Collaborative Proposal: Elucidating Chemical Mechanisms of DNA Repair Using Transition State Analogs

通过这一奖项，化学系的生命过程化学项目资助加州大学戴维斯分校的Sheila David博士和犹他大学的Martin Horvath博士研究DNA损伤是如何检测和修复的。DNA是生命的蓝图，细胞新陈代谢或环境危害对这一分子的破坏可能会导致突变、细胞死亡或在进化过程中蓝图的变化。DNA的保存依赖于DNA修复酶的作用。尽管多年来的研究已经发现了DNA修复酶及其作用于哪些类型的损伤，但这些令人惊叹的酶如何在化学水平上发挥作用仍是个谜。这个项目使用合成DNA化学和X射线结晶学来捕捉和可视化DNA修复过程中的步骤，否则这些步骤太过短暂，无法研究。这一策略提供了DNA修复过程的详细分子图像。该项目应用了一种多方面的方法来研究几种专门修复受损DNA碱基的酶。参与该项目的研究生和本科生正在接受合成、生物化学和X射线结晶学方面的培训。该项目的发现和结果将被纳入加州大学戴维斯分校和犹他大学的DNA损伤与修复本科生实验室课程。这些课程的本科生将培养批判性思维技能和概念知识，这些知识与生命信息如何在DNA中编码并由DNA修复酶保持有关。这个研究项目描述了碱基切除修复(BER)糖基酶的化学机制，并说明了这些酶如何有效地找到罕见的修饰DNA碱基。模拟过渡态的修饰核苷酸正在通过合成化学方法制备。对几种与含有这些过渡态类似物的DNA结合的BER糖基酶的结构研究揭示了这些酶催化碱基切除的策略。初步工作揭示了BER糖基酶MutY和AlkD的几个令人惊讶的特征，并推动了对这些酶和相关BER糖基酶的新的结构和机制研究。该项目揭示了DNA修复基础化学中的共同主题和独特特征。

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Sheila David at The University of California - Davis and Dr. Martin Horvath at The University of Utah to investigate how DNA damage is detected and repaired. DNA is the blueprint for life, and damage to this molecule caused by cellular metabolism or by environmental hazards can lead to mutations, cell death or changes in the blueprint over the course of evolution. The preservation of DNA relies on the action of DNA repair enzymes. Despite years of work that has uncovered DNA repair enzymes and the types of damage upon which they act, mysteries remain as to how these amazing enzymes work at the chemical level. This project uses synthetic DNA chemistry and X-ray crystallography to trap and visualize steps, in the DNA repair process, that are otherwise too fleeting to study. This strategy provides a detailed molecular picture of the DNA repair process. The project applies a multi-faceted approach to investigate several enzymes that specialize in repairing damaged DNA bases. Graduate and undergraduate students involved in this project are receiving training in synthesis, biochemistry and X-ray crystallography. The discoveries and results produced by this project are being incorporated into a DNA damage and repair undergraduate laboratory class at UC Davis and at the University of Utah. Undergraduate students in these courses will emerge with skills in critical thinking and conceptual knowledge related to how the information of life is encoded in DNA and maintained by DNA repair enzymes.This research project delineates chemical mechanisms of base excision repair (BER) glycosylases and illuminates how these enzymes efficiently find rare modified DNA bases. Modified nucleotides that mimic transition states are being prepared through synthetic chemistry. Structural studies of several BER glycosylases bound to DNA containing these transition state analogs are revealing the strategies used by these enzymes to catalyze base excision. Preliminary work has revealed several surprising features of the BER glycosylases MutY and AlkD, and prompted novel structural and mechanistic studies on these and related BER glycosylases. This project is revealing common themes and unique features in the chemistry underlying DNA repair.