0.2 mM As(III) stressed yap1 deletion mutant vs 0.2 mM As(III) stressed wild-type after 1 hour . Saccharomyces cerevisiae

Arsenic is ubiquitously present in nature and various mechanisms have evolved enabling cells to evade toxicity and acquire tolerance. Herein, we explored how Saccharomyces cerevisiae (budding yeast) respond to trivalent arsenic (arsenite) by quantitative and kinetic transcriptome, proteome and sulfur metabolite profiling. Arsenite exposure affected transcription of genes encoding functions related to protein biosynthesis, arsenic detoxification, oxidative stress defense, redox maintenance and proteolytic activity. Importantly, enzymes involved in sulfate assimilation and glutathione biosynthesis were induced at both gene and protein levels. Kinetic metabolic profiling evidenced a significant increase in the pools of sulfur metabolites as well as elevated glutathione levels. Moreover, the flux in the sulfur assimilation pathway as well as the glutathione synthesis rate strongly increased with a concomitant reduction of sulfur incorporation into proteins. By combining comparative genomics and molecular analyses, we pin-pointed transcription factors that mediate thecore of the transcriptional response to arsenite. Taken together, our data reveals that arsenite-exposed cells channel a large part of assimilated sulfur into glutathione biosynthesis and we provide evidence that the transcriptional regulators Yap1p and Met4p control this response in concert. Keywords: stress Overall design: Direct comparisons

砷在自然界中广泛分布，生物体已演化出多种机制以规避砷的毒性并获得耐受性。本研究通过定量转录组、蛋白质组与硫代谢物动力学谱分析，探究酿酒酵母（Saccharomyces cerevisiae，又称出芽酵母）对三价砷（亚砷酸盐，arsenite）的应答过程。亚砷酸盐暴露会影响编码以下功能相关基因的转录：蛋白质生物合成、砷解毒、氧化应激防御、氧化还原稳态维持及蛋白水解活性。尤为重要的是，参与硫酸盐同化与谷胱甘肽生物合成的酶在基因与蛋白水平均被诱导表达。动力学代谢谱分析结果显示，硫代谢物池显著扩大，谷胱甘肽水平亦随之升高。此外，硫酸盐同化通路的代谢通量与谷胱甘肽合成速率均显著提升，同时硫向蛋白质中的掺入量随之减少。本研究结合比较基因组学与分子分析手段，精准鉴定出介导亚砷酸盐应答核心转录调控过程的转录因子。综上，本研究数据表明，暴露于亚砷酸盐的细胞会将大部分同化而来的硫导向谷胱甘肽生物合成；同时我们证实，转录调控因子Yap1p与Met4p可协同调控该应答过程。关键词：应激；整体设计：直接对比分析