Mitochondrial DNA Recombination Proteins in Arabidopsis

描述（由申请人提供）：线粒体是真核细胞呼吸过程的关键部位，含有与细胞核分离的DNA，仅编码线粒体功能所需的一些基因。线粒体基因序列的突变和缺失与各种人类疾病有关，包括心肌病、神经病变和各种衰老疾病。在植物中，线粒体基因组的改变与细胞质雄性不育有关，这导致花粉生产失败。我们的长期目标是了解线粒体基因组重组与基因组维护和修复之间的关系，以及由此产生的对线粒体功能的影响。我们选择拟南芥作为这些研究的模型系统，因为拟南芥拥有完整的基因组（核、线粒体和叶绿体），繁殖容易，繁殖时间短，可以进行遗传研究。我们的直接目标是鉴定和表征拟南芥中线粒体靶向重组蛋白的基因，并表征基因产物。具有线粒体靶向序列的大肠杆菌rec A和ssb基因的同源物将首先进行研究。我们已经获得了这些基因的克隆，并将通过northern和western blot分析它们在植物不同组织和年龄中的表达，以确定这些基因的表达是否存在空间或发育差异。recA或ssb基因的过表达效应，无论是由全局或组织特异性强启动子驱动，将在转基因拟南芥植物中确定。通过基因敲除或反义技术对内源性基因的破坏也将被检查，以确定线粒体DNA重组是否对正常的I生长和发育至关重要，以及基因破坏是否导致对DNA损伤剂的更大易感性。其他拟南芥基因与预测线粒体靶向序列的蛋白质参与重组将被鉴定和类似地表征。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，这可能扩展到其他真核生物的线粒体。

DESCRIPTION (provided by applicant): Mitochondria are the site of the essential process of respiration in eukaryotic cells, and contain DNA separate from the nucleus, which encodes only some of the genes needed for mitochondrial function. Mitochondrial gene 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 cytoplasmic male sterility, which results in abortive pollen production. Our long-term goals are to understand the relationship between mitochondrial genome recombination and genome maintenance and repair, and resulting effects on mitochondrial function. We have chosen Arabidopsis thaliana as a model system for these studies, as the complete genome (nuclear, mitochondrial and chloroplast) is now available, propagation of this plant is easy and generation time is short, and genetic studies are possible with this species. Our immediate goals are to identify and characterize genes for mitochondria-targeted recombination proteins in A. thaliana, and characterize the gene products. Homologues of the E. coli rec A and ssb genes, which have mitochondrial targeting sequences, will initially be studied. We have obtained clones of these genes, and their expression will be analyzed in various tissues and ages of plants by northern and western blot analysis to determine if there are spatial or developmental differences in expression of these genes. The effect of over expression of the recA or ssb genes, driven either by global or tissue-specific strong promoters, will be determined in transgenic Arabidopsis plants. Disruption of the endogenous genes by gene knockout or antisense technology will also be examined to determine if mitochondrial DNA recombination is essential for proper I growth and development, and if gene disruption leads to greater susceptibility to DNA damaging agents. Additional Arabidopsis genes with predicted mitochondrial targeting sequences for proteins involved in recombination will be identified and like wise characterized. Our findings will provide greater insights into processes affecting mitochondrial genome integrity, which may be extended to mitochondria from other eukaryotes.