PDF(Pubmed)
Abstract：
BACKGROUND: Organisms frequently experience environmental stresses that occur in predictable patterns and combinations. For wild Saccharomyces cerevisiae yeast growing in natural environments, cells may experience high osmotic stress when they first enter broken fruit, followed by high ethanol levels during fermentation, and then finally high levels of oxidative stress resulting from respiration of ethanol. Yeast have adapted to these patterns by evolving sophisticated \"cross protection\" mechanisms, where mild \'primary\' doses of one stress can enhance tolerance to severe doses of a different \'secondary\' stress. For example, in many yeast strains, mild osmotic or mild ethanol stresses cross protect against severe oxidative stress, which likely reflects an anticipatory response important for high fitness in nature.
RESULTS: During the course of genetic mapping studies aimed at understanding the mechanisms underlying natural variation in ethanol-induced cross protection against H2O2, we found that a key H2O2 scavenging enzyme, cytosolic catalase T (Ctt1p), was absolutely essential for cross protection in a wild oak strain. This suggested the absence of other compensatory mechanisms for acquiring H2O2 resistance in that strain background under those conditions. In this study, we found surprising heterogeneity across diverse yeast strains in whether CTT1 function was fully necessary for acquired H2O2 resistance. Some strains exhibited partial dispensability of CTT1 when ethanol and/or salt were used as mild stressors, suggesting that compensatory peroxidases may play a role in acquired stress resistance in certain genetic backgrounds. We leveraged global transcriptional responses to ethanol and salt stresses in strains with different levels of CTT1 dispensability, allowing us to identify possible regulators of these alternative peroxidases and acquired stress resistance in general.
CONCLUSIONS: Ultimately, this study highlights how superficially similar traits can have different underlying molecular foundations and provides a framework for understanding the diversity and regulation of stress defense mechanisms.
RESULTS: During the course of genetic mapping studies aimed at understanding the mechanisms underlying natural variation in ethanol-induced cross protection against H2O2, we found that a key H2O2 scavenging enzyme, cytosolic catalase T (Ctt1p), was absolutely essential for cross protection in a wild oak strain. This suggested the absence of other compensatory mechanisms for acquiring H2O2 resistance in that strain background under those conditions. In this study, we found surprising heterogeneity across diverse yeast strains in whether CTT1 function was fully necessary for acquired H2O2 resistance. Some strains exhibited partial dispensability of CTT1 when ethanol and/or salt were used as mild stressors, suggesting that compensatory peroxidases may play a role in acquired stress resistance in certain genetic backgrounds. We leveraged global transcriptional responses to ethanol and salt stresses in strains with different levels of CTT1 dispensability, allowing us to identify possible regulators of these alternative peroxidases and acquired stress resistance in general.
CONCLUSIONS: Ultimately, this study highlights how superficially similar traits can have different underlying molecular foundations and provides a framework for understanding the diversity and regulation of stress defense mechanisms.
摘要：
背景：生物经常经历以可预测的模式和组合发生的环境压力。对于在自然环境中生长的野生酿酒酵母，当细胞第一次进入破碎的果实时，它们可能会经历高渗透胁迫，其次是发酵过程中的高乙醇水平，最后是乙醇呼吸导致的高水平氧化应激。酵母通过发展复杂的“交叉保护”机制适应了这些模式，其中轻度的“初级”剂量的一种压力可以增强对严重剂量的不同“次级”压力的耐受性。例如,在许多酵母菌株中，轻度渗透或轻度乙醇胁迫交叉保护免受严重的氧化应激，这可能反映了预期的反应对自然界的高适应性很重要。
结果：在旨在了解乙醇诱导的H2O2交叉保护天然变异的机制的遗传作图研究过程中，我们发现了一种关键的H2O2清除酶，胞质过氧化氢酶T（Ctt1p），对于野生橡树株的交叉保护是绝对必要的。这表明在那些条件下,在该菌株背景中不存在用于获得H2O2抗性的其他补偿机制。在这项研究中,我们发现，在不同的酵母菌株中，CTT1功能是否是获得性H2O2抗性所必需的，存在令人惊讶的异质性。当乙醇和/或盐用作轻度应激源时，一些菌株表现出CTT1的部分可分配性，这表明在某些遗传背景下，补偿性过氧化物酶可能在获得性胁迫抗性中起作用。我们利用了具有不同CTT1可分配性水平的菌株对乙醇和盐胁迫的全局转录反应，使我们能够确定这些替代过氧化物酶的可能调节因子和获得的一般应激抗性。
结论：最终，这项研究强调了表面相似的性状如何具有不同的潜在分子基础，并为理解压力防御机制的多样性和调节提供了一个框架。
结果：在旨在了解乙醇诱导的H2O2交叉保护天然变异的机制的遗传作图研究过程中，我们发现了一种关键的H2O2清除酶，胞质过氧化氢酶T（Ctt1p），对于野生橡树株的交叉保护是绝对必要的。这表明在那些条件下,在该菌株背景中不存在用于获得H2O2抗性的其他补偿机制。在这项研究中,我们发现，在不同的酵母菌株中，CTT1功能是否是获得性H2O2抗性所必需的，存在令人惊讶的异质性。当乙醇和/或盐用作轻度应激源时，一些菌株表现出CTT1的部分可分配性，这表明在某些遗传背景下，补偿性过氧化物酶可能在获得性胁迫抗性中起作用。我们利用了具有不同CTT1可分配性水平的菌株对乙醇和盐胁迫的全局转录反应，使我们能够确定这些替代过氧化物酶的可能调节因子和获得的一般应激抗性。
结论：最终，这项研究强调了表面相似的性状如何具有不同的潜在分子基础，并为理解压力防御机制的多样性和调节提供了一个框架。
