Glycogen hyperaccumulation in <i>Saccharomyces cerevisiae ras2</i> mutant A biochemical study

Fernández-Bañares, Isabel; Clotet, Josep; Ariño, Joaquı́n; Guinovart, Joan J.

doi:10.1016/0014-5793(91)81220-3

Cited by 10 publications

(3 citation statements)

References 37 publications

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“…Deletion of RAS2 leads to hyperaccumulation of glycogen [ 39 , 54 ]. A biochemical study attributed the hyperaccumulation of glycogen in the ras2∆ mutants to the glycogen synthase activation state which rises continuously and reaches its peak before the diauxic shift, even though the glycogen phosphorylase activity is up to 40 times higher in the mutant than in the WT strain [ 55 ]. Whether the activation state of glycogen synthase in the ras2∆ mutants is enhanced due to defective respiration remains to be decided.…”

Section: Discussionmentioning

confidence: 99%

The Yeast GSK-3 Homologue Mck1 Is a Key Controller of Quiescence Entry and Chronological Lifespan

et al. 2015

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Upon starvation for glucose or any other core nutrient, yeast cells exit from the mitotic cell cycle and acquire a set of G0-specific characteristics to ensure long-term survival. It is not well understood whether or how cell cycle progression is coordinated with the acquisition of different G0-related features during the transition to stationary phase (SP). Here, we identify the yeast GSK-3 homologue Mck1 as a key regulator of G0 entry and reveal that Mck1 acts in parallel to Rim15 to activate starvation-induced gene expression, the acquisition of stress resistance, the accumulation of storage carbohydrates, the ability of early SP cells to exit from quiescence, and their chronological lifespan. FACS and microscopy imaging analyses indicate that Mck1 promotes mother-daughter cell separation and together with Rim15, modulates cell size. This indicates that the two kinases coordinate the transition-phase cell cycle, cell size and the acquisition of different G0-specific features. Epistasis experiments place MCK1, like RIM15, downstream of RAS2 in antagonising cell growth and activating stress resistance and glycogen accumulation. Remarkably, in the ras2∆ cells, deletion of MCK1 and RIM15 together, compared to removal of either of them alone, compromises respiratory growth and enhances heat tolerance and glycogen accumulation. Our data indicate that the nutrient sensor Ras2 may prevent the acquisition of G0-specific features via at least two pathways. One involves the negative regulation of the effectors of G0 entry such as Mck1 and Rim15, while the other likely to involve its functions in promoting respiratory growth, a phenotype also contributed by Mck1 and Rim15.

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Section: Discussionmentioning

confidence: 99%

The Yeast GSK-3 Homologue Mck1 Is a Key Controller of Quiescence Entry and Chronological Lifespan

et al. 2015

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“…The cAMP-dependent PKA was activated leading to the degradation of trehalose and glycogen by activating neutral trehalases (encoded by NTH1 ⁄ 2) and glycogen phosphorylase (GPH1). In contrast, the Ras ⁄ PKA signaling pathway has been reported to inactivate glycogen synthase [34] and the mutation of RAS2 in which the cAMP level decreased induced hyperaccumulation of glycogen [35]. Furthermore, the activity of purified glycogen synthase was inhibited after phosphorylation by PKA in vitro [36].…”

Section: Discussionmentioning

confidence: 99%

A potential mechanism of energy‐metabolism oscillation in an aerobic chemostat culture of the yeast Saccharomyces cerevisiae

