Dependence on cyclic AMP of glucose‐induced inactivation of yeast gluconeogenetic enzymes

Tortora, Paolo; Burlini, Nedda; Leoni, Flavio; Guerritore, A

doi:10.1016/0014-5793(83)80204-x

Cited by 29 publications

(10 citation statements)

References 21 publications

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“…The values obtained are similar to those previously published for stationary phase cells and acetate-grown cells of yeast (Thevelein, 19846). They also agree very well with those published by other workers for stationary phase cells (Van der Plaat, 1974;Purwin et al, 1982;Tortora et al, 1982Tortora et al, , 1983 with the exception of Mazon et al (1982) who found an increase of the estimated intracellular cAMP concentration from 0.3 PM to 1.2 WM.…”

Section: Discussionsupporting

confidence: 93%

Cyclic AMP and the Stimulation of Trehalase Activity in the Yeast Saccharomyces cerevisiae by Carbon Sources, Nitrogen Sources and Inhibitors of Protein Synthesis

1985

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Addition of glucose to acetate-grown cells of Saccharomyces cerevisiae caused a rapid transient increase in the cAMP level followed by a 10-fold, transient increase in the activity of trehalase. Ethidium bromide and acridine analogues inhibited both glucose-induced responses in a similar way, confirming the role of the cAMP signal as the second messenger in the sugar-induced activation of trehalase. When nitrogen sources or protein synthesis inhibitors were added after the transient glucose-induced increase in the trehalase activity, a rapid reactivation of trehalase occurred. In this case, however, there was only a very small increase in the cAMP level, which appeared to be insignificant. When the nitrogen source or the protein synthesis inhibitor was added together with glucose, the trehalase activity remained high for a much longer time also without a significant effect on the cAMP level. When a membrane depolarizing agent was added together with the glucose, both the trehalase activity and the cAMP level remained high. Reversibility experiments in which trehalase was activated to different degrees also showed that for high sugar-induced trehalase activation a high cAMP level is needed, while nitrogen sources stimulate trehalase activity without affecting cAMP levels. In cell extracts, both cAMP and cGMP were able to activate trehalase, the latter however only at 10-fold higher concentrations. The cGMP level in vivo was about 10-fold lower than the cAMP level and was not significantly affected by nitrogen sources or protein synthesis inhibitors. Hence, neither cAMP nor cGMP seem to be involved as the second messenger in the stimulating effect of nitrogen sources and protein synthesis inhibitors on trehalase activity in yeast. Since all other evidence obtained here and before strongly points to regulation of trehalase by a 'cAMP-dependent' protein kinase, we suggest that the presence of a nitrogen source in the growth medium of yeast induces the rapid synthesis of an alternative second messenger able to activate this or another protein kinase.

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Section: Discussionsupporting

confidence: 93%

Cyclic AMP and the Stimulation of Trehalase Activity in the Yeast Saccharomyces cerevisiae by Carbon Sources, Nitrogen Sources and Inhibitors of Protein Synthesis

1985

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“…In S. cerevisiae there is no evidence showing that K increases the cAMP levels. It is important to say at this point that we did not find any trehalase activation by 200 mM K + (Table 1) and that Tortora et al [13] utilize 100 mM potassium phosphate buffer pH 6.0 in the media before the addition of glucose to determine the CAMP-dependent glucose-induced inactivation of various yeast gluconeogenetic enzymes. These findings, together with the data in Table 1 and Figs.…”

