Site-specific Srb10-dependent phosphorylation of the yeast Mediator subunit Med2 regulates gene expression from the 2-microm plasmid.
The yeast Mediator complex is required for transcriptional regulation both in vivo and in vitro, and its function is conserved in all eukaryotes. Mediator interacts with both transcriptional activators and RNA polymerase II, but little is known about the mechanisms by which it operates at the molecular level. Here, we show that the cyclin-dependent kinase Srb10 interacts with, and phosphorylates, the Med2 subunit of Mediator both in vivo and in vitro. A point mutation of the single phosphorylation site in Med2 results in a strongly reduced expression of the REP1, REP2, FLP1, and RAF1 genes, which are all located on the endogenous 2-microm plasmid. Combined with previous studies on the effects of SRB10/SRB11 deletions, our data suggest that posttranslational modifications of Mediator subunits are important for regulation of gene expression.
Hallberg
Magnus
M
Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87 Umeå, Sweden.
Polozkov
Gennady V
GV
Hu
Guo-Zhen
GZ
Beve
Jenny
J
Gustafsson
Claes M
CM
Ronne
Hans
H
Björklund
Stefan
S
D000595:Amino Acid Sequence; D001665:Binding Sites; D056850:Cyclin-Dependent Kinase 8; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D056892:Mediator Complex; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D010957:Plasmids / Q000235:genetics; D021122:Protein Subunits; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
C470560:MED2 protein, S cerevisiae; D056892:Mediator Complex; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D056850:Cyclin-Dependent Kinase 8; D018844:Cyclin-Dependent Kinases; C498309:SSN3 protein, S cerevisiae