Effects of various types of stress on the metabolism of reserve carbohydrates in Saccharomyces cerevisiae: genetic evidence for a stress-induced recycling of glycogen and trehalose (original) (raw)
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Stress co-tolerance and trehalose content in baking strains of Saccharomyces cerevisiae
Journal of Industrial Microbiology and Biotechnology, 1997
Fourteen wild-type baking strains of Saccharomyces cerevisiae were grown in batch culture to true stationary phase (exogenous carbon source exhausted) and tested for their trehalose content and their tolerance to heat (52°C for 4.5 min), ethanol (20% v/v for 30 min), H 2 O 2 (0.3 M for 60 min), rapid freezing (−196°C for 20 min, cooling rate 200°C min −1 ), slow freezing (−20°C for 24 h, cooling rate 3°C min −1 ), salt (growth in 1.5 M NaCl agar) or acetic acid (growth in 0.4% w/v acetic acid agar) stresses. Stress tolerance among the strains was highly variable and up to 1000-fold differences existed between strains for some types of stress. Compared with previously published reports, all strains were tolerant to H 2 O 2 stress. Correlation analysis of stress tolerance results demonstrated relationships between tolerance to H 2 O 2 and tolerance to all stresses except ethanol. This may imply that oxidative processes are associated with a wide variety of cellular stresses and also indicate that the general robustness associated with industrial yeast may be a result of their oxidative stress tolerance. In addition, H 2 O 2 tolerance might be a suitable marker for the general assessment of stress tolerance in yeast strains. Trehalose content failed to correlate with tolerance to any stress except acetic acid. This may indicate that the contribution of trehalose to tolerance to other stresses is either small or inconsistent and that trehalose may not be used as a general predictor of stress tolerance in true stationary phase yeast.
Trehalose metabolism in Saccharomyces cerevisiae during heat-shock
Biochimica et Biophysica Acta (BBA) - General Subjects, 1994
When different strains of Saccharomyces cerevisiae grown at 23°C were transferred to 36°C, trehalose and glycogen were accumulated. Glycogen accumulation was less extensive and its synthesis started at least 15 min after initiation of trehalose synthesis. The steady-state intracellular concentration of trehalose increased simultaneously with the activities of the enzymes trehalose-6P synthase, UDPG-pyrophosphorylase, phosphoglucomutase and trehalase. A small but significant change was observed in hexokinase activity. Our results directly implicate isoform PII of hexokinase and the minor isoform of phosphoglucomutase in the pathway of trehalose formation during heat-shock. We also showed that the major isoform of phosphoglucomutase increased in activity but was not essential for trehalose accumulation. Studies with the glucose uptake system indicated that trehalose accumulation could be primarily determined by intracellular availability of substrates due to the increase in the rate of glucose uptake. The increased uptake appears to have two components: a kinetic effect of temperature upon glucose transporters and an increase in the numbers of molecules of the transporters, probably mediated by synthesis de novo.
Applied and Environmental Microbiology, 1995
The trehalose content in laboratory and industrial baker's yeast is widely believed to be a major determinant of stress resistance. Fresh and dried baker's yeast is cultured to obtain a trehalose content of more than 10% of the dry weight. Initiation of fermentation, e.g., during dough preparation, is associated with a rapid loss of stress resistance and a rapid mobilization of trehalose. Using specific Saccharomyces cerevisiae mutants affected in trehalose metabolism, we confirm the correlation between trehalose content and stress resistance but only in the absence of fermentation. We demonstrate that both phenomena can be dissociated clearly once the cells initiate fermentation. This was accomplished both for cells with moderate trehalose levels grown under laboratory conditions and for cells with trehalose contents higher than 10% obtained under pilot-scale conditions. Retention of a high trehalose level during fermentation also does not prevent the loss of fermentation c...
Microbiology, 1998
A pma1-1 mutant of Saccharomyces cerevisiae with reduced H+-ATPase activity and the isogenic wild-type strain accumulated high levels of trehalose in response to a temperature upshift to 40 éC and after addition of 10% ethanol, but only modest levels in response to a rapid drop in external pH and after addition of decanoic acid. There was, however, no correlation between the absolute levels of trehalose in the stressed cells and their viability. All these treatments induced a significant decrease in intracellular pH, and surprisingly, this decrease was very similar in both strains, indicating that intracellular acidification could not be the triggering mechanism for trehalose accumulation in response to stress. A careful investigation of metabolic parameters was carried out to explain how trehalose accumulated under the four different stress conditions tested. No single and common mechanism for trehalose accumulation could be put forward and the transcriptional activation of TPS1 wa...
