Radical-mediated DNA damage: Product analysis, mechanistic studies and biochemical processing

自由基介导的 DNA 损伤：产品分析、机制研究和生化加工

• 批准号: RGPIN-2022-03974
• 负责人: Wagner, James
• 金额: $ 1.75万
• 依托单位: Université de Sherbrooke
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=760623
• 关键词: Radical; mediated; DNA; damage; Product

DNA is composed of a continuous string of alternating DNA bases that define the genetic code (T,A,G,C) connected together by repeating sugar and phosphate substructures. X-rays, gamma-rays, and other types of ionizing radiation break chemical bonds resulting in the generation of radical species. Numerous physical and chemical agents also create radical species, including sunlight, oxidizing agents such as hydrogen peroxide, as well as natural oxidants that are generated by biochemical reactions in aerobic organisms. In turn, these radical species can react with DNA subunits (nucleobase, sugar and phosphate groups) to induce changes in the primary structure of DNA. The ensemble of chemical changes, referred collectively as DNA damage, can have serious long-term consequences, such as genetic mutations, or immediate consequences, such as cell death if the damage cannot be tolerated or repaired within a reasonable time. We have a good understanding of the pathways that are implicated in the formation of DNA damage on a small molecule scale with DNA subunits. However, the pathways going from initial radical species to irreversible damage is much more complicated in DNA due to its specific arrangement of DNA bases (i.e., sequence) and the 3-dimensional polymeric structure. Indeed, radicals physically bound to DNA have a different reactivity compared to radicals that are free to diffuse in solution. From knowledge gleaned by small molecule scale studies, my research program strives toward a more complete understanding of the chemistry of DNA damage in more complicated systems, including long strings of DNA nucleobases and ones that assume unique 3D conformations. We will focus our attention on specific areas of DNA radical-mediated chemistry that are crucial to future advancements: the reaction of low energy electrons with DNA, the ability of gold nanoparticles to amplify DNA damage upon irradiation, and the fate of peroxyl radicals within DNA that can induce two contiguous damaged sites. In addition, we will examine the enzymatic repair of various types of damage in this and previous studies. We will develop precise and unique scientific approaches to advance this area of research tapping into an arsenal of sophisticated instruments (e.g., radiation sources, mass spectrometers, nuclear magnetic resonance). The proposed studies will help clarify the chemical structures of DNA damage and the mechanism of formation of this damage, which is necessary to understand the nature and consequences of DNA damage in natural biological contexts (e.g., cells and organisms). Our studies will nurture a well-rounded training environment for future scientists in the growing field of DNA damage and repair.

DNA是由一串连续的交替的DNA碱基组成的，这些碱基定义了通过重复的糖和磷酸盐亚结构连接在一起的遗传密码（T，A，G，C）。X射线、伽马射线和其他类型的电离辐射破坏化学键，导致产生自由基物质。许多物理和化学试剂也产生自由基物质，包括阳光，氧化剂如过氧化氢，以及由需氧生物体中的生化反应产生的天然氧化剂。反过来，这些自由基物质可以与DNA亚基（核碱基，糖和磷酸基团）反应，诱导DNA一级结构的变化。化学变化的集合，统称为DNA损伤，可能会产生严重的长期后果，如基因突变，或直接后果，如细胞死亡，如果损伤不能在合理的时间内被容忍或修复。我们对DNA亚基在小分子尺度上形成DNA损伤的途径有很好的了解。然而，由于DNA碱基的特定排列（即，序列）和三维聚合物结构。事实上，与DNA物理结合的自由基与在溶液中自由扩散的自由基相比具有不同的反应性。从小分子规模研究收集的知识，我的研究计划致力于在更复杂的系统中更完整地了解DNA损伤的化学，包括DNA核碱基的长串和具有独特3D构象的DNA。我们将把注意力集中在DNA自由基介导的化学的特定领域，这对未来的发展至关重要：低能电子与DNA的反应，金纳米粒子在照射后放大DNA损伤的能力，以及DNA内过氧自由基的命运，可以诱导两个相邻的损伤位点。此外，我们将在本研究和以前的研究中检查各种类型损伤的酶修复。我们将开发精确和独特的科学方法，以推进这一研究领域，利用先进仪器（例如，辐射源、质谱仪、核磁共振）。拟议的研究将有助于澄清DNA损伤的化学结构和这种损伤的形成机制，这对于理解自然生物环境中DNA损伤的性质和后果是必要的（例如，细胞和生物体）。我们的研究将为未来的科学家在不断增长的DNA损伤和修复领域培养一个全面的培训环境。