Tautomerization-dependent recognition and excision of oxidation damage in base-excision DNA repair
Tautomerization-dependent recognition and excision of oxidation damage in base-excision DNA repair
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DOI：
10.1073/pnas.1604591113
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发表时间：
2016-06
期刊：
影响因子：
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通讯作者：
Chenxu Zhu;Lining Lu;Jun Zhang;Zongwei Yue;Jinghui Song;S. Zong*;Menghao Liu;O. Stovicek;Y. Gao-Y.
中科院分区：
文献类型：
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作者：
Chenxu Zhu;Lining Lu;Jun Zhang;Zongwei Yue;Jinghui Song;S. Zong*;Menghao Liu;O. Stovicek;Y. Gao-Y.
重要意义氧化性DNA损伤可能对细胞产生细胞毒性或致突变作用。NEIL1(Nei-like 1)是一种DNA修复糖基酶，保护哺乳动物基因组免受各种DNA碱基的氧化；然而，NEIL1如何识别和催化其底物的去除仍然知之甚少。在这里，我们整合了NEIL1/双链DNA复合体的晶体结构、计算模拟和生化分析，并表明NEIL1促进胸腺嘧啶乙醇-同源底物-的互变异构化，以实现有效的底物识别和切除。据我们所知，这种依赖于互变异构体的底物识别和催化在酶催化反应中是第一次报道。NeIL1(Nei-like 1)是一种保护哺乳动物基因组免受DNA碱基氧化损伤的DNA修复糖基酶。作为碱基切除修复途径中的第一种酶，糖基酶必须识别同源底物并催化它们的切除。在这里，我们介绍了与一系列双链DNA结合的人NEIL1的晶体结构。结合计算和生化分析，我们的结果表明，NEIL1促进胸腺嘧啶二醇(TG)的互变异构化--胸腺嘧啶二醇(TG)--一种首选底物--在其活性部位实现最佳结合。此外，这种互变异构化事件也促进了NEIL1催化的TG切除。据我们所知，目前的例子是第一个记录的情况下酶促进的互变异构化，以有效的底物识别和催化的酶催化反应。
Significance Oxidative DNA damage can be cytotoxic or mutagenic to cells. NEIL1 (Nei-like 1) is a DNA repair glycosylase guarding the mammalian genome against various oxidized DNA bases; yet how NEIL1 recognizes and catalyzes the removal of its substrates remains poorly understood. Here we integrate crystal structures of a NEIL1/double-stranded DNA complex, computational simulations, and biochemical analyses and show that NEIL1 promotes tautomerization of thymine glycol—a cognate substrate—for efficient substrate recognition and excision. Such tautomerism-dependent substrate recognition and catalysis is, to the best of our knowledge, reported for the first time in an enzyme-catalyzed reaction. NEIL1 (Nei-like 1) is a DNA repair glycosylase guarding the mammalian genome against oxidized DNA bases. As the first enzymes in the base-excision repair pathway, glycosylases must recognize the cognate substrates and catalyze their excision. Here we present crystal structures of human NEIL1 bound to a range of duplex DNA. Together with computational and biochemical analyses, our results suggest that NEIL1 promotes tautomerization of thymine glycol (Tg)—a preferred substrate—for optimal binding in its active site. Moreover, this tautomerization event also facilitates NEIL1-catalyzed Tg excision. To our knowledge, the present example represents the first documented case of enzyme-promoted tautomerization for efficient substrate recognition and catalysis in an enzyme-catalyzed reaction.