Abstract

Fission yeast (Schizosaccharomyces pombe) is used as a platform for analyzing the activity of heterologous G protein-coupled receptors (GPCR). This type of yeast has two GPCR systems; one for detecting pheromones, and another for detecting glucose. We previously reported on a green fluorescent protein (GFP) reporter system in fission yeast that evaluated ligand concentrations by measuring the activity of endogenous pheromones. In this paper, we describe the use of the GFP reporter system as a glucose receptor assay. We engineered yeast to express reporter plasmids in which the fbp1 promoter was fused with GFP. The expression of Fbp1 is inhibited by glucose, so the transformed cells expressed high levels of GFP in the absence of glucose. When the transformed yeast cells were cultured in varying concentrations of glucose, the level of GFP expression was dependent on ligand (glucose) concentration. This method enabled 10 µM glucose to be measured, and could be used as a glucose biosensor.