Trading places on DNA-a three-point switch underlies primer handoff from primase to the replicative DNA polymerase
Trading places on DNA-a three-point switch underlies primer handoff from primase to the replicative DNA polymerase
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DOI：
10.1016/s0092-8674(00)80968-x
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发表时间：
1999-01-08
期刊：
影响因子：
64.5
通讯作者：
O'Donnell, M
中科院分区：
文献类型：
--
作者：
Yuzhakov, A;Kelman, Z;O'Donnell, M
这项研究报告了大肠杆菌中的引物酶到聚合酶的转换，该转换将引物酶的作用与 DNA 聚合酶 III 全酶的延伸密切相关。我们发现引物酶紧紧抓住它的RNA引物，保护它免受其他蛋白质的作用。然而，在将 β 滑动夹组装到涂底漆的部位之前，必须先移动涂底漆酶。全酶的单个亚基 chi 专门负责这种引物酶置换任务。置换机制取决于第三种蛋白质，SSB。 Primase 需要与 SSB 接触才能抓住底漆位点。 chi 亚基还结合 SSB，导致引物酶与 SSB 的接触不稳定，导致引物酶解离并将 β 组装到 RNA 引物上。讨论了这种三点开关的保守性，其中两种蛋白质通过与第三种蛋白质互斥的相互作用交换 DNA 上的位置。
This study reports a primase-to-polymerase switch in E. coli that closely links primase action with extension by DNA polymerase III holoenzyme. We find that primase tightly grips its RNA primer, protecting it from the action of other proteins. However, primase must be displaced before the beta sliding clamp can be assembled on the primed site. A single subunit of the holoenzyme, chi, is dedicated to this primase displacement task. The displacement mechanism depends on a third protein, SSB. Primase requires contact to SSB for its grip on the primed site. The chi subunit also binds SSB, upon which the primase-to-SSB contact is destabilized leading to dissociation of primase and assembly of beta onto the RNA primer. The conservation of this three-point switch, in which two proteins exchange places on DNA via mutually exclusive interaction with a third protein, is discussed.