Chromosome structure, duplication and stability in yeast

项目摘要/摘要 真核基因组复制需要有效地复制每个染色体碱基对， 每个细胞分裂准确且只有一次，这是一个巨大的需求，给了数百万到数十亿 组成真核生物基因组的碱基对和形成所需的无数细胞分裂 并维持生物体的生存。DNA复制的严重缺陷与生命是不相容的。然而， 在这个过程中有轻微的扰动，但仍然能够支持细胞分裂，并且可以 使用生化方法进行鉴定具有挑战性，可能会影响开发和 在多个细胞分裂的过程中保持健康。调控的第一步，DNA的启动 发生在称为起始点的染色体位置上的复制在 真核细胞，因为它们的染色体需要多个空间和时间分布 精准高效复制的原点。原点编号或分布中的扰动可能 促进癌症、干细胞老化或发育障碍。而与起源结合的蛋白 定义起源的分子步骤是已知的，也就是调节 染色体的起源、数量和分布尚不清楚。一个挑战是染色质 异质性存在于染色体之间，是基因组功能的内在组成部分 组织。因此，起源结合蛋白必须在不同的基因中充分发挥作用。 染色质环境，以实现来源分布的水平，平衡竞争 对细胞增殖和基因组稳定性的要求。福克斯博士的实验室解决了 了解天然染色质结构如何通过结合严谨的 遗传学和基因组学揭示染色质介导的影响结构的机制 和功能酿酒酵母(酵母)的起源。重点放在第一步 起源形成，起源许可反应，发生在细胞周期的G1期 在S阶段之前--在这个阶段，起源执行它们的实际功能，父母的解体 用于新DNA合成的DNA。越来越多的证据表明，许可步骤是 尤其与基因组稳定性和细胞命运决定有关，但缺乏 关于它如何在体内被调控以实现染色体起源的分子机制 分发。起源结合蛋白的进化保守性及其多重特征 染色质允许福克斯实验室利用酵母的实验强度来确定 染色质和原基结合蛋白协同形成的基本机制 并将起源分布在基因组上。

Project Summary/Abstract Eukaryotic genome duplication requires that each chromosomal base pair is copied efficiently, accurately and only once per cell division, a monumental demand given the millions to billions of base pairs that comprise eukaryotic genomes and the countless cell divisions required to form and sustain organisms. Severe defects in DNA replication are incompatible with life. However, mild perturbations in this process, while still capable of supporting cell division, and which can be challenging to identify using biochemical approaches, can compromise development and health over the course of multiple cell divisions. Regulation of the first step, the initiation of DNA replication that occurs at chromosomal positions called origins, is particularly critical in eukaryotic cells because their chromosomes require multiple spatially and temporally distributed origins for accurate and efficient duplication. Perturbations in origin number or distribution can promote cancer, stem cell aging, or developmental disorders. While the origin-binding proteins and molecular steps that define an origin are known, the mechanisms that regulate chromosomal origin number and distribution are unclear. A challenge is that chromatin heterogeneity exists across chromosomes as an intrinsic part of genome functional organization. Thus, the origin-binding proteins must work sufficiently enough within distinct chromatin environments to achieve a level of origin distribution that balances the competing demands for cell proliferation and genome stability. Dr. Fox's lab addresses the gaps in understanding how native chromatin structures regulate origin function by combining rigorous genetics and genomics to reveal chromatin-mediated mechanisms that impinge on the structure and function of Saccharomyces cerevisiae (yeast) origins. Emphasis is placed on the first step of origin formation, the origin licensing reaction, which occurs in G1-phase of the cell cycle that precedes the S-phase where origins perform their actual function, unwinding of the parental DNA for new DNA synthesis. Accumulating evidence reveals that the licensing step is particularly relevant to both genome stability and cell-fate decisions, but there is a paucity of molecular mechanisms regarding how it is regulated in vivo to achieve chromosomal origin distribution. Evolutionary conservation of the origin-binding proteins and multiple features of chromatin allow the Fox laboratory to leverage the experimental strengths of yeast to define fundamental mechanisms by which chromatin and the origin-binding proteins collaborate to form and distribute origins over the genome.