The Swi5 activator recruits the Mediator complex to the<i>HO</i>promoter without RNA polymerase II

Bhoite, Leena T.; Yu, Yan; Stillman, David J.

doi:10.1101/gad.921601

Cited by 119 publications

(170 citation statements)

References 69 publications

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“…This simple model could perhaps also explain the mild phenotypes that are identified for ⌬spsrb8 and ⌬sptrap240. The recruitment of Mediator to the yeast HO promoter and to Drosophila HSF-binding sites without pol II supports this view (34)(35)(36). Thus, lack of Srb8-11 may have more profound effects on the kinetics͞timing of transcriptional activation at specific promoters, rather than on the overall levels of gene expression.…”

Section: Discussionsupporting

confidence: 51%

TRAP230/ARC240 and TRAP240/ARC250 Mediator subunits are functionally conserved through evolution

Samuelsen¹,

Baraznenok

Khorosjutina

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

108

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In Saccharomyces cerevisiae Mediator, a subgroup of proteins (Srb8, Srb9, Srb10, and Srb11) form a module, which is involved in negative regulation of transcription. Homologues of Srb10 and Srb11 are found in some mammalian Mediator preparations, whereas no clear homologues have been reported for Srb8 and Srb9. Here, we identify a TRAP240͞ARC250 homologue in Schizosaccharomyces pombe and demonstrate that this protein, spTrap240, is stably associated with a larger form of Mediator, which also contains conserved homologues of Srb8, Srb10, and Srb11. We find that spTrap240 and Sch. pombe Srb8 (spSrb8) regulate the same distinct subset of genes and have indistinguishable phenotypic characteristics. Importantly, Mediator containing the spSrb8͞spTrap240͞spSrb10͞spSrb11 subunits is isolated only in free form, devoid of RNA polymerase II. In contrast, Mediator lacking this module associates with the polymerase. Our findings provide experimental evidence for recent suggestions that TRAP230͞ARC240 and TRAP240͞ARC250 may indeed be the Srb8 and Srb9 homologues of mammalian Mediator. Apparently Srb8͞ TRAP230͞ARC240, Srb9͞TRAP240͞ARC250, Srb10, and Srb11 constitute a conserved Mediator submodule, which is involved in negative regulation of transcription in all eukaryotes.Schizosaccharomyces pombe ͉ RNA polymerase II ͉ transcription ͉ repression

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Section: Discussionsupporting

confidence: 51%

TRAP230/ARC240 and TRAP240/ARC250 Mediator subunits are functionally conserved through evolution

Samuelsen¹,

Baraznenok

Khorosjutina

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

108

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“…This breadth could ref lect a range of preferred binding sites at different promoters or, alternatively, could indicate that Mediator is distinctly present at both UAS and proximal promoter regions (perhaps at different times) of active genes. There is precedence for this idea in studies of the HO promoter in yeast and heat shock promoters in Drosophila (44,46). Interestingly, Rgr1 association with the core promoter regions of the genes examined here was substantially decreased in srb4 ts yeast, but association of Rgr1 with the UAS region showed a less marked decrease (Fig.…”

Section: Discussionmentioning

confidence: 83%

Mediator complex association with constitutively transcribed genes in yeast

Ansari

Morse

2009

Proc. Natl. Acad. Sci. U.S.A.

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Mediator is a large, multisubunit complex that is essential for transcription of mRNA by RNA Pol II in eukaryotes and is believed to bridge transcriptional activators and the general transcription machinery. However, several recent studies suggest that the requirement for Mediator during transcriptional activation is not universal, but rather activator dependent, and may be indirect for some genes. Here we have investigated Mediator association with several constitutively transcribed genes in yeast by comparing a yeast strain that harbors a temperature-sensitive mutation in an essential Mediator subunit, Srb4, with its wild-type (WT) counterpart. We find modest association of Mediator with constitutively active genes and show that this association is strongly decreased in srb4 ts yeast, whereas association with a nontranscribed region or repressed gene promoters is lower and unaffected in the mutant yeast. The tail module of Mediator remains associated with ribosomal protein (RP) gene promoters in srb4 ts yeast, while subunits from the head and middle modules are lost. Tail module association at Rap1-dependent gene promoters is lost in rap1 ts yeast, indicating that Rap1 is required for Mediator recruitment at these gene promoters and that its recruitment occurs via the tail module. Pol II association is also rapidly and severely affected in srb4 ts yeast, indicating that Mediator is directly required for pol II association at constitutively transcribed genes. Our results are consistent with Mediator functioning as a general transcription factor in yeast. Rap1 ͉ transcription

