The major human AP endonuclease (Ape1) is involved in the nucleotide incision repair pathway
The major human AP endonuclease (Ape1) is involved in the nucleotide incision repair pathway
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DOI：
10.1093/nar/gkh165
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发表时间：
2004-01-01
影响因子：
14.9
通讯作者：
Saparbaev, MK
中科院分区：
文献类型：
--
作者：
Gros, L;Ishchenko, AA;Saparbaev, MK
在核苷酸切口修复（NIR）中，一种内切酶以不依赖于DNA糖基酶的方式切割氧化损伤的DNA，为DNA合成提供正确的末端，并修复剩余的5'悬垂修饰核苷酸。这种机制特征不同于DNA糖基酶介导的碱基切除修复。在这里，我们报道Ape1是人类细胞中主要的无嘌呤/无嘧啶内切酶，是参与近红外的损伤特异性内切酶。我们发现Ape1切割含有5,6-二氢-2'-脱氧尿嘧啶、5,6-二氢胸腺嘧啶、5-羟基-2'-脱氧尿嘧啶、α -2'-脱氧腺苷和α -胸腺嘧啶加合物的DNA，产生3'-羟基和5'-磷酸端。动力学常数表明，ape1催化的近红外活性是高效的。Ape1的底物特异性和蛋白质构象受到MgCl2浓度的调节，从而为NIR成为无细胞提取物的主要活性提供了条件。虽然Ape1的n端区域不是AP内切酶功能所必需的，但我们发现它调节近红外活性。讨论了哺乳动物近红外通路的生理相关性。
In nucleotide incision repair (NIR), an endonuclease nicks oxidatively damaged DNA in a DNA glycosylase-independent manner, providing the correct ends for DNA synthesis coupled to the repair of the remaining 5'-dangling modified nucleotide. This mechanistic feature is distinct from DNA glycosylase-mediated base excision repair. Here we report that Ape1, the major apurinic/apyrimidinic endonuclease in human cells, is the damage- specific endonuclease involved in NIR. We show that Ape1 incises DNA containing 5,6-dihydro-2'-deoxyuridine, 5,6-dihydrothymidine, 5-hydroxy-2'-deoxyuridine, alpha-2'-deoxyadenosine and alpha-thymidine adducts, generating 3'-hydroxyl and 5'-phosphate termini. The kinetic constants indicate that Ape1-catalysed NIR activity is highly efficient. The substrate specificity and protein conformation of Ape1 is modulated by MgCl2 concentrations, thus providing conditions under which NIR becomes a major activity in cell-free extracts. While the N-terminal region of Ape1 is not required for AP endonuclease function, we show that it regulates the NIR activity. The physiological relevance of the mammalian NIR pathway is discussed.