Project description:TFIID and SAGA complexes play a critical role in RNA Polymerase II dependent activated transcription. Although the two regulatory complexes are recruited to promoters by activation domain-interactions, the contribution of the different subunits or the different domains of the individual subunits is not completely understood. Taf9 is a shared subunit in TFIID and SAGA and has an N-terminal H3-like histone fold domain and a highly conserved C-terminal domain, Taf9-CTD. In this study, we have uncovered an essential role for the Taf9-CTD in transcriptional activation. The Taf9-CTD was not essential for the histone-fold mediated interaction with Taf6, SAGA and TFIID integrity or Gcn4 interaction with SAGA. Transcriptome profiling performed under Gcn4 activating conditions showed that the Taf9-CTD is required for expression of ~17% of the yeast genome and provides a coactivator function to recruit TFIID and SAGA complexes to the promoters in vivo during transcriptional activation. Integrated genome-wide data analysis showed that the Taf9-CTD is required for activation of promoters bound by several transcription factors indicating a broad role for Taf9-CTD in promoter occupancy of TFIID or SAGA complexes. Interestingly, only a subset of the promoters seemed to be dependent on the Taf9-CTD for assembly of the pre-initiation complex indicating redundancy in activator targets to assemble PIC in vivo. Together these results indicate that evolutionarily conserved domains in shared subunits of TFIID and SAGA have a pervasive role in genome-wide transcription. This GEO series consists of 14 microarray hybridizations using the Agilent two-color experiment with the Agilent Custom Saccharomyces cerevisiae 8x15k gene expression array. Four biological replicates each for the wild-type (TAF9), the mutant taf9-tCRD2 strain treated or untreated with SM, and the wild-type (TAF9) versus mutant taf9-tCRD2 treated with SM hybridized as dye-swapped replicates. Two biological replicates for wild-type (SPT20) vs spt20D strains treated with SM, and hybridized as dye-swapped replicates to identify the fraction of SAGA dependent genes under amino-acid starvation conditions. The overall aim was to identify genes dependent on the conserved C-terminal region domain of TAF9 and determine their dependence on the SAGA subunit Spt20 for expression.

Project description:RNA polymerase II (Pol II) transcription initiation starts with the assembly of the preinitiation complex (PIC) on core promoters. The PIC is composed of six general transcription factors (GTFs). The recognition of the core promoter sequences by the TFIID GTF complex is the first step of the PIC assembly. In metazoans, holo-TFIID is composed of the TATA binding protein (TBP) and of 13 TBP associated factors (TAFs). Genetic depletion of different murine TAFs have shown that TAFs such as TAF7 or TAF10, can be either required, or dispensable for Pol II transcription, depending on different cellular contexts. In this report, we depleted TAF7 and/or TAF10 in the same cellular system; either in mesodermal progenitors during mouse development or in mESCs. In these two models, TAF7 depletion leads to a milder phenotype compared to TAF10 depletion. As TAF10 is also a subunit of the transcriptional co-activator Spt-Ada-Gcn5 acetyl transferase (SAGA), we first showed that the difference in phenotype between the Taf7 and Taf10 mutant is not due to the SAGA effect, at least for mESCs. Immunoprecipitations coupled with mass spectrometry analyses from mESCs lysates assembly of holo-TFIID complex is rapidly affected after induction of the depletion. In line with the model of holo-TFIID sequential assembly, TAF10 depletion leads to an early defect with formation of the core-TFIID, while TAF7 depletion results in the formation of a TAF7-less TFIID. Thus, the difference in phenotype severity correlates with the degree of TFIID disassembly. Surprisingly, no major global changes in Pol II transcription could be observed after either TAF7 or TAF10 depletion. Our data suggest that the inducible loss of fully assembled canonical TFIID does not correlate with the lack of global Pol II transcription activity changes suggesting that partially assembled TFIID complexes can participate in Pol II transcription initiation, with only limited effect on Pol II nascent transcription.

			Action	DRS
	20161025_OR12_A4_TY_SA_TAF6_Cyto_GFP01.raw	Raw
	20161025_OR12_A4_TY_SA_TAF6_Cyto_GFP02.raw	Raw
	20161025_OR12_A4_TY_SA_TAF6_Cyto_GFP03.raw	Raw
	20161025_OR12_A4_TY_SA_TAF6_Cyto_NGFP01.raw	Raw
	20161025_OR12_A4_TY_SA_TAF6_Cyto_NGFP02.raw	Raw

Dataset Information

Chaperonin CCT Checkpoint Function in Basal Transcription Factor TFIID Assembly

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Publications

Chaperonin CCT checkpoint function in basal transcription factor TFIID assembly.

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