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“…7B), and thus, both chromatin remodeling and histone acetylation are required for these two complexes to associate stably at HO. Swi5 also interacts directly with Mediator, and both Swi5 and SWI/SNF are required for Mediator binding to the HO promoter (12). We speculate that there may also be interactions between SAGA and Mediator that stabilize the binding of both complexes (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Swi5 interacts directly with SWI/SNF (66), and Swi5 is required for the subsequent recruitment of SWI/SNF. The Mediator complex then binds to the URS1 region, long before the arrival of RNA polymerase II (Pol II) (12). There is a direct interaction between Mediator and Swi5, and genetic experiments have shown that both Swi5 and SWI/SNF are required for Mediator recruitment (12).…”

mentioning

confidence: 99%

“…The Mediator complex then binds to the URS1 region, long before the arrival of RNA polymerase II (Pol II) (12). There is a direct interaction between Mediator and Swi5, and genetic experiments have shown that both Swi5 and SWI/SNF are required for Mediator recruitment (12). The SAGA complex containing the Gcn5 HAT binds next, and a mutation in the SWI2 subunit of the SWI/SNF complex prevents SAGA binding (25).…”

mentioning

confidence: 99%

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SWI/SNF Binding to the HO Promoter Requires Histone Acetylation and Stimulates TATA-Binding Protein Recruitment

Mitra¹,

Parnell

Landon

et al. 2006

Molecular and Cellular Biology

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We use chromatin immunoprecipitation assays to show that the Gcn5 histone acetyltransferase in SAGA is required for SWI/SNF association with the HO promoter and that binding of SWI/SNF and SAGA are interdependent. Previous results showed that SWI/SNF binding to HO was Gcn5 independent, but that work used a strain with a mutation in the Ash1 daughter-specific repressor of HO expression. Here, we show that Ash1 functions as a repressor that inhibits SWI/SNF binding and that Gcn5 is required to overcome Ash1 repression in mother cells to allow HO transcription. Thus, Gcn5 facilitates SWI/SNF binding by antagonizing Ash1. Similarly, a mutation in SIN3, like an ash1 mutation, allows both HO expression and SWI/SNF binding in the absence of Gcn5. Although Ash1 has recently been identified in a Sin3-Rpd3 complex, our genetic analysis shows that Ash1 and Sin3 have distinct functions in regulating HO. Analysis of mutant strains shows that SWI/SNF binding and HO expression are correlated and regulated by histone acetylation. The defect in HO expression caused by a mutant SWI/SNF with a Swi2(E834K) substitution can be partially suppressed by ash1 or spt3 mutation or by a gain-of-function V71E substitution in the TATA-binding protein (TBP). Spt3 inhibits TBP binding at HO, and genetic analysis suggests that Spt3 and TBP(V71E) act in the same pathway, distinct from that of Ash1. We have detected SWI/SNF binding at the HO TATA region, and our results suggest that SWI/SNF, either directly or indirectly, facilitates TBP binding at HO.The Saccharomyces cerevisiae HO gene encodes an endonuclease that initiates mating-type switching in haploid yeast cells, and the gene is governed by complex transcriptional regulation (for reviews, see references 22, 41, and 62). The gene is expressed only during the late G 1 phase of the cell cycle, and only in mother cells, one of the two progeny after mitotic division. The Ash1 repressor protein is required for this asymmetric expression, as HO is expressed in both mother and daughter cells in an ash1 mutant (14, 76).Chromatin structure plays an important role in transcriptional regulation, including at HO. There are two major classes of chromatin-modifying factors that alleviate the repressive effects of chromatin, the ATP-dependent chromatin-remodeling factors, such as SWI/SNF, and histone acetyltransferases (HATs) that covalently modify the N-terminal tails of histones by acetylation (84). Recent work has shown that transcription factors recruit chromatin-modifying factors to promoters and that at some promoters, the concerted action of chromatinremodeling and HAT complexes is required for gene activation (61). It has been shown for a number of promoters that sequence-specific DNA-binding proteins recruit chromatin remodelers and HATs in a temporal order.Sequential recruitment of transcription factors was first shown at the HO gene (25). HO contains two defined upstream promoter regions, URS1 and URS2, which contain recognition sites for the Swi5 and SBF sequence-specific DNA-binding factors,...

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The Swi5 activator recruits the Mediator complex to theHOpromoter without RNA polymerase II

Abstract: Regulation of HO gene expression in the yeast

Cited by 119 publications

References 69 publications

TRAP230/ARC240 and TRAP240/ARC250 Mediator subunits are functionally conserved through evolution

TRAP230/ARC240 and TRAP240/ARC250 Mediator subunits are functionally conserved through evolution

Mediator complex association with constitutively transcribed genes in yeast

SWI/SNF Binding to the HO Promoter Requires Histone Acetylation and Stimulates TATA-Binding Protein Recruitment

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