The Ku Heterodimer and the Metabolism of Single-Ended DNA Double-Strand Breaks
The Ku Heterodimer and the Metabolism of Single-Ended DNA Double-Strand Breaks
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DOI：
10.1016/j.celrep.2013.05.026
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发表时间：
2013-06-01
期刊：
影响因子：
8.8
通讯作者：
Petrini, John H. J.
中科院分区：
文献类型：
--
作者：
Balestrini, Alessia;Ristic, Dejan;Petrini, John H. J.
单端双链断裂 (DSB) 是自发 DNA 断裂的常见形式，当复制体遇到 DNA 模板中的不连续性时就会产生。鉴于其普遍存在，了解控制单端 DSB 命运的机制非常重要。我们描述了 Ku 异二聚体和 Mre11 核酸酶活性对单端 DSB 加工的影响。 yku70 的功能分离等位基因源自单端 DSB 的表型 Ku 缺陷，但对 NHEJ 仍然有效。 Ku 突变体无法调节 Exo1 活性，并且在修复喜树碱诱导的单端 DSB 时绕过了 Mre11 核酸酶活性的要求。 Ku 突变体表现出对 DNA 末端的亲和力降低，表现为末端接合减少和线性 DNA 向内扩散的可能性增加。这项研究揭示了单端 DSB 代谢中 Ku 和 Mre11 之间的相互作用，这与双端 DSB 的修复途径选择不同。
Single-ended double-strand breaks (DSBs) are a common form of spontaneous DNA break, generated when the replisome encounters a discontinuity in the DNA template. Given their prevalence, understanding the mechanisms governing the fate(s) of single-ended DSBs is important. We describe the influence of the Ku heterodimer and Mre11 nuclease activity on processing of single-ended DSBs. Separation-of-function alleles of yku70 were derived that phenocopy Ku deficiency with respect to single-ended DSBs but remain proficient for NHEJ. The Ku mutants fail to regulate Exo1 activity, and bypass the requirement for Mre11 nuclease activity in the repair of camptothecin-induced single-ended DSBs. Ku mutants exhibited reduced affinity for DNA ends, manifest as both reduced end engagement and enhanced probability of diffusing inward on linear DNA. This study reveals an interplay between Ku and Mre11 in the metabolism of single-ended DSBs that is distinct from repair pathway choice at double-ended DSBs.