Simian virus 40 large T antigen interacts with human TFIIB-related factor and small nuclear RNA-activating protein complex for transcriptional activation of TATA-containing polymerase III promoters.
The TATA-binding protein (TBP) is common to the basal transcription factors of all three RNA polymerases, being associated with polymerase-specific TBP-associated factors (TAFs). Simian virus 40 large T antigen has previously been shown to interact with the TBP-TAFII complexes, TFIID (B. Damania and J. C. Alwine, Genes Dev. 10:1369-1381, 1996), and the TBP-TAFI complex, SL1 (W. Zhai, J. Tuan, and L. Comai, Genes Dev. 11: 1605-1617, 1997), and in both cases these interactions are critical for transcriptional activation. We show a similar mechanism for activation of the class 3 polymerase III (pol III) promoter for the U6 RNA gene. Large T antigen can activate this promoter, which contains a TATA box and an upstream proximal sequence element but cannot activate the TATA-less, intragenic VAI promoter (a class 2, pol III promoter). Mutants of large T antigen that cannot activate pol II promoters also fail to activate the U6 promoter. We provide evidence that large T antigen can interact with the TBP-containing pol III transcription factor human TFIIB-related factor (hBRF), as well as with at least two of the three TAFs in the pol III-specific small nuclear RNA-activating protein complex (SNAPc). In addition, we demonstrate that large T antigen can cofractionate and coimmunoprecipitate with the hBRF-containing complex TFIIIB derived from HeLa cells infected with a recombinant adenovirus which expresses large T antigen. Hence, similar to its function with pol I and pol II promoters, large T antigen interacts with TBP-containing, basal pol III transcription factors and appears to perform a TAF-like function.
Damania
B
B
Department of Microbiology, University of Pennsylvania, Philadelphia 19104-6142, USA.
Mital
R
R
Alwine
J C
JC
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics / Q000378:metabolism*; D002458:Cell Fractionation; D002460:Cell Line; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D016296:Mutagenesis; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012320:RNA Polymerase III / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics*; D012367:RNA, Viral; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016385:TATA Box; D035581:Transcription Factor TFIIB; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
D000952:Antigens, Polyomavirus Transforming; D004268:DNA-Binding Proteins; D011506:Proteins; D012342:RNA, Small Nuclear; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C093069:SNAPC1 protein, human; C099437:SNAPC2 protein, human; C101746:SNAPC3 protein, human; D035581:Transcription Factor TFIIB; D014157:Transcription Factors; C052835:adenovirus associated RNA; D012320:RNA Polymerase III