Genomic studies of chimeric mitochondria in cybrids from Solanaceae

描述（由申请人提供）：“茄科胞质杂交体中嵌合线粒体的基因组研究”本研究将主要在阿根廷国立库约大学与Marma Virginia Sanchez Puerta博士合作进行，作为R 01 GM 070612 -4的延伸。研究线粒体基因组的进化、动力学、外源DNA的摄取以及与核基因组的相互作用对于深入了解真核细胞是必不可少的。线粒体基因组提供了一个极好的系统，以增加我们对基因组重排、嵌合基因、核质不相容性和水平基因转移（HGT）的了解。植物线粒体具有独特的通过HGT获得基因的倾向。HGT在真核生物中最普遍的例子涉及cox 1内含子，其编码一种推定的归巢核酸内切酶，该核酸内切酶通过水平转移增加内含子固定的频率。我们建议研究两个不同的线粒体基因组之间的相互作用，重组在胞质杂种植物原生质体融合实验获得的方面。在胞质杂种形成期间，两种线粒体亲本类型及其基因组（仅一种含有cox 1内含子）将融合，产生杂交线粒体基因组。我们将建立一些20 cybrid线来自cox 1内含子和缺乏物种之间的体细胞杂交，以解决以下两个目标：首先，我们将测试的假设，cox 1内含子编码一个功能性归巢核酸内切酶在植物中，评估率的内含子殖民化，并测量长度的外显子coconversion tracts，伴随内含子插入。其次，我们将测序和分析多达20个胞质杂种系的整个线粒体基因组。这将作为一个实验模型，重演的自然过程中的HGT在植物线粒体，并将提供一个丰富的图片的过程和模式的线粒体基因组重组在不同的水平。维持一个完整的、功能正常的线粒体基因组对生存至关重要。鉴于植物和动物之间存在许多相似的分子，该项目将对动物基因治疗和植物基因工程的发展具有价值。公共卫生相关性：基因组重排、核苷酸取代和外源DNA的引入塑造了真核生物的线粒体基因组，并且通常对人类健康产生严重后果，如几种重要的遗传性疾病所证明的。此外，本研究的关键实验生物（烟草）被广泛用作疫苗、抗生素和许多治疗性蛋白质的生物制药生产的表达系统。因此，了解线粒体DNA进化的分子机制对人类健康和疾病具有相当重要的意义。

DESCRIPTION (provided by applicant): "Genomic studies of chimeric mitochondria in cybrids from Solanaceae" This research will be conducted primarily in Argentina at Universidad Nacional de Cuyo in collaboration with Dr. Marma Virginia Sanchez Puerta, as an extension of R01 GM070612-4. The study of mitochondrial genome evolution, dynamics, uptake of foreign DNA, and interactions with the nuclear genome is essential to a deep understanding of the eukaryotic cell. Mitochondrial genomes provide an excellent system to increase our knowledge of genome rearrangements, chimeric genes, nuclear- cytoplasmic incompatibilities, and horizontal gene transfer (HGT). Plant mitochondria are unique in their propensity to acquire genes by HGT. The most pervasive example of HGT in eukaryotes involves the cox1 intron, which encodes a putative homing endonuclease that increases the frequency of the intron's fixation via horizontal transfer. We propose to study aspects of the interactions between two distinct mitochondrial genomes that recombine in a cybrid plant obtained by protoplast fusion experiments. During cybrid formation, the two mitochondrial parental types and their genomes (only one containing the cox1 intron) will fuse, resulting in a hybrid mitochondrial genome. We will establish some 20 cybrid lines derived from somatic crosses between cox1 intron-containing and -lacking species in order to address the following two aims: First, we will test the hypothesis that the cox1 intron encodes a functional homing endonuclease in plants, assess rates of intron colonization, and measure lengths of exonic coconversion tracts that accompany intron insertion. Second, we will sequence and analyze the entire mitochondrial genomes of up to 20 cybrid lines. This will serve as an experimental model for recapitulating the natural process of HGT in plant mitochondria and will provide a rich picture of the process and pattern of mitochondrial genome recombination at various levels. Maintenance of an intact, functioning mitochondrial genome is critical for survival. Given the many molecular parallels between plants and animals, this project will be valuable for the development of both animal gene therapy and plant genetic engineering. PUBLIC HEALTH RELEVANCE: Genome rearrangements, nucleotide substitutions, and the introduction of foreign DNA shape the mitochondrial genomes of eukaryotes and often have severe consequences for human health, as evidenced by several important mitochondrially-inherited diseases. In addition, the key experimental organism of this study (tobacco) is widely used as an expression system for biopharmaceutical production of vaccines, antibiotics, and a number of therapeutic proteins. Understanding the molecular mechanisms of mitochondrial DNA evolution is therefore of considerable importance to human health and disease.