytochromes P450 and induction by xenobiotics

Abstract

Cytochrome P450 (CYP) enzyme catalysed metabolism of xenobiotics such as polycyclic aromatic hydrocarbons (PAHs) are known to occur in polychaetes. Yet specific polychaete CYP enzymes have so far not been identified. Here, we report two partial CYP cDNA sequences, both of 453 bp, characterised from Nereis virens. These are the first CYP sequences reported in annelids. The deduced amino acid sequences both share highest identities to mammalian CYP4F enzymes (61% and 58%), indicating membership of the CYP4 family (accordingly, referred to as CYP4(1) and CYP4(2), respectively). The CYP4(2) gene expression was significantly higher in vehicle controls (corn oil) compared to untreated controls. Clofibrate increased the expression of the CYP4(2) genes. The induction by clofibrate and corn oil indicates regulatory similarities to vertebrate CYP4 enzymes, which are primarily involved in the metabolism of endogenous compounds such as fatty acids. Crude oil and benz(a)anthracene significantly induced CYP4(2) gene expression 2.6-fold, and because CYP enzymes often are induced by their own substrates, this induction may indicate involvement of N. virens CYP4 enzymes in the detoxification of environmental contaminants such as PAHs. The present study demonstrates that these N. virens CYP genes are transcriptionally inducible, and suggests that N. virens CYP4 enzymes may be involved in the metabolism of both exogenous and endogenous compounds.