Nuclear Regulation of Mitochondrial Genome Integrity

9728329麦肯齐，与酵母和动物系统中的对应基因组相比，植物线粒体基因组的大小异常可变，组织高度复杂。这个项目特别令人感兴趣的是观察到不同的线粒体DNA分子，每个分子只包含一部分遗传信息，在基因组中以显著不同的相对拷贝数保留。植物中这种不寻常的组织是什么原因还不是很清楚。很明显，线粒体基因组的许多特征，包括DNA拷贝数，都受到核基因的控制。该项目旨在测试线粒体DNA分子的核定向拷贝数控制作为抑制植物线粒体突变的一种手段的假设。为了验证这一假设，我们克隆了拟南芥的CHM基因。该基因的突变会导致含有突变的线粒体DNA分子的放大。因此，对这种基因、其产物及其作用方式的表征应该允许对所述假设的直接检验。我们计划确认CHM克隆的身份，定位其基因产物，并从基因上测试其功能。

9728329 Mackenzie The plant mitochondrial genome is unusually variable in its size and highly complex in its organization when compared to its counterparts in yeast and animal systems. Of particular interest for this project is the observation that distinct mitochondrial DNA molecules, each containing only a portion of the genetic information, are retained in the genome at strikingly different relative copy number. What accounts for this unusual organization in plants is not well understood. It is clear that many features of the mitochondrial genome, including DNA copy number, are under nuclear gene control. This project is designed to test the hypothesis that nuclear-directed copy number control of mitochondrial DNA molecules serves as a means of suppressing mitochondrial mutations in plants. To test this hypothesis, the CHM gene in Arabidopsis thaliana has been cloned. Mutations in this gene result in the amplification of mitochondrial DNA molecules that contain mutations. Thus, characterization of this gene, its product, and its mode of action should allow a direct test of the stated hypothesis. We plan to confirm the identity of the CHM clone, to localize its gene product, and to genetically test its function.