Faculty Opinions recommendation of Aspergillus nidulans HOG pathway is activated only by two-component signalling pathway in response to osmotic stress.

2005 ◽  
Author(s):  
Gerhard Braus
Keyword(s):  
Osmotic Stress ◽  
Aspergillus Nidulans ◽  
Signalling Pathway ◽  
Hog Pathway ◽  
Two Component

scholarly journals Aspergillus nidulans HOG pathway is activated only by two-component signalling pathway in response to osmotic stress

2005 ◽  
Vol 56 (5) ◽  
pp. 1246-1261 ◽  
Author(s):  
Kentaro Furukawa ◽  
Yukiko Hoshi ◽  
Tatsuya Maeda ◽  
Tasuku Nakajima ◽  
Keietsu Abe
Keyword(s):  
Osmotic Stress ◽  
Aspergillus Nidulans ◽  
Signalling Pathway ◽  
Hog Pathway ◽  
Two Component

scholarly journals The Eukaryotic Two-Component Histidine Kinase Sln1p RegulatesOCH1via the Transcription Factor, Skn7p

2002 ◽  
Vol 13 (2) ◽  
pp. 412-424 ◽  
Author(s):  
Sheng Li ◽  
Susan Dean ◽  
Zhijian Li ◽  
Joe Horecka ◽  
Robert J. Deschenes ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Osmotic Stress ◽  
Binding Site ◽  
Histidine Kinase ◽  
Response Regulators ◽  
Hog Pathway ◽  
Receiver Domain ◽  
Osmotic Response ◽  
Two Component

The yeast “two-component” osmotic stress phosphorelay consists of the histidine kinase, Sln1p, the phosphorelay intermediate, Ypd1p and two response regulators, Ssk1p and Skn7p, whose activities are regulated by phosphorylation of a conserved aspartyl residue in the receiver domain. Dephospho-Ssk1p leads to activation of the hyper-osmotic response (HOG) pathway, whereas phospho-Skn7p presumably leads to activation of hypo-osmotic response genes. The multifunctional Skn7 protein is important in oxidative as well as osmotic stress; however, the Skn7p receiver domain aspartate that is the phosphoacceptor in the SLN1 pathway is dispensable for oxidative stress. Like many well-characterized bacterial response regulators, Skn7p is a transcription factor. In this report we investigate the role of Skn7p in osmotic response gene activation. Our studies reveal that the Skn7p HSF-like DNA binding domain interacts with acis-acting element identified upstream ofOCH1 that is distinct from the previously defined HSE-like Skn7p binding site. Our data support a model in which Skn7p receiver domain phosphorylation affects transcriptional activation rather than DNA binding to this class of DNA binding site.

GPD1, which encodes glycerol-3-phosphate dehydrogenase, is essential for growth under osmotic stress in Saccharomyces cerevisiae, and its expression is regulated by the high-osmolarity glycerol response pathway

1994 ◽  
Vol 14 (6) ◽  
pp. 4135-4144
Author(s):  
J Albertyn ◽  
S Hohmann ◽  
J M Thevelein ◽  
B A Prior
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Osmotic Stress ◽  
Yeast Cells ◽  
Mrna Levels ◽  
Hog Pathway ◽  
Hypertonic Medium ◽  
High Osmolarity ◽  
High Osmolarity Glycerol ◽  
Enhanced Production ◽  
Glycerol 3 Phosphate Dehydrogenase