The Journal of biological chemistry, 2015
Trehalose is a stable disaccharide commonly found in nature, from bacteria to fungi and plants. For the model yeast Saccharomyces cerevisiae, claims that trehalose is a stress protectant were based indirectly either on correlation between accumulation of trehalose and high resistance to various stresses or on stress hypersensitivity of mutants deleted for TPS1, which encodes the first enzyme in trehalose biosynthetic pathway. Our goal was to investigate more directly which one, between trehalose and/or the Tps1 protein, may serve yeast cells to withstand exposure to stress. By employing an original strategy that combined the use of mutant strains expressing catalytically inactive variants of Tps1, with MAL(+) yeast strains able to accumulate trehalose from an exogenous supply, we bring for the first time unbiased proof that trehalose does not protect yeast cells from dying and that the stress-protecting role of trehalose in this eukaryotic model was largely overestimated. Conversely...
Role of trehalose in survival of Saccharomyces cerevisiae under osmotic stress
Microbiology, 1998
Trehalose is an enigmatic compound that accumulates in Saccharomyces cerevisiae and has been implicated in survival under various stress conditions by acting as membrane protectant, as a supplementary compatible solute or as a reserve carbohydrate that may be mobilized during stress. In this study, specific mutants in trehalose metabolism were used to evaluate whether trehalose contributes to survival under severe osmotic stress and generates the compatible solute glycerol under moderate osmotic stress. The survival under severe osmotic stress (0.866 a W, NaCI or sorbitol) of mutants was compared to that of the wild-type strain when cultivated to either the mid-exponential or the stationary growth phase on glucose, galactose or ethanol. Stationary-phase cells survived better than exponential-phase cells. The death rates of ethanol-grown cells were lower than those of galactose-grown cells, which in turn survived better than glucose-grown cells. There was a strong relationship betwee...
On the mechanism by which a heat shock induces trehalose accumulation in Saccharomyces cerevisiae
Biochemical Journal, 1992
When the temperature of exponential-phase cultures of Saccharomyces cerevisiae was abruptly raised from 28 to 40 degrees C, trehalose immediately accumulated, whereas the activities of trehalase and trehalose-6-phosphate synthase/trehalose-6-phosphate phosphatase complex increased after a lag period of about 10 min. Heat shock also induced a sudden rise in intracellular glucose, simultaneously with a decrease in the concentration of hexose phosphate and fructose 2,6-bisphosphate. The increase of trehalose-metabolizing enzymes, but not the accumulation of glucose and trehalose, was prevented by cycloheximide. Investigation of the kinetic properties of partially purified enzymes showed that both non-activated and cyclic AMP-dependent-protein-kinase-activated forms of trehalase are almost inactive in the absence of Ca2+ and that the concentration of free Ca2+ required for half-maximal activity increased with increasing temperature, being approx. 1 microM at 30 degrees C and 20 microM a...
FEMS Yeast Research, 2003
Several factors may control trehalose and glycogen synthesis, like the glucose flux, the growth rate, the intracellular glucose-6phosphate level and the glucose concentration in the medium. Here, the possible relation of these putative inducers to reserve carbohydrate accumulation was studied under well-defined growth conditions in nitrogen-limited continuous cultures. We showed that the amounts of accumulated trehalose and glycogen were regulated by the growth rate imposed on the culture, whereas other implicated inducers did not exhibit a correlation with reserve carbohydrate accumulation. Trehalose accumulation was induced at a dilution rate (D) 9 0.10 h 31 , whereas glycogen accumulation gradually increased at decreasing growth rates. The growth rate dependency of trehalose accumulation was supported by studies in cells overexpressing the G 1-cyclin CLN3. The trehalose level appeared to be dependent on the duration of the G 1 phase, as trehalose was only accumulated at a G 1 phase duration of more than 5 h in both wild-type and CLN3overexpressing cells. On the other hand, the glycogen level was reduced by CLN3 overexpression in a cell cycle-independent manner. A possible regulatory mechanism that links trehalose and glycogen accumulation to the growth rate is discussed.