P3 promoter element of bovine papillomavirus.

The P3 promoter activity of Bovine papillomavirus (BPV) and cis-acting DNA element of P3 promoter required for transcription were examined using chloramphenicol acetyltransferase (CAT) assay. The results show that 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 are required for efficient transcription of the P3 promoter. This 90 bp region contains SV40 enhancer core sequences and an ATF binding site.