Structure, genetic mapping, and function of the cytochrome P450 3A37 gene in the turkey (Meleagris gallopavo)

Cytochromes P450 (P450 for protein; CYP for gene) are a superfamily of membrane-bound hemoproteins that oxidize a large number of endogenous and exogenous compounds. Through oxidation reactions, these enzymes are often responsible for the toxic and carcinogenic effects of natural food-borne toxicants, such as the mycotoxin aflatoxin B1 (AFB1). Previous studies in our laboratory have shown that the extreme sensitivity of turkeys to AFB1 is in part explained by efficient hepatic P450-mediated epoxidation to the toxic and reactive metabolite the exo-AFB1-8,9-epoxide (AFBO). Using 3'-5'-rapid amplification of cDNA ends (RACE), we amplified CYP3A37 from turkey liver RNA, the E. coli-expressed protein which efficiently epoxidates AFB(1). Turkey CYP3A37 has an ORF of 1512 bp, and the protein is predicted to be 504 amino acids with 97% homology to chicken CYP3A37. The turkey gene is organized into 13 exons and 12 introns. A single nucleotide polymorphism in the 11th intron was used to assign CYP3A37 to turkey linkage group 10 (corresponding to chicken chromosome 14, GGA14). Because of the important role of P450s in the extreme sensitivity of turkeys to the toxic effects of AFB(1), this study will contribute to the identifying allelic variants of this important gene in poultry.