CMG-Pol epsilon 动态表明了真核复制体中领头链合成建立的机制。
CMG-Pol epsilon dynamics suggests a mechanism for the establishment of leading-strand synthesis in the eukaryotic replisome.
机构信息
Macromolecular Machines Laboratory, The Francis Crick Institute, London, NW1 1AT, United Kingdom.
Chromosome Replication Laboratory, The Francis Crick Institute, London, NW1 1AT, United Kingdom.
出版信息
Proc Natl Acad Sci U S A. 2017 Apr 18;114(16):4141-4146. doi: 10.1073/pnas.1700530114. Epub 2017 Apr 3.
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.
复制体解开并合成 DNA 以进行基因组复制。在真核生物中，Cdc45-MCM-GINS（CMG）解旋酶和领头链聚合酶 Pol epsilon 形成稳定的组装体。虽然已经开始阐明将 DNA 解旋与合成偶联的机制，但复制叉的结构和动态仍仅部分被理解，这阻碍了对染色体复制的分子理解。为了解决这个问题，我们对重组的 CMG-Pol epsilon 组装体的多种排列进行了系统的单颗粒 EM 研究。Pol epsilon 包含两个灵活连接的叶。非催化叶附着在解旋酶的马达上，而聚合结构域则伸向解旋酶的一侧。我们在 CMG 结合的 Pol epsilon 中观察到 DNA 合成结构域的两种交替构象。我们提出，这种构象转换可能控制 DNA 模板的结合和释放，调节复制体的前进。
Zotero 插件