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Structure of a Complete Mediator-RNA Polymerase II Pre-Initiation Complex, and the Regulation of Transcription

ABSTRACT: MedPIC: Crosslinking-MS of 54 subunit pre-initiation complex from yeast. MedPolII: Crosslinking-MS of 33 subunit Mediator + polII complex from yeast.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Saccharomyces Cerevisiae (ncbitaxon:4932)

SUBMITTER: Roger Kornberg

PROVIDER: MSV000080013 | MassIVE | Tue Aug 02 13:43:00 BST 2016

REPOSITORIES: MassIVE

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Structure of a Complete Mediator-RNA Polymerase II Pre-Initiation Complex.

Robinson Philip J PJ Trnka Michael J MJ Bushnell David A DA Davis Ralph E RE Mattei Pierre-Jean PJ Burlingame Alma L AL Kornberg Roger D RD

Cell 20160901 6

A complete, 52-protein, 2.5 million dalton, Mediator-RNA polymerase II pre-initiation complex (Med-PIC) was assembled and analyzed by cryo-electron microscopy and by chemical cross-linking and mass spectrometry. The resulting complete Med-PIC structure reveals two components of functional significance, absent from previous structures, a protein kinase complex and the Mediator-activator interaction region. It thereby shows how the kinase and its target, the C-terminal domain of the polymerase, co ...[more]

PMID: 27610567

Similar Datasets

Structure of a Complete Mediator-RNA Polymerase II Pre-Initiation Complex.

Project description:A complete, 52-protein, 2.5 million dalton, Mediator-RNA polymerase II pre-initiation complex (Med-PIC) was assembled and analyzed by cryo-electron microscopy and by chemical cross-linking and mass spectrometry. The resulting complete Med-PIC structure reveals two components of functional significance, absent from previous structures, a protein kinase complex and the Mediator-activator interaction region. It thereby shows how the kinase and its target, the C-terminal domain of the polymerase, control Med-PIC interaction and transcription.

| S-EPMC5589196 | biostudies-literature

Crosslinking mass spectrometry of yeast Pol I pre-initiation complex

Project description:In eukaryotic cells, ribosomal RNA is transcribed by RNA polymerase I (Pol I). To initiate transcription, Pol I requires the assembly of a multi-subunit pre-initiation complex (PIC). In yeast, the minimal PIC includes Pol I, the transcription factor Rrn3 and Core Factor (CF) composed of subunits Rrn6, Rrn7 and Rrn11. We have determined the cryo-EM structure of a 18-subunit yeast Pol I complex together with CF, Rrn3 and transcription scaffold. To aid in modeling the structure based on the cryo-EM map, we performed crosslinking mass spectrometry.

2017-07-31 | PXD006510 | Pride

Structure of Saccharomyces cerevisiae Mediator-RNA polymerase II pre-initiation complex for divergent transcription

Project description:This study has determined structure of transcription initiation complexes including a DNA-bound activator, RNA polymerase II (Pol II), and Mediator on a divergent promoter GAL80/SUT719 using a combination of cryo-EM and XL-MS analyses. Our cryo-EM single-particle analysis reveals a dimeric form of Med-PIC through the Mediator Tail module induced by the activator protein. Density of the upstream DNA bound to the Gal4-VP16 was identifiable along the Mediator Tail module, while XL-MS localized flexible regions that were not visible by cryo-EM analysis, such as activator-binding domains (ABDs and KIX).

2024-05-22 | PXD036149 | Pride

The Cdk8 kinase module regulates Mediator-RNA polymerase II interaction

Project description:The Cdk8 kinase module (CKM) is a dissociable part of the coactivator complex Mediator that regulates RNA polymerase II (Pol II transcription. The CKM has negative and positive functions in gene transcription that remain poorly understood at the mechanistic level. Here, we prepare recombinant CKM from the yeast Saccharomyces cerevisiae and show that it binds core Mediator (cMed) to sterically inhibit cMed binding to the Pol II preinitiation complex (PIC) in vitro. We further show that the Cdk8 kinase activity of CKM counteracts CKM-cMed interaction,thereby releasing CKM and enabling Mediator to bind the PIC. Finally, we report that the kinase activity of Cdk8 is required for gene activation during heat shock in vivo, but not under steady state growth conditions. These results converge with previous literature on a model for CKM function. In this model, CKM negatively regulates Mediator function at upstream activating sequences by preventing Mediator binding to the PIC at the promoter. During gene activation, Cdk8 kinase activity may release Mediator and allow its binding to the PIC, thereby stimulating transcription initiation and accounting for the positive function of CKM.

