title: Mediator phosphorylation prevents stress response transcription during non-stress conditions.
abstract: The multiprotein complex Mediator is a coactivator of RNA polymerase (Pol) II transcription that is required for the regulated expression of protein-coding genes. Mediator serves as an end point of signaling pathways and regulates Pol II transcription, but the mechanisms it uses are not well understood. Here, we used mass spectrometry and dynamic transcriptome analysis to investigate a functional role of Mediator phosphorylation in gene expression. Affinity purification and mass spectrometry revealed that Mediator from the yeast Saccharomyces cerevisiae is phosphorylated at multiple sites of 17 of its 25 subunits. Mediator phosphorylation levels change upon an external stimulus set by exposure of cells to high salt concentrations. Phosphorylated sites in the Mediator tail subunit Med15 are required for suppression of stress-induced changes in gene expression under non-stress conditions. Thus dynamic and differential Mediator phosphorylation contributes to gene regulation in eukaryotic cells.
authors.affiliation: Gene Center Munich and Department of Biochemistry, Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Miller
authors.forename: Ivan
authors.initials: I
authors.lastname: Matic
authors.forename: Kerstin C
authors.initials: KC
authors.lastname: Maier
authors.forename: Björn
authors.initials: B
authors.lastname: Schwalb
authors.forename: Susanne
authors.initials: S
authors.lastname: Roether
authors.forename: Katja
authors.initials: K
authors.lastname: Strässer
authors.forename: Achim
authors.initials: A
authors.lastname: Tresch
authors.forename: Matthias
authors.initials: M
authors.lastname: Mann
authors.forename: Patrick
authors.initials: P
authors.lastname: Cramer
mesh_terms: D020816:Amino Acid Motifs; D015966:Gene Expression Regulation, Fungal; D056892:Mediator Complex / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: C058337:GAL11 protein, S cerevisiae; D056892:Mediator Complex; D029701:Saccharomyces cerevisiae Proteins; D012319:RNA Polymerase II