Genomic studies of chimeric mitochondria in cybrids from Solanaceae

描述（由申请人提供）：“茄科细胞系嵌合线粒体的基因组研究”这项研究将主要在阿根廷的Cuyo国立大学进行，与Marma Virginia Sanchez Puerta博士合作，作为R01 GM070612-4的延伸。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的研究对于深入了解真核细胞至关重要。线粒体基因组提供了一个很好的系统来增加我们对基因组重排、嵌合基因、核-细胞质不相容和水平基因转移（HGT）的认识。植物线粒体通过HGT获得基因的倾向是独特的。真核生物中最普遍的HGT例子涉及cox1内含子，它编码一种假定的归巢内切酶，通过水平转移增加内含子固定的频率。我们建议研究通过原生质体融合实验获得的杂交植物中重组的两个不同线粒体基因组之间相互作用的各个方面。在杂交形成过程中，两种线粒体亲本类型及其基因组（只有一种含有cox内含子）将融合，产生杂交线粒体基因组。为了实现以下两个目标，我们将建立大约20个由含有和缺乏cox1内含子的物种之间的体细胞杂交衍生的杂交系：首先，我们将验证cox1内含子在植物中编码功能性归巢内切酶的假设，评估内含子定殖率，并测量内含子插入的外显子共转化束的长度。其次，我们将对多达20个杂交系的整个线粒体基因组进行测序和分析。这将为概括植物线粒体HGT的自然过程提供一个实验模型，并将在不同水平上提供线粒体基因组重组过程和模式的丰富图景。维持一个完整的、功能性的线粒体基因组对生存至关重要。鉴于植物和动物在分子上有许多相似之处，该项目将对动物基因治疗和植物基因工程的发展具有重要价值。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，并往往对人类健康产生严重后果，一些重要的线粒体遗传疾病证明了这一点。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.