DNA SEARCH AND BASE FLIPPING MECHANISMS OF DNA GLYCOSYLASE, MUTM

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 MutM是一种细菌DNA糖基酶，它特异性地识别氧化损伤的DNA碱基，启动碱基切除修复途径。鉴于病变碱基8-氧鸟嘌呤和正常DNA碱基鸟嘌呤的微妙构象差异，以及病变的稀缺性，一个基本的问题出现了：MutM如何在庞大的基因组中定位罕见的病变位置？此外，碱基翻转是DNA糖基酶催化的一个重要步骤，目前还不清楚，蛋白质是否积极促进碱基挤出目前仍存在争议。使用二硫键交联策略，我们已经共价捕获了在MutM搜索核苷酸碱基挤出过程中的损伤过程中通常的瞬时中间体。这些中间体不仅揭示了病变识别和催化的机制，而且也为我们对碱基挤出途径的计算研究提供了有价值的起点。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. MutM is a bacterial DNA glycosylase that specifically recognizes oxidatively damaged DNA bases and initiates the base excision repair pathway. Given the subtle conformational differences in the lesion base, 8-oxoguanine, and normal DNA base, guanine, and the scarcity of the lesions, a fundamental question arises: how does MutM locate the rare lesion sites among the vast genome? In addition, base flipping, an essential step for DNA glycosylase catalysis, is not well understood and whether protein is actively promoting base extrusion is currently in debate. Using the disulfide crosslinking strategy, we have covalently trapped ordinarily transient intermediates during the search by MutM for lesions during nucleobase extrusion. These intermediates not only shed light on the mechanism of lesion recognition and catalysis, but have also provided valuable starting points for our computational studies of the base extrusion pathway.