The yeast Saccharomyces cerevisiae responds to osmotic stress, i.e., an increase in osmolarity of the growth medium, by enhanced production and intracellular accumulation of glycerol as a compatible solute. We have cloned a gene encoding the key enzyme of glycerol synthesis, the NADH-dependent cytosolic glycerol-3-phosphate dehydrogenase, and we named it GPD1. gpd1 delta mutants produced very little glycerol, and they were sensitive to osmotic stress. Thus, glycerol production is indeed essential for the growth of yeast cells during reduced water availability. hog1 delta mutants lacking a protein kinase involved in osmostress-induced signal transduction (the high-osmolarity glycerol response [HOG] pathway) failed to increase glycerol-3-phosphate dehydrogenase activity and mRNA levels when osmotic stress was imposed. Thus, expression of GPD1 is regulated through the HOG pathway. However, there may be Hog1-independent mechanisms mediating osmostress-induced glycerol accumulation, since a hog1 delta strain could still enhance its glycerol content, although less than the wild type. hog1 delta mutants are more sensitive to osmotic stress than isogenic gpd1 delta strains, and gpd1 delta hog1 delta double mutants are even more sensitive than either single mutant. Thus, the HOG pathway most probably has additional targets in the mechanism of adaptation to hypertonic medium.

scholarly journals Repressors and Upstream Repressing Sequences of the Stress-Regulated ENA1 Gene in Saccharomyces cerevisiae: bZIP Protein Sko1p Confers HOG-Dependent Osmotic Regulation

1999 ◽  
Vol 19 (1) ◽  
pp. 537-546 ◽  
Author(s):  
Markus Proft ◽  
Ramón Serrano
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Salt Stress ◽  
Osmotic Stress ◽  
Transcriptional Repression ◽  
Glucose Repression ◽  
Osmotic Shock ◽  
Mitogen Activated Protein Kinase ◽  
Deletion Strain ◽  
Binding Motif ◽  
Hog Pathway

ABSTRACT The yeast ENA1/PMR2A gene encodes a cation extrusion ATPase in Saccharomyces cerevisiae which is essential for survival under salt stress conditions. One important mechanism ofENA1 transcriptional regulation is based on repression under normal growth conditions, which is relieved by either osmotic induction or glucose starvation. Analysis of the ENA1promoter revealed a Mig1p-binding motif (−533 to −544) which was characterized as an upstream repressing sequence (URSMIG-ENA1 ) regulated by carbon source. Its function was abolished in a mig1 mig2 double-deletion strain as well as in either ssn6 or tup1 single mutants. A second URS at −502 to −513 is responsible for transcriptional repression regulated by osmotic stress and is similar to mammalian cyclic AMP response elements (CREs) that are recognized by CREB proteins. This URSCRE-ENA1 element requires for its repression function the yeast CREB homolog Sko1p (Acr1p) as well as the integrity of the Ssn6p-Tup1p corepressor complex. When targeted to the GAL1 promoter by fusing with the Gal4p DNA-binding domain, Sko1p acts as an Ssn6/Tup1p-dependent repressor regulated by osmotic stress. A glutathione S -transferase–Sko1 fusion protein binds specifically to the URSCRE-ENA1 element. Furthermore, ahog1 mitogen-activated protein kinase deletion strain could not counteract repression on URSCRE-ENA1 during osmotic shock. The loss of SKO1 completely restoredENA1 expression in a hog1 mutant and partially suppressed the osmotic stress sensitivity, qualifying Sko1p as a downstream effector of the HOG pathway. Our results indicate that different signalling pathways (HOG osmotic pathway and glucose repression pathway) use distinct promoter elements of ENA1(URSCRE-ENA1 and URSMIG-ENA1 ) via specific transcriptional repressors (Sko1p and Mig1/2p) and via the general Ssn6p-Tup1p complex. The physiological importance of the relief from repression during salt stress was also demonstrated by the increased tolerance ofsko1 or ssn6 mutants to Na+ or Li+ stress.

