In vivo functional analysis of the histone 3-like TAF9 and a TAF9-related factor, TAF9L.
The majority of the TATA-binding protein (TBP)-associated factors (TAFs) that constitute transcription factor II D (TFIID) contain histone fold motifs (HFMs). Our previous results utilizing DT40 cells containing a conditional TAF9 allele indicated that the histone 3-like TAF9 is essential for cell viability but largely dispensable for general transcription. In this study, we investigated further the role of TAF9 structural domains in TFIID integrity and cell growth and the functions of a TAF9-related factor, TAF9L. We first show that TAF9 depletion severely disrupts TFIID, indicating that the observed ongoing transcription is initiated with at least partially TAF-free TATA-binding protein. We also provide evidence for specific roles of TAF HFMs, highlighting the functional significance of HFM specificity observed in vitro and, importantly, of the TAF9-histone 3 similarity. Although we provide evidence that TAF9 and TAF9L are partly redundant, RNA interference experiments suggest that TAF9L is essential for HeLa cell growth. Strikingly, we provide evidence that TAF9L plays a role in transcriptional repression and/or silencing.
Chen
Zheng
Z
Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Manley
James L
JL
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D002645:Chickens; D004330:Drosophila; D017353:Gene Deletion; D005822:Genetic Vectors; D006657:Histones / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D035381:TATA-Binding Protein Associated Factors / Q000235:genetics / Q000378:metabolism*; D035362:Transcription Factor TFIID / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D006657:Histones; D011993:Recombinant Fusion Proteins; C106849:TAF9 protein, human; D035381:TATA-Binding Protein Associated Factors; C491456:Taf9b protein, rat; D035362:Transcription Factor TFIID