Osmostress-induced transcription by Hot1 depends on a Hog1-mediated recruitment of the RNA Pol II.
In budding yeast, the mitogen-activated protein kinase (MAPK) Hog1 coordinates the transcriptional program required for cell survival upon osmostress. The Hot1 transcription factor acts downstream of the MAPK and regulates a subset of Hog1-responsive genes. In response to high osmolarity, Hot1 targets Hog1 to specific osmostress-responsive promoters. Here, we show that assembly of the general transcription machinery at Hot1-dependent promoters depends on the presence of Hot1 and active Hog1 MAPK. Unexpectedly, recruitment of RNA polymerase (Pol) II complex to target promoters does not depend on the phosphorylation of the Hot1 activator by the MAPK. Hog1 interacts with the RNA Pol II and with general components of the transcription machinery. More over, when tethered to a promoter as a LexA fusion protein, Hog1 activates transcription in a stress- regulated manner. Thus, anchoring of active Hog1 to promoters by the Hot1 activator is essential for recruitment and activation of RNA Pol II. The mammalian p38 also interacts with the RNA Pol II, which might suggest a conserved mechanism for regulation of gene expression by SAPKs among eukaryotic cells.
Cell Signaling Unit, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), E-08003 Barcelona, Spain.
Paula M
PM
Alepuz
Eulàlia
E
de Nadal
Meritxell
M
Zapater
Gustav
G
Ammerer
Francesc
F
Posas
D004789:Enzyme Activation; D015966:Gene Expression Regulation, Fungal; D017930:Genes, Reporter; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009997:Osmotic Pressure; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012319:RNA Polymerase II / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques
C120535:HOT1 protein, S cerevisiae; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; C470555:STL1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; D012319:RNA Polymerase II