scholarly journals Cooperative Regulation of DOG2, Encoding 2-Deoxyglucose-6-Phosphate Phosphatase, by Snf1 Kinase and the High-Osmolarity Glycerol–Mitogen-Activated Protein Kinase Cascade in Stress Responses of Saccharomyces cerevisiae

2000 ◽  
Vol 182 (18) ◽  
pp. 5121-5126 ◽  
Author(s):  
Yoshiyuki Tsujimoto ◽  
Shingo Izawa ◽  
Yoshiharu Inoue
Keyword(s):  
Oxidative Stress ◽  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Osmotic Stress ◽  
Mitogen Activated Protein Kinase ◽  
High Osmolarity ◽  
High Osmolarity Glycerol ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Protein Kinase Cascade

ABSTRACT We screened the genome of Saccharomyces cerevisiae for the genes responsive to oxidative stress by using the lacZtransposon-insertion library. As a result, we found that expression of the DOG2 gene coding for 2-deoxyglucose-6-phosphate phosphatase was induced by oxidative stress. The expression ofDOG2 was also induced by osmotic stress. We found a putative cis element (STRE, a stress response element) in the DOG2 promoter adjacent to a consensus sequence to which the Mig1p repressor is known to bind. The basal levels ofDOG2 gene expression were increased in amig1Δ mutant, while the derepression of DOG2was not observed in a snf1Δ mutant under glucose-deprived conditions. Induction of the DOG2 gene expression by osmotic stress was observed in any of the three disruptantspbs2Δ, hog1Δ, and snf1Δ. However, the osmotic induction was completely abolished in both thesnf1Δ pbs2Δ mutant and the snf1Δ hog1Δ mutant. Additionally, these single mutants as well as double mutants failed to induce DOG2 expression by oxidative stress. These results suggest that Snf1p kinase and the high-osmolarity glycerol–mitogen-activated protein kinase cascade are likely to be involved in the signaling pathway of oxidative stress and osmotic stress in regulation of DOG2.

scholarly journals Osmotic Stress-Induced Gene Expression in Saccharomyces cerevisiae Requires Msn1p and the Novel Nuclear Factor Hot1p

1999 ◽  
Vol 19 (8) ◽  
pp. 5474-5485 ◽  
Author(s):  
Martijn Rep ◽  
Vladimír Reiser ◽  
Ulrike Gartner ◽  
Johan M. Thevelein ◽  
Stefan Hohmann ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Osmotic Stress ◽  
Transcriptional Response ◽  
Mitogen Activated Protein Kinase ◽  
The Novel ◽  
Hog Pathway ◽  
High Osmolarity ◽  
Nuclear Factors ◽  
Mitogen Activated Protein ◽  
Protective Genes

ABSTRACT After a sudden shift to high osmolarity, Saccharomyces cerevisiae cells respond by transiently inducing the expression of stress-protective genes. Msn2p and Msn4p have been described as two transcription factors that determine the extent of this response. Inmsn2 msn4 mutants, however, many promoters still show a distinct rise in transcriptional activity upon osmotic stress. Here we describe two structurally related nuclear factors, Msn1p and a newly identified protein, Hot1p (for high-osmolarity-induced transcription), which are also involved in osmotic stress-induced transcription.hot1 single mutants are specifically compromised in the transient induction of GPD1 and GPP2, which encode enzymes involved in glycerol biosynthesis, and exhibit delayed glycerol accumulation after stress exposure. Similar to agpd1 mutation, a hot1 defect can rescue cells from inappropriately high HOG pathway activity. In contrast, Hot1p has little influence on the osmotic stress induction of CTT1, where Msn1p appears to play a more prominent role. Cells lacking Msn1p, Msn2p, Msn4p, and Hot1p are almost devoid of the short-term transcriptional response of the genes GPD1,GPP2, CTT1, and HSP12 to osmotic stress. Such cells also show a distinct reduction in the nuclear residence of the mitogen-activated protein kinase Hog1p upon osmotic stress. Thus, Hot1p and Msn1p may define an additional tier of transcriptional regulators that control responses to high-osmolarity stress.