Tsurugi

2006

The FEBS Journal

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Biological rhythms are considered to be ubiquitous in eukaryotic and prokaryotic organisms and are synchronized so the organism can adapt to environmental changes. Circadian rhythm is the most common of the biological rhythms and the molecular clock mechanism has been studied extensively. However, no circadian rhythm has been discovered in yeast and instead two kinds of ultradian rhythms of energy metabolism have been reported. One is a KCN-induced oscillation of the glycolytic pathway and the other is an energymetabolism oscillation (EMO) found in aerobic chemostat cultures. The KCN-induced oscillations were evoked after addition of glucose by inhibiting mitochondrial respiration with cyanide [1] and show a periodicity of 1-2 min as monitored by measuring the level of NAD(P)H. The glycolytic pathway has been The energy-metabolism oscillation in aerobic chemostat cultures of yeast is a periodic change of the respiro-fermentative and respiratory phase. In the respiro-fermentative phase, the NADH level was kept high and respiration was suppressed, and glucose was anabolized into trehalose and glycogen at a rate comparable to that of catabolism. On the transition to the respiratory phase, cAMP levels increased triggering the breakdown of storage carbohydrates and the increased influx of glucose into the glycolytic pathway activated production of glycerol and ethanol consuming NADH. The resulting increase in the NAD + ⁄ NADH ratio stimulated respiration in combination with a decrease in the level of ATP, which was consumed mainly in the formation of biomass accompanying budding, and the accumulated ethanol and glycerol were gradually degraded by respiration via NAD + -dependent oxidation to acetate and the respiratory phase ceased after the recovery of NADH and ATP levels. However, the mRNA levels of both synthetic and degradative enzymes of storage carbohydrates were increased around the early respiro-fermentative phase, when storage carbohydrates are being synthesized, suggesting that the synthetic enzymes were expressed directly as active forms while the degradative enzymes were activated late by cAMP. In summary, the energy-metabolism oscillation is basically regulated by a feedback loop of oxido-reductive reactions of energy metabolism mediated by metabolites like NADH and ATP, and is modulated by metabolism of storage carbohydrates in combination of post-translational and transcriptional regulation of the related enzymes. A potential mechanism of energy-metabolism oscillation is proposed.Abbreviations ADH, alcohol dehydrogenase; ALD, aldehyde dehydrogenase; DO, dissolved oxygen; EMO, energy-metabolism oscillation; FBP, fructose-1,6-bisphosphate; F-2,6-BP, fructose-2,6-bisphosphate; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; OUR, oxygen uptake rate; PDC, pyruvate dehydrogenase complex; PKA, protein kinase A.

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“…Cells with constitutively active PKA activity (bcy1 mutants) fail to accumulate glycogen, are sporulation deficient, and possess various growth defects (7). Conversely, cells with low PKA activity (ras2 mutants) exhibit growth defects, hyperaccumulate glycogen, and sporulate precociously in the presence of nutrients (10,24). In other words, the phenotypes associated with elevated levels of cAMP-PKA are qualitatively similar to those caused by disruption of YVH1.…”

Section: Vol 182 2000mentioning

confidence: 99%

The Dual-Specificity Protein Phosphatase Yvh1p Regulates Sporulation, Growth, and Glycogen Accumulation Independently of Catalytic Activity in Saccharomyces cerevisiae via the Cyclic AMP-Dependent Protein Kinase Cascade

Beeser

Cooper

2000

J Bacteriol

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Yvh1p, a dual-specific protein phosphatase induced specifically by nitrogen starvation, regulates cell growth as well as initiation and completion of sporulation. We demonstrate that yvh1 disruption mutants are also unable to accumulate glycogen in stationary phase. A catalytically inactive variant of yvh1 (C117S) and a DNA fragment encoding only the Yvh1p C-terminal 159 amino acids (which completely lacks the phosphatase domain) complement all three phenotypes as well as the wild-type allele; no complementation occurs with a fragment encoding only the C-terminal 74 amino acids. These observations argue that phosphatase activity is not required for the Yvh1p functions we measured. Mutations which decrease endogenous cyclic AMP (cAMP) levels partially suppress the sporulation and glycogen accumulation defects. In addition, reporter gene expression supported by a DRR2 promoter fragment, containing two stress response elements known to respond to cAMP-protein kinase A, decreases in a yvh1 disruption mutant. Therefore, our results identify three cellular processes that both require Yvh1p and respond to alterations in cAMP, and they lead us to suggest that Yvh1p may be a participant in and/or a contributor to regulation of the cAMP-dependent protein kinase cascade. The fact that decreasing the levels of cAMP alleviates the need for Yvh1p function supports this suggestion.

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Glycogen hyperaccumulation in Saccharomyces cerevisiae ras2 mutant A biochemical study

Cited by 10 publications

References 37 publications

The Yeast GSK-3 Homologue Mck1 Is a Key Controller of Quiescence Entry and Chronological Lifespan

The Yeast GSK-3 Homologue Mck1 Is a Key Controller of Quiescence Entry and Chronological Lifespan

A potential mechanism of energy‐metabolism oscillation in an aerobic chemostat culture of the yeast Saccharomyces cerevisiae

The Dual-Specificity Protein Phosphatase Yvh1p Regulates Sporulation, Growth, and Glycogen Accumulation Independently of Catalytic Activity in Saccharomyces cerevisiae via the Cyclic AMP-Dependent Protein Kinase Cascade

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