Stable Maintenance of an Extrachromosomal Selfish DNA Element

染色体外自私 DNA 元件的稳定维持

• 批准号: 7191904
• 负责人: Makkuni JAYARAM
• 金额: $ 26.86万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-05-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7191904
• 关键词: Accounting; Affect; Anaphase; Architecture; Benign; Biochemical; Biological; Biological Assay; Cell Cycle; Cells; Centromere; Chromatin; Chromatin Modeling; Chromatin Remodeling Factor; Chromosome Arm; Chromosome Segregation; Chromosomes; Complex; Count; Coupling; DNA; DNA biosynthesis; Data; Device Safety; Drops; Elements; Ensure; Event; Frequencies; Funding; Genetic; Genome; Glean; Histone H3; Homologous Gene; Integration Host Factors; Investigation; Kinetochores; Life; Light; Maintenance; Mediating; Mitotic spindle; Modeling; Molecular; Mothers; Mutation; Neck; Nuclear; Nucleosomes; Numbers; Pathway interactions; Phase; Phenotype; Plasmids; Play; Population; Proteins; Recombinant DNA; Recruitment Activity; Replication Initiation; Ribosomal DNA; Role; Saccharomyces cerevisiae; Selfish DNA; Sister; Sister Chromatid; Staging; System; Testing; Thinking; Time; Variant; Work; Yeasts; centromere protein A; chromatin remodeling; cohesin; cohesion; daughter cell; design; fitness; parasite genome; prevent; recombinase; research study; segregation; stem; telomere; yeast protein

DESCRIPTION (provided by applicant): The yeast plasmid 2 micron circle provides a simple model for a 'benign parasite genome'. The genetic organization of the plasmid has been evolutionarily optimized for its high-copy propagation without compromising the fitness of the host cells. The central molecular component responsible for plasmid persistence is a stability system that ensures equal distribution of replicated plasmid molecules to daughter cells. Two plasmid encoded proteins (Replp and Rep2p), together with a cis-acting DNA locus (called STB), constitute this stability system. In addition, the plasmid has evolved an amplification system as a safety device. It comes into play only when a rare missegregation event causes a drop in copy number. Amplification is mediated by the Flp recombinase (Flp ='Flip' for flipping or inverting DNA), whose activity converts a single replication initiation event into a multiple copying mechanism, thus quickly restoring copy number to steady state levels. We recently discovered several unsuspected features of the plasmid segregation mechanism. First, the yeast cohesin complex, required for faithful segregation of sister chromosomes, is recruited to the STB locus in a Replp and Rep2p dependent manner. Second, in contrast to cohesin recruitment at chromosome arms that at the plasmid is absolutely dependent on the integrity of the mitotic spindle. The timing as well as the life-time of plasmid cohesin-association during the cell cycle is critical. Equal plasmid segregation fails if the plasmid does not acquire cohesin concomitant with DNA replication or if the anaphase disassembly of cohesin is blocked. In this proposal, we describe experiments that attempt to shed light on (1) the mechanisms by which the Rep1 and Rep2 proteins help the plasmid gain access to the chromosome segregation pathway, (2) the role of the mitotic spindle in promoting plasmid-cohesin association, (3) the influence of chromatin architecture and remodeling on plasmid partitioning and (4) the potential molecular connection between plasmid segregation and repeated chromosomal DNA segregation. Some of the principles gleaned from this study will have implications in global symbiotic or commensalist relationships among host-parasite genomes.

描述（由申请人提供）：酵母质粒2微米圆圈为“良性寄生虫基因组”提供了一个简单的模型。质粒的遗传组织已因其高拷贝的传播而在不损害宿主细胞的适应性的情况下进化优化。负责质粒持久性的中央分子成分是一个稳定系统，可确保复制的质粒分子在子细胞上相等分布。两个质粒编码的蛋白质（REPLP和REP2P）以及顺式作用DNA基因座（称为STB）构成了该稳定系统。此外，质粒已进化为放大系统作为安全装置。只有当罕见的错误分析事件导致复制号下降时，它才会发挥作用。放大是由FLP重组酶（用于翻转或反相DNA的FLP ='FLIP'）介导的，其活性将单个复制起始事件转换为多复制机制，从而将拷贝数迅速恢复为稳态水平。我们最近发现了质粒隔离机制的几个未引起的特征。首先，忠实的姐妹染色体隔离所需的酵母粘着蛋白复合体以replp和rep2p的依赖方式招募到STB基因座。其次，与染色体臂上的粘蛋白募集相反，质粒处的粘合素绝对取决于有丝分裂纺锤体的完整性。在细胞周期中，质粒粘着蛋白缔合的质粒凝聚的时间和寿命至关重要。如果质粒未获得与DNA复制的粘着素相关的粘着蛋白，或者如果粘附蛋白的后期拆卸被阻断，则相等的质粒分离会失败。在该提案中，我们描述了试图阐明（1）REP1和REP2蛋白有助于质粒获得染色体分离途径的机制的实验，（2）有丝分裂纺锤体在促进质粒粘合素缔合中的作用分离和重复的染色体DNA分离。这项研究收集的一些原则将对宿主 - 寄生虫基因组之间的全球共生或共生关系产生影响。