POSITIONAL CLONING OF THE FR LOCUS

描述：本提案涉及核-线粒体的主题 互动。核基因组如何维持正常的问题 阐述了高等真核生物中线粒体的功能。特别是， 该提案的重点是可能的监管机制 异质性线粒体的分离和传递 种群，以及阻止线粒体积累的那些 突变。正在研究的系统是一个有趣的核- 菜豆中线粒体的相互作用。线粒体突变 是一种细胞质雄性不育(CMS)突变，导致 植物不能产生可存活的花粉。菜豆的细胞质雄性不育 与线粒体基因组的插入有关，该插入 产生命名为pVS-orf239的新的开放阅读框。这个 线粒体重排与新奇生物的产生 蛋白质是植物CMS系统中的一个共同主题。然而，豆类CMS 该系统具有一些独特的特点。PVS蛋白的表达 在花粉母细胞发育过程中导致花粉粒的积累 这种异常蛋白并不像预期的那样存在于线粒体中，而是在 发育中的痂质层中细胞的外围。这大概就是 干扰胞质分裂事件，导致产生 正常的花粉粒。繁殖力在含有 几种核恢复因子中的一种作用引起的线粒体突变 基因。这些基因中的一个，Fr基因，是这一点的焦点 求婚。FR明显通过以下方式恢复CMS品系的育性 实现线粒体突变的定向消除。至 阐明FR作用的分子基础，该提案概述了 进行了一系列Fr.物理 定位基因座，构建可使用的大片段文库 在紧密连锁标记的染色体行走中，以及分离 概述了从推测的Fr基因中获得的cDNA克隆。

DESCRIPTION: This proposal deals with the topic of nuclear-mitochondrial interactions. The question of how the nuclear genome maintains normal mitochondrial function in higher eukaryotes is addressed. In particular, the proposal focuses on the possible mechanisms that regulate segregation and transmission of mitochondria in a heteroplasmic population, and those that preclude the accumulation of mitochondrial mutations. The system under study is an interesting nuclear- mitochondrial interaction in common bean. The mitochondrial mutation is a cytoplasmic male sterility (CMS) mutation that results in the inability of the plant to produce viable pollen. The CMS trait in bean is associated with an insertion in the mitochondrial genome which generates a novel open reading frame designated pvs-orf239. The association of a mitochondrial rearrangement and production of novel proteins are a common theme in plant CMS systems. However, the bean CMS system has some unique features. The expression of the pvs protein during development of the pollen meiocytes leads to the accumulation of this aberrant protein not in mitochondria as expected but at the periphery of the cell in the developing callose layer. This presumably interferes with the cytokinesis events that lead to the production of normal pollen grains. Fertility is restored in strains containing the mitochondrial mutation by the action of one of several nuclear restorer genes. One of these genes, the Fr locus, is the focus of this proposal. Fr restores fertility to the CMS strain apparently by effecting the directed elimination of the mitochondrial mutation. To elucidate the molecular basis of Fr action, the proposal outlines a series of experiments aimed at the positional cloning of Fr. Physical mapping of the locus, the construction of a large-insert library for use in chromosome walking from tightly linked markers, and the isolation of cDNA clones derived from the putative Fr gene are outlined.