role of hexose transport and phosphorylation in cAMP signalling in the yeast Saccharomyces cerevisiae

• Published in: FEMS yeast research 2001-04, Vol.1 (1), p.33-45
• Main Authors: Rolland, Filip, Wanke, Valeria, Cauwenberg, Liesbet, Ma, Pingsheng, Boles, Eckhard, Vanoni, Marco, de Winde, Johannes H, Thevelein, Johan M, Winderickx, Joris
• Format: Article
• Language: English
• Subjects: acidification; adenosine triphosphate; Biological Transport; cAMP; cyclic AMP; Cyclic AMP - metabolism; Fungal Proteins - metabolism; G-protein coupled receptors; Gal2 protein; Gene Expression Regulation, Fungal; glucose; Glucose - metabolism; Glucose phosphorylation; Glucose transport; GPCR system; GTP-Binding Protein alpha Subunits; Heterotrimeric GTP-Binding Proteins - metabolism; hexokinase; Hexokinase - metabolism; hexose transport; Hydrogen-Ion Concentration; hydrolysis; Intracellular acidification; maltose; metabolism; permease; Phosphorylation; phosphotransferases (kinases); Receptors, Cell Surface - metabolism; Receptors, G-Protein-Coupled; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Signal Transduction; yeasts
• ISSN: 1567-1356; 1567-1364
• DOI: 10.1111/j.1567-1364.2001.tb00011.x

Glucose-induced cAMP signalling in Saccharomyces cerevisiae requires extracellular glucose detection via the Gpr1-Gpa2 G-protein coupled receptor system and intracellular glucose-sensing that depends on glucose uptake and phosphorylation. The glucose uptake requirement can be fulfilled by any glucose carrier including the Gal2 permease or by intracellular hydrolysis of maltose. Hence, the glucose carriers do not seem to play a regulatory role in cAMP signalling. Also the glucose carrier homologues, Snf3 and Rgt2, are not required for glucose-induced cAMP synthesis. Although no further metabolism beyond glucose phosphorylation is required, neither Glu6P nor ATP appears to act as metabolic trigger for cAMP signalling. This indicates that a regulatory function may be associated with the hexose kinases. Consistently, intracellular acidification, another known trigger of cAMP synthesis, can bypass the glucose uptake requirement but not the absence of a functional hexose kinase. This may indicate that intracellular acidification can boost a downstream effect that amplifies the residual signal transmitted via the hexose kinases when glucose uptake is too low.