Role of Tos3, a Snf1 protein kinase kinase, during growth of Saccharomyces cerevisiae on nonfermentable carbon sources
Role of Tos3, a Snf1 protein kinase kinase, during growth of Saccharomyces cerevisiae on nonfermentable carbon sources
复制标题
DOI：
10.1128/ec.4.5.861-866.2005
复制
发表时间：
2005-05-01
期刊：
影响因子：
--
通讯作者：
Carlson, M
中科院分区：
文献类型：
--
作者：
Kim, MD;Hong, SP;Carlson, M
在酿酒酵母（Saccharomyces cerevisiae）中，Snf1/AMP激活的蛋白激酶家族的Snf1蛋白激酶是在不可发酵碳源和非首选糖类上生长所必需的。三种激酶Pak1、Elm1和Tos3通过磷酸化其激活环苏氨酸激活Snf1，并且这三种激酶全部缺失会导致Snf（-）表型。此前尚未有关于tos3Δ单突变的表型报道。我们在此表明，当细胞在甘油 - 乙醇上生长时，tos3Δ会降低生长速率、Snf1催化活性以及糖异生基因启动子中依赖于Snf1的碳源响应元件（CSRE）的激活。相反，在葡萄糖突然耗尽期间，tos3Δ并未显著影响Snf1催化活性或CSRE功能，这表明在不可发酵碳源上生长时，Tos3在激活Snf1蛋白激酶方面比在急性碳胁迫期间具有更重要的作用。我们还报道，在葡萄糖或甘油 - 乙醇中生长时，Tos3定位在细胞质中。这些发现支持了这样一种观点，即Snf1蛋白激酶激酶在不同生长条件下对细胞调节有不同的贡献。
In Saccharomyces cerevisiae, Snf1 protein kinase of the Snf1/AMP-activated protein kinase family is required for growth on nonfermentable carbon sources and nonpreferred sugars. Three kinases, Pak1, Elm1, and Tos3, activate Sun by phosphorylation of its activation-loop threonine, and the absence of all three causes the Snf(-) phenotype. No phenotype has previously been reported for the tos3 Delta single mutation. We show here that, when cells are grown on glycerol-ethanol, tos3 Delta reduces growth rate, Snf1 catalytic activity, and activation of the Snf1-dependent carbon source-responsive element (CSRE) in the promoters of gluconeogenic genes. In contrast, tos3 Delta did not significantly affect Sun catalytic activity or CSRE function during abrupt glucose depletion, indicating that Tos3 has a more substantial role in activating Snf1 protein kinase during growth on a nonfermentable carbon source than during acute carbon stress. We also report that Tos3 is localized in the cytosol during growth in either glucose or glycerol-ethanol. These findings lend support to the idea that the Snf1 protein kinase kinases make different contributions to cellular regulation under different growth conditions.