Unique <scp>SNPs</scp> in the promoter of the peptide transporter gene <scp> <i>PTR2</i> </scp> increase its expression in the <i>Saccharomyces cerevisiae</i> sake strain

Although the mechanism of action of the tripeptide-like herbicide bialaphos is well understood, its cellular uptake process remains elusive. We report that a peptide transporter mediates its uptake in Saccharomyces cerevisiae. The Japanese sake yeast strain Kyokai 7 (K7) was supersensitive to bialaphos compared to S288C. Disruption of PTR2, which encodes a peptide transporter, alleviated bialaphos sensitivity in K7. PTR2 mRNA and protein levels were higher in K7 than in S288C. Higher expression levels were observed in the S288C strain when Ptr2 was expressed using the K7-derived genomic promoter of PTR2. We identified single-nucleotide polymorphisms (SNPs) in the PTR2 promoter responsible for the increased expression levels. One of the critical SNPs was specifically found in sake strains of K7-lineage.