Mammalian base excision repair by DNA polymerases δ and ε
Mammalian base excision repair by DNA polymerases δ and ε
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DOI：
10.1038/sj.onc.1202001
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发表时间：
1998-08-20
期刊：
影响因子：
8
通讯作者：
Dogliotti, E
中科院分区：
文献类型：
--
作者：
Stucki, M;Pascucci, B;Dogliotti, E
在真核生物中发现了碱基切除修复（BER）完成的两种不同途径：DNA聚合酶β (Pol β)依赖的短补丁途径涉及单个核苷酸的替换，以及需要2-6个核苷酸重新合成并需要PCNA的长补丁途径。我们使用从Pol β缺失的小鼠成纤维细胞中提取的细胞提取物来分离含有Pol δ或Pol epsilon的亚组分。然后，在体外修复试验中，使用圆形DNA模板测试这些组分执行短补丁和长补丁BER的能力，该模板在指定位置包含单个基本位点。值得注意的是，Pol delta和Pol epsilon都能够取代损伤部位的单核苷酸，但与Pol β取代单核苷酸相比，修复反应延迟。此外，我们的观察表明，Pol delta和/或Pol epsilon都参与了长斑块的BER。此过程需要PCNA和RF-C，但不需要RP-A。我们的数据首次表明，Pol δ和/或Pol epsilon直接参与了基位的长补丁BER，并可能在单间隙填充反应中作为Pol β的备用系统。
Two distinct pathways for completion of base excision repair (BER) have been discovered in eukaryotes: the DNA polymerase beta (Pol beta)-dependent short-patch pathway that involves the replacement of a single nucleotide and the long-patch pathway that entails the resynthesis of 2-6 nucleotides and requires PCNA, We have used cell extracts from Pol beta-deleted mouse fibroblasts to separate subfractions containing either Pol delta or Pol epsilon. These fractions were then tested for their ability to perform both short- and long-patch BER in an in vitro repair assay, using a circular DNA template, containing a single abasic site at a defined position. Remarkably, both Pol delta and Pol epsilon were able to replace a single nucleotide at the lesion site, but the repair reaction is delayed compared to single nucleotide replacement by Pol beta, Furthermore, our observations indicated, that either Pol delta and/or Pol epsilon participate in the long-patch BER. PCNA and RF-C, but not RP-A are required for this process. Our data show for the first time that Pol delta and/or Pol epsilon are directly involved in the long-patch BER of abasic sites and might function as back-up system for Pol beta in one-gap filling reactions.