Our laboratory has cloned the cDNA (Sutter, T. R., Tang Y, M., Hayes,
C. L., Wo, Y.-Y. P., Jabs, E. W., Li, X., Yin, H., Cody, C. W., and Gr
eenlee, W. P. (1994) J. Biol. Chem. 269, 13092-13099) and gene (Tang,
Y. M., Wo, Y.-Y.P., Jabs, E. pi,, Stewart, J. C., Sutter, T. R. and Gr
eenlee, W. F. (1996) J. Biol. Chem. 271, 28324-28350) for human CYP1B1
, a new member of the cytochrome P450 superfamily, Here, we report on
the mapping and function of the CYP1B1 promoter, The CYP1B1 promoter i
s fully functional, when if: is uncoupled from upstream enhancer eleme
nts. Deletion analysis and site-directed mutagenesis identified four r
egulatory elements required for maximum promoter activity: two antisen
se Spl sites (-84 to -89 and -68 to -73), a TATA-like box (-84 to -29)
, and an initiator motif (-5 to +3). The initiator and the TATA-like e
lements are both required for basal promoter activity, with enhanced a
ctivity mediated by the two antisense Sp1 elements. The GYP1B1 initiat
or was demonstrated by in vitro transcription analysis to be a positio
ning element that maintained fidelity of transcription from a single s
ite. Specific binding to a CYP1B1 initiator probe by human nuclear ext
ract proteins was competed either by the highly homologous murine term
inal deoxynucleotidyl transferase initiator or, to a lesser extent, by
the adenovirus major late initiator. Taken together, these results in
dicate that the structure and function of the CYP1B1 promoter confers
constitutive expression of the gene and assures fidelity of transcript
ion initiation from a single site, The CYP1B1 promoter is distinct fro
m the promoters of the closely related cytochrome P450s CYP1A1 and CYP
1A2 and is structurally and functionally similar to the promoters of c
onstitutively expressed genes and at least two viruses.