Differential regulation of glucose transport activity in yeast by specific cAMP signatures

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 glucose transporter, which provides an advantage during early phases after glucose resupply. cAMP and glucose FRET sensors helped identifying three signaling pathways that cooperate in the anticipatory Hxt5p activity in glucose-starved cells: expectedly the Snf1 AMP kinase pathway; surprisingly, the sugar-dependent G-protein-coupled Gpr1/cAMP/PKA pathway, and the Pho85/Plc6/7 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, while cAMP spiking leads to a shift to high capacity Hxt isoforms.
Source: BJ Cell - Category: Biochemistry Authors: Tags: BJ Signal Source Type: research