Section: Discussionmentioning

confidence: 77%

Trehalase activation in yeasts is mediated by an internal acidification

et al. 1986

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It has been reported that the addition of glucose, uncouplers and nystatin to yeast cells grown in a sugarfree medium causes trehalase activation; it has been postulated that this activation might be mediated by the depolarization of the plasma membrane. In this article the values of membrane potential and pH gradient across the plasma membrane of Saccharomyces cerevisiae have been determined under the same conditions as those in which trehalase is activated. Membrane potential was evaluated from the distribution of triphenylmethylphosphonium, the pH gradient from the distribution of benzoic acid across the plasma membrane. When the effect of several agents on the two components of the electrochemical proton gradient across the plasma membrane of ethanol-grown yeast cells were studied, under trehalase activation conditions, the following observations were made. (a) The addition of glucose activated trehalase and caused internal acidification of the cells, but had practically no effect on the membrane potential. (b) The addition of 200 mM KCI depolarized the cell membrane but did not affect the internal pH, nor trehalase activity. (c) Although carbonyl cyanide mchlorophenylhydrazone depolarized the cells at external pH 6.0 and 7.0, it only activated trehalase at an external pH 6.0, leading to the acidification of the internal medium at this pH. (d) Nystatin caused an increase in the triphenylmethylphosphonium accumulation at external pH 6.0 and 7.0, but only activated trehalase at external pH 6.0, causing acidification of the cell interior at this pH. (e) Activation of trehalase was also observed when the internal acidification was caused by addition of a weak acid such as acetate. It is concluded that trehalase activation is mediated by an intracellular acidification and is independent of the membrane potential.It has been established by several authors that glucose, proton conductors and nystatin cause trehalose breakdown [l], gluconeogenesis inhibition [2, 31 and glycolysis stimulation [4] in Succharomyces cerevisiae. The regulatory effects of these agents is believed to be mediated by an increase in the levels of intracellular CAMP which leads to an activation of the CAMP-dependent protein kinase. This enzyme causes the subsequent activation of trehalase and phosphofructo-2-kinase and the partial inactivation of fructose-l,6-bisphosphatase among other enzymes [l -41. It has been postulated that the increase in internal CAMP is caused by the depolarization of the plasma membrane, since glucose, uncouplers and nystatin produce rapid depolarization in Neurospora crama [5, 61. Although these agents elicited an increase of the CAMP levels in several yeast strains [2 -51, proof of a direct relationship between changes in membrane potential ( A y ) and fluctuations in CAMP concentrations in S. cerevisiue is still lacking. Proton conductors and nystatin [7] are known to cause an influx of protons which could affect both parameters of the electrochemical proton gradient. Therefore, the increase in internal CAMP leve...

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“…Most experiments showing increases in cAMP levels (Maz6n et al, 1982;Tortora et a/., 1983;Franqois et a/., 1984) and the subsequent modification of FBPase (Mazbn el a/., 1982), trehalase (Franqois et a/., 1984) and various other enzymes (Tortora et a/., 1983;Franqois et a/., 1984;Caspani et al, 1985) have been done with glucose-grown cells collected at the stationary phase and suspended in a medium with K+. Thus, it was important to determine whether reversal of glucose-induced acidification was necessary to obtain the CAMP-dependent enzyme modification.…”

Section: R E S U L T Smentioning

confidence: 97%

External K+ Affects the Internal Acidification Caused by the Addition of Glucose to Yeast Cells

Valle

Bergillos²,

Ramos³

1987

Microbiology

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In glucose-grown cells of Saccharomyces cerevisiae, collected during the stationary phase of growth, the addition of K+ to the external medium reversed glucose-induced internal acidification in 2 min. However, in ethanol-grown cells external K+ did not reverse the effect of glucose even after 20 min. The presence or absence of external K+ did not alter the modification of trehalase and fructose-1,6-bisphosphatase induced by glucose. It is concluded that transient acidification may be sufficient to cause the associated transient increase in cAMP.

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Dependence on cyclic AMP of glucose‐induced inactivation of yeast gluconeogenetic enzymes

Abstract: and keywords not received

Cited by 29 publications

References 21 publications

Cyclic AMP and the Stimulation of Trehalase Activity in the Yeast Saccharomyces cerevisiae by Carbon Sources, Nitrogen Sources and Inhibitors of Protein Synthesis

Cyclic AMP and the Stimulation of Trehalase Activity in the Yeast Saccharomyces cerevisiae by Carbon Sources, Nitrogen Sources and Inhibitors of Protein Synthesis

Trehalase activation in yeasts is mediated by an internal acidification

External K+ Affects the Internal Acidification Caused by the Addition of Glucose to Yeast Cells

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