Molecular basis for DNA double-strand break annealing and primer extension by an NHEJ DNA polymerase.
Molecular basis for DNA double-strand break annealing and primer extension by an NHEJ DNA polymerase.
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DOI：
10.1016/j.celrep.2013.10.016
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发表时间：
2013-11-27
期刊：
影响因子：
8.8
通讯作者：
Doherty AJ
中科院分区：
文献类型：
--
作者：
Brissett NC;Martin MJ;Bartlett EJ;Bianchi J;Blanco L;Doherty AJ
非同源末端连接（NHEJ）是DNA双链断裂（DSB）修复的主要途径之一。在NHEJ过程中，断裂被有效地聚集在一起并延伸的机制知之甚少。由于聚合酶通过向引物添加核苷酸以5′-3′方向延伸DNA，因此不清楚NHEJ聚合酶如何填充含有缺少引物链的3′突出端的断裂末端。在这里，我们描述了，在分子水平上，原核NHEJ聚合酶如何配置引物模板基板退火的3 '突出链从相对的断裂，形成一个缺口的中间，可以在反式延伸。我们确定的结构元件，促进对接的3'端的活性位点的相邻聚合酶，并揭示如何作为引物的末端退火断裂的延伸，本研究阐明了聚合酶如何将断裂突触与催化偶联，提供了一种分子机制来解释引物延伸是如何在DNA断裂上实现的。与退火DNA双链断裂结合的NHEJ聚合酶的结构通过微同源性和聚合酶表面环稳定断裂突触引物链的3′羟基定位到反式中的活性位点口袋中模板碱基选择依赖于环1和保守的苯丙氨酸残基在本文中，Alfressett及其同事阐明了通过分枝杆菌NHEJ修复聚合酶延伸突触DNA双链断裂末端的分子基础。这种结构捕获了断裂退火后的瞬间，揭示了断裂的末端如何定位到相邻聚合酶的活性位点中，以准备填充剩余的缺口，最终促进DNA连接酶对断裂的重新连接。
Nonhomologous end-joining (NHEJ) is one of the major DNA double-strand break (DSB) repair pathways. The mechanisms by which breaks are competently brought together and extended during NHEJ is poorly understood. As polymerases extend DNA in a 5′-3′ direction by nucleotide addition to a primer, it is unclear how NHEJ polymerases fill in break termini containing 3′ overhangs that lack a primer strand. Here, we describe, at the molecular level, how prokaryotic NHEJ polymerases configure a primer-template substrate by annealing the 3′ overhanging strands from opposing breaks, forming a gapped intermediate that can be extended in trans. We identify structural elements that facilitate docking of the 3′ ends in the active sites of adjacent polymerases and reveal how the termini act as primers for extension of the annealed break, thus explaining how such DSBs are extended in trans. This study clarifies how polymerases couple break-synapsis to catalysis, providing a molecular mechanism to explain how primer extension is achieved on DNA breaks. Structure of a NHEJ polymerase bound to an annealed DNA double-strand break Break synapsis is stabilized by microhomology and polymerase surface loops 3′ hydroxyl of the primer strand is positioned into active-site pocket in trans Templating base selection relies on loop 1 and conserved phenylalanine residues In this article, Brissett and colleagues have elucidated the molecular basis for the extension of the termini of a synapsed DNA double-strand break by a mycobacterial NHEJ repair polymerase. This structure captures the moments after the break has been annealed back together, revealing how the broken ends are positioned into the active site of adjacent polymerases in readiness for filling in of the remaining gaps to, ultimately, facilitate rejoining of the break by DNA ligase.
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DOI：
10.1107/s0907444905036693
发表时间：
2006-01-01
影响因子：
2.2
作者：
Evans, P
通讯作者：
Evans, P
DOI：
10.1042/bj20080413
发表时间：
2009-02-01
期刊：
The Biochemical journal
影响因子：
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作者：
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通讯作者：
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影响因子：
16.8
作者：
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通讯作者：
Glickman, MS
影响因子：
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作者：
Pitcher, Robert S.;Green, Andrew J.;Doherty, Aidan J.
通讯作者：
Doherty, Aidan J.
影响因子：
56.9
作者：
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通讯作者：
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