title: Differential regulation of glucose transport activity in yeast by specific cAMP signatures.
abstract: Successful colonization and survival in variable environments require a competitive advantage during the initial growth phase after experiencing nutrient changes. Starved yeast cells anticipate exposure to glucose by activating the Hxt5p (hexose transporter 5) glucose transporter, which provides an advantage during early phases after glucose resupply. cAMP and glucose FRET (fluorescence resonance energy transfer) sensors were used to identify three signalling pathways that co-operate in the anticipatory Hxt5p activity in glucose-starved cells: as expected the Snf1 (sucrose nonfermenting 1) AMP kinase pathway, but, surprisingly, the sugar-dependent G-protein-coupled Gpr1 (G-protein-coupled receptor 1)/cAMP/PKA (protein kinase A) pathway and the Pho85 (phosphate metabolism 85)/Plc (phospholipase C) 6/7 pathway. Gpr1/cAMP/PKA are key elements of a G-protein-coupled sugar response pathway that produces a transient cAMP peak to induce growth-related genes. A novel function of the Gpr1/cAMP/PKA pathway was identified in glucose-starved cells: during starvation the Gpr1/cAMP/PKA pathway is required to maintain Hxt5p activity in the absence of glucose-induced cAMP spiking. During starvation, cAMP levels remain low triggering expression of HXT5, whereas cAMP spiking leads to a shift to the high capacity Hxt isoforms.
authors.affiliation: Carnegie Institution for Science, 260 Panama Street, Stanford, CA 94305, USA.
authors.forename: Clara
authors.initials: C
authors.lastname: Bermejo
authors.forename: Farzad
authors.initials: F
authors.lastname: Haerizadeh
authors.forename: Mayuri S C
authors.initials: MS
authors.lastname: Sadoine
authors.forename: Diane
authors.initials: D
authors.lastname: Chermak
authors.forename: Wolf B
authors.initials: WB
authors.lastname: Frommer
mesh_terms: D000263:Adenylate Kinase / Q000502:physiology; D001693:Biological Transport, Active; D000242:Cyclic AMP / Q000737:chemistry* / Q000502:physiology; D005947:Glucose / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins / Q000378:metabolism / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
chemical_list: C466910:HXT5 protein, S cerevisiae; D009004:Monosaccharide Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; D000242:Cyclic AMP; D000263:Adenylate Kinase; D005947:Glucose