The P3 promoter activity of Bovine papillomavirus (BPV) and cis-acting
DNA element of P3 promoter required for transcription were examined u
sing chloramphenicol acetyltransferase (CAT) assay. The results show t
hat P3 promoter is a very weak promoter compared to P2 promoter in BPV
and E2 transactivator is required for the maximal transcription of P3
promoter in a BPV upstream regulatory region (URR)-dependent manner.
Deletion experiments by nuclease Bal-31 were carried out to define P3
promoter element. The DNA sequences between nt 712 and nt 802 of BPV a
re required for efficient transcription of the P3 promoter. This 90 bp
region contains SV40 enhancer core sequences and an ATF binding site.