The functional BPV-1 E2 trans-activating protein can act as a repressor by preventing formation of the initiation complex.
TLDR
In vitro DNA-binding experiments with purified E2 and TFIIDs showed that binding of E2 to its DNA target placed at different positions with respect to the TATA box differentially affects binding of TFIID to its cognate site.Abstract:
The products encoded by the E2 open reading frame of the papillomaviruses are DNA-binding transcription factors involved in the positive or negative regulation of multiple viral promoters. To further understand the mechanisms by which the same transcription factor may act differentially, the full-length BPV-1 E2 protein was expressed and purified from yeast and assayed in vitro for its capacity to modulate transcription. E2 stimulated transcription of the HSV thymidine kinase (TK) promoter when E2-binding sites were positioned in an enhancer configuration approximately 100 bp upstream of the promoter start site. In contrast, the same full-length E2 protein repressed transcription of the HPV-18 E6/E7 P105 promoter. This repression was mediated through binding to the E2 DNA-binding site immediately upstream of the P105 promoter TATA box and could be abrogated by preincubation of the HPV-18 P105 promoter template with the nuclear extract allowing the formation of the preinitiation complex. In vitro DNA-binding experiments with purified E2 and TFIID showed that binding of E2 to its DNA target placed at different positions with respect to the TATA box differentially affects binding of TFIID to its cognate site. In these respects, E2 is similar to the bacteriophage lambda repressor, which can act either as a repressor or an activator of transcription depending on the position of its binding sites relative to the promoter sequences.read more
Citations
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Papillomavirus infections — a major cause of human cancers
TL;DR: Reports on the presence of HPV infections in cancers of the oral cavity, the larynx, and the esophagus further emphasize the importance of this virus group as proven and suspected human carcinogens.
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Pathogenesis of Human Papillomaviruses in Differentiating Epithelia
TL;DR: The characterization of the cellular targets of these viral proteins and the mechanisms regulating the differentiation-dependent viral life cycle remain active areas for the study of these important human pathogens.
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The papillomavirus E2 proteins.
TL;DR: Structural and functional aspects of the E2 proteins and their binding sites on the viral genome are described to be a reference guide to this viral protein.
Journal ArticleDOI
Suppression of cellular proliferation by the papillomavirus E2 protein.
TL;DR: It is found that the HPV-16 and HPV-18 E2 proteins share with BPV-1 E2-TA the ability to suppress HeLa cell growth, thereby enabling the cellular targets of E6 and E7 to resume regulation of the cell cycle.
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Expression of the papillomavirus E2 protein in HeLa cells leads to apoptosis.
TL;DR: The results suggest that the effects of E2 on cell cycle progression and cell death follow distinct pathways involving two different functions of p53.
References
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