CMG-Pol epsilon dynamics suggests a mechanism for the establishment of leading-strand synthesis in the eukaryotic replisome
CMG-Pol epsilon dynamics suggests a mechanism for the establishment of leading-strand synthesis in the eukaryotic replisome
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DOI：
10.1073/pnas.1700530114
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发表时间：
2017-04-18
影响因子：
11.1
通讯作者：
Costa, Alessandro
中科院分区：
文献类型：
--
作者：
Zhou, Jin Chuan;Janska, Agnieszka;Costa, Alessandro
复制体解旋并合成用于基因组复制的DNA。在真核生物中，Cdc 45-MCM-GINS（CMG）解旋酶和前导链聚合酶Pol β形成稳定的组装体。耦合DNA解旋与合成的机制开始被阐明，但是复制叉的结构和动力学仍然只有部分理解，阻止了对染色体复制的分子理解。为了解决这个问题，我们进行了系统的单粒子EM研究的多重排列的重组CMG-Pol的组装。有两个柔软的叶子。非催化叶锚定在解旋酶的马达上，而聚合结构域则向解旋酶一侧延伸。我们观察到两个交替配置的DNA合成结构域中CMG结合的聚合物。我们认为，这种构象开关可能控制DNA模板的接合和释放，调节复制体的进展。
The replisome unwinds and synthesizes DNA for genome duplication. In eukaryotes, the Cdc45-MCM-GINS (CMG) helicase and the leading-strand polymerase, Pol epsilon, form a stable assembly. The mechanism for coupling DNA unwinding with synthesis is starting to be elucidated, however the architecture and dynamics of the replication fork remain only partially understood, preventing a molecular understanding of chromosome replication. To address this issue, we conducted a systematic single-particle EM study on multiple permutations of the reconstituted CMG-Pol epsilon assembly. Pol epsilon contains two flexibly tethered lobes. The noncatalytic lobe is anchored to the motor of the helicase, whereas the polymerization domain extends toward the side of the helicase. We observe two alternate configurations of the DNA synthesis domain in the CMG-bound Pol epsilon. We propose that this conformational switch might control DNA template engagement and release, modulating replisome progression.