Metabolic regulation rather than de novo enzyme synthesis dominates the osmo-adaptation of yeast
Metabolic regulation rather than de novo enzyme synthesis dominates the osmo-adaptation of yeast
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DOI：
10.1002/yea.1819
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发表时间：
2011-01-01
期刊：
影响因子：
2.6
通讯作者：
Bakker, Barbara M.
中科院分区：
文献类型：
--
作者：
Bouwman, Jildau;Kiewiet, Jose;Bakker, Barbara M.
甘油的胞内积累是酵母细胞在高渗胁迫下生存所必需的。在高渗胁迫下，甘油途径中的酶的基因表达被强烈诱导。然而，最近显示，这种基因表达应答对于渗透压休克的存活不是必需的[Mettetal JT et al.（2008）Science 319：482-484和Westfall PJ et al.（2008）Proc Natl Acad Sci 105：12212-12217]。相反，纯粹的代谢适应可以拯救酵母。两种替代机制的存在，促使这些机制占主导地位的野生型酵母在生理条件下的渗透胁迫的时间依赖性适应的问题。甘油途径的调节进行了分析，在有氧，葡萄糖限制的培养物后，添加1 M的山梨醇，导致高渗休克。与早期的研究一致，甘油产生酶的mRNA水平以及它们的催化能力增加。定性地，这种诱导遵循与甘油通量增加相似的时间过程。然而，数据的定量调控分析显示，最初的调节代谢单独。几分钟后，基因表达开始发挥作用，但即使在一小时后，80%的甘油流量增加是由细胞中的代谢变化解释的，20%是由基因表达诱导解释的。这表明这种新的代谢机制不仅仅是一种次要的拯救机制，而且是生理条件下调节甘油通量的最重要机制。版权所有（C）2010约翰威利父子有限公司
Intracellular accumulation of glycerol is essential for yeast cells to survive hyperosmotic stress. Upon hyperosmotic stress the gene expression of enzymes in the glycerol pathway is strongly induced. Recently, however, it was shown that this gene-expression response is not essential for survival of an osmotic shock [Mettetal JT et al. (2008) Science 319: 482-484 and Westfall PJ et al. (2008) Proc Natl Acad Sci 105: 12212-12217]. Instead, pure metabolic adaptation can rescue the yeast. The existence of two alternative mechanisms urged the question which of these mechanisms dominates time-dependent adaptation of wild-type yeast to osmotic stress under physiological conditions. The regulation of the glycerol pathway was analysed in aerobic, glucose-limited cultures upon addition of 1 M of sorbitol, leading to a hyperosmotic shock. In agreement with earlier studies, the mRNA levels of the glycerol-producing enzymes as well as their catalytic capacities increased. Qualitatively this induction followed a similar time course to the increase of the glycerol flux. However, a quantitative regulation analysis of the data revealed an initial regulation by metabolism alone. After only a few minutes gene expression came into play, but even after an hour, 80% of the increase in the glycerol flux was explained by metabolic changes in the cell, and 20% by induction of gene expression. This demonstrates that the novel metabolic mechanism is not just a secondary rescue mechanism, but the most important mechanism to regulate the glycerol flux under physiological conditions. Copyright (C) 2010 John Wiley & Sons, Ltd.