Specific Interactions and Potential Functions of Human TAFII100

Yong Tao,Mohamed Guermah,Ernest Martinez,Thomas Oelgeschläger,Satoshi Hasegawa,Ritsuko Takada,Tohru Yamamoto,Masami Horikoshi,Robert G Roeder

doi:10.1074/jbc.272.10.6714

Yong Tao, Mohamed Guermah + Show 7 more

Open Access

https://doi.org/10.1074/jbc.272.10.6714

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Abstract

Human transcription initiation factor TFIID contains the TATA-binding protein (TBP) and several TBP-associated factors (TAFs). To investigate the structural organization and function of TFIID, we have cloned and expressed a DNA encoding the third largest human TFIID subunit, hTAFII100. Immunoprecipitation studies demonstrate that hTAFII100 is an integral subunit that is associated with all transcriptionally-competent forms of TFIID. They further suggest that at least part of the N-terminal region lies on the surface of TFIID, while a C-terminal region containing conserved WD-40 repeats appears inaccessible. Both in vivo and in vitro assays indicate that hTAFII100 interacts strongly with the histone H4-related hTAFII80 and the histone H3-related hTAFII31, as well as a stable complex comprised of both hTAFII80 and hTAFII31. Apparently weaker interactions of hTAFII100 with TBP, hTAFII250, hTAFII28, and hTAFII20, but not hTAFII55, also have been observed. These results suggest a role for hTAFII100 in stabilizing interactions of TAFs, especially the histone-like TAFs, in TFIID. In addition, functional studies show that anti-hTAFII100 antibodies selectively inhibit basal transcription from a TATA-less initiator-containing promoter, relative to a TATA-containing promoter, suggesting a possible core promoter-specific function for hTAFII100.

Highlights

TFIID is a general transcription initiation factor comprised of a small TATA-binding polypeptide (TBP)1 and a large number of TATA-binding protein (TBP)-associated factors (TAFs), all of which are highly conserved in evolution
The primary interaction with core promoters containing TATA elements is through TBP, which is sufficient to mediate basal transcription in the absence of TAFs; in contrast, primary interactions with core promoters lacking TATA elements is thought to involve recognition of alternative core promoter elements by TAFs and/or other factors that are essential for basal transcription from these promoters
Consistent with earlier studies showing that activators have qualitative and quantitative effects on TFIID binding that correlate with enhanced recruitment and function of other general factors, more recent studies have described specific activatorTAF interactions that are relevant to the overall function of the activators in vitro

Summary

Introduction

TFIID is a general transcription initiation factor comprised of a small TATA-binding polypeptide (TBP)1 and a large number of TBP-associated factors (TAFs), all of which are highly conserved in evolution (reviewed in Ref. 1). 5 ml of nuclear extract was cycled through 2 ml of cross-linked anti-hTAFII100-protein ASepharose (2 mg/ml antibody) 5 times and the flow-through was used for Western blotting analysis and transcription assay.

Results

Conclusion