title: Msb2 is a Ste11 membrane concentrator required for full activation of the HOG pathway.
abstract: The high osmolarity glycerol (HOG) pathway, composed of membrane-associated osmosensors, adaptor proteins and core signaling kinases, is essential for the survival of yeast cells under hyper-osmotic stress. Here, we studied how the MAPKKK Ste11 might change its protein interaction profile during acute stress exposure, with an emphasis on the sensory system of the so-called Sho1/Msb2 signaling branch. To characterize the transience of protein-protein interactions we utilized a recently described enzymatic in vivo protein proximity assay (M-track). Accordingly, interaction signals between Ste11 and many of its signaling partners can already be detected even under basal conditions. In most cases these signals increase after stress induction. All the interactions are completely dependent on the function of the Ste11-adaptor protein Ste50. Moreover, the presence of either Msb2 or Hkr1 is necessary for observing the interaction between Ste11 and scaffolding factors such as Sho1 and Pbs2. Additional assays suggest that Msb2 is not only in close proximity to Ste11 but might function as an individual Ste11 concentrator at the plasma membrane. Our results confirm the existence of negative feedback systems targeting the protein levels of Ste11 and Msb2 and also hint at changes in the dissociation rates of intermediate signaling complexes.
authors: Dept. of Biochemistry and Molecular Cell Biology, University of Vienna, Dr. Bohrgasse 9, 1030 Vienna, Austria.
authors: Aurora
authors: A
authors: Zuzuarregui
authors: Departamento de Bioquímica y Biología Molecular and ERI Biotecmed, Universitat de València, Dr. Moliner 50, Burjassot 46100 Spain.
authors: Tianlu
authors: T
authors: Li
authors: Dept. of Biochemistry and Molecular Cell Biology, University of Vienna, Dr. Bohrgasse 9, 1030 Vienna, Austria.
authors: Christina
authors: C
authors: Friedmann
authors: Dept. of Biochemistry and Molecular Cell Biology, University of Vienna, Dr. Bohrgasse 9, 1030 Vienna, Austria. Electronic address: Gustav.ammerer@univie.ac.at.
authors: Gustav
authors: G
authors: Ammerer
authors: Departamento de Bioquímica y Biología Molecular and ERI Biotecmed, Universitat de València, Dr. Moliner 50, Burjassot 46100 Spain. Electronic address: paula.alepuz@uv.es.
authors: Paula
authors: P
authors: Alepuz
mesh_terms: D025461:Feedback, Physiological; D005990:Glycerol / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D060066:Protein Interaction Maps / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: C512735:HKR1 protein, S cerevisiae; D047908:Intracellular Signaling Peptides and Proteins; C076360:MSB2 protein, S cerevisiae; D008565:Membrane Proteins; C459787:SHO1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D020930:MAP Kinase Kinase Kinases; C067018:Ste11 protein, S cerevisiae; D005990:Glycerol
keywords: HOG pathway; M-track; Msb2; Osmotic stress; Signaling protein complexes; Ste11