scholarly journals Differential Regulation of Two Ca2+ Influx Systems by Pheromone Signaling in Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 159 (4) ◽  
pp. 1527-1538
Author(s):  
Eric M Muller ◽  
Emily G Locke ◽  
Kyle W Cunningham
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Differential Regulation ◽  
Calcium Signals ◽  
Yeast Saccharomyces Cerevisiae ◽  
Constitutive Activation ◽  
Cycle Arrest ◽  
Pheromone Signaling ◽  
Rich Media ◽  
Calcineurin Activity

Abstract The budding yeast Saccharomyces cerevisiae generates calcium signals during the response to mating pheromones that promote survival of unmated cells. A Ca2+ channel composed of Cch1p and Mid1p was previously shown to be necessary for the production of these calcium signals. However, we find that the Cch1p-Mid1p high-affinity Ca2+ influx system (HACS) contributes very little to signaling or survival after treatment with α-factor in rich media. HACS activity was much greater after calcineurin inactivation or inhibition, suggesting the Cch1p-Mid1p Ca2+ channel is subject to direct or indirect regulation by calcineurin. Instead a distinct low-affinity Ca2+ influx system (LACS) was stimulated by pheromone signaling in rich medium. LACS activity was insensitive to calcineurin activity, independent of Cch1p and Mid1p, and sufficient to elevate cytosolic free Ca2+ concentrations ([Ca2+]c) in spite of its 16-fold lower affinity for Ca2+. Overexpression of Ste12p or constitutive activation of this transcription factor in dig1 dig2 double mutants had no effect on LACS activity but stimulated HACS activity when calcineurin was also inactivated. Ste12p activation had no effect on Cch1p or Mid1p abundance, suggesting the involvement of another target of Ste12p in HACS stimulation. LACS activation required treatment with mating pheromone even in dig1 dig2 double mutants and also required FAR1, SPA2, and BNI1, which are necessary for proper cell cycle arrest and polarized morphogenesis. These results show that distinct branches of the pheromone-signaling pathway independently regulate HACS and LACS activities, either of which can promote survival during long-term responses.

scholarly journals Induction of the synthesis of an additional family of long-chain dolichols in the yeast Saccharomyces cerevisiae. Effect of starvation and ageing.

2002 ◽  
Vol 49 (3) ◽  
pp. 781-787 ◽  
Author(s):  
Anna Szkopinska ◽  
Ewa Swiezewska ◽  
Joanna Rytka
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Stationary Phase ◽  
Yeast Cells ◽  
Logarithmic Phase ◽  
Cellular Membranes ◽  
Yeast Saccharomyces Cerevisiae ◽  
Chemical Changes ◽  
Physico Chemical ◽  
Long Chain

The yeast Saccharomyces cerevisiae strain W303 synthesizes in the early logarithmic phase of growth dolichols of 14-18 isoprene residues. The analysis of the polyisoprenoids present in the stationary phase revealed an additional family which proved to be also dolichols but of 19-24 isoprene residues, constituting 39% of the total dolichols. The transfer of early logarithmic phase cells to a starvation medium lacking glucose or nitrogen resulted in the synthesis of the longer chain dolichols. The additional family of dolichols represented 13.8% and 10.3% of total dolichols in the glucose and nitrogen deficient media, respectively. The level of dolichols in yeast cells increased with the age of the cultures. Since both families of dolichols are present in stationary phase cells we postulate that the longer chain dolichols may be responsible for the physico-chemical changes in cellular membranes allowing yeast cells to adapt to nutrient deficient conditions to maintain long-term viability.

scholarly journals Acute ethanol stress induces sumoylation of conserved chromatin structural proteins in Saccharomyces cerevisiae

2021 ◽  
pp. mbc.E20-11-0715
Author(s):  
Amanda I. Bradley ◽  
Nicole M. Marsh ◽  
Heather R. Borror ◽  
Kaitlyn E. Mostoller ◽  
Amber I. Gama ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Ethanol Exposure ◽  
S Phase ◽  
Structural Proteins ◽  
Ethanol Stress ◽  
Post Translational Modification ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cycle Arrest ◽  
Chromatin Structural ◽  
Acute Ethanol

