Trehalase activation in yeasts is mediated by an internal acidification

Valle, Eulalia; Bergillos, Lourdes; Gascón, Sonia; Parra, Francisco; Ramos, Sofı́a

doi:10.1111/j.1432-1033.1986.tb09389.x

Cited by 40 publications

(22 citation statements)

References 29 publications

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“…As described previously (den Hollander et al, 1981 ; Nicolay et al, Caspani et al, 1985;Valle et al, 1986), the addition of 20 mM-glucose or other sugars which are degraded through glycolysis lowered pHin to about 6.4 (Table 1). Among the non-metabolizable sugars and sugar derivatives tested, those which are not efficiently phosphorylated (Sols et al, 1958;Gancedo & Gancedo, 1985;Siverio et al, 1986) such as xylose (150 mM), 3-0-methyl D-glucoside (20 mM) or 6-deoxy-~-glucose (100 mM) had little effect on pHin.…”

Section: Efect Of Sugars On P H Of S Cerevisiaesupporting

confidence: 64%

“…Two different methods were used: measuring the accumulation of the weak acid benzoic acid and/or following the changes in fluorescence of fluorescein. Unless indicated the determination of internal pH with [14C]benzoic acid [29-4 Ci mol-l (1.088 TBq mol-I; 1.4 pM)] was done using the acid concentration gradient reached at steady state as previously described (Valle et al, 1986), in cells suspended in 5 0 m~-6-aminohexanoate/HCl buffer, pH 4.5, at a density of 1.6 x lo8 cells ml-l. The determination of pHi, with fluorescein was done according to the method described by Slavik (1982) with some modifications.…”

Section: Methodsmentioning

confidence: 99%

“…This system has been characterized in Neurospora crassa (Blaat & Slayman, 1987) and observed in Saccharomyces cerevisiae (Valle et al, 1987). This alkalinization is preceded by an acidification (den Hollander et al, 1981 ;Nicolay et al, 1982;Caspani et al, 1985;Valle et al, 1986;Thevelein et al, 1987b) which, in the presence of external K+, is transient but in its absence lasts for at least 10 min (Valle et al, 1987). The cause of the decrease of pHi, induced by glucose is not fully understood, but may be due to the accumulation of either C 0 2 (den Hollander et al, 1981), glucose 6-phosphate (Valle et al, 1987;Eraso et al, 1987) or other organic acids, since one of the known effects of glucose is the production and secretion of these substances (Duro & Serrano, 1981;Wurst et al, 1981).…”

Section: S Ramos a N D Othersmentioning

confidence: 99%

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The Mechanism of Intracellular Acidification Induced by Glucose in Saccharomyces cerevisiae

Ramos¹,

Balbı́n²,

Raposo³

et al. 1989

Microbiology

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Addition of glucose or fructose to cells of Saccharomyces cerevisiae adapted to grow in the absence of glucose induced an acidification of the intracellular medium. This acidification appeared to be due to the phosphorylation of the sugar since : (i) glucose analogues which are not efficiently phosphorylated did not induce internal acidification; (ii) glucose addition did not cause internal acidification in a mutant deficient in all the three sugar-phosphorylating enzymes; (iii) fructose did not affect the intracellular pH in a double mutant having only glucokinase activity; (iv) glucose was as effective as fructose in inducing the internal pH drop in a mutant deficient in phosphoglucose isomerase activity; and (v) in strains deficient in two of the three sugar-phosphorylating activities, there was a good correlation between the specific glucose-or fructose-phosphorylating activity of cell extracts and the sugar-induced internal acidification. In addition, in whole cells any of the three yeast sugar kinases were capable of mediating the internal acidification described. Glucose-induced internal acidification was observed even when yeast cells were suspended in growth medium and in cells suspended in buffer containing K+, which supports the possible signalling function of the glucose-induced internal acidification. Evaluation of internal pH by following fluorescence changes of fluorescein-loaded cells indicated that the change in intracellular pH occurred immediately after addition of sugar. The apparent K , for glucose in this process was 2 mM. Changes in both the internal and external pH were determined and it was found that the internal acidification induced by glucose was followed by a partial alkalinization coincident with the initiation of H+ efflux. This reversal of acidification could be due to the activity of the H+-ATPase, since it was inhibited by diethylstilboestrol. Coincidence between internal alkalinization and the H+ efflux was also observed after addition of ethanol.

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Section: Efect Of Sugars On P H Of S Cerevisiaesupporting

confidence: 64%

Section: Methodsmentioning

confidence: 99%

Section: S Ramos a N D Othersmentioning

confidence: 99%

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The Mechanism of Intracellular Acidification Induced by Glucose in Saccharomyces cerevisiae

Ramos¹,

Balbı́n²,

Raposo³

et al. 1989

Microbiology

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“…The average experimental accumulation factor of acetate added to S. cerevisiae CBS 8066, as calculated from the difference between the reservoir concentration and the residual concentration in the fermenter in steady state was 84 & 10 (Table 2). In this calculation, it was assumed that the cytosolic volume was 2 ml (g cells)-' (Valle et al, 1986;Warth, 1988). The accumulation factor was independent of the amount of acetate added ( …”

Section: (V)mentioning

confidence: 99%

Physiology of Saccharomyces Cerevisiae in Anaerobic Glucose-Limited Chemostat Culturesx

