Promoter activation by the varicella-zoster virus major transactivator IE62 and the cellular transcription factor USF.
The varicella-zoster virus major transactivator, IE62, can activate expression from homologous and heterologous promoters. High levels of IE62-mediated activation appear to involve synergy with cellular transcription factors. The work presented here focuses on functional interactions of IE62 with the ubiquitously expressed cellular factor USF. We have found that USF can synergize with IE62 to a similar extent on model minimal promoters and the complex native ORF28/29 regulatory element, neither of which contains a consensus IE62 binding site. Using Gal4 fusion constructs, we have found that the activation domain of USF1 is necessary and sufficient for synergistic activation with IE62. We have mapped the regions of USF and IE62 required for direct physical interaction. Deletion of the required region within IE62 does not ablate synergistic activation but does influence its efficiency depending on promoter architecture. Both proteins stabilize/increase binding of TATA binding protein/TFIID to promoter elements. These findings suggest a novel mechanism for the observed synergistic activation which requires neither site-specific IE62 binding to the promoter nor a direct physical interaction with USF.
Yang
Min
M
Department of Microbiology and Immunology, 138 Farber Hall, University at Buffalo, Buffalo, NY 14214-3000, USA.
Peng
Hua
H
Hay
John
J
Ruyechan
William T
WT
D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D047468:Immunoprecipitation; D008545:Melanoma / Q000378:metabolism / Q000473:pathology; D011401:Promoter Regions, Genetic / Q000502:physiology*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017384:Sequence Deletion; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D035581:Transcription Factor TFIIB / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured; D051720:Upstream Stimulatory Factors / Q000235:genetics / Q000378:metabolism*; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; C074221:IE62 protein, Human herpesvirus 3; D017874:Immediate-Early Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D035581:Transcription Factor TFIIB; C497181:USF1 protein, human; D051720:Upstream Stimulatory Factors; D014759:Viral Envelope Proteins