REGULATION OF MITOCHONDRIAL INHERITANCE IN YEAST

线粒体不能从头合成;相反，新形成的子体 细胞必须从母细胞继承线粒体， 师. 虽然线粒体的代谢功能一直是 经过广泛的研究，对分子机制知之甚少 控制线粒体的传递 最近，一个重要的类 基因（称为MDM的“线粒体分布和形态”）， 通过使用温度敏感的突变体， 在酵母出芽过程中破坏线粒体遗传。 的精确 这些基因产物的功能尚不清楚。 除两 这些MDM基因由单突变等位基因代表，表明 线粒体分配装置的其它组分保留 待鉴定 我们已经确定了八个新的基因， 转移到新形成的子细胞中。 我们提出 研究酵母线粒体分配的分子基础， 这8种新MDM的遗传、分子和生化特征 基因和它们编码的蛋白质。 首先，我们将结合使用 活体染色、间接免疫荧光和电子显微镜检查， 表征线粒体遗传和形态缺陷的范围 是由MDM基因突变引起的 第二，野生型和突变体等位基因 对这8个MDM基因进行克隆、测序和分析。 该分析 将使我们能够识别任何重要的结构基序和功能 预测蛋白质中的结构域。 第三，使用间接 免疫荧光和细胞分级分离实验，以确定 Mdm蛋白的亚细胞定位。 第四，分析 在MDM突变体中减数分裂期间的线粒体分配。 这些研究 将使我们能够确定Mdm蛋白是否介导线粒体 在减数分裂和有丝分裂过程中的运动，并可能揭示细节 在有丝分裂中不能容易地观察到的线粒体分配 分裂细胞 我们提出的实验将为未来的分子， Mdm蛋白功能的生化和遗传分析。 在漫长的- 这些研究应该有助于我们基本了解 细胞周期中线粒体运动的分子机制 在其他生物的早期发育过程中。

Mitochondria cannot be synthesized de novo; instead, newly-formed daughter cells must inherit their mitochondria from the mother cell during division. Although the metabolic functions of mitochondria have been extensively studied, very little is known about the molecular mechanisms controlling mitochondrial transmission. Recently, an important class of genes (termed MDM for "mitochondrial distribution and morphology") has been identified through the use of temperature-sensitive mutants that disrupt mitochondrial inheritance during yeast budding. The precise functions of these gene products are not yet understood. All but two of these MDM genes are represented by single mutant alleles suggesting that additional components of the mitochondrial partitioning apparatus remain to be identified. We have identified eight new genes that are required for mitochondrial transfer into newly formed daughter cells during east budding. We propose to study the molecular basis of mitochondrial partitioning in yeast via the genetic, molecular and biochemical characterization of these 8 new MDM genes and the proteins they encode. FIRST, we will use a combination of vital staining, indirect immunofluorescence, and electron microscopy to characterize the range of mitochondrial inheritance and morphology defects caused by mutations in MDM genes. SECOND, wild-type and mutant alleles of the 8 MDM genes will be cloned, sequenced and analyzed. This analysis will allow us to identify any important structural motifs and functional domains in the predicted proteins. THIRD, we will use indirect immunofluorescence and cell fractionation experiments to determine the subcellular location of Mdm protein. FOURTH, we will analyze mitochondrial partitioning during meiosis in mdm mutants. These studies will allow us to determine whether Mdm proteins mediate mitochondrial movements during both meiosis and mitosis and may reveal details of mitochondrial partitioning that cannot be easily visualized in mitotically dividing cells. The experiments we propose will lay the foundation for future molecular, biochemical and genetic analyses of Mdm protein function. In the long- term, these studies should contribute to our basic understanding of the molecular mechanisms underlying mitochondrial movements during cell division and during early development in other organisms.