Stress is ubiquitous to life and can irreparably damage essential biomolecules and organelles in cells. To survive, organisms must sense and adapt to stressful conditions. One highly conserved adaptive stress response is through the post-translational modification of proteins by the small ubiquitin-like modifier (SUMO). Here, we examine the effects of acute ethanol stress on protein sumoylation in the budding yeast Saccharomyces cerevisiae . We found that cells exhibit a transient sumoylation response after acute exposure to ≤ 7.5% ethanol. By contrast, the sumoylation response becomes chronic at 10% ethanol exposure. Mass spectrometry analyses identified 18 proteins that are sumoylated after acute ethanol exposure, with 15 known to associate with chromatin. Upon further analysis, we found that the chromatin structural proteins Smc5 and Smc6 undergo ethanol-induced sumoylation that depends on the activity of the E3 SUMO ligase Mms21. Using cell-cycle arrest assays, we observed that Smc5 and Smc6 ethanol-induced sumoylation occurs during G1 and G2/M phases but not S phase. Acute ethanol exposure also resulted in the formation of Rad52 foci at levels comparable to Rad52 foci formation after exposure to the DNA alkylating agent methyl methanesulfonate (MMS). MMS exposure is known to induce the intra-S phase DNA damage checkpoint via Rad53 phosphorylation, but ethanol exposure did not induce Rad53 phosphorylation. Ethanol abrogated the effect of MMS on Rad53 phosphorylation when added simultaneously. From these studies, we propose that acute ethanol exposure induces a change in chromatin leading to sumoylation of specific chromatin-structural proteins.

scholarly journals Genome-Scale Analysis Reveals Sst2 as the Principal Regulator of Mating Pheromone Signaling in the Yeast Saccharomyces cerevisiae

2006 ◽  
Vol 5 (2) ◽  
pp. 330-346 ◽  
Author(s):  
Scott A. Chasse ◽  
Paul Flanary ◽  
Stephen C. Parnell ◽  
Nan Hao ◽  
Jiyoung Y. Cha ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Transition State ◽  
G Protein ◽  
Common Property ◽  
Rgs Proteins ◽  
Homologous Proteins ◽  
Yeast Saccharomyces Cerevisiae ◽  
Α Subunit ◽  
Pheromone Signaling

ABSTRACT A common property of G protein-coupled receptors is that they become less responsive with prolonged stimulation. Regulators of G protein signaling (RGS proteins) are well known to accelerate G protein GTPase activity and do so by stabilizing the transition state conformation of the G protein α subunit. In the yeast Saccharomyces cerevisiae there are four RGS-homologous proteins (Sst2, Rgs2, Rax1, and Mdm1) and two Gα proteins (Gpa1 and Gpa2). We show that Sst2 is the only RGS protein that binds selectively to the transition state conformation of Gpa1. The other RGS proteins also bind Gpa1 and modulate pheromone signaling, but to a lesser extent and in a manner clearly distinct from Sst2. To identify other candidate pathway regulators, we compared pheromone responses in 4,349 gene deletion mutants representing nearly all nonessential genes in yeast. A number of mutants produced an increase (sst2, bar1, asc1, and ygl024w) or decrease (cla4) in pheromone sensitivity or resulted in pheromone-independent signaling (sst2, pbs2, gas1, and ygl024w). These findings suggest that Sst2 is the principal regulator of Gpa1-mediated signaling in vivo but that other proteins also contribute in distinct ways to pathway regulation.

scholarly journals Point Mutations Identify a Conserved Region of the Saccharomyces cerevisiae AFR1 Gene That Is Essential for Both the Pheromone Signaling and Morphogenesis Functions

