Elucidating the molecular mechanisms of structure-selective endonucleases in DNA repair and genome stability

每一个生物体的基本组成部分是DNA，它提供了生命的蓝图，是每一个细胞的生物过程所必需的。在正常细胞生长过程中，这种遗传信息必须精确地复制并繁殖到两个子细胞中。矛盾的是，DNA极易受到自然（如代谢副产物）和环境（如紫外线辐射、致癌化学物质）的损害。如果不进行修复，受损的DNA会引发突变、染色体重排和基因组不稳定。为了对抗基因毒性物质的有害影响，细胞含有复杂的DNA修复网络，以保护基因组的完整性并确保适当的细胞功能。了解支撑这些基本细胞通路的复杂机制是研究DNA修复和基因组稳定性的基本生物学过程的科学家的主要目标。大多数DNA修复途径需要结构选择性内切酶（sse）的作用，sse是一种分子剪刀，可以去除DNA修复（和正常细胞生长）过程中形成的潜在毒性DNA结构。如果不能去除这些结构，就会损害染色体的稳定性。然而，DNA切割为不加区分的修复打开了大门，可以促进基因重排，强调了控制sse活性和防止不受控制的DNA切割的调节机制的重要性。在大多数真核生物中，保守的sssslx1 - slx4、MUS81-EME1和XPF-ERCC1是DNA重组和修复所必需的。SLX4蛋白为与SLX1、MUS81-EME1和XPF-ERCC1相互作用形成的SMX三核酸酶复合体提供了一个支架。SLX4与其他几种基因组稳定蛋白相互作用，导致普遍的模型认为SLX4为多种大分子复合物的组装提供了一个中心，这些大分子复合物协调各种蛋白质- dna交易。关于这些复合物的结构、功能和调控的关键问题仍有待解决。我的研究将阐明大分子SLX4复合物的细胞作用、调控和生化机制。这一信息将为理解这些复合物的功能和介导基因组稳定性提供一个机制框架。我的研究也将为DNA重组和修复提供基本的新见解，这两者都是必不可少的细胞过程。我的研究为加拿大人带来了许多实实在在的好处，包括培养高素质人才、发展研究能力和知识进步。我的研究将提升加拿大作为DNA修复和基因组稳定领域的研究创新和卓越中心的地位，从而通过招聘和培训世界级科学家来刺激经济和社会的发展。

An essential component of every living organism is DNA, which provides the blueprint for life and is required for the biological processes in each and every cell. During normal cell growth, this genetic information must be accurately replicated and propagated to two daughter cells. Paradoxically, DNA is highly susceptible to damage by agents that occur naturally (e.g. metabolic by-products) and in the environment (e.g. ultraviolet radiation, carcinogenic chemicals). If left unrepaired, damaged DNA can trigger mutations, chromosomal rearrangements and genome instability. To counteract the deleterious effects of genotoxic agents, cells contain sophisticated DNA repair networks that safeguard genome integrity and ensure proper cell function. Understanding the intricate mechanisms that underpin these essential cellular pathways is a major goal of scientists that study the basic biological processes of DNA repair and genome stability. Most DNA repair pathways require the actions of structure-selective endonucleases (SSEs), which are molecular scissors that remove potentially toxic DNA structures that form during DNA repair (and normal cell growth). The failure to remove these structures compromises chromosome stability. Nevertheless, DNA cleavage opens the door for indiscriminate repair that can fuel genetic rearrangements, emphasizing the importance of regulatory mechanisms to control the activity of SSEs and prevent uncontrolled DNA cleavage.The conserved SSEs SLX1-SLX4, MUS81-EME1 and XPF-ERCC1 are required for DNA recombination and repair in most eukaryotes. The SLX4 protein provides a scaffold for the SMX tri-nuclease complex, formed by interactions with SLX1, MUS81-EME1 and XPF-ERCC1. SLX4 interacts with several other genome stability proteins, leading to the prevailing model that SLX4 provides a hub for the assembly of versatile macromolecular complexes that orchestrate diverse protein-DNA transactions. Key questions about the structure, function and regulation of these complexes remain to be addressed. My research will elucidate the cellular roles, regulation and biochemical mechanisms of macromolecular SLX4 complexes. This information will provide a mechanistic framework for understanding how these complexes function and mediate genome stability. My studies will also provide fundamental new insights into DNA recombination and repair, both of which are essential cellular processes. My research has numerous tangible benefits for Canadians, including the training of high quality personnel, development of research capacity, and knowledge advancement. My studies will elevate Canada's recognition as a hub for research innovation and excellence in the fields of DNA repair and genome stability, thereby stimulating economic and societal growth through the recruitment and training of world-class scientists.