trans activation by the full-length E2 proteins of human papillomavirus type 16 and bovine papillomavirus type 1 in vitro and in vivo: cooperation with activation domains of cellular transcription factors.
Papillomaviral E2 genes encode proteins that regulate viral transcription. While the full-length bovine papillomavirus type 1 (BPV-1) E2 peptide is a strong trans activator, the homologous full-length E2 product of human papillomavirus type 16 (HPV-16) appeared to vary in function in previous studies. Here we show that when expressed from comparable constructs, the full-length E2 products of HPV-16 and BPV-1 trans activate a simple E2- and Sp1-dependent promoter up to approximately 100-fold in human keratinocytes and other epithelial cells as well as human and animal fibroblasts. Vaccinia virus-expressed, purified full-length HPV-16 and BPV-1 E2 proteins bound a consensus E2 site with high specific affinities (Kd = approximately 10(-9) M) and stimulated in vitro transcription up to six- to eightfold. In vivo and in vitro trans activation by either E2 protein required cooperation with another activator, such as Sp1, or other factors that interact with papillomavirus promoters, such as AP-1, Oct-1, nuclear factor 1/CTF, transcriptional enhancer factor 1, or USF. The glutamine-rich domain B of Sp1 or the mutually unrelated activation domains of other transcription factors were necessary and sufficient for cooperation with either E2 factor. We conclude that like BPV-1 E2, the HPV-16 E2 protein has the potential to function as a strong activator of viral gene expression in cooperation with cellular transcription factors.
Ushikai
M
M
Department of Pathology, VA Medical Center, Iowa City, Iowa.
Lace
M J
MJ
Yamakawa
Y
Y
Kono
M
M
Anson
J
J
Ishiji
T
T
Parkkinen
S
S
Wicker
N
N
Valentine
M E
ME
Davidson
I
I
D001483:Base Sequence; D052688:Bovine papillomavirus 1 / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000032:analysis / Q000096:biosynthesis; D003001:Cloning, Molecular; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005822:Genetic Vectors; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D009856:Oncogene Proteins, Viral / Q000378:metabolism*; D027383:Papillomaviridae / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection; D014764:Viral Proteins / Q000378:metabolism*
D017931:DNA Primers; D004268:DNA-Binding Proteins; C051550:E2 protein, Bovine papillomavirus; C054855:E2 protein, Human papillomavirus type 16; D009838:Oligodeoxyribonucleotides; D009856:Oncogene Proteins, Viral; D014157:Transcription Factors; D014764:Viral Proteins; D015500:Chloramphenicol O-Acetyltransferase