Cytochrome P450 (CYP) enzymes constitute a multigene family that metabolize many endogenous and xenobiotic substances. The CYP1 family is of particular interest in environmental toxicology because its members are dominant in the metabolism of different pollutants which may enter fish through the diet or by water-borne exposure. A new partial complementary DNA of the CYP1A subfamily encoding CYP1A was isolated from carp liver after intraperitoneal injection with 3-methylcholanthrene (3-MC) or -napthoflavone (BNF). The obtained cDNA was 2059 bp contained an open reading frame of 1204 bp coding for 401 amino acids, a stop codon, and a 3' noncoding region of 855 bp. The predicted molecular weight of the protein was approximately 45.3 kDa. The deduced amino acid sequence of this cDNA was 76.1, 68.4, 65.9, and 64.4% similar to that of zebra fish, rainbow trout, Japanese eel, and toadfish, respectively. With mammals CYP1A1 sequences, carp CYP1A exhibited similarities of 49.5, 52.0, and 52.2% with human, rat, and mouse, respectively. The phylogenetic tree constructed using fish and mammalian CYP1 family sequences suggested a closer relationship of the CYP1C subfamily to CYP1B than to CYP1A. The tree clearly showed carp CYP1A clustered with Zebra fish CYP1A showing more correlation to each other than any other CYP1A subfamily members. The Northern blot analysis using the poly(A)+ RNA from the control and treated fish using a probe derived from the 3' noncoding region of the carp CYP1A cDNA showed the induction of carp CYP1A in the liver, kidney, intestine, and gills with either of 3-MC or BNF. Nucleotide sequence of carp CYP1A has been deposited in the GenBank with the accession number: AB048939.
Key words: Cyprinus carpio, carp, ß-naphthoflavone, cytochrome P450, CYP1A.
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