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TAF II ‐independent activation mediated by human TBP in the presence of the positive cofactor PC4
Author(s) -
Wu ShwuYuan,
Kershnar Eric,
Chiang ChengMing
Publication year - 1998
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/17.15.4478
Subject(s) - biology , cofactor , biochemistry , enzyme
TFIID is a multiprotein complex comprised of the TATA‐binding protein (TBP) and an array of TBP‐associated factors (TAF II s). Whereas TBP is sufficient for basal transcription in conjunction with other general transcription factors and RNA polymerase II, TAF II s are additionally required for activator‐dependent transcription in mammalian cell‐free transcription systems. However, recent in vivo studies carried out in yeast suggest that TAF II s are not globally required for activator function. The discrepancy between in vivo yeast studies and in vitro mammalian cell‐free systems remains to be resolved. In this study, we describe a mammalian cell‐free transcription system reconstituted with only recombinant proteins and epitope‐tagged multiprotein complexes. Transcriptional activation can be recapitulated in this highly purified in vitro transcription system in the absence of TAF II s. This TBP‐mediated activation is not induced by human mediator, another transcriptional coactivator complex potentially implicated in activator response. In contrast, general transcription factors TFIIH and TFIIA play a significant role in TBP‐mediated activation, which can be detected in vitro with Gal4 fusion proteins containing various transcriptional activation domains. Our data, therefore, suggest that TFIIH and TFIIA can mediate activator function in the absence of TAF II s.