Structure and chromosomal localization of CYP6A1, a cytochrome P450-encoding gene from the house fly

We determined the sequence of a cytochrome P450-encoding gene, CYP6A1, in an insecticide-resistant strain (Rutgers) and in insecticide-susceptible strains (aabys and sbo) of the house fly Musca domestica. The deduced amino acid (aa) sequence of CYP6A1 is 98% identical between Rutgers and aabys, and it is identical between Rutgers and sbo. Differences in aa sequence occur in regions that are not thought to participate in the active site. CYP6A1 has a single intron, 60 bp in length. It does not occur in a position homologous to intron sites in genes of the related CYP3 family or other vertebrate P450 families. We mapped the transcription start point (tsp), TATA box and barbie box [Shaw and Fulco, J. Biol. Chem. 269 (1993) 2997-3004] of this phenobarbital-inducible gene. Although overexpression of CYP6A1 in strain Rutgers is controlled by a locus on chromosome II [Cariño et al., Insect Biochem. Mol. Biol. 24 (1994) 411-418], we have localized CYP6A1 to chromosome V, thus showing that a trans-acting factor controls the overexpression of the gene in the Rutgers strain.