Unhooking of an interstrand cross-link at DNA fork structures by the DNA glycosylase NEIL3
Unhooking of an interstrand cross-link at DNA fork structures by the DNA glycosylase NEIL3
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DOI：
10.1016/j.dnarep.2019.102752
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发表时间：
2020-02-01
期刊：
影响因子：
3.8
通讯作者：
Gates, Kent S.
中科院分区：
文献类型：
--
作者：
Nejad, Maryam Imani;Housh, Kurt;Gates, Kent S.
DNA-DNA 链间交联 (ICL) 由内源过程、药物和环境毒素产生。了解各种 ICL 修复的细胞途径对于了解其生物学效应至关重要。最近的研究表明，ICL 的复制依赖性修复源自脱碱基 (AP) 位点与双链 DNA 相对链上的腺嘌呤残基 (dA) 的反应，通过一种新机制进行，其中 DNA 糖基化酶 NEIL3 解开 ICL。在这里，我们检查了鼠 NEIL3 (MmuNEIL3-GD) 的糖基化酶结构域解开 dA-AP ICL 的能力。该酶选择性地解开位于张开双链体的双链体/单链连接处的 dAAP ICL，该双链体模拟复制叉前缘的链分离 DNA。我们证明，解开 dA-AP ICL 的能力是 NEIL3 的一项特殊功能，因为在其他 BER 酶中未观察到这种活性。重要的是，只有当 AP 残基位于模型复制叉的前导模板链上时，NEIL3 才会解开 dA-AP ICL。用 5,6-二氢胸腺嘧啶单加合物观察到对前导模板链的相同特异性，证明这种偏好是糖基化酶的一般特征，并且与 DNA 损伤的类型无关。总体而言，结果表明，缺乏 C 端 NPL4 和 GRF 锌指基序的 NEIL3 糖基化酶结构域能够解开展开底物中的 dA-AP ICL，并独立地在修复过程中强制执行重要的底物偏好。
Interstrand DNA-DNA cross-links (ICLs) are generated by endogenous processes, drugs, and environmental toxins. Understanding the cellular pathways by which various ICLs are repaired is critical to understanding their biological effects. Recent studies showed that replication-dependent repair of an ICL derived from the reaction of an abasic (AP) site with an adenine residue (dA) on the opposing strand of duplex DNA proceeds via a novel mechanism in which the DNA glycosylase NEIL3 unhooks the ICL. Here we examined the ability of the glycosylase domain of murine NEIL3 (MmuNEIL3-GD) to unhook dA-AP ICLs. The enzyme selectively unhooks the dAAP ICL located at the duplex/single-strand junction of splayed duplexes that model the strand-separated DNA at the leading edge of a replication fork. We show that the ability to unhook the dA-AP ICL is a specialized function of NEIL3 as this activity is not observed in other BER enzymes. Importantly, NEIL3 only unhooks the dA-AP ICL when the AP residue is located on what would be the leading template strand of a model replication fork. The same specificity for the leading template strand was observed with a 5,6-dihydrothymine monoadduct, demonstrating that this preference is a general feature of the glycosylase and independent of the type of DNA damage. Overall, the results show that the glycosylase domain of NEIL3, lacking the C-terminal NPL4 and GRF zinc finger motifs, is competent to unhook the dA-AP ICL in splayed substrates and independently enforces important substrate preferences on the repair process.