A novel transcriptional element in circular DNA monomers of the duck hepatitis B virus.
We report the presence of two elements, pet and net, that are required for proper transcription of the duck hepatitis B virus (DHBV). These regions were previously identified by using plasmid clones of the virus in transient expression assays (M. Huang and J. Summers, J. Virol. 68:1564-1572, 1994). In this study, we further analyzed these regions by using in vitro-synthesized circular DHBV DNA monomers to mimic the authentic transcriptional template. We observed that pet was required for pregenome transcription from circular viral monomers, and in the absence of pet-dependent transcription, expression of the viral envelope genes was increased. We found that deletion of net in circularized DNA monomers led to the production of abnormally long transcripts due to a failure to form 3' ends during transcription. In addition, we report the presence of a net-like region in the mammalian hepadnavirus woodchuck hepatitis virus. These results are consistent with a model that net is a region involved in transcription termination and that in DHBV, pet is required for transcription complexes to read through this region during the first pass through net.
Beckel-Mitchener
A
A
Department of Cell Biology, University of New Mexico School of Medicine, Albuquerque 87131, USA.
Summers
J
J
D000818:Animals; D006528:Carcinoma, Hepatocellular; D002645:Chickens; D002678:Chimera; D003001:Cloning, Molecular; D004270:DNA, Circular / Q000737:chemistry / Q000378:metabolism*; D016679:Genome, Viral; D015611:Hepatitis B Virus, Duck / Q000235:genetics* / Q000378:metabolism*; D017919:Hepatitis B Virus, Woodchuck / Q000235:genetics; D008113:Liver Neoplasms; D015513:Oncogene Proteins; D010957:Plasmids; D050783:Proto-Oncogene Proteins c-ets; D012367:RNA, Viral / Q000096:biosynthesis; D015183:Restriction Mapping; D013698:Templates, Genetic; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D014764:Viral Proteins
D004270:DNA, Circular; C086924:Elk3 protein, mouse; D015513:Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D012367:RNA, Viral; D014157:Transcription Factors; D014764:Viral Proteins