Mitochondrial DNA Recombination Proteins in Arabidopsis

描述(申请人提供)：线粒体是真核细胞中呼吸的基本过程的位置，含有与核分离的DNA，只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多种人类疾病有关，包括心肌病、神经病和各种衰老疾病。在植物中，线粒体基因组的改变与细胞质雄性不育有关，细胞质雄性不育导致败育的花粉产生。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，因为现在已经有了完整的基因组(核、线粒体和叶绿体)，这种植物的繁殖很容易，世代时间很短，而且可以对这种物种进行遗传研究。我们的近期目标是鉴定和鉴定拟南芥中线粒体靶向重组蛋白的基因，并鉴定基因产物。最初将研究具有线粒体靶向序列的E.Colirec A和SSB基因的同源物。我们已经获得了这些基因的克隆，并将通过Northern和Western印迹分析来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。在转基因拟南芥中，由全局或组织特异性强启动子驱动的recA或SSB基因过表达的影响将被确定。还将检查通过基因敲除或反义技术破坏内源基因，以确定线粒体DNA重组是否对I的正常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。更多的拟南芥基因与预测的线粒体重组相关蛋白的靶向序列将被识别，并类似WISE特征。我们的发现将为影响线粒体基因组完整性的过程提供更大的洞察力，这可能会从其他真核生物延伸到线粒体。

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.