The two activation domains of the CCAAT-binding factor CBF interact with the dTAFII110 component of the Drosophila TFIID complex.
The CCAAT-binding factor CBF is a heterotrimeric transcription factor that specifically binds to CCAAT sequences in many eukaryotic genes. Previous studies have shown that CBF contains two transcription activation domains: a glutamine-rich, serine-threonine-rich domain present in the CBF-B subunit and a glutamine-rich domain in the CBF-C subunit. In this study, by using a series of deletion mutations of CBF-B and CBF-C in transcription assay in vitro, we further delineated smaller segments in these domains that were sufficient to support transcriptional activation by CBF. To test whether transcription activation by CBF requires co-activators, we examined the interaction between CBF and dTAF110, a component of the Drosophila TFIID complex. Recent work has demonstrated that glutamine-rich domains of the Sp1 transcription factor interact with dTAF110 and that this interaction has an important role in mediating transcription activation. Here we first demonstrate in a direct interaction assay in vitro that CBF binds dTAF110. By using a yeast two-hybrid system we show that both of the transcription activation domains of CBF interact with dTAF110. A deletion analysis suggests that a segment of CBF-B needed for transcription activation is also involved in interaction with dTAF110. In CBF-C the C-terminal portion of the molecule seems to be needed for these two activities. Our results suggest that TAF110 might represent one of the co-activators that mediate transcriptional activation by CBF.
Coustry
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F
Department of Molecular Genetics, The University of Texas, M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX77030, USA.
Sinha
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S
Maity
S N
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Crombrugghe
B
B
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D050660:Core Binding Factors; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila; D029721:Drosophila Proteins; D009363:Neoplasm Proteins; D011485:Protein Binding; D035381:TATA-Binding Protein Associated Factors; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D019473:Transcription Factors, TFII / Q000235:genetics / Q000378:metabolism*
D050660:Core Binding Factors; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D009363:Neoplasm Proteins; D035381:TATA-Binding Protein Associated Factors; C103338:Taf4 protein, Drosophila; D035362:Transcription Factor TFIID; D014157:Transcription Factors; D019473:Transcription Factors, TFII