Transcriptional profiling for Aspergillus nidulans HogA MAPK signaling pathway in response to fludioxonil and osmotic stress

2009 ◽  
Vol 46 (11) ◽  
pp. 868-878 ◽  
Author(s):  
Daisuke Hagiwara ◽  
Yoshihiro Asano ◽  
Junichiro Marui ◽  
Akira Yoshimi ◽  
Takeshi Mizuno ◽  
...  
Keyword(s):  
Osmotic Stress ◽  
Aspergillus Nidulans ◽  
Signaling Pathway ◽  
Transcriptional Profiling ◽  
Mapk Signaling ◽  
Mapk Signaling Pathway

AtfA bZIP-type transcription factor regulates oxidative and osmotic stress responses in Aspergillus nidulans

2010 ◽  
Vol 283 (3) ◽  
pp. 289-303 ◽  
Author(s):  
Anita Balázs ◽  
Imre Pócsi ◽  
Zsuzsanna Hamari ◽  
Éva Leiter ◽  
Tamás Emri ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Osmotic Stress ◽  
Aspergillus Nidulans ◽  
Stress Responses

scholarly journals Altered Phosphotransfer in an Activated Mutant of the Saccharomyces cerevisiae Two-Component Osmosensor Sln1p

2002 ◽  
Vol 1 (2) ◽  
pp. 174-180 ◽  
Author(s):  
A. D. Ault ◽  
J. S. Fassler ◽  
R. J. Deschenes
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Osmotic Stress ◽  
Stress Responses ◽  
Mitogen Activated Protein Kinase ◽  
Phosphoryl Group ◽  
Response Regulators ◽  
Two Component ◽  
Mitogen Activated Protein ◽  
Receiver Module ◽  
Kinase Pathway

ABSTRACT The SLN1 two-component signaling pathway of Saccharomyces cerevisiae utilizes a multistep phosphorelay mechanism to control osmotic stress responses via the HOG1 mitogen-activated protein kinase pathway and the transcription factor Skn7p. Sln1p consists of a sensor kinase module that undergoes histidine autophosphorylation and a receiver module that autocatalytically transfers the phosphoryl group from histidine to aspartate. The Sln1p aspartyl phosphate is then transferred to Ypd1p, which in turn transfers the phosphoryl group to a conserved aspartate on one of two response regulators, Ssk1p and Skn7p. Activated alleles of SLN1 (sln1*) were previously identified that appear to increase the level of phosphorylation of downstream targets Ssk1p and Skn7p. In principle, the phenotype of sln1* alleles could arise from an increase in autophosphorylation or phosphotransfer activities or a decrease in an intrinsic or extrinsic dephosphorylation activity. Genetic analysis of the activated mutants has been unable to distinguish between these possibilities. In this report, we address this issue by analyzing phosphorelay and phosphohydrolysis reactions involving the Sln1p-associated receiver. The results are consistent with a model in which the activated phenotype of the sln1* allele, sln1-22, arises from a shift in the phosphotransfer equilibrium from Sln1p to Ypd1p, rather than from impaired dephosphorylation of the system in response to osmotic stress.

scholarly journals Ineffective Phosphorylation of Mitogen-Activated Protein Kinase Hog1p in Response to High Osmotic Stress in the Yeast Kluyveromyces lactis

2015 ◽  
Vol 14 (9) ◽  
pp. 922-930 ◽  
Author(s):  
Nancy Velázquez-Zavala ◽  
Miriam Rodríguez-González ◽  
Rocío Navarro-Olmos ◽  
Laura Ongay-Larios ◽  
Laura Kawasaki ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Osmotic Stress ◽  
Kluyveromyces Lactis ◽  
Chimeric Protein ◽  
High Sensitivity ◽  
Hyperosmotic Stress ◽  
Mitogen Activated Protein Kinase ◽  
Hog Pathway ◽  
Content Type ◽  
Mitogen Activated Protein

