Global Repair Profile of Human Alkyladenine DNA Glycosylase on Nucleosomes Reveals DNA Packaging Effects
Global Repair Profile of Human Alkyladenine DNA Glycosylase on Nucleosomes Reveals DNA Packaging Effects
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DOI：
10.1021/acschembio.9b00263
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发表时间：
2019-08-01
影响因子：
4
通讯作者：
Delaney, Sarah
中科院分区：
文献类型：
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作者：
Kennedy, Erin E.;Li, Chuxuan;Delaney, Sarah
烷基腺嘌呤DNA糖基化酶（Alkyladenine DNA glycosylase，AAG）是目前已知的唯一一种能够从DNA中切除烷基化嘌呤的人糖基化酶，包括高度致突变的1，N-6-乙烯基腺嘌呤（Ethenoadenine，AGA）损伤。在这里，我们研究的能力，AAG切除从核小体核心颗粒（NCP），这是在真核生物中的DNA包装的主要重复单位的caseA。使用化学合成技术，我们组装了一个全球人口的NCP，其中A被替换为NCP A。虽然每个NCP包含不超过一个NTA病变，但总人群在49个不同的几何位置包含NTA。使用这个全球性的AAG含NCP系统，我们得到了整个NCP架构的AAG的动力学参数。我们在整个NCP中观察到单相反应动力学，但AAG切除量不同。AAG活性与溶液可及性和局部组蛋白结构相关。值得注意的是，我们确定了一些高度解决方案可访问的损伤，没有很好地修复，并在核小体DNA末端的不对称解包区域内的修复增加。这些观察结果支持在体内的工作，并提供分子水平的洞察修复和NCP架构之间的关系。
Alkyladenine DNA glycosylase (AAG) is the only known human glycosylase capable of excising alkylated purines from DNA, including the highly mutagenic 1,N-6-ethenoadenine (epsilon A) lesion. Here, we examine the ability of AAG to excise epsilon A from a nucleosome core particle (NCP), which is the primary repeating unit of DNA packaging in eukaryotes. Using chemical synthesis techniques, we assembled a global population of NCPs in which A is replaced with epsilon A. While each NCP contains no more than one epsilon A lesion, the total population contains epsilon A in 49 distinct geometric positions. Using this global epsilon A-containing NCP system, we obtained kinetic parameters of AAG throughout the NCP architecture. We observed monophasic reaction kinetics across the NCP, but varying amounts of AAG excision. AAG activity is correlated with solution accessibility and local histone architecture. Notably, we identified some highly solution-accessible lesions that are not repaired well, and an increase in repair within the region of asymmetric unwrapping of the nucleosomal DNA end. These observations support in vivo work and provide molecular-level insight into the relationship between repair and NCP architecture.