Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia.
Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, and Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia.
Curr Opin Struct Biol. 2018 Dec;53:159-168. doi: 10.1016/j.sbi.2018.09.006. Epub 2018 Oct 4.
Bacterial replisomes are dynamic multiprotein DNA replication machines that are inherently difficult for structural studies. However, breakthroughs continue to come. The structures of Escherichia coli DNA polymerase III (core)-clamp-DNA subcomplexes solved by single-particle cryo-electron microscopy in both polymerization and proofreading modes and the discovery of the stochastic nature of the bacterial replisomes represent notable progress. The structures reveal an intricate interaction network in the polymerase-clamp subassembly, providing insights on how replisomes may work. Meantime, ensemble and single-molecule functional assays and fluorescence microscopy show that the bacterial replisomes can work in a decoupled and uncoordinated way, with polymerases quickly exchanging and both leading-strand and lagging-strand polymerases and the helicase working independently, contradictory to the elegant textbook view of a highly coordinated machine.
细菌复制体是动态的多蛋白 DNA 复制机器，结构研究具有固有的难度。然而，突破仍在继续。通过单颗粒冷冻电子显微镜在聚合和校对模式下解决的大肠杆菌 DNA 聚合酶 III（核心）-夹-DNA 亚复合物的结构，以及细菌复制体的随机性的发现，代表了显著的进展。这些结构揭示了聚合酶-夹组件中的复杂相互作用网络，为复制体如何工作提供了见解。同时，整体和单分子功能测定和荧光显微镜表明，细菌复制体可以以解耦和不协调的方式工作，聚合酶快速交换，前导链和滞后链聚合酶以及解旋酶独立工作，与高度协调的机器的优雅教科书观点相矛盾。
