The mechanism of DNA replication termination in vertebrates.
The mechanism of DNA replication termination in vertebrates.
复制标题
DOI：
10.1038/nature14887
复制
发表时间：
2015-09-17
期刊：
影响因子：
64.8
通讯作者：
Walter JC
中科院分区：
文献类型：
--
作者：
Dewar JM;Budzowska M;Walter JC
当来自相邻复制起点的复制体会聚时，真核DNA复制终止。终止包括DNA合成的局部完成、子分子的解链和复制体的解体。终止一直难以研究，因为终止事件通常是异步的和序列非特异性的。为了克服这些挑战，我们暂停收敛复制体与特定位点的障碍爪蟾卵提取物。在移除屏障后，叉进行同步和位点特异性终止，允许对该过程进行机械解剖。我们发现，DNA合成并没有明显放缓，因为叉相互接近，并且在连接到下游滞后链之前，前导链不受阻碍地相互传递。CMG解旋酶的解离仅发生在最后的连接步骤之后，并且不需要完成DNA合成，这强烈表明会聚的CMG彼此通过并从双链DNA解离。这种终止机制允许快速完成DNA合成，同时避免过早的复制体解体
Eukaryotic DNA replication terminates when replisomes from adjacent replication origins converge. Termination involves local completion of DNA synthesis, decatenation of daughter molecules, and replisome disassembly. Termination has been difficult to study because termination events are generally asynchronous and sequence non-specific. To overcome these challenges, we paused converging replisomes with a site-specific barrier in Xenopus egg extracts. Upon removal of the barrier, forks underwent synchronous and site-specific termination, allowing mechanistic dissection of this process. We show that DNA synthesis does not slow detectably as forks approach each other and that leading strands pass each other unhindered before undergoing ligation to downstream lagging strands. Dissociation of CMG helicases occurs only after the final ligation step, and is not required for completion of DNA synthesis, strongly suggesting that converging CMGs pass one another and dissociate from double-stranded DNA. This termination mechanism allows rapid completion of DNA synthesis while avoiding premature replisome disassembly