Evolutionary engineering of an iron-resistant Saccharomyces cerevisiae mutant and its physiological and molecular characterization. Saccharomyces cerevisiae strain:CEN.PK 113-7D

Iron plays an essential role in all organisms and is involved in the structure of many biomolecules. It also regulates the Fenton reaction where highly reactive hydroxyl radicals occur. Excessive iron levels can cause oxidative damage in cells. Saccharomyces cerevisiae evolved mechanisms to regulate its iron levels. To study the iron stress response of S. cerevisiae, evolutionary engineering was employed. The evolved iron stress-resistant mutant “M8FE” was analyzed physiologically, transcriptomically and by whole genome re-sequencing. M8FE showed cross-resistance to other transition metals: cobalt, chromium, and nickel. M8FE seemed to cope with the iron stress by both avoidance and sequestration strategies. PHO84, encoding the high-affinity phosphate transporter, was the most down-regulated gene in the mutant, and may play a crucial role in iron-resistance. M8FE had upregulated many oxidative stress response, reserve carbohydrate metabolism, and mitophagy genes; while ribosome biogenesis genes were downregulated. As a possible result of the induced oxidative stress response genes, lower intracellular oxidation levels were observed. M8FE also had high trehalose and glycerol production levels, with the GPH1, PGM2, and TSL1 genes upregulated. Genome re-sequencing analyses indicated mutations that emphasize the potential roles of phosphate transport and metabolism, cell wall, and multidrug resistance-related transcription factors.

铁元素在所有生物体中均发挥不可或缺的作用，并参与众多生物大分子的结构组成。它还可调控活性羟基自由基生成的芬顿反应（Fenton reaction）。细胞内铁水平过高则会引发氧化损伤。酿酒酵母（Saccharomyces cerevisiae）已演化出调控自身铁水平的机制。为探究酿酒酵母的铁胁迫响应机制，研究人员采用了进化工程手段。研究人员从生理学、转录组学以及全基因组重测序三个维度对获得的铁胁迫抗性突变株“M8FE”进行了分析。M8FE对钴（cobalt）、铬（chromium）、镍（nickel）等其他过渡金属均表现出交叉抗性。M8FE似乎通过规避和螯合两种策略应对铁胁迫。编码高亲和力磷酸盐转运蛋白（high-affinity phosphate transporter）的PHO84基因是该突变株中下调幅度最大的基因，可能在铁抗性中发挥关键作用。M8FE中众多氧化应激响应、储备碳水化合物代谢以及线粒体自噬（mitophagy）相关基因均出现上调，而核糖体生物发生（ribosome biogenesis）相关基因则呈现下调趋势。受诱导的氧化应激响应基因可能带来了这一结果：研究人员观察到突变株的细胞内氧化水平有所降低。M8FE的海藻糖（trehalose）与甘油（glycerol）生成水平较高，且GPH1、PGM2、TSL1基因均出现上调。全基因组重测序分析发现的突变位点，进一步凸显了磷酸盐转运与代谢、细胞壁以及多药耐药相关转录因子（multidrug resistance-related transcription factors）在该过程中的潜在作用。