Two distinct triggers for cycling of the lagging strand polymerase at the replication fork
Two distinct triggers for cycling of the lagging strand polymerase at the replication fork
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DOI：
10.1074/jbc.m006556200
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发表时间：
2000-11-03
影响因子：
4.8
通讯作者：
Marians, KJ
中科院分区：
文献类型：
--
作者：
Li, XJ;Marians, KJ
在复制叉处有两种DNA合成模式。前导链以连续的方式合成，其长度在大肠杆菌中可以超过2兆碱基。另一方面，滞后链在相对短的2个酶的延伸中合成。然而，DNA聚合酶In：核心与β滑动夹连接的相同组件导致了两种DNA合成模式。然而，相同的滞后链聚合酶在复制叉处负责所有冈崎片段的合成，从刚刚完成的片段的S '端到新引物的3'端每隔1或2秒重复循环。已经调用了几种模型来解释聚合酶复合物的快速循环，该聚合酶复合物可以保持与模板结合长达40分钟。通过使用分离的复制蛋白-DNA模板复合物，我们已经测试了这些模型，并在此表明，滞后链聚合酶的循环可以通过引物酶与复制体结合并合成引物的作用或通过滞后链的碰撞来触发。在另一个实施方案中，将聚合酶与先前的冈崎片段的5'末端连接。
There are two modes of DNA synthesis at a replication fork. The leading strand is synthesized in a continuous fashion in lengths that in Escherichia coli can be in excess of 2 megabases. On the other hand, the lagging strand is synthesized in relatively short stretches of 2 kilobases. Nevertheless, identical assemblies of the DNA polymerase In: core tethered to the beta sliding clamp account for both modes of DNA synthesis. Yet the same lagging strand polymerase accounts for the synthesis of all Okazaki fragments at a replication fork, cycling repeatedly every 1 or 2 s from the S'-end of the just-completed fragment to the 3'-end of the new primer. Several models have been invoked to account for the rapid cycling of a polymerase complex that can remain bound to the template for upward of 40 min. By using isolated replication protein-DNA template complexes, we have tested these models and show here that cycling of the lagging strand polymerase can be triggered by either the action of primase binding to the replisome and synthesizing a primer or by collision of the lagging strand polymerase with the 5' end of the previous Okazaki fragment.