The Chaperonin Genes of Jakobid Protists

雅各布原生生物的伴侣蛋白基因

• 批准号: 0078008
• 负责人: Charles OKelly
• 金额: $ 15万
• 依托单位: Bigelow Laboratory for Ocean Sciences
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0078008&HistoricalAwards=false
• 关键词: Chaperonin; Genes; Jakobid; Protists

AbstractOrganisms with the most eubacterial-like mitochondrial genomes should have the most ancestral mechanisms for mitochondrial and eukaryotic protein-folding machinery. Sequences of the group I (cpn60, mitochondrial, descended from eubacteria) and group II (CCT, cytosolic, descended from archaea) chaperonin genes, compared with those from prokaryotic outgroups and from other protists including amitochondriate exemplars, should reveal whether this is so. In addition, the organisms with the most eubacterial-like mitochondrial genomes should have an ancestral intron distribution. Most eukaruyotes that are considered to be ancestral lack spliceosomal introns, but evidence is accumulating that these introns were lost. Consistent with this interpretation, preliminary data show the presence of numerous spliceosomal introns in jakobids. Cpn 60 and CCT subunits in jakobid flagellates, of which there are currently eight mitochondriate species in culture, will be sequenced. Initial sequence surveys using PCR techniques will be followed by more complete sequencing based upon genomic liberties. The evolutionary histories of these sequences will be inferred through phylogenetic analyses that correct for the deleterious effects of sparse taxon sampling and such artifacts as long-branch attraction. The abundance and structure of included introns will be assessed in the light of current hypotheses about the evolution of introns in eukaryotic cells. The jakobid flagellates are potentially among the ancestral of living eukaryotes. Jakobid mitochondrial genomes represent the most eubacterial-like mitochondrial genomes discovered, in terms of gene content, gene organization, and putative gene function. Moreover, nearly all groups of amitochondrial protist have been shown to retain genes of mitochondrial origin, suggesting that they are derived from mitochondriate ancestors. The jakobid flagellates may represent an informative model system for the study of early eukaryote evolution.

具有最类似真细菌线粒体基因组的生物体应该具有最古老的线粒体和真核生物蛋白质折叠机制。第一组（cpn60，线粒体，真细菌的后裔）和第二组（CCT，胞质，古细菌的后裔）伴侣蛋白基因的序列，与那些从原核外群和其他原生生物，包括无线粒体的例子，应该揭示是否如此。此外，具有最像真细菌的线粒体基因组的生物体应该具有祖先内含子分布。大多数被认为是祖先的真核生物缺乏剪接体内含子，但越来越多的证据表明这些内含子丢失了。与这种解释一致，初步数据显示，在jakobids中存在许多剪接体内含子。Cpn 60和CCT亚基的jakobid鞭毛虫，其中目前有8个物种的文化，将测序。使用PCR技术进行初步序列调查之后，将根据基因组自由度进行更完整的测序。这些序列的进化历史将推断通过系统发育分析，纠正了有害的影响稀疏类群采样和长分支吸引力等文物。所包括的内含子的丰度和结构将根据目前关于真核细胞中内含子进化的假设进行评估。jakobid鞭毛虫可能是现存真核生物的祖先。在基因内容、基因组织和推定的基因功能方面，Jakobid线粒体基因组代表了所发现的最像真细菌的线粒体基因组。此外，几乎所有的无线粒体原生生物群体都保留了线粒体起源的基因，这表明它们起源于无线粒体祖先。jakobid鞭毛虫可能是研究早期真核生物进化的模式系统。