Cloning a new cytochrome P450 isoform (CYP356A1) from oyster Crassostrea gigas

We have cloned the full-length cDNA of the first member of a new cytochrome P450 (CYP) family from the Pacific oyster Crassostrea gigas. This new CYP gene was obtained based on an initial 331bp fragment previously identified among the list of the differentially expressed genes in oysters exposed to untreated domestic sewage. The full-length CYP has an open reading frame of 1500bp and based on its deduced amino acid sequence was classified as a member of a new subfamily, CYP356A1. A phylogenetic analysis showed that CYP356A1 is closely related to members of the CYP17 and CYP1 subfamilies. Semi-quantitative RT-PCR was performed to analyze the CYP356A1 expression in different tissues of the oyster (digestive gland, gill, mantle and adductor muscle). Results showed slightly higher CYP356A1 expression in digestive gland and mantle, than the other tissues, indicating a possible role of the CYP356A1 in xenobiotic biotransformation and/or steroid metabolism.