Transcriptomic profile of yeast cells lacking the high affinity K+-transport system

Potassium is the major intracellular cation in S. cerevisiae, which can be concentrated up to 200-300 mM even from relatively low potassium (< 1 mM) environments. This is achieved by mean of a high affinity K+-transport system encoded by the genes TRK1 and TRK2. Recently, our group became interested in the effects of sudden shortage of extracellular potassium. Transcriptomic analysis indicates that lack of potassium drastically alters sulfur metabolism (mainly Met and Cys metabolism), triggers an oxidative stress response and activates the mitochondrial retrograde pathway. We also observe a dramatic halt in the expression of genes required for ribosome biogenesis and translation, as well as decrease in expression of diverse genes (cyclins, protein kinases) required for progression through the cell cycle. Only subsets of these changes were observed in a strain deleted for the TRK1 and TRK2 genes growing in the presence of sufficient potassium (50 mM). Research involving molecular genetics and metabolomic approaches aiming to clarify the primary targets for potassium requirements is currently ongoing. We compare the expression profile of two yeast strains: WT and trk1 trk2 double mutant, growing in a Translucent K-free medium containing 50 mM KCl until OD600 = 0.6. Two independent experiments were performed, and for each experiment a dye-swap was carried out. Total number of chips analyzed: 4.钾是酿酒酵母（S. cerevisiae）内主要的细胞内阳离子，即便在钾浓度低于1 mM的低钾环境中，酵母仍可将胞内钾富集至200~300 mM。这一过程由TRK1与TRK2基因编码的高亲和力钾转运系统介导完成。近期，本研究团队聚焦于胞外钾离子突然匮乏所引发的生物学效应。转录组学分析结果显示，钾缺失会显著改变硫代谢途径（主要涉及甲硫氨酸（Met）与半胱氨酸（Cys）代谢），触发氧化应激应答，并激活线粒体逆行通路。本研究同时观察到，核糖体生物发生与翻译过程相关基因的表达出现显著下调，且参与细胞周期进程的各类基因（如细胞周期蛋白、蛋白激酶）的表达水平均有所降低。而在钾离子充足（50 mM）的环境中培养的TRK1与TRK2双基因缺失菌株内，仅能观测到上述变化中的部分效应。目前，本团队正采用分子遗传学与代谢组学手段，旨在阐明调控钾离子需求的核心作用靶点。本实验对比了两种酵母菌株的转录表达谱：野生型（WT）与trk1 trk2双突变体，两种菌株均在添加了50 mM氯化钾的无钾透明培养基中培养至OD600=0.6。实验共开展两次独立重复，且每次实验均进行了染料互换（dye-swap）操作，最终共计分析4张基因芯片。