Cleavage of a model DNA replication fork by a Type I restriction endonuclease
Cleavage of a model DNA replication fork by a Type I restriction endonuclease
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DOI：
10.1093/nar/gkp214
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发表时间：
2009-06-01
影响因子：
14.9
通讯作者：
Kobayashi, Ichizo
中科院分区：
文献类型：
--
作者：
Ishikawa, Ken;Handa, Naofumi;Kobayashi, Ichizo
DNA复制叉的切割通过重组修复导致叉的恢复。在携带限制修饰系统的原核细胞中，叉代减少了修饰酶引起的基因组甲基化，并使染色体暴露于限制酶的攻击。各种各样的观察表明了分叉和I型限制酶之间的关系，I型限制酶在距离识别序列一定距离处切割DNA。在这里，我们证明了I型限制性内切酶制备物在其分支切割模型复制叉。该酶可能从子DNA上的未甲基化识别位点沿着沿着DNA追踪，并在遇到分支点时切断分叉。我们的发现表明，这些restrictionmodification系统有助于通过细胞死亡的基因组维护，并表明DNA复制叉切割代表了一个关键点，在基因组维护之间的恢复途径和破坏途径的选择。
Cleavage of a DNA replication fork leads to fork restoration by recombination repair. In prokaryote cells carrying restrictionmodification systems, fork passage reduces genome methylation by the modification enzyme and exposes the chromosome to attack by the restriction enzyme. Various observations have suggested a relationship between the fork and Type I restriction enzymes, which cleave DNA at a distance from a recognition sequence. Here, we demonstrate that a Type I restriction enzyme preparation cleaves a model replication fork at its branch. The enzyme probably tracks along the DNA from an unmethylated recognition site on the daughter DNA and cuts the fork upon encountering the branch point. Our finding suggests that these restrictionmodification systems contribute to genome maintenance through cell death and indicates that DNA replication fork cleavage represents a critical point in genome maintenance to choose between the restoration pathway and the destruction pathway.