Polarized localization of yeast Pbs2 depends on osmostress, the membrane protein Sho1 and Cdc42.
In Saccharomyces cerevisiae cells, high external osmolarity leads to the activation of a p38-related mitogen-activated protein (MAP) kinase though Pbs2. Pbs2 tagged with green fluorescent protein (Pbs2-GFP) is evenly distributed in the cytoplasm but excluded from the nucleus before and after exposure to stress. Here we show that a catalytically inactive form of Pbs2 attains a highly polarised localization during osmostress. This phenomenon depends of the osmosensor Sho1 and on a functional Cdc42 GTPase. Cdc42, but not the actin cytoskeleton, influences Sho1-dependent activation of the MAP kinase. Sho1 itself accumulates at sites of polar growth, but independently of stress conditions and Cdc42. These observations allow us to define the sequence of events that occurs during propogation of osmostress signals.
Reiser
V
V
Department of Biochemistry and Molecular Cell Biology, Ludwig Boltzmann Forschungsstelle, University of Vienna, Dr. Bohrgasse 9, A1030, Vienna, Austria.
Salah
S M
SM
Ammerer
G
G
D000199:Actins / Q000378:metabolism; D002455:Cell Division; D003599:Cytoskeleton / Q000378:metabolism; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000032:analysis* / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016296:Mutagenesis; D009994:Osmolar Concentration; D010710:Phosphates / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae / Q000378:metabolism*
D000199:Actins; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D010710:Phosphates; C079506:STE50 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; C078754:STE20 protein, S cerevisiae; C067018:Ste11 protein, S cerevisiae; D020929:Mitogen-Activated Protein Kinase Kinases; C089356:PBS2 protein, S cerevisiae; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae