MAP kinase-mediated stress relief that precedes and regulates the timing of transcriptional induction.
In yeast, hyperosmotic stress causes an immediate dissociation of most proteins from chromatin, presumably because cells are unprepared for, and initially unresponsive to, increased ion concentrations in the nucleus. Osmotic stress activates Hog1 MAP kinase, which phosphorylates at least two proteins located at the plasma membrane, the Nha1 Na+/H+ antiporter and the Tok1 potassium channel. Hog1 phosphorylation stimulates Nha1 activity, and this is crucial for the rapid reassociation of proteins with their target sites in chromatin. This initial response to hyperosmolarity precedes and temporally regulates the activation of stress-response genes that depends on Hog1 phosphorylation of transcription factors in the nucleus. Thus, a single MAP kinase coordinates temporally, spatially, and mechanistically distinct responses to stress, thereby providing very rapid stress relief that facilitates subsequent changes in gene expression that permit long-term adaptation to harsh environmental conditions.
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
Markus
M
Proft
Kevin
K
Struhl
D027682:Cation Transport Proteins / Q000502:physiology; D006657:Histones / Q000502:physiology; D007700:Kinetics; D008565:Membrane Proteins / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D009997:Osmotic Pressure; D010766:Phosphorylation; D015221:Potassium Channels / Q000502:physiology; D012319:RNA Polymerase II / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*; D012462:Saline Solution, Hypertonic; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology; D013912:Threonine / Q000502:physiology; D014158:Transcription, Genetic
D027682:Cation Transport Proteins; D006657:Histones; D008565:Membrane Proteins; C000631624:NHA1 protein, S cerevisiae; D015221:Potassium Channels; D029701:Saccharomyces cerevisiae Proteins; D012462:Saline Solution, Hypertonic; D017923:Sodium-Hydrogen Exchangers; C095220:TOK1 protein, S cerevisiae; D013912:Threonine; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; D012319:RNA Polymerase II