复制体结构揭示了连续叉推进和复制后修复的机制。
Replisome structure suggests mechanism for continuous fork progression and post-replication repair.
机构信息
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA.
Laboratory of Molecular Gerontology, National Institute of Aging, National Institutes of Health, 251 Bayview Blvd, Baltimore, MD, 21224, USA.
出版信息
DNA Repair (Amst). 2019 Sep;81:102658. doi: 10.1016/j.dnarep.2019.102658. Epub 2019 Jul 8.
What happens to DNA replication when it encounters a damaged or nicked DNA template has been under investigation for five decades. Initially it was thought that DNA polymerase, and thus the replication-fork progression, would stall at road blocks. After the discovery of replication-fork helicase and replication re-initiation factors by the 1990s, it became clear that the replisome can "skip" impasses and finish replication with single-stranded gaps and double-strand breaks in the product DNA. But the mechanism for continuous fork progression after encountering roadblocks is entangled with translesion synthesis, replication fork reversal and recombination repair. The recently determined structure of the bacteriophage T7 replisome offers the first glimpse of how helicase, primase, leading-and lagging-strand DNA polymerases are organized around a DNA replication fork. The tightly coupled leading-strand polymerase and lagging-strand helicase provides a scaffold to consolidate data accumulated over the past five decades and offers a fresh perspective on how the replisome may skip lesions and complete discontinuous DNA synthesis. Comparison of the independently evolved bacterial and eukaryotic replisomes suggests that repair of discontinuous DNA synthesis occurs post replication in both.
当 DNA 复制遇到受损或缺口的 DNA 模板时会发生什么,这个问题已经被研究了五十年。最初,人们认为 DNA 聚合酶,也就是复制叉的推进,会在障碍物处停滞。在 20 世纪 90 年代发现复制叉解旋酶和复制起始因子后,人们清楚地认识到,复制体可以“跳过”障碍,并在产物 DNA 中留下单链缺口和双链断裂,完成复制。但在遇到障碍后,连续的叉推进机制与跨损伤合成、复制叉反转和重组修复交织在一起。最近确定的噬菌体 T7 复制体结构首次揭示了解旋酶、引发酶、前导链和滞后链 DNA 聚合酶如何围绕 DNA 复制叉组织在一起。紧密偶联的前导链聚合酶和滞后链解旋酶为整合过去五十年积累的数据提供了一个支架,并为复制体如何跳过损伤并完成不连续的 DNA 合成提供了新的视角。对独立进化的细菌和真核复制体的比较表明,在这两种复制体中,不连续的 DNA 合成的修复都发生在复制之后。
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