Mapping of Two Novel Transcripts of Bovine Papillomavirus Type 4

Abstract

SUMMARYA cDNA library was synthesized using RNA from bovine papillomavirus type 4 (BPV-4)-induced papillomas. The major viral transcript was characterized by sequencing of its cDNA, primer extension mapping and S 1 nuclease protection studies. The transcript initiates at multiple sites between nucleotide (nt) 777 and nt 902, contains a splice junction between nt 1016 and nt 3376 and terminates at nt 4034, using the early polyadenylation signal at nt 4009. Sequencing of viral cDNAs and mRNA revealed deviations from the reported genomic sequence between nt 3412 and nt 3460. These resulted in a temporary frameshift, abolished the translation termination codon of the E5a open reading flame (ORF), and introduced a new termination codon in the E40RF. The new uninterrupted E50RF was found to have greater homology to the E40RFs of other papillomaviruses than to their E50RFs. The E50RF of BPV-4 is joined to a five codon ORF in the leader exon of the major transcript, in the same way as the E40RF in the major transcripts of BPV-1 and human papillomavirus type 11. On this basis, it has been redesignated E4, and the viral genomic sequence revised. Two novel transcriptional promoters of BPV-4 were defined: a putative controller of the multiple major RNA start sites around nt 870 and a minor TATA box at nt 691. In addition, minor early region transcripts were mapped which initiate between nt 3071 and nt 3152. None of these transcripts utilizes the splice site at nt 3376. These messages may express E2-encoded functions.

Cooperation Between Bovine Papillomavirus Type 4 and ras in the Morphological Transformation of Primary Bovine Fibroblasts

“…1 is different from that previously published (Patel et al, 1987), owing to DNA sequence corrections (Stamps & Campo, 1988). The BPV-4 genome lacks an identifiable E6 ORF, a feature shared by BPV-3, another member of the subgroup B bovine papillomaviruses (our unpublished results).…”

Both viral E2 protein and the cellular factor PEBP2 regulate transcription via E2 consensus sites within the bovine papillomavirus type 4 long control region

“…For BPV1 it has been demonstrated that in addition to the full-length E2 transcription factor, a shorter form (sE2) which lacks the N-terminal transactivation domain and acts as a repressor is also produced (30). Although the existence of sE2 protein has not been demonstrated for BPV4, minor transcripts which have the potential to encode sE2 proteins have been detected in BPV4-induced papillomas (46); thus, sE2 may add a further level of complexity to regulation of BPV4 promoter activity.…”

Mutational analysis of human papillomavirus E4 proteins: identification of structural features important in the formation of cytoplasmic E4/cytokeratin networks in epithelial cells

“…The N-terminal 5 amino acids of the HPV 1 El E4 protein are derived from the N terminus of the El open reading frame (7). Conservation of a spliced El' E4 structure between other papillomavirus types (1,6,9,17,28,39) does, in itself, suggest that the extreme N-terminal amino acids are likely to be important in E4 function. Furthermore, it has been noted that the HPV 1 El E4 N-terminal sequence (MADNKA) corresponds to a conserved motif (MADXXA), also found at the N terminus of other E4 proteins (37).…”