MITOCHONDRIAL DYNAMICS-MORPHOLOGY/DIVISION/SEGREGATION

线粒体是几乎所有真核细胞中的重要细胞器，在许多不同的细胞类型中，线粒体的数量、位置和形状都表现出显著的异质性。由于介导这些过程的分子和机制尚不清楚，我们从酿酒酵母中分离并分析了线粒体融合和分裂、线粒体向子细胞的分离以及线粒体形状维持方面存在缺陷的突变体。我们的研究已经确定了几种蛋白质，它们介导了线粒体形态发生的不同方面。关于这些新的蛋白质，我们提出了以下问题。Fzo1p、Ugo1p和Ugo2p在线粒体融合中的作用是什么？Fzo1突变体存在线粒体融合缺陷，含有大量线粒体片段。Fzo1p是一种外膜定位的GTP酶。Ugo1p和Ugo2p是在线粒体融合突变体的遗传筛查中发现的新蛋白。Dnm1p和Net2p如何介导线粒体分裂？DNM1和net2突变体在线粒体分裂方面存在缺陷，在这些细胞中，线粒体形成一个由相互连接的小管网络组成的单一细胞器。Dnm1p是一种与动力蛋白相关的GTP酶，位于线粒体表面的线粒体分裂部位。Net2p是一种新的与Dnm1p相互作用的蛋白，也位于线粒体表面。MMM1p和SLM1p在线粒体形状和分离中的作用是什么？Mm1突变体在线粒体形状、线粒体向子代细胞的分离和线粒体DNA(MtDNA)的维持方面存在缺陷。我们发现MMM1蛋白位于线粒体外膜，以离散的点状结构存在，这些结构也与线粒体DNA核团共存。我们推测，MMM1p是线粒体外膜和内膜蛋白质复合体的一部分，该复合体形成了细胞质中的肌动蛋白细胞骨架和基质中的mtDNA之间的连接。SLM1是在筛选与Mm1突变体相互作用的突变时被鉴定出来的。Slm1p和Mmm1p一样，位于线粒体外膜，是线粒体形状所必需的。线粒体动力学还需要哪些其他蛋白质？最近，已经产生了大约6000个酵母菌株的集合，每个酵母菌株在不同的ORF中被破坏。使用基于显微镜的分析，我们将筛选在线粒体形状、分离、分裂或融合方面有缺陷的突变体。

Mitochondria are essential organelles found in virtually all eukaryotic cells and show a striking heterogeneity in their number, location and shape in many different cell types. Since the molecules and mechanisms that mediate these processes are largely unknown, we have isolated and analyzed mutants in the yeast Saccharomyces cervisiae defective in mitochondrial fusion and division, in the segregation of mitochondria to daughter cells, and in the maintenance of mitochondrial shape. Our studies have identified several proteins that mediate different aspects of mitochondrial morphogenesis. We are asking the following questions about these new proteins. What is the function of Fzo1p, Ugo1p, and Ugo2p in mitochondrial fusion? fzo1 mutants are defective in mitochondrial fusion and contain numerous mitochondrial fragments. Fzo1p is an outer membrane-localized GTPase. Ugo1p and Ugo2p are new proteins identified in a genetic screen for mitochondrial fusion mutants. How do Dnm1p and Net2p mediate mitochondrial division? dnm1 and net2 mutants are defective in mitochondrial division, and in these cells mitochondria form a single organelle consisting of a network of interconnected tubules. Dnm1p is a dynamin-related GTP-ase located on the mitochondrial surface at sites of mitochondrial division. Net2p is a novel Dnm1p-interacting protein also located on the mitochondrial surface. What is the role of Mmm1p and Slm1p in mitochondrial shape and segregation? mmm1 mutants are defective in the shape of their mitochondria, in the segregation o the mitochondria to daughter cells, and in the maintenance of mitochondrial DNA (mtDNA). We find the Mmm1 protein located in the mitochondrial outer membrane in discrete, punctate structures that also colocalize with mtDNA nucleoids. We speculate that Mmm1p is part of a complex of proteins in the mitochondrial outer and inner membrane that forms a connection between the actin cytoskeleton in the cytosol, and mtDNA in the matrix. slm1 was identified in a screen for mutations that interact with mmm1 mutants. Slm1p, like Mmm1p, is located in the mitochondrial outer membrane and is required for mitochondrial shape. What other proteins are required for mitochondrial dynamics? Recently, a collection of approximately 6000 yeast strains, each disrupted in a different ORF, has been generated. Using a microscope-based assay, we will screen this collection for mutants defective in mitochondria shape, segregation, division or fusion.