Adenylate cyclase activity in permeabilised yeast

Varimo, Kaija; Londesborough, John

doi:10.1016/0014-5793(82)80153-1

Cited by 6 publications

(1 citation statement)

References 21 publications

(25 reference statements)

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“…When the ATP level drops, the intracellular pH will inevitably also drop. The synthesis of cAMP under these conditions will be limited by the low ATP level, probably because the K m of adenylate cyclase is relatively high (2–5 mM in the physiological pH range of 6.4–7.5) (Varimo and Londesborough, 1982). Evidence has been provided for this possibility previously with the demonstration that glucose‐repressed cells suspended in buffer were unable to increase their cAMP level when challenged with a protonophore causing intracellular acidification, but rapidly responded when a small amount of glucose was added just before the protonophore (Argüelles et al ., 1990).…”

Section: Discussionmentioning

confidence: 99%

Involvement of distinct G-proteins, Gpa2 and Ras, in glucose-and intracellular acidification-induced cAMP signalling in the yeast Saccharomyces cerevisiae

et al. 1998

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S.Colombo and P.Ma contributed equally to this workAdenylate cyclase activity in Saccharomyces cerevisiae is dependent on Ras proteins. Both addition of glucose to glucose-deprived (derepressed) cells and intracellular acidification trigger an increase in the cAMP level in vivo. We show that intracellular acidification, but not glucose, causes an increase in the GTP/GDP ratio on the Ras proteins independent of Cdc25 and Sdc25. Deletion of the GTPase-activating proteins Ira1 and Ira2, or expression of the RAS2 val19 allele, causes an enhanced GTP/GDP basal ratio and abolishes the intracellular acidification-induced increase. In the ira1Δ ira2Δ strain, intracellular acidification still triggers a cAMP increase. Glucose also did not cause an increase in the GTP/GDP ratio in a strain with reduced feedback inhibition of cAMP synthesis. Further investigation indicated that feedback inhibition by cAPK on cAMP synthesis acts independently of changes in the GTP/GDP ratio on Ras. Stimulation by glucose was dependent on the Gα-protein Gpa2, whose deletion confers the typical phenotype associated with a reduced cAMP level: higher heat resistance, a higher level of trehalose and glycogen and elevated expression of STRE-controlled genes. However, the typical fluctuation in these characteristics during diauxic growth on glucose was still present. Overexpression of Ras2 val19 inhibited both the acidification-and glucose-induced cAMP increase even in a protein kinase A-attenuated strain. Our results suggest that intracellular acidification stimulates cAMP synthesis in vivo at least through activation of the Ras proteins, while glucose acts through the Gpa2 protein. Interaction of Ras2 val19 with adenylate cyclase apparently prevents its activation by both agonists.

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Section: Discussionmentioning

confidence: 99%

Involvement of distinct G-proteins, Gpa2 and Ras, in glucose-and intracellular acidification-induced cAMP signalling in the yeast Saccharomyces cerevisiae

et al. 1998

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Effect of ozone on ATP, cytosolic enzymes and permeability of Saccharomyces cerevisiae

1987

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Treatment of a yeast suspension with ozone inactivates a number of cytosolic enzymes. Among 15 studied, the most drastic inactivation was found for glyceraldehyde-3-phosphate dehydrogenase and to lesser extents: NAD-glutamate dehydrogenase, pyruvate decarboxylase, phosphofructokinase-1 and NAD-alcohol dehydrogenase. Ozone treatment also effects the quantity of ATP and of other nucleoside triphosphates, reducing to about 50% of the initial value. The ATP missing in the cells appears in the medium. NAD and protein also accumulate in the medium suggesting that the yeast cells have been permeabilized. Permeabilization of the yeast cells by treatment with ozone precedes the inactivation of glyceraldehyde-3-phosphate dehydrogenase and other cytosolic enzymes.

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Guanine nucleotide regulation of adenylate cyclase in permeabilized cells of Saccharomyces cerevisiae

Becker

Enari

Levitzki

1988

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

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Adenylate cyclase activity in permeabilised yeast

Cited by 6 publications

References 21 publications

Involvement of distinct G-proteins, Gpa2 and Ras, in glucose-and intracellular acidification-induced cAMP signalling in the yeast Saccharomyces cerevisiae

Involvement of distinct G-proteins, Gpa2 and Ras, in glucose-and intracellular acidification-induced cAMP signalling in the yeast Saccharomyces cerevisiae

Effect of ozone on ATP, cytosolic enzymes and permeability of Saccharomyces cerevisiae

Guanine nucleotide regulation of adenylate cyclase in permeabilized cells of Saccharomyces cerevisiae

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