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Molecular cloning of a gene involved in glucose sensing in the yeast Saccharomyces cerevisiae (1993)

Aelst, Linda ; Hohmann, Stefan ; Bulaya, Botchaka ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Molecular microbiology 8 (1993), S. 0

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ISSN: 1365-2958

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology , Medicine

Notes: Cells of the yeast Saccharomyces cerevisiae display a wide range of glucose-induced regulatory phenomena, including glucose-induced activation of the RAS-adenylate cyclase pathway and phosphatidylinositol turnover, rapid post-translational effects on the activity of different enzymes as well as long-term effects at the transcriptional level. A gene called GGS1 (for General Glucose Sensor) that is apparently required for the glucose-induced regulatory effects and several ggs1 alleles (fdp1, byp1 and cif1) has been cloned and characterized. A GGS1 homologue is present in Methanobacterium thermoautotrophicum. Yeast ggs1 mutants are unable to grow on glucose or related readily fermentable sugars, apparently owing to unrestricted influx of sugar into glycolysis, resulting in its rapid deregulation. Levels of intracellular free glucose and metabolites measured over a period of a few minutes after addition of glucose to cells of a ggsi1Δ strain are consistent with our previous suggestion of a functional interaction between a sugar transporter, a sugar kinase and the GGS1 gene product. Such a glucose-sensing system might both restrict the influx of glucose and activate several signal transduction pathways, leading to the wide range of glucose-induced regulatory phenomena. Deregulation of these pathways in ggs1 mutants might explain phenotypic defects observed in the absence of glucose, e.g. the inability of ggs1 diploids to sporulate.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-2958.1993.tb01638.x

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The growth and signalling defects of the ggs1 (fdp1/byp1) deletion mutant on glucose are suppressed by a deletion of the gene encoding hexokinase PII (1993)

Hohmann, Stefan ; Neves, Maria José ; Koning, Wim ; [et al.]

Springer

Current genetics 23 (1993), S. 281-289

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ISSN: 1432-0983

Keywords: Yeast ; Glycolysis ; Glucose sensor ; Hexokinase ; Trehalose ; Signalling

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Yeast cells defective in the GGS1 (FDP1/BYP1) gene are unable to adapt to fermentative metabolism. When glucose is added to derepressed ggs1 cells, growth is arrested due to an overloading of glycolysis with sugar phosphates which eventually leads to a depletion of phosphate in the cytosol. Ggs1 mutants lack all glucose-induced regulatory effects investigated so far. We reduced hexokinase activity in ggs1 strains by deleting the gene HXK2 encoding hexokinase PII. The double mutant ggs1Δ, hxk2Δ grew on glucose. This is in agreement with the idea that an inability of the ggs1 mutants to regulate the initiation of glycolysis causes the growth deficiency. However, the ggs1Δ, hxk2Δ double mutant still displayed a high level of glucose-6-phosphate as well as the rapid appearance of free intracellular glucose. This is consistent with our previous model suggesting an involvement of GGS1 in transport-associated sugar phosphorylation. Glucose induction of pyruvate decarboxylase, glucoseinduced cAMP-signalling, glucose-induced inactivation of fructose-1,6-bisphosphatase, and glucose-induced activation of the potassium transport system, all deficient in ggs1 mutants, were restored by the delection of HXK2. However, both the ggs1Δ and the ggs1Δ, hk2Δ mutant lack detectable trehalose and trehalose-6-phosphate synthase activity. Trehalose is undetectable even in ggs1Δ strains with strongly reduced activity of protein kinase A which normally causes a very high trehalose content. These data fit with the recent cloning of GGS1 as a subunit of the trehalose-6-phosphate synthase/phosphatase complex. We discuss a possible requirement of trehalose synthesis for a metabolic balance of sugar phosphates and free inorganic phosphate during the transition from derepressed to fermentative metabolism.