ABSTRACT When treated with a hyperosmotic stimulus, Kluyveromyces lactis cells respond by activating the mitogen-activated protein kinase (MAPK) K. lactis Hog1 (KlHog1) protein via two conserved branches, SLN1 and SHO1. Mutants affected in only one branch can cope with external hyperosmolarity by activating KlHog1p by phosphorylation, except for single Δ Klste11 and Δ Klste50 mutants, which showed high sensitivity to osmotic stress, even though the other branch (SLN1) was intact. Inactivation of both branches by deletion of KlSHO1 and KlSSK2 also produced sensitivity to high salt. Interestingly, we have observed that in Δ Klste11 and Δ Klsho1 Δ Klssk2 mutants, which exhibit sensitivity to hyperosmotic stress, and contrary to what would be expected, KlHog1p becomes phosphorylated. Additionally, in mutants lacking both MAPK kinase kinases (MAPKKKs) present in K. lactis (KlSte11p and KlSsk2p), the hyperosmotic stress induced the phosphorylation and nuclear internalization of KlHog1p, but it failed to induce the transcriptional expression of KlSTL1 and the cell was unable to grow in high-osmolarity medium. KlHog1p phosphorylation via the canonical HOG pathway or in mutants where the SHO1 and SLN1 branches have been inactivated requires not only the presence of KlPbs2p but also its kinase activity. This indicates that when the SHO1 and SLN1 branches are inactivated, high-osmotic-stress conditions activate an independent input that yields active KlPbs2p, which, in turn, renders KlHog1p phosphorylation ineffective. Finally, we found that KlSte11p can alleviate the sensitivity to hyperosmotic stress displayed by a Δ Klsho1 Δ Klssk2 mutant when it is anchored to the plasma membrane by adding the KlSho1p transmembrane segments, indicating that this chimeric protein can substitute for KlSho1p and KlSsk2p.

Response to high osmotic conditions and elevated temperature in Saccharomyces cerevisiae is controlled by intracellular glycerol and involves coordinate activity of MAP kinase pathways

Microbiology ◽  
2003 ◽  
Vol 149 (5) ◽  
pp. 1193-1204 ◽  
Author(s):  
Iwona Wojda ◽  
Rebeca Alonso-Monge ◽  
Jan-Paul Bebelman ◽  
Willem H. Mager ◽  
Marco Siderius
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Osmotic Stress ◽  
Map Kinase ◽  
Growth Temperature ◽  
Wild Type ◽  
Hog Pathway ◽  
Map Kinase Pathway ◽  
Kinase Pathway ◽  
Intracellular Glycerol

In the yeast Saccharomyces cerevisiae, response to an increase in external osmolarity is mediated by the HOG (high osmolarity glycerol) MAP kinase pathway. HOG pathway mutant strains display osmosensitive phenotypes. Recently evidence has been obtained that the osmosensitivity of HOG pathway mutants is reduced during growth at elevated temperature (37 °C). A notable exception is the ste11ssk2ssk22 mutant, which displays hypersensitivity to osmotic stress at 37 °C. This paper reports that overexpression of FPS1 or GPD1 (encoding the glycerol transport facilitator and glycerol-3-phosphate dehydrogenase, respectively, and both affecting intracellular glycerol levels) reduces the hypersensitivity to osmotic stress of ste11ssk2ssk22 at 37 °C. Although in this particular HOG pathway mutant a correlation between suppression of the phenotype and glycerol content could be demonstrated, the absolute level of intracellular glycerol per se does not determine whether a strain is osmosensitive or not. Rather, evidence was obtained that the glycerol level may have an indirect effect, viz. by influencing signalling through the PKC (protein kinase C) MAP kinase pathway, which plays an important role in maintenance of cellular integrity. In order to validate the data obtained with a HOG pathway mutant strain for wild-type yeast cells, MAP kinase signalling under different growth conditions was examined in wild-type strains. PKC pathway signalling, which is manifest at elevated growth temperature by phosphorylation of MAP kinase Mpk1p, is rapidly lost when cells are shifted to high external osmolarity conditions. Expression of bck1-20 or overexpression of WSC3 in wild-type cells resulted in restoration of PKC signalling. Both PKC and HOG signalling, cell wall phenotypes and high osmotic stress responses in wild-type cells were found to be influenced by the growth temperature. The data taken together indicate the intricate interdependence of growth temperature, intracellular glycerol, cell wall structure and MAP kinase signalling in the hyperosmotic stress response of yeast.

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