Mitochondrial DNA Recombination Proteins in Arabidopsis

描述（由申请人提供）： 线粒体是真核细胞中呼吸的基本过程的场所，并且含有与细胞核分离的DNA。线粒体基因组仅编码线粒体功能所需的少数蛋白质，其余蛋白质从细胞质中从核编码基因输入。 线粒体序列突变和缺失与多种人类疾病有关， 包括心肌病、神经病和各种老化疾病。在植物中，线粒体基因组的改变与一些新的开放阅读框架的产生和细胞质雄性不育有关，这导致败育的花粉产生。本研究的总体目标是确定mtDNA重组是否是基因组复制或维持所必需的，或者它是否参与高等植物mtDNA损伤的修复。我们使用拟南芥作为这些研究的模型系统，因为完整的基因组（核，线粒体和叶绿体）是可用的，并且用这种植物进行繁殖和遗传研究相对容易。本更新提案的目标是：1。研究拟南芥recA基因表达改变对植物生长、线粒体超微结构、功能和基因组结构的影响; 2.完整表征的两个拟南芥E. coli的靶向同源物。coli ssb基因; 3.确定酵母Pif 1解旋酶的拟南芥同源物的靶向和功能，并分析表达改变的影响。将在转基因植物中确定由全局或组织特异性强启动子驱动的recA、ssb、解旋酶和其他参与DNA重组的尚未鉴定的基因的过表达的影响。还将检查通过基因敲除或RNAi技术破坏或减少内源性基因的表达，以确定线粒体DNA重组是否对正常生长和发育至关重要，或者基因破坏是否导致对DNA损伤剂的更大易感性。 我们的发现将为影响线粒体基因组完整性的过程提供更深入的见解，这可能会扩展到其他生物的线粒体。

DESCRIPTION (provided by applicant): Mitochondria are the site of the essential process of respiration in eukaryotic cells, and contain DNA separate from the nucleus. The mitochondrial genome encodes only a few of the proteins needed for mitochondrial function, with the remainder imported from the cytoplasm from nuclear-encoded genes. Mitochondrial sequence mutations and deletions have been linked with various human diseases, including cardiomyopathy, neuropathy and various aging disorders. In plants, mitochondrial genome alterations are associated with generation of some novel open reading frames and cytoplasmic male sterility, which results in abortive pollen production. The overall goal of this research is to determine whether mtDNA recombination is essential for genome replication or maintenance, or whether it is involved in repair of mtDNA damage in higher plants. We are using Arabidopsis thaliana as a model system for these studies, as the complete genome (nuclear, mitochondrial and chloroplast) is available, and propagation and genetic studies with this plant are relatively easy. The goals of this renewal proposal are to: 1. Examine the effect of alteration of expression of the Arabidopsis recA gene on plant growth and mitochondrial ultrastructure, function, and genome structure; 2. Complete characterization of the two Arabidopsis thaliana mitochondria-targeted homologues of the E. coli ssb gene; 3. Determine targeting and function of the Arabidopsis homologue of yeast Pif1 helicase, and analyze the effect of alteration of expression. The effect of overexpression of the recA, ssb, helicase and other yet to be identified genes involved in DNA recombination, driven either by global or tissue-specific strong promoters, will be determined in transgenic plants. Disruption or reduced expression of endogenous genes by gene knockout or RNAi technology will also be examined to determine if mitochondrial DNA recombination is essential for proper growth and development, or if gene disruption leads to greater susceptibility to DNA damaging agents. Our findings will provide greater insights into processes affecting mitochondrial genome integrity, which may be extended to mitochondria from other organisms.