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: 7674140
• 负责人: Makkuni JAYARAM
• 金额: $ 2.2万
• 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/7674140
• 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 微米圆提供了“良性寄生虫基因组”的简单模型。质粒的遗传组织已针对其高拷贝繁殖进行了进化优化，而不会影响宿主细胞的适应性。负责质粒持久性的核心分子成分是一个稳定系统，确保复制的质粒分子均匀分布到子细胞。两个质粒编码蛋白（Replp 和 Rep2p）与顺式作用 DNA 基因座（称为 STB）一起构成了这个稳定系统。此外，质粒还进化出了扩增系统作为安全装置。仅当罕见的错误分离事件导致拷贝数下降时，它才会发挥作用。扩增由 Flp 重组酶介导（Flp =“Flip”，用于翻转或反转 DNA），其活性将单个复制起始事件转化为多重复制机制，从而快速将拷贝数恢复到稳态水平。我们最近发现了质粒分离机制的几个意想不到的特征。首先，姐妹染色体忠实分离所需的酵母粘连蛋白复合物以 Replp 和 Rep2p 依赖性方式被招募到 STB 基因座。其次，与染色体臂上的粘连蛋白招募相反，质粒上的粘连蛋白绝对依赖于有丝分裂纺锤体的完整性。细胞周期中质粒粘连蛋白结合的时间和寿命至关重要。如果质粒在 DNA 复制时未获得粘连蛋白，或者粘连蛋白的后期分解被阻断，则同等质粒分离会失败。在本提案中，我们描述了一些实验，试图阐明（1）Rep1和Rep2蛋白帮助质粒进入染色体分离途径的机制，（2）有丝分裂纺锤体在促进质粒-粘连蛋白结合中的作用，（3）染色质结构和重塑对质粒分配的影响，以及（4）质粒之间的潜在分子联系 分离和重复的染色体DNA分离。从这项研究中收集到的一些原理将对宿主-寄生虫基因组之间的全球共生或共生关系产生影响。