Genetics ◽  
2000 ◽  
Vol 155 (1) ◽  
pp. 43-55
Author(s):  
Cordell R DeMattei ◽  
Colleen P Davis ◽  
James B Konopka
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Distinct Point ◽  
Sequence Similarity ◽  
Point Mutations ◽  
Yeast Saccharomyces Cerevisiae ◽  
Reading Frame ◽  
Pheromone Signaling ◽  
Essential Region ◽  
The Relationship ◽  
Mutant Genes

Abstract Mating pheromone receptors activate a G protein signal pathway that leads to the conjugation of the yeast Saccharomyces cerevisiae. This pathway also induces the production of Afr1p, a protein that negatively regulates pheromone receptor signaling and is required to form pointed projections of new growth that become the site of cell fusion during mating. Afr1p lacks strong similarity to any well-characterized proteins to help predict how it acts. Therefore, we investigated the relationship between the different functions of Afr1p by isolating and characterizing seven mutants that were defective in regulating pheromone signaling. The AFR1 mutants were also defective when expressed as fusions to STE2, the α-factor receptor, indicating that the mutant Afr1 proteins are defective in function and not in co-localizing with receptors. The mutant genes contained four distinct point mutations that all occurred between codons 254 and 263, identifying a region that is critical for AFR1 function. Consistent with this, we found that the corresponding region is very highly conserved in the Afr1p homologs from the yeasts S. uvarum and S. douglasii. In contrast, there were no detectable effects on pheromone signaling caused by deletion or overexpression of YER158c, an open reading frame with overall sequence similarity to Afr1p that lacks this essential region. Interestingly, all of the AFR1 mutants showed a defect in their ability to form mating projections that was proportional to their defect in regulating pheromone signaling. This suggests that both functions may be due to the same action of Afr1p. Thus, these studies identify a specific region of Afr1p that is critical for its function in both signaling and morphogenesis.

scholarly journals Tributyltin induces cell cycle arrest at G1 phase in the yeast Saccharomyces cerevisiae

2014 ◽  
Vol 39 (2) ◽  
pp. 311-317 ◽  
Author(s):  
Takayuki Sekito ◽  
Naoko Sugimoto ◽  
Masaya Ishimoto ◽  
Miyuki Kawano-Kawada ◽  
Koichi Akiyama ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
G1 Phase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cycle Arrest

scholarly journals Ammodytoxin, a secretory phospholipase A2, inhibits G2 cell-cycle arrest in the yeast Saccharomyces cerevisiae

2005 ◽  
Vol 391 (2) ◽  
pp. 383-388 ◽  
Author(s):  
Uroš Petrovič ◽  
Jernej Šribar ◽  
Maja Matis ◽  
Gregor Anderluh ◽  
Jasna Peter-Katalinić ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Phospholipase A2 ◽  
Cell Cycle Arrest ◽  
Biologically Active ◽  
Secretory Phospholipase A2 ◽  
Yeast Saccharomyces Cerevisiae ◽  
Secretory Phospholipase ◽  
Cycle Arrest ◽  
G2 Cell Cycle Arrest

Ammodytoxin (Atx), an sPLA2 (secretory phospholipase A2), binds to γ and ε isoforms of porcine 14-3-3 proteins in vitro. 14-3-3 proteins are evolutionarily conserved eukaryotic regulatory proteins involved in a variety of biological processes, including cell-cycle regulation. We have now shown that Atx binds to yeast 14-3-3 proteins with an affinity similar to that for the mammalian isoforms. Thus yeast Saccharomyces cerevisiae can be used as a model eukaryotic cell, which lacks endogenous phospholipases A2, to assess the in vivo relevance of this interaction. Atx was expressed in yeast cells and shown to be biologically active inside the cells. It inhibited G2 cell-cycle arrest in yeast, which is regulated by 14-3-3 proteins. Interference with the cell cycle indicates a possible mechanism by which sPLA2s are able to cause the opposing effects, proliferation and apoptosis, in mammalian cells.

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