Oxidatively damaged DNA Repair and Its Related Enzymes

氧化损伤DNA修复及其相关酶

• 批准号: 13480193
• 负责人: KURAMITSU Seiki
• 金额: $ 9.28万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13480193/
• 关键词: DNA repair; damaged DNA; nucleotide; catalytic mechanism; substrate recognition; extreme thermophile; 酸化傷害DNA修復; 8-オキソグアニン; MutM; フリップアウト; Thermus thermophilus HB8; 立体構造反応解析; 基質特異性; 分子機能解析; DNA repair; damaged DNA; nucleotide; catalytic mechanism; substrate recognition; extreme thermophile; 酸化傷害DNA修復; 8-オキソグアニン; MutM; フリップアウト; Thermus thermophilus HB8; 立体構造反応解析; 基質特異性; 分子機能解析

DNA is oxidatively damaged by oxidative stress especially reactive oxygen species. Such damages result in mutations and cause a number of diseases including cancer. Among oxidatively damaged bases 8-oxoguanine can lead to increased frequency of G : C to T : A transversion. MutM is a base excision repair enzyme that recognize oxidatively damaged guanines including 8-oxoguanine. This enzyme catalyzes three reactions: excision of the 8-oxoguanine base (glycosylase activity). and b-and d-elimination of the resultant abasic site (AP-lyase activity), Recently, we also determined the structures of MutM-DNA complex. These structures suggest involvement of many amino acid residues in DNA-binding and catalytic activities. However, proposed roles of those residues have not been verified experimentally. To establish the detailed mechanism of MutM reaction, this study investigated functional roles of several amino acid residues in the catalysis. We selected several conserved residues based on the crystal structure of the complex and replaced them by other residues using site-directed mutagenesis. The obtained results demonstrate that some residues are involved in the catalytic reaction of MutM.

DNA被氧化应激尤其是活性氧氧化受损。这种损害导致突变并导致许多疾病在内。在氧化损坏的碱中，8-氧气鸟氨酸会导致G：C至T：A trans术的频率增加。 MUTM是一种碱性切除修复酶，识别包括8-氧气氨酸在内的氧化受损的鸟嘌呤。这种酶催化了三种反应：切除8-氧气甘氨酸碱（糖基化酶活性）。最近，我们还确定了MUTM-DNA复合物的结构。这些结构表明许多氨基酸残基参与DNA结合和催化活性。但是，这些残基提出的作用尚未通过实验验证。为了建立MUTM反应的详细机制，本研究研究了几个氨基酸残基在催化中的功能作用。我们根据复合物的晶体结构选择了几个保守的残基，并使用定位诱变将它们取代了其他残基。获得的结果表明，某些残基参与MUTM的催化反应。