Novel cofactors and TFIIA mediate functional core promoter selectivity by the human TAFII150-containing TFIID complex.
TATA-binding protein-associated factors (TAFIIs) within TFIID control differential gene transcription through interactions with both activators and core promoter elements. In particular, TAFII150 contributes to initiator-dependent transcription through an unknown mechanism. Here, we address whether TAFIIs within TFIID are sufficient, in conjunction with highly purified general transcription factors (GTFs), for differential core promoter-dependent transcription by RNA polymerase II and whether additional cofactors are required. We identify the human homologue of Drosophila TAFII150 through cognate cDNA cloning and show that it is a tightly associated component of human TFIID. More importantly, we demonstrate that the human TAFII150-containing TFIID complex is not sufficient, in the context of all purified GTFs and RNA polymerase II, to mediate transcription synergism between TATA and initiator elements and initiator-directed transcription from a TAFII-dependent TATA-less promoter. Therefore, TAFII-promoter interactions are not sufficient for the productive core promoter-selective functions of TFIID. Consistent with this finding, we have partially purified novel cofactor activities (TICs) that potentiate the TAFII-mediated synergism between TATA and initiator elements (TIC-1) and TAFII-dependent transcription from TATA-less promoters (TIC-2 and -3). Furthermore, we demonstrate an essential function for TFIIA in TIC- and TAFII-dependent basal transcription from a TATA-less promoter. Our results reveal a parallel between the basal transcription activity of TAFIIs through core promoter elements and TAFII-dependent activator function.
Martinez
E
E
Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, New York 10021, USA.
Ge
H
H
Tao
Y
Y
Yuan
C X
CX
Palhan
V
V
Roeder
R G
RG
D056930:ARNTL Transcription Factors; D000595:Amino Acid Sequence; D051792:Basic Helix-Loop-Helix Proteins; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D029721:Drosophila Proteins; D005786:Gene Expression Regulation / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012319:RNA Polymerase II / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D017422:Sequence Analysis, DNA; D035381:TATA-Binding Protein Associated Factors; D015534:Trans-Activators / Q000378:metabolism*; D035561:Transcription Factor TFIIA; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics; D015533:Transcriptional Activation / Q000502:physiology
D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D012319:RNA Polymerase II; D011994:Recombinant Proteins; D035381:TATA-Binding Protein Associated Factors; D015534:Trans-Activators; D035561:Transcription Factor TFIIA; D035362:Transcription Factor TFIID; D014157:Transcription Factors; C538960:BMAL1 protein, human; C486221:TAF2 protein, human; C084120:e(y)1 protein, Drosophila