Yeast Skn7p activity is modulated by the Sln1p-Ypd1p osmosensor and contributes to regulation of the HOG pathway

Abstract Activation and control of the yeast HOG (High Osmolarity Glycerol) MAP kinase cascade is accomplished, in part, by a two-component sensory-response circuit comprised of the osmosensing histidine protein kinase Sln1p, the phospho-relay protein Ypd1p, and the response regulator protein Ssk1p. We found that deletion of SLN1 and/or YPD1 reduces reporter gene transcription driven by a second two-component response regulator – Skn7p. The effect of sln1Δ and ypd1Δ mutations upon Skn7p activity is dependent on a functional two-component phosphorylation site (D427) in Skn7p, suggesting that Sln1p and Ypd1p may act as phosphodonors for Skn7p. We also observed that loss of PTC1 (a protein serine/threonine phosphatase implicated in negative control of the HOG pathway) in a skn7Δ background results in severely retarded growth and in morphological defects. Deletion of either PBS2 or HOG1 alleviates the slow growth phenotype of ptc1Δskn7Δ cells, suggesting that Skn7p may participate, in concert with known regulatory components, in modulating HOG pathway activity. The contribution of Skn7p to HOG pathway regulation appears to be modulated by the receiver domain, since non-phosphorylatable Skn7pD427N is unable to fully restore growth to ptc1/skn7 cells.

[1]  P. Philippsen,et al.  New heterologous modules for classical or PCR‐based gene disruptions in Saccharomyces cerevisiae , 1994, Yeast.

[2]  B. Morgan,et al.  The Mcs4 response regulator coordinately controls the stress-activated Wak1-Wis1-Sty1 MAP kinase pathway and fission yeast cell cycle. , 1997, Genes & development.

[3]  I. Ota,et al.  Two Protein-tyrosine Phosphatases Inactivate the Osmotic Stress Response Pathway in Yeast by Targeting the Mitogen-activated Protein Kinase, Hog1* , 1997, The Journal of Biological Chemistry.

[4]  R. Davis,et al.  MAPKs: new JNK expands the group. , 1994, Trends in biochemical sciences.

[5]  L. Johnston,et al.  A yeast transcription factor bypassing the requirement for SBF and DSC1/MBF in budding yeast has homology to bacterial signal transduction proteins. , 1995, The EMBO journal.

[6]  H. Bussey,et al.  SKN7, a yeast multicopy suppressor of a mutation affecting cell wall beta-glucan assembly, encodes a product with domains homologous to prokaryotic two-component regulators and to heat shock transcription factors , 1993, Journal of bacteriology.

[7]  J. Polazzi,et al.  Complete nucleotide sequence of a gene conferring polymyxin B resistance on yeast: similarity of the predicted polypeptide to protein kinases. , 1987, Proceedings of the National Academy of Sciences of the United States of America.

[8]  E. Winter,et al.  An osmosensing signal transduction pathway in yeast. , 1993, Science.

[9]  I. Herskowitz.  MAP kinase pathways in yeast: For mating and more , 1995, Cell.

[10]  Francesc Posas,et al.  Yeast HOG1 MAP Kinase Cascade Is Regulated by a Multistep Phosphorelay Mechanism in the SLN1–YPD1–SSK1 “Two-Component” Osmosensor , 1996, Cell.

[11]  T. Maeda,et al.  Mutations in a protein tyrosine phosphatase gene (PTP2) and a protein serine/threonine phosphatase gene (PTC1) cause a synthetic growth defect in Saccharomyces cerevisiae , 1993, Molecular and cellular biology.

[12]  D. Raitt,et al.  The Skn7 response regulator controls gene expression in the oxidative stress response of the budding yeast Saccharomyces cerevisiae , 1997, The EMBO journal.

[13]  T. Maeda,et al.  Activation of yeast PBS2 MAPKK by MAPKKKs or by binding of an SH3-containing osmosensor. , 1995, Science.

[14]  J. Hegemann,et al.  Green fluorescent protein as a marker for gene expression and subcellular localization in budding yeast , 1996, Yeast.

[15]  S. Fields,et al.  Overproduction of the yeast STE12 protein leads to constitutive transcriptional induction. , 1990, Genes & development.

[16]  J. S. Parkinson,et al.  Communication modules in bacterial signaling proteins. , 1992, Annual review of genetics.

[17]  Jonathan A. Cooper,et al.  Mitogen and stress response pathways: MAP kinase cascades and phosphatase regulation in mammals and yeast. , 1995, Current opinion in cell biology.

[18]  E. Meyerowitz,et al.  Arabidopsis ethylene-response gene ETR1: similarity of product to two-component regulators. , 1993, Science.

[19]  F. Posas,et al.  Osmotic activation of the HOG MAPK pathway via Ste11p MAPKKK: scaffold role of Pbs2p MAPKK. , 1997, Science.

[20]  T. Maeda,et al.  Regulation of the Saccharomyces cerevisiae HOG1 mitogen-activated protein kinase by the PTP2 and PTP3 protein tyrosine phosphatases , 1997, Molecular and cellular biology.

[21]  I. Ota,et al.  A yeast protein similar to bacterial two-component regulators. , 1993, Science.

[22]  R C Stewart,et al.  Yeast Skn7p functions in a eukaryotic two‐component regulatory pathway. , 1994, The EMBO journal.

[23]  Tatsuya Maeda,et al.  A two-component system that regulates an osmosensing MAP kinase cascade in yeast , 1994, Nature.