Analysis of the pyruvate permease gene (JEN1) in glucose derepression yeast (Saccharomyces cerevisiae) isolated from a 2-deoxyglucose-tolerant mutant, and its application to sake making

We isolated mutants of S. cereviside in which expression of the JEN1 gene encoding a pyruvate transporter was insensitive to glucose repression. The isolated mutant GDR19 expressed JEN1 and absorbed pyruvate in the presence of glucose. In a DNA microarray analysis, GDR19 highly expressed many more genes, including JEN1, in the presence of glucose compared with the parental strain B29. Some of these genes are under the control of the transcription factor Mig1p and are normally repressed in the presence of glucose. The concentrations of organic acids in sake made with GDR19 were different from those in sake made with B29. Changes in the pyruvate concentration in the sake mash made with GDR19 were not very different from those in sake mash made with B29, and both GDR19 and B29 expressed JEN1 during fermentation. When the ethanol concentration was over 2%, JEN1 expression in B29 was similar in the presence and absence of glucose. The expression of JEN1 in sake mash in spite of the presence of glucose appeared to be caused by the coexistence of ethanol.