Human alkyladenine DNA glycosylase employs a processive search for DNA damage.
Human alkyladenine DNA glycosylase employs a processive search for DNA damage.
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DOI：
10.1021/bi801046y
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发表时间：
2008-11-04
期刊：
影响因子：
2.9
通讯作者：
O'Brien, Patrick J.
中科院分区：
文献类型：
--
作者：
Hedglin, Mark;O'Brien, Patrick J.
DNA 修复蛋白进行全基因组搜索，以检测和修复 DNA 损伤位点（无论其发生在何处）。人烷基腺嘌呤 DNA 糖基化酶 (AAG) 负责识别各种碱基损伤，包括烷基化和脱氨基嘌呤，并通过碱基切除修复途径启动其修复。我们研究了 AAG 使用含有两个 DNA 损伤位点的寡核苷酸底物定位损伤位点的机制。该底物的设计使 AAG 随机结合到两个病变中的任何一个。 AAG 催化的碱基切除产生修复中间体，随后解离和扩散到第二个位点之间的分配可以根据不同产物的形成速率进行量化。我们的结果表明，AAG 能够在生理盐浓度下沿着 DNA 短距离滑动。 AAG 的持续合成能力随着离子强度的增加而降低，在高离子强度下变得完全分布，这表明带负电的 DNA 和带正电的 DNA 结合表面之间的静电相互作用对于非特异性 DNA 结合很重要。尽管蛋白质的氨基末端对于单个位点的糖基化酶活性来说是可有可无的，但我们发现氨基末端 80 个氨基酸的缺失显着降低了 AAG 的持续合成能力。这些观察结果支持这样的观点：未受损 DNA 上的扩散有助于寻找 DNA 损伤位点。
DNA repair proteins conduct a genome-wide search to detect and repair sites of DNA damage wherever they occur. Human alkyladenine DNA glycosylase (AAG) is responsible for recognizing a variety of base lesions, including alkylated and deaminated purines, and initiating their repair via the base excision repair pathway. We have investigated the mechanism by which AAG locates sites of damage using an oligonucleotide substrate containing two sites of DNA damage. This substrate was designed so that AAG randomly binds to either of the two lesions. AAG-catalyzed base excision creates a repair intermediate and the subsequent partitioning between dissociation and diffusion to the second site can be quantified from the rates of formation of the different products. Our results demonstrate that AAG has the ability to slide for short distances along DNA at physiological salt concentrations. The processivity of AAG decreases with increasing ionic strength to become fully distributive at high ionic strength, suggesting that electrostatic interactions between the negatively charged DNA and the positively charged DNA binding surface are important for nonspecific DNA binding. Although the amino terminus of the protein is dispensable for glycosylase activity at a single site, we find that deletion of the amino terminal 80 amino acids significantly decreases the processivity of AAG. These observations support the idea that diffusion on undamaged DNA contributes to the search for sites of DNA damage.
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影响因子：
2.9
作者：
Carey, DC;Strauss, PR
通讯作者：
Strauss, PR
影响因子：
14.9
作者：
CHEN, DS;HERMAN, T;DEMPLE, B
通讯作者：
DEMPLE, B
影响因子：
11.4
作者：
Gowers, DM;Halford, SE
通讯作者：
Halford, SE
影响因子：
4.8
作者：
Abner, CW;Lau, AY;Bloom, LB
通讯作者：
Bloom, LB
DOI：
10.1073/pnas.0509723103
发表时间：
2006-04-11
影响因子：
11.1
作者：
Blainey, PC;van Oijent, AM;Xie, XS
通讯作者：
Xie, XS