The architecture of a eukaryotic replisome.
The architecture of a eukaryotic replisome.
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DOI：
10.1038/nsmb.3113
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发表时间：
2015-12
影响因子：
16.8
通讯作者：
O'Donnell ME
中科院分区：
文献类型：
--
作者：
Sun J;Shi Y;Georgescu RE;Yuan Z;Chait BT;Li H;O'Donnell ME
在真核生物的DNA复制分叉，人们普遍认为cdc45-mcm2-7-gins(CMG)解旋酶在DNA解离的前面，而DNA聚合酶(Pol)在解旋酶的后面。在这里，我们使用单粒子电子显微镜直接成像复制体。与预期相反，领先链POLε位于CMG解旋酶的前面，而CTF4和滞后链POLα-Primase(POLα)位于解旋酶的后面。这种意想不到的结构表明，领先的链dna在到达POLε之前会经过很长一段距离，它首先穿过McM2-7环，然后在底部掉头到达CMG顶部的POLε。我们的工作揭示了真核生物复制体的一种意想不到的配置，提出了这种结构的可能原因，并为进一步的结构和生化复制体研究提供了基础。
At the eukaryotic DNA replication fork, it is widely believed that the Cdc45-Mcm2-7-GINS (CMG) helicase leads the way in front to unwind DNA, and that DNA polymerases (Pol) trail behind the helicase. Here we use single particle electron microscopy to directly image a replisome. Contrary to expectations, the leading strand Pol ε is positioned ahead of CMG helicase, while Ctf4 and the lagging strand Pol α-primase (Pol α) are behind the helicase. This unexpected architecture indicates that the leading strand DNA travels a long distance before reaching Pol ε, it first threads through the Mcm2-7 ring, then makes a U-turn at the bottom to reach Pol ε at the top of CMG. Our work reveals an unexpected configuration of the eukaryotic replisome, suggests possible reasons for this architecture, and provides a basis for further structural and biochemical replisome studies.