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四聚体 UvrD 解旋酶由于频繁的复制障碍而位于大肠杆菌复制体上。

Tetrameric UvrD Helicase Is Located at the E. Coli Replisome due to Frequent Replication Blocks.

机构信息

School of Physics, Engineering and Technology, University of York, York YO10 5DD, United Kingdom; Department of Biology, University of York, York YO10 5DD, United Kingdom.

Bioscience Technology Facility, Department of Biology, University of York, York YO10 5DD, United Kingdom.

出版信息

J Mol Biol. 2024 Jan 15;436(2):168369. doi: 10.1016/j.jmb.2023.168369. Epub 2023 Nov 15.

Abstract

DNA replication in all organisms must overcome nucleoprotein blocks to complete genome duplication. Accessory replicative helicases in Escherichia coli, Rep and UvrD, help remove these blocks and aid the re-initiation of replication. Mechanistic details of Rep function have emerged from recent live cell studies; however, the division of UvrD functions between its activities in DNA repair and role as an accessory helicase remain unclear in live cells. By integrating super-resolved single-molecule fluorescence microscopy with biochemical analysis, we find that UvrD self-associates into tetrameric assemblies and, unlike Rep, is not recruited to a specific replisome protein despite being found at approximately 80% of replication forks. Instead, its colocation with forks is likely due to the very high frequency of replication blocks composed of DNA-bound proteins, including RNA polymerase and factors involved in repairing DNA damage. Deleting rep and DNA repair factor genes mutS and uvrA, and inhibiting transcription through RNA polymerase mutation and antibiotic inhibition, indicates that the level