Morishima N, Nakagawa K, Yamamoto E, Shibata T
Laboratory of Microbiology, Riken Institute, Saitama, Japan.
J Biol Chem. 1990 Sep 5;265(25):15189-97.
Endo.SceI of Saccharomyces cerevisiae is a heterodimeric site-specific endonuclease, which is distinguishable from prokaryotic restriction endonucleases in the mode of recognition of its cleavage site. We have used monoclonal antibodies specific to the larger subunit (75 kDa) of Endo.SceI to isolate the gene for the subunit (ENS1) from S. cerevisiae. Unexpectedly, ENS1 was found to encode a 70-kDa heat shock protein-related polypeptide and to be identical to recently cloned SSC1. Subcellular fractionation experiments on yeast cells revealed that the primary target site of the larger subunit is mitochondria, where almost all the Endo.SceI activity is localized. Molecular genetic analysis of ENS1 demonstrated its indispensability for growth and the requirement of a high level of its expression at the sporulation and germination stages. The data suggest that ENS1 plays an important role, especially at these differentiation stages.
酿酒酵母的内切核酸酶Endo.SceI是一种异源二聚体位点特异性内切核酸酶，在识别其切割位点的模式上与原核限制性内切核酸酶不同。我们使用了对Endo.SceI较大亚基（75 kDa）特异的单克隆抗体，从酿酒酵母中分离出该亚基的基因（ENS1）。出乎意料的是，发现ENS1编码一种70 kDa的热休克蛋白相关多肽，并且与最近克隆的SSC1相同。对酵母细胞进行的亚细胞分级分离实验表明，较大亚基的主要靶位点是线粒体，几乎所有的Endo.SceI活性都定位于此。对ENS1的分子遗传学分析表明，它对生长是不可或缺的，并且在孢子形成和萌发阶段需要高水平表达。数据表明ENS1发挥着重要作用，尤其是在这些分化阶段。
