A promoter with an internal regulatory domain is part of the origin of replication in BPV-1.

Extrachromosomal elements that are stably maintained at a constant copy number through cell doublings are a good model system for the study of the regulation of DNA replication in higher eukaryotes. Previous studies have defined both cis and trans functions required for the regulated plasmid replication of the bovine papilloma virus in stably transformed cells. Here, a sequence known to be a cis-dominant element of the replication origin of the plasmid is shown to contain a promoter for transcription. Both in vitro and in vivo assays have been used to define this promoter and show that a sequence located just 3' to the transcriptional start site is required for activity. This DNA sequence element, which has been defined through deletions, coincides with a binding site for a cellular factor and is also required for a functional origin of replication. Possible models for how a transcription factor may play a role in the regulation of DNA replication are discussed.