2021-06-16 | GSE161140 | GEO

Functional metabolomics as a tool to analyze Mediator function and structure in plants

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.

2018-01-30 | MTBLS450 | MetaboLights

Puf6 primes nuclear export of 60S pre-ribosomes at low temperature

Project description:Puf6 contributes to biogenesis of the large subunit in yeast. UV-crosslinking (CRAC) was used to determine binding sites of Puf6 on RNA.

2021-06-25 | GSE174587 | GEO

Mediator directs co-transcriptional heterochromatin assembly by RNAi-dependent and -independent pathways.

Project description:Background: Heterochromatin at the pericentromeric repeats in fission yeast is assembled and spread by an RNAi-dependent mechanism, which is coupled to the transcription of non-coding RNA from the repeats by RNA polymerase II. In addition, Rrp6, a component of the nuclear exosome, also contributes to heterochromatin assembly and is coupled to non-coding RNA transcription. The multi-subunit complex Mediator, which directs initiation of RNA polymerase II-dependent transcription, has recently been suggested to function after initiation in processes such as elongation of transcription and splicing. However, the role of Mediator in the regulation of chromatin structure is not well understood. Results: We investigated the role of Mediator in pericentromeric heterochromatin formation and found that deletion of specific subunits of the head domain of Mediator compromised heterochromatin structure. The Mediator head domain was required for Rrp6-dependent heterochromatin nucleation at the pericentromere and for RNAi-dependent spreading of heterochromatin into the neighboring region. In the latter process, Mediator appeared to contribute to efficient processing of siRNA from transcribed non-coding RNA, which was required for efficient spreading of heterochromatin. Furthermore, the head domain directed efficient transcription in heterochromatin. Conclusions: These results reveal a pivotal role for Mediator in multiple steps of transcription-coupled formation of pericentromeric heterochromatin. This observation further extends the role of Mediator to co-transcriptional chromatin regulation. Gene expression profile at exponentially-growing phase.in the fission yeast deletion mutants of pmc6, med20 and dcr1.

2013-08-31 | E-GEOD-43543 | biostudies-arrayexpress

Expression-profiling of the Mediator transcription complex

Project description:Proteins from within the Saccharomyces cerevisiae Mediator transcription complex were knocked out and compared against wild type yeast using two-color oligo arrays.

2005-08-15 | E-UMCU-20 | biostudies-arrayexpress

Cdk11-Cyclin L controls the assembly of the RNA polymerase II Mediator [expression]

Project description:The L-Mediator is a general co-activator of RNA Polymerase II transcription and is formed by the reversible association of the S-Mediator and the kinase module harbouring Cdk8. We describe the Cdk11-Lcp1 complex and show that its inactivation alter the global expression profiles in a very similar way than mutations of the kinase module. Cdk11 is broadly distributed onto chromatin and phosphorylate the Med27 and Med4 Mediator subunits on conserved residues. The inactivation of either Cdk11 or the mutation of its target residues on the Mediator leads to a strongly decreased association of the kinase module and the S-Mediator. The results show that Cdk11-Lcp1 regulates that assembly of the L-Mediator complex. Total RNA was isolated from two biological replicates for all conditions, and each biological replicate was hybridized in duplicate on Agilent arrays (dye-swap).

2014-07-11 | E-GEOD-37960 | biostudies-arrayexpress

Mediator Complex Regulates Alternative mRNA Processing via the Med23 Subunit

Project description:Mediator complex is an integrative hub for transcriptional regulation. Here we show that Mediator regulates alternative mRNA processing via its Med23 subunit. Combining tandem affinity purification and mass spectrometry, we identified a number of mRNA processing factors that bind to a soluble recombinant Mediator subunit MED23 but not to several other Mediator components. One of these factors, hnRNP L, specifically interacts with MED23 in vitro and in vivo. Consistently, Mediator partially colocalizes with hnRNP L and the splicing machinery in the cell. Functionally Med23 regulates a subset of hnRNP L-targeted alternative splicing (AS) and alternative cleavage and polyadenylation (APA) events as shown by minigene reporters and exon array analysis. ChIP-seq analysis revealed that Med23 can regulate hnRNP L occupancy at their co-regulated genes. Taken together, these results demonstrate a crosstalk between Mediator and the splicing machinery, suggesting a novel mechanism for coupling mRNA processing to transcription. Examination of hnRNP L and H3K36me3 enrichment in sictrl and si23 Hela cells

2012-02-24 | E-GEOD-33887 | biostudies-arrayexpress

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