Cell extensions in pkc1 mutants of Saccharomyces cerevisiae

1999 ◽  
Vol 45 (1) ◽  
pp. 38-44 ◽  
Author(s):  
M Azuma ◽  
S Torii ◽  
J Kato ◽  
H Ooshima
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Isoamyl Alcohol ◽  
Mitogen Activated Protein Kinase ◽  
Cell Integrity ◽  
Actin Cable ◽  
Mitogen Activated Protein ◽  
Kinase Cascade ◽  
Cell Surface Structure ◽  
Protein Kinase Cascade

To obtain information on cell wall synthesis and its relationship to morphology, we examined the induction of cell extensions of yeast upon the addition of isoamyl alcohol in osmotically fragile mutants that had mutations in genes related to the cell integrity pathway through activation of the mitogen-activated protein kinase cascade. We found that isoamyl alcohol induces cell extensions in pkc1 deletion mutants but not in mutants with mutations in genes positioned downstream or upstream of the PKC1 gene. These results suggest that Pkc1p functions not only in the integrity pathway but also in the induction. We characterized the elongated cells; many had two or more nuclei. We found no difference in cell surface structure between round and elongated cells from the results of chitin staining and cell wall extraction. Actin cytoskeleton was organized in elongated cells, as well as round cells. Cytochalasin D (0.08 mg/mL) inhibited the formation of actin cable but did not affect the induction of cell extensions.Key words: Saccharomyces cerevisiae, pkc1, isoamyl alcohol, cell extension.

scholarly journals Requirement of STE50 for Osmostress-Induced Activation of the STE11 Mitogen-Activated Protein Kinase Kinase Kinase in the High-Osmolarity Glycerol Response Pathway

1998 ◽  
Vol 18 (10) ◽  
pp. 5788-5796 ◽  
Author(s):  
Francesc Posas ◽  
Elizabeth A. Witten ◽  
Haruo Saito
Keyword(s):  
Osmotic Stress ◽  
Map Kinase ◽  
Kinase Activation ◽  
High Osmolarity ◽  
High Osmolarity Glycerol ◽  
Terminal Domain ◽  
Map Kinase Cascade ◽  
Two Component ◽  
Mitogen Activated Protein ◽  
Kinase Cascade

ABSTRACT Exposure of yeast cells to increases in extracellular osmolarity activates the HOG1 mitogen-activated protein (MAP) kinase cascade, which is composed of three tiers of protein kinases: (i) the SSK2, SSK22, and STE11 MAP kinase kinase kinases (MAPKKKs), (ii) the PBS2 MAPKK, and (iii) the HOG1 MAP kinase. Activation of the MAP kinase cascade is mediated by two upstream mechanisms. The SLN1-YPD1-SSK1 two-component osmosensor activates the SSK2 and SSK22 MAPKKKs by direct interaction of the SSK1 response regulator with these MAPKKKs. The second mechanism of HOG1 MAP kinase activation is independent of the two-component osmosensor and involves the SHO1 transmembrane protein and the STE11 MAPKKK. Only PBS2 and HOG1 are common to the two mechanisms. We conducted an exhaustive mutant screening to identify additional elements required for activation of STE11 by osmotic stress. We found that strains with mutations in the STE50 gene, in combination with ssk2Δ ssk22Δ mutations, were unable to induce HOG1 phosphorylation after osmotic stress. Both two-hybrid analyses and coprecipitation assays demonstrated that the N-terminal domain of STE50 binds strongly to the N-terminal domain of STE11. The binding of STE50 to STE11 is constitutive and is not affected by osmotic stress. Furthermore, the two proteins relocalize similarly after osmotic shock. It was concluded that STE50 fulfills an essential role in the activation of the high-osmolarity glycerol response pathway by acting as an integral subunit of the STE11 MAPKKK.

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