CAREER: The Formation and Repair of Oxidative Damage in Nucleosome Core Particles

在适当的条件下，自由基甚至氧气本身都会破坏基因组DNA。这种攻击的一个主要后果是形成来自DNA的四个天然核碱基的诱变损伤。因此，迫切需要了解导致这些氧化损伤形成的化学反应，这些损伤在双链DNA中的结构后果，以及负责从基因组中移除这些损伤的修复过程的动力学。以前的工作主要集中在分析分离的DNA双链中的这些过程。真核细胞核中的DNA并不是孤立的，而是由组蛋白紧密包装成染色质。DNA与组蛋白核心颗粒的结合形成核小体，核小体是染色质的基本构件。当核小体形成时，DNA结构和对溶剂的可及性发生了巨大的变化。任何或所有这些结构变化都可能影响DNA氧化损伤的形成、传播和修复。这个项目的第一个目标是定义将DNA包装到核小体中如何扰乱与氧化性碱基损伤形成相关的过程。其次，该项目将量化核小体核心颗粒表面DNA修复的效率和速率。该项目将通过主要由从选定的四年制学院和大学招聘的研究生和少数暑期本科生研究助理设计和开展的实验室研究，加强研究生和本科教育。

Free radicals and even oxygen itself can, under the right conditions, damage genomic DNA. One major consequence of this assault is the formation of mutagenic lesions derived from the four native nucleobases of DNA. Therefore, there exists a critical need to understand the chemical reactions leading to the formation of these oxidative lesions, the structural consequences of these lesions in duplex DNA, and the dynamics of repair processes responsible for the removal these lesions from the genome. Previous work has focused primarily upon analyzing these processes in isolated DNA duplexes. DNA in the eukaryotic nucleus is not isolated, but tightly packaged by histone proteins into chromatin. The binding of DNA to a histone core particle forms a nucleosome, the fundamental building block of chromatin. Dramatic changes in DNA structure and accessibility to solvent are induced upon nucleosome formation. Any or all of these structural changes could impact oxidative damage formation, propagation, and repair in DNA. The first objective of this project is to define how packaging DNA into a nucleosome perturbs processes related to the formation of oxidized nucleobase lesions. Second, this project will quantify the efficiency and rates of DNA repair at the surface of nucleosome core particles. This project will enhance both graduate and undergraduate education through laboratory research designed and carried out predominantly by graduate students and minority summer undergraduate research associates recruited from selected four-year colleges and universities.