Transcriptomic shift in ethanol and amino acid metabolic genes regulated by Med15 during fermentation

Wine yeast are specialized strains that are adapted to survive in the wine making environment while producing high concentrations of ethanol. In addition to large genomic changes that differentiate wine yeast from yeast used in other industries, single nucleotide and polyglutamine tract polymorphisms in the transcriptional regulator Med15 are associated with the fermentation efficiency and stress response phenotypes of wine yeast. In this study we investigated the transcriptional differences during wine fermentation in transgenic lab strain yeast having integrated wine yeast MED15 alleles. Compared to the lab strain, a strain with a MED15 allele from a palm wine yeast strain, exhibited enhanced expression of glycolytic, fermentation, and amino acid biosynthesis genes. Our experimental data confirms the importance of arginine biosynthetic genes during the fermentation process and suggests that the improvement in fermentation efficiency in strains with MED15 alleles from wine yeast strains may be related to the role of Med15 in expression of the genes of the arginine biosynthetic pathway. The global benefit conferred by polymorphisms in a single transcriptional regulator, makes Med15 a prime target for engineering of strains devoted to various types of alcohol production.葡萄酒酵母是一类特化菌株，能够适应葡萄酒酿造环境并合成高浓度乙醇。除了使葡萄酒酵母与其他工业用酵母产生显著差异的大规模基因组变异外，转录调节因子Med15中的单核苷酸及聚谷氨酰胺束多态性，也与葡萄酒酵母的发酵效率及应激反应表型密切相关。本研究针对整合了葡萄酒酵母MED15等位基因的转基因实验室酵母菌株，探究其在葡萄酒发酵过程中的转录差异。与亲本实验室菌株相比，携带棕榈酒酵母MED15等位基因的菌株，其糖酵解、发酵及氨基酸生物合成相关基因的表达水平显著上调。本实验数据证实了精氨酸生物合成基因在发酵过程中的重要性，并表明携带葡萄酒酵母MED15等位基因的菌株发酵效率提升，可能与Med15在精氨酸生物合成通路基因表达中的调控作用相关。单个转录调节因子的多态性即可带来全局性的表型增益，这使得Med15成为针对各类酒精生产专用菌株进行基因工程改造的首选靶标。