Project description:Previous studies suggested that expression of most yeast mRNAs is dominated by either transcription factor TFIID or SAGA. We reexamined this longstanding problem by rapid depletion of TFIID subunits and measurement of changes in nascent transcription. We find that transcription of nearly all mRNAs is strongly dependent on TFIID function. Degron-dependent depletion of Tafs 1,2,7,11, and 13 showed similar transcription decreases for genes in the Taf1-depleted, Taf1-enriched, TATA-containing and TATA-less gene classes. The magnitude of TFIID-dependence varies with growth conditions, although this variation is similar at all gene classes. Many studies have suggested differences in gene regulatory mechanisms between TATA and TATA-less genes and these differences have been attributed in part to differential dependence on SAGA or TFIID. Our work indicates that TFIID contributes significantly to expression of nearly all yeast mRNAs and that differences in regulation between these two gene classes is due to other properties.
Project description:The transcriptional machinery involved in RNA polymerase II (Pol II) transcription during oogenesis is not well characterized. In somatic cells, the Pol II general transcription factor, TFIID, containing the TATA binding protein (TBP) and 13 TBP-associated factors, is the first to bind gene promoters to nucleate pre-initiation complex formation. During oocyte growth TBP is replaced by TBP2 and Tbp2-/- female mice are sterile. Here, we show that in oocytes TBP2 stably associates with TFIIA but does not assemble into a TFIID-type complex but stabily associates with TFIIA. we demonstrate that in female germ cells the specific TBP2-TFIIA-containing transcription machinery drives transcription from oocyte-specific core promoters, which are different from those occupied by TBP/TFIID in somatic cells.
Project description:We have analyzed the global effect of the conserved transcription-mRNA export factor Sus1 on transcription and its association with chromatin. We used genomic run-on experiments to show that Sus has a broad impact on the stability of most RNA polymerase II-transcribed genes. Genome association of Sus1 by the chromatin immunoprecipitation technique showed that Sus1 was widely distributed throughout coding regions, tending to accumulate towards the 3â ends of highly transcribed transcription factor IID (TFIID) and Spt-Ada-Gcn5 acetyltransferase (SAGA) dependent genes. This accumulation depends on growth conditions, the transcriptional rate and whether the genes are TFIID- or SAGA-regulated. Validation of Sus1 occupancy data also revealed that Sus1 appears at tRNAs. Concomitantly, deletion of SUS1 leads to tRNA overexpression. In addition, we discovered that distinctive SAGA subunits Spt8 and Spt7 play a key role in Sus1 enrichment at the 3â ends of SAGA-regulated genes upon temperature shift and at tRNAs. Thus, our study identifies the molecular mechanisms by which a SAGA factor is recruited genome-wide, and provides evidence of a more general role for this conserved coactivator in eukaryotic transcription. Genome wide analysis of Sus1 in wild type and Spt7 and Spt8 deletion mutants using ChIP-exo and genomic run-on experiments
Project description:The human general transcription factor TFIID is composed of the TATA-binding protein (TBP) and 13 TBP-associated factors (TAFs). In eukaryotic cells, TFIID nucleates RNA Polymerase II (Pol II) preinitiation complex formation on gene promoters and thus, is crucial for Pol II transcription. Germline knock out of several mouse TFIID subunits (Tbp, Taf7, Taf8, and Taf10) results in lethality at embryonic day 4.0, demonstrating the fundamental role of holo-TFIID in transcription. We identified a child harboring a splice-site mutation in TAF8, who has intellectual disability, poor growth, progressive spasticity and microcephaly. The c.781-G>A TAF8 mutation in this patient resulted in a frame shift, which affected the final 50 carboxy terminal amino acids of TAF8. We found that the mutant TAF8 protein is unstable and the patient c.781-G>A TAF8 primary fibroblasts did not form canonical TFIID complexes. Astonishingly however, genome-wide RNA pol II occupancy and pre-mRNA transcription on the tested genes was unaffected in the patient’s primary fibroblasts. This study indicates that perturbed TFIID function is less deleterious for transcription in human cells than originally anticipated.
Project description:Replication forks face multiple obstacles that slow their progression. By two-dimensional gel analysis, yeast forks pause at stable DNA protein complexes, and this pausing is greatly increased in the absence of the Rrm3 helicase. We used a genome wide approach to identify 96 sites of very high DNA polymerase binding in wild type cells. Most of these binding sites were not previously identified pause sites. Rather, the most highly represented genomic category among high DNA polymerase binding sites was the open reading frames (ORFs) of highly transcribed RNA polymerase II genes. Twice as many pause sites were identified in rrm3 compared to wild type cells as pausing in this strain occurred at both highly transcribed RNA polymerase II genes and the previously identified protein DNA complexes. ORFs of highly transcribed RNA polymerase II genes are the first class of natural pause sites that are not exacerbated in rrm3 cells. We alse mapped pause sites using a second replication fork component, Rrm3-13MYC and got similar results.
Project description:We have analyzed the global effect of the conserved transcription-mRNA export factor Sus1 on transcription and its association with chromatin. We used genomic run-on experiments to show that Sus has a broad impact on the stability of most RNA polymerase II-transcribed genes. Genome association of Sus1 by the chromatin immunoprecipitation technique showed that Sus1 was widely distributed throughout coding regions, tending to accumulate towards the 3’ ends of highly transcribed transcription factor IID (TFIID) and Spt-Ada-Gcn5 acetyltransferase (SAGA) dependent genes. This accumulation depends on growth conditions, the transcriptional rate and whether the genes are TFIID- or SAGA-regulated. Validation of Sus1 occupancy data also revealed that Sus1 appears at tRNAs. Concomitantly, deletion of SUS1 leads to tRNA overexpression. In addition, we discovered that distinctive SAGA subunits Spt8 and Spt7 play a key role in Sus1 enrichment at the 3’ ends of SAGA-regulated genes upon temperature shift and at tRNAs. Thus, our study identifies the molecular mechanisms by which a SAGA factor is recruited genome-wide, and provides evidence of a more general role for this conserved coactivator in eukaryotic transcription.
Project description:TFIID is an essential eukaryotic transcription factor, which is required for RNA polymerase II promoter recognition and activation. As a multiprotein complex, TFIID contains several intrinsically disordered regions (IDRs), but the functions of these IDRs are unknown. Here, we show that a conserved IDR drives the TFIID subunit TAF2 to nuclear speckles, where it forms biomolecular condensates, separate from the TFIID complex. Quantitative mass spectrometry analyses reveal that the TAF2 IDR is required for the interaction with the nuclear speckle and spliceosome-associated protein SRRM2, which is thereby recruited to TFIID. The formation of SRRM2-free TFIID complexes elicits a set of unique alternative splicing events. These include events in RNAs coding for proteins involved in transcription and transmembrane transport. Together, these data identify an IDR of the basal transcription machinery as a molecular switch between nuclear compartments to control protein complex composition and pre-mRNA splicing.