Replisome fate upon encountering a leading strand block and clearance from DNA by recombination proteins
Replisome fate upon encountering a leading strand block and clearance from DNA by recombination proteins
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DOI：
10.1074/jbc.m703777200
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发表时间：
2007-08-31
影响因子：
4.8
通讯作者：
O'Donnell, Mike
中科院分区：
文献类型：
--
作者：
McInerney, Peter;O'Donnell, Mike
在遇到前导链损伤时崩溃的复制叉通过称为复制重启的重组修复过程重新激活。使用滚环 DNA 底物模拟复制叉，我们检查了当前导链聚合酶被阻断时解旋酶和两种 DNA 聚合酶的命运。我们发现解旋酶持续超过 0.5 kb 但小于 3 kb，并且滞后链 DNA 聚合酶尽管与停滞的前导链酶连接，但仍保持活性。此外，被阻断的前链聚合酶仍然稳定地结合在复制叉上，这意味着它必须从 DNA 上拆除才能重新开始复制。遗传学研究已经确定了复制重启所需的至少四种基因产物：RecF、RecO、RecR 和 RecA。我们在这里发现这些蛋白质取代了 DNA 模板损伤处停滞的聚合酶。讨论了这些结果对复制叉崩溃和恢复的影响。
Replication forks that collapse upon encountering a leading strand lesion are reactivated by a recombinative repair process called replication restart. Using rolling circle DNA substrates to model replication forks, we examine the fate of the helicase and both DNA polymerases when the leading strand polymerase is blocked. We find that the helicase continues over 0.5 kb but less than 3 kb and that the lagging strand DNA polymerase remains active despite its connection to a stalled leading strand enzyme. Furthermore, the blocked leading strand polymerase remains stably bound to the replication fork, implying that it must be dismantled from DNA in order for replication restart to initiate. Genetic studies have identified at least four gene products required for replication restart, RecF, RecO, RecR, and RecA. We find here that these proteins displace a stalled polymerase at a DNA template lesion. Implications of these results for replication fork collapse and recovery are discussed.