Human papillomavirus type 16 expresses a variety of alternatively spliced mRNAs putatively encoding the E2 protein.
The full-length E2 protein of human papillomavirus type 16 is believed to act as a trans-repressor of the viral p97 promoter. Previous reports have provided evidence that transcripts with the potential to encode the E2 protein contain the 880/2708 splice junction. We have further analyzed the structure of the E2-encoding transcripts. Employing the RNA polymerase chain reaction (PCR) technique and analyses of the RNA PCR products by Southern blot hybridization and DNA sequencing, we revealed the existence of a variety of alternatively spliced mRNAs, with the capacity to encode the full-length E2 protein. Two novel splice junctions were identified at nucleotides 880/2581 and 226/2708. E2 mRNAs characterized by the 880/2581 splice junction contain sequences from the E1 orf predicted to encode a truncated E1 polypeptide consisting mainly of the C terminal amino acids. Transcripts with the 226/2708 splice junction could encode a novel E6 protein, designated E6IV, containing C terminal amino acids derived from an out-of-frame region of the E1 ORF. Three different E6-E7 exons were identified in mRNAs containing the 880/2708 and the 880/2581 splice junctions, namely, E6-E7, E6I-E7, E6II-E7. The E6I-E7 mRNAs are the most abundant. Expression of the various E2 mRNAs was detected in human keratinocytes immortalized by HPV16, in cervical tumors, and in carcinoma cell lines.
Sherman
L
L
Department of Human Microbiology, Sackler School of Medicine, Tel-Aviv University, Israel.
Alloul
N
N
D017398:Alternative Splicing; D002478:Cells, Cultured; D002874:Chromosome Mapping; D004268:DNA-Binding Proteins / Q000235:genetics*; D005091:Exons; D006801:Humans; D015603:Keratinocytes / Q000166:cytology; D008957:Models, Genetic; D027383:Papillomaviridae / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012322:RNA Precursors / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics*
D004268:DNA-Binding Proteins; C051550:E2 protein, Bovine papillomavirus; D012322:RNA Precursors; D012333:RNA, Messenger; D012097:Repressor Proteins; D014764:Viral Proteins