Project description:Mediator subunits Med17 (Srb4) and Med15 (Gal11) were subjected to ChIP in wild type yeast, med18 (srb5), med20 (srb2), and med2 med3 med15 (triple mutant) yeast, all in kin28-anchor away yeast after 1 hr rapamycin treatment to evict Kin28 from the nucleus. This results in inactivation of Kin28, which reduces Mediator turnover at promoters and allows stronger Mediator ChIP signal at promoters. <br></br>Both Med17 and Med15 were tagged with myc and precipitated using the monoclonal antibody against c-myc. Please note that a specific control for rapamycin treatment was not performed in this experiment, as that has been well documented in the literature for this experiment, using what is called the anchor away method. The untagged sample is a control for non-specific immunoprecipitation.
Project description:The yeast Mediator complex can be divided into three modules, designated Head, Middle and Tail. Tail comprises the Med2, Med3, Med5, Med15 and Med16 protein subunits, which are all encoded by genes that are individually non-essential for viability. In cells lacking Med16, Tail is displaced from Head and Middle. However, inactivation of MED5/MED15 and MED15/MED16 are synthetically lethal, indicating that Tail performs essential functions as a separate complex even when it is not bound to Middle and Head. We have used the N-Degron method to create temperature sensitive (ts) mutants in the Mediator tail subunits Med5, Med15 and Med16 to study the immediate effects on global gene expression when each subunit is individually inactivated, and when MED5/15 or MED15/16 are inactivated together.
Project description:The yeast Mediator complex can be divided into three modules, designated Head, Middle and Tail. Tail comprises the Med2, Med3, Med5, Med15 and Med16 protein subunits, which are all encoded by genes that are individually non-essential for viability. In cells lacking Med16, Tail is displaced from Head and Middle. However, inactivation of MED5/MED15 and MED15/MED16 are synthetically lethal, indicating that Tail performs essential functions as a separate complex even when it is not bound to Middle and Head. We have used the N-Degron method to create temperature sensitive (ts) mutants in the Mediator tail subunits Med5, Med15 and Med16 to study the immediate effects on global gene expression when each subunit is individually inactivated, and when MED5/15 or MED15/16 are inactivated together. All Degron constructs were expressed from their normal chromosomal location under the control of their respective endogenous promoters. We isolated RNA from each strain as early as 45 minutes after changing from the permissive to the restrictive growth conditions to minimize possible secondary effects on gene expression that are not directly caused by the Degron construct(s).
Project description:Saccharomyces cerevisiae strains carrying mutations of the essential Mediator subunit Med11 as well as strains lacking the non-essential Mediator subunits Med2 and Med20 were compared to the corresponding wild-type strains.
Project description:Mediator is a multiprotein transcriptional co-regulator complex composed of four modules; Head, Middle, Tail, and Kinase. It conveys signals from promoter-bound transcriptional regulators to RNA polymerase II and thus plays an essential role in eukaryotic gene regulation. We describe subunit localization and activities of Mediator in Arabidopsis through metabolome and transcriptome analyses from a set of Mediator mutants. Functional metabolomic analysis based on the metabolite profiles of Mediator mutants using multivariate statistical analysis and heat-map visualization shows that different subunit mutants display distinct metabolite profiles, which cluster according to the reported localization of the corresponding subunits in yeast. Based on these results, we suggest localization of previously unassigned plant Mediator subunits to specific modules. We also describe novel roles for individual subunits in development, and demonstrate changes in gene expression patterns and specific metabolite levels in med18 and med25, which can explain their phenotypes. We find that med18 displays levels of phytoalexins normally found in wild type plants only after exposure to pathogens. Our results indicate that different Mediator subunits are involved in specific signaling pathways that control developmental processes and tolerance to pathogen infections.
Project description:In this study, we measured histone H3Lys4 trimethylation in budding yeast S. cerevisiae for wild type and cnc1Djhd2D yeast mutants. These experiments were performed for yeast cultured to mid-logarithmic phase in non-fermentable carbon.
Project description:Eukaryotic RNA polymerase II (RNAPII) transcribes mRNA genes and non-protein coding RNAs (ncRNAs) including small nuclear and nucleolar RNAs (sn/snoRNAs). In metazoans, RNAPII transcription of sn/snoRNAs is facilitated by a number of specialized complexes, but no such complexes have been discovered in yeast. It has been proposed that yeast sn/snoRNA promoters use the same factors as mRNA promoters, but the extent to which regulators of mRNA genes function at yeast sn/snoRNA genes is unclear. Here, we investigated a potential role for the Mediator complex, essential for mRNA gene transcription, in the transcription of sn/snoRNA genes. We found that the Mediator maps to most sn/snoRNA gene regulatory regions and that rapid depletion of the essential structural subunit Med14 strongly reduces RNAPII and TFIIB occupancy as well as nascent transcription of sn/snoRNA genes. Deletion of Med3 and Med15, subunits of the activator-interacting Mediator tail module, does not affect Mediator recruitment to or RNAPII and TFIIB occupancy of sn/snoRNA genes. Our analyses suggest that Mediator promotes PIC formation and transcription at sn/snoRNA genes, expanding the role of this critical regulator beyond its known functions in mRNA gene transcription and demonstrating further mechanistic similarity between the transcription of mRNA and sn/snoRNA genes.