Elucidating the mechanisms that govern replication restart efficiency and fidelity

阐明控制复制重启效率和保真度的机制

• 批准号: MR/P028292/1
• 负责人: Matthew Whitby
• 金额: $ 52.19万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FP028292%2F1
• 关键词: Elucidating; mechanisms; govern; replication; restart

Before a cell divides it has to replicate its genetic material so that each new daughter cell can receive a copy. This process of DNA replication is performed by complex, multi-component protein machines known as replisomes, which are assembled onto DNA at chromosomal sites known as replication origins. These machines unwind the DNA double helix to form "fork" structures, at which the copying occurs. During the cell cycle, multiple origins along every chromosome "fire", each releasing a pair of "replication forks" that travel in opposite directions away from their origin. DNA replication is completed when forks from adjacent origins merge. The failure of even a single pair of forks to merge results in a region of unreplicated DNA that can lead to DNA breakage, and ultimately genetic mutations that cause diseases such as cancer. The many proteins that bind chromosomal DNA threaten successful completion of replication by physically impeding the progress of the replication fork. When a replication fork encounters such a barrier, it can undergo a process termed fork collapse in which its replisome partially or completely dissociates from the DNA. Following fork collapse, cells seem to make use of two different mechanisms to ensure completion of DNA replication: 1) passive DNA replication by an opposing fork, which may be promoted by the firing of normally dormant origins nearby; and 2) restart of the failed fork by a poorly understood process that depends on proteins that catalyse DNA recombination. Intriguingly, restarting replication can itself cause harmful mutations and chromosomal rearrangements and, therefore, is presumably strictly regulated to limit its deleterious effects. To better understand how cells deal with failed replication forks, we aim to identify the factors that affect the efficiency and fidelity of replication restart. We also aim to discover whether dormant replication origins fire in response to a single collapsed replication fork, and whether this is an active or passive process. By deciphering these fundamental processes, we will gain a better understanding of the molecular basis of diseases, such as cancer, whose development and progression are often rooted in problems that arise during DNA replication. Ultimately, the knowledge obtained from this project will underpin future endeavours to develop new diagnostics and therapeutics for clinical use.

在细胞分裂之前，它必须复制它的遗传物质，以便每个新的子细胞都能得到一个拷贝。这个DNA复制过程是由复杂的多组分蛋白质机器（称为复制体）完成的，复制体在染色体上的复制起点组装到DNA上。这些机器将DNA双螺旋展开，形成“叉”结构，在此进行复制。在细胞周期中，每条染色体上的多个起点沿着“开火”，每一个都释放出一对“复制叉”，它们以相反的方向远离它们的起点。当来自相邻起点的分叉合并时，DNA复制完成。即使是一对分叉的失败也会导致一个不可复制的DNA区域，这可能导致DNA断裂，最终导致基因突变，导致癌症等疾病。结合染色体DNA的许多蛋白质通过物理上阻碍复制叉的进展来威胁复制的成功完成。当复制叉遇到这样的障碍时，它可以经历一个称为叉崩溃的过程，其中它的复制体部分或完全与DNA分离。在分叉崩溃之后，细胞似乎利用两种不同的机制来确保DNA复制的完成：1）通过相对的分叉进行被动DNA复制，这可能是通过附近正常休眠的起点的激发来促进的;以及2）通过一个知之甚少的过程重新启动失败的分叉，该过程依赖于催化DNA重组的蛋白质。有趣的是，重新开始复制本身会导致有害的突变和染色体重排，因此，可能会受到严格的监管，以限制其有害影响。为了更好地了解细胞如何处理失败的复制叉，我们的目标是确定影响复制重新启动的效率和保真度的因素。我们还旨在发现是否休眠的复制起源火灾响应于一个单一的崩溃复制叉，以及这是一个主动或被动的过程。通过破译这些基本过程，我们将更好地了解疾病的分子基础，例如癌症，其发展和进展往往植根于DNA复制过程中出现的问题。最终，从该项目中获得的知识将支持未来开发新的临床诊断和治疗方法的努力。

项目成果

Rad52's DNA annealing activity drives template switching associated with restarted DNA replication.

• DOI: 10.1038/s41467-022-35060-4
• 发表时间: 2022-11-26
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Kishkevich, Anastasiya;Tamang, Sanjeeta;Nguyen, Michael O.;Oehler, Judith;Bulmaga, Elena;Andreadis, Christos;Morrow, Carl A.;Osman, Fekret;Whitby, Matthew C.
• 通讯作者: Whitby, Matthew C.

The PCNA unloader Elg1 promotes recombination at collapsed replication forks in fission yeast.

PCNA 卸载器 Elg1 促进裂殖酵母中折叠复制叉处的重组。

• DOI: 10.7554/elife.47277
• 发表时间: 2019
• 期刊: eLife
• 影响因子: 7.7
• 作者: Tamang S