Role of the putative structural protein Sed1p in mitochondrial genome maintenance.
Role of the putative structural protein Sed1p in mitochondrial genome maintenance.
复制标题
假定的结构蛋白 Sed1p 在线粒体基因组维护中的作用。
DOI：
10.1016/j.jmb.2004.07.096
复制
发表时间：
2004
影响因子：
5.6
通讯作者：
AyresSia,Elaine
中科院分区：
文献类型：
--
作者：
Phadnis,Naina;AyresSia,Elaine
核基因MIP 1编码负责复制酿酒酵母中线粒体基因组的线粒体DNA聚合酶。许多其他因素参与复制和分离线粒体基因组尚未确定。在这里，我们报告说，细菌双杂交筛选线粒体聚合酶，Mip1p，作为诱饵确定酵母蛋白Sed1p。Sed1p是在稳定期高度表达的细胞表面蛋白。我们发现，Sed1p的几种修饰形式的表达和最大的这些形式在体外与线粒体聚合酶相互作用。SED1的缺失导致线粒体DNA点突变率增加3.5倍，呼吸丧失率增加4.3倍。相反，我们没有看到核点突变率的变化，表明Sed1p功能在线粒体基因组稳定性中的特定作用。Sed1p定位的间接免疫荧光分析表明，Sed1p是针对线粒体。此外，在纯化的线粒体组分中检测到Sed1p，并且最大修饰形式的线粒体定位对蛋白酶K的作用不敏感。sed1基因的缺失导致Mip1p的数量减少，也影响了卵巢表达蛋白Cox3p的水平。我们的研究结果指向Sed1p在线粒体基因组维护中的作用。
The nuclear gene MIP1 encodes the mitochondrial DNA polymerase responsible for replicating the mitochondrial genome in Saccharomyces cerevisiae. A number of other factors involved in replicating and segregating the mitochondrial genome are yet to be identified. Here, we report that a bacterial two-hybrid screen using the mitochondrial polymerase, Mip1p, as bait identified the yeast protein Sed1p. Sed1p is a cell surface protein highly expressed in the stationary phase. We find that several modified forms of Sed1p are expressed and the largest of these forms interacts with the mitochondrial polymerase in vitro. Deletion of SED1 causes a 3.5-fold increase in the rate of mitochondrial DNA point mutations as well as a 4.3-fold increase in the rate of loss of respiration. In contrast, we see no change in the rate of nuclear point mutations indicating the specific role of Sed1p function in mitochondrial genome stability. Indirect immunofluorescence analysis of Sed1p localization shows that Sed1p is targeted to the mitochondria. Moreover, Sed1p is detected in purified mitochondrial fractions and the localization to the mitochondria of the largest modified form is insensitive to the action of proteinase K. Deletion of the sed1 gene results in a reduction in the quantity of Mip1p and also affects the levels of a mitochondrially-expressed protein, Cox3p. Our results point towards a role for Sed1p in mitochondrial genome maintenance.