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Involvement of the SAGA and TFIID coactivator complexes in transcriptional dysregulation caused by separation of core and tail Mediator modules (ChEC-Seq)

ABSTRACT: Regulation of RNA polymerase II (RNAPII) transcription requires the concerted efforts of several multisubunit coactivator complexes, which interact with the RNAPII preinitiation complex (PIC) to stimulate transcription. We previously showed that separation of the Mediator core (cMed) from Mediator’s tail module results in modest overactivation of genes annotated as highly dependent on TFIID for expression. However, it is unclear if other coactivators are involved in this phenomenon. Here, we show that the overactivation of certain genes by cMed/tail separation is blunted by disruption of the SAGA complex through removal of its structural Spt20 subunit, though this downregulation does not appear to depend on reduced SAGA association with the genome. Consistent with the enrichment of TFIID-dependent genes among genes overactivated by cMed/tail separation, depletion of the essential TFIID subunit Taf13 suppressed overactivation of these genes when Med16 was simultaneously removed. As with SAGA, this effect did not appear to be dependent on reduced genomic association of TFIID. Given that the observed changes in gene expression could not be clearly linked to alterations in SAGA or TFIID occupancy, our data may suggest that the cMed/tail connection is important for modulation of SAGA and/or TFIID conformation and/or function at target genes.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE207369 | GEO | 2022/10/03

REPOSITORIES: GEO

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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.

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Involvement of the SAGA and TFIID coactivator complexes in transcriptional dysregulation caused by separation of core and tail Mediator modules (ChEC-Seq)

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