Simian virus 40 large T antigen stabilizes the TATA-binding protein-TFIIA complex on the TATA element.
Large T antigen (T antigen), the early gene product of simian virus 40 (SV40), is a potent transcriptional activator of both cellular and viral genes. Recently we have shown that T antigen is tightly associated with TFIID and, in this position, performs a TATA-binding protein (TBP)-associated factor (TAF)-like function. Based on this observation, we asked whether T antigen affected steps in preinitiation complex assembly. Using purified components in in vitro complex assembly assays, we found that T antigen specifically enhances the formation of the TBP-TFIIA complex on the TATA element. T antigen accomplishes this by increasing the rate of formation of the TBP-TFIIA complex on the TATA element and by stabilizing the complexes after they are formed on the promoter. In addition, DNA immunoprecipitation experiments indicate that T antigen is associated with the stabilized TBP-TFIIA complexes bound to the DNA. In this regard, it has previously been shown that T antigen interacts with TBP; in the present study, we show that T antigen also interacts with TFIIA in vitro. In testing the ability of T antigen to stabilize the TBP-TFIIA complex, we found that stabilization is highly sensitive to the specific sequence context of the TATA element. Previous studies showed that T antigen could activate simple promoters containing the TATA elements from the hsp70 and c-fos gene promoters but failed to significantly activate similar promoters containing the TATA elements from the promoters of the SV40 early and adenovirus E2a genes. We find that the ability to stabilize the TBP-TFIIA complex on the hsp70 and c-fos TATA elements, and not on the SV40 early and E2A TATA elements, correlates with the ability or inability to activate promoters containing these TATA elements.
Damania
B
B
Graduate Group of Cell and Molecular Biology, Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6142, USA.
Lieberman
P
P
Alwine
J C
JC
D017502:Adenovirus E2 Proteins / Q000235:genetics; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002460:Cell Line; D002522:Chlorocebus aethiops; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D016385:TATA Box; D035181:TATA-Box Binding Protein; D035561:Transcription Factor TFIIA; D035581:Transcription Factor TFIIB; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000378:metabolism*; D019473:Transcription Factors, TFII / Q000378:metabolism
D017502:Adenovirus E2 Proteins; D000952:Antigens, Polyomavirus Transforming; D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D016760:Proto-Oncogene Proteins c-fos; D035181:TATA-Box Binding Protein; D035561:Transcription Factor TFIIA; D035581:Transcription Factor TFIIB; D035362:Transcription Factor TFIID; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D003850:Deoxyribonuclease I