Verduyn

Postma²,

Scheffers³

et al. 1990

Journal of General Microbiology

427

364

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The physiology of Saccharomyces cerevisiae CBS 8066 was studied in anaerobic glucose-limited chemostat cultures in a mineral medium supplemented with ergosterol and Tween 80. The organism had a pmax of 0.31 h-l and a K, for glucose of 0.55 mM. At a dilution rate of 0.10 h-l, a maximal yield of 0.10 g biomass (g glucose)-' was observed. The yield steadily declined with increasing dilution rates, so a maintenance coefficient for anaerobic growth could not be estimated At a dilution rate of 0.10 h-l, the yield of the S . cereuisiae strain H1022 was considerably higher than for CBS 8066, despite a similar cell composition. The major difference between the two yeast strains was that S . cerevisiae H1022 did not produce acetate, suggesting that the observed difference in cell yield may be ascribed to an uncoupling effect of acetic acid. The absence of acetate formation in H1022 correlated with a relatively high level of acetyl-CoA synthetase. The uncoupling effect of weak acids on anaerobic growth was confirmed in experiments in which a weak acid (acetate or propionate) was added to the medium feed. This resulted in a reduction in yield and an increase in specific ethanol production. Both yeasts required approximately 35 mg oleic acid (g biomass)-' for optimal growth. Lower or higher concentrations of this fatty acid, supplied as Tween 80, resulted in uncoupling of dissimilatory and assimilatory processes.

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“…The mechanism by which glucose triggers the cAMP signal is not known. At first, rather unspecific mechanisms such as transient plasma membrane depolarization (23,31) and transient intracellular acidification (10,36,46) were proposed. However, these hypotheses were shown to be wrong, and other rather unspecific mechanisms, such as increased energy supply, were also excluded (17,41,42).…”

mentioning

confidence: 99%

Requirement of one functional RAS gene and inability of an oncogenic ras variant to mediate the glucose-induced cyclic AMP signal in the yeast Saccharomyces cerevisiae.

Mbonyi¹,

Beullens²,

Detremerie³

et al. 1988

Mol. Cell. Biol.

106

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Addition of glucose to Saccharomyces cerevisiae cells grown on a nonfermentable carbon source triggers a cyclic AMP (cAMP) signal, which induces a protein phosphorylation cascade. In a yeast strain lacking functional RAS] and RAS2 genes and containing a bcy mutation to suppress the lethality of RAS deficiency, the cAMP signal was absent. Addition of dinitrophenol, which stimulates in vivo cAMP synthesis by lowering intracellular pH, also did not enhance the cAMP level. A bcy control strain, with functional RAS genes present, showed cAMP responses similar to those of a wild-type strain. In disruption mutants containing either a functional RAS] gene or a functional RAS2 gene, the cAMP signal was not significantly different from the one in wild-type cells, indicating that RAS function cannot be a limiting factor for cAMP synthesis during induction of the signal. Compared with wild-type cells, the cAMP signal decreased in intensity with increasing temperature in a ras2 disruption mutant. When the mutant RAS2V'-l9, which carries the equivalent of the human H-rasVa~2 oncogene, was grown under conditions in which RAS] expression is repressed, the cAMP signal was absent. The oncogene product is known to be deficient in GTPase activity. However, the amino acid change at position 19 (or 12 in the corresponding human oncogene product) might also have other effects, such as abolishing receptor interaction. Such an additional effect probably provides a better explanation for the lack of signal transmission than the impaired GTPase activity. When the RAS2val-19 mutant was grown under conditions in which RAS] is expressed, the cAMP signal was present but significantly delayed compared with the signal in wild-type cells. This indicates that oncogenic RAS proteins inhibit normal functioning of wild-type RAS proteins in vivo and also that in spite of the presence of the RAS2va'-9 oncogene, adenyl cyclase is not maximally stimulated in vivo. Expression of only the RAS2Va'-l9 gene product also prevented most of the stimulation of cAMP synthesis by dinitrophenol, indicating that lowered intracellular pH does not act directly on adenyl cyclase but on a step earlier in the activation pathway of the enzyme. The results obtained with the control bcy strain, the RAS2va'-I9 strain under conditions in which RAS] is expressed, and with dinitrophenol show that the inability of the oncogene product to mediate the cAMP signal is not due to feedback inhibition by the high protein kinase activity in strains containing the RAS2Va-l9 oncogene. Hence, the present results show that the RAS proteins in S. cerevisiae are involved in the transmission of the glucose-induced cAMP signal and that the oncogenic RAS protein is unable to act as a signal transducer. The RAS proteins in S. cerevisiae apparently act similarly to the G. proteins of mammalian adenyl cyclase, but instead of being involved in hormone signal transmission, they function in a nutrient-induced signal transmission pathway. (23,31) and transient intracellular acidification (10,36,46) we...

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Trehalase activation in yeasts is mediated by an internal acidification

Cited by 40 publications

References 29 publications

The Mechanism of Intracellular Acidification Induced by Glucose in Saccharomyces cerevisiae

The Mechanism of Intracellular Acidification Induced by Glucose in Saccharomyces cerevisiae

Physiology of Saccharomyces Cerevisiae in Anaerobic Glucose-Limited Chemostat Culturesx

Requirement of one functional RAS gene and inability of an oncogenic ras variant to mediate the glucose-induced cyclic AMP signal in the yeast Saccharomyces cerevisiae.

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