Structural Studies of DNA repair proteins

描述：（由申请人提供）碱基切除修复是一种重要的 因为已知受损的DNA碱基会产生突变， 会导致遗传性疾病和癌症一个烷基化特异性 DNA糖基化酶负责定位和去除几种类型的DNA。 修改基地一些3-甲基腺嘌呤（3-MeA）糖基化酶特异性地针对 某些类型的烷基化碱，而其他具有广泛的特异性。 此外，这些不同类别的3-MeA糖基化酶在图1中示出。 螺旋-发夹-螺旋（HhH）糖基化酶大家族。的目标 建议的研究是了解差异的结构原因， 共享共同折叠的3-MeA DNA糖基化酶的底物特异性，和 以阐明这些酶定位和清除受损碱基的机制 从DNA 为了解决这些问题，三个HhH 3-MeA DNA的晶体结构 代表底物特异性的两个极端的糖基化酶将是 在存在和不存在DNA底物的情况下测定。H. pylori MagIII是 对3-MeA残基高度特异，而S. cerevisiae MAO和S.马吉粟酒 具有广泛的特异性。MagIII蛋白和MagI/DNA复合物的晶体 已经获得。

DESCRIPTION: (provided by applicant) Base excision repair is an important process to understand because damaged DNA bases are known to produce mutations, which can cause hereditary diseases and cancer. A family of alkylation-specific DNA glycosylases is responsible for locating and removing several types of modified bases. Some 3-methyladenine (3-MeA) glycosylases are specific for a certain type of alkylated base, whereas others have a broad specificity. Moreover, these different classes of 3-MeA glycosylases are represented in the large family of helix-hairpin-helix (HhH) glycosylases. The goal of the proposed studies is to understand the structural reason for differences in the substrate specificities of 3-MeA DNA glycosylases that share common folds, and to address the mechanism by which these enzymes locate and remove damaged bases from DNA. To address these questions, the crystal structures of three HhH 3-MeA DNA glycosylases representing two extremes in substrate specificity will be determined in the presence and absence of DNA substrates. H. pylori MagIII is highly specific for 3-MeA residues, while S. cerevisiae MAO and S. pombe MagI have a broad specificity. Crystals of MagIII protein and of MagI/DNA complexes have already been obtained.