1.0 mM As(III) stressed wild-type vs (non-stressed) wild-type after 1 hour

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 Stressed wild-type 1mM 1h versus untreated wild-type using 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能力。本研究通过定量与动态转录组（transcriptome）、蛋白质组（proteome）及硫代谢物谱分析，探究了酿酒酵母（Saccharomyces cerevisiae，即出芽酵母）对三价砷（亚砷酸盐，arsenite）的应答机制。亚砷酸盐暴露会影响编码蛋白质生物合成、砷解毒、氧化应激防御、氧化还原维持以及蛋白水解活性相关功能的基因的转录。值得注意的是，参与硫酸盐同化（sulfate assimilation）与谷胱甘肽（glutathione）生物合成的酶在基因与蛋白质水平均被诱导表达。动态代谢谱分析结果显示，硫代谢物池显著扩增，谷胱甘肽水平亦有所升高。此外，硫酸盐同化通路的代谢通量与谷胱甘肽合成速率显著提升，同时硫元素掺入蛋白质的比例随之降低。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的硫分流至谷胱甘肽生物合成途径；同时我们证实，转录调控因子Yap1p与Met4p可协同调控这一应答过程。关键词：应激；1mM亚砷酸盐处理1h的野生型与未处理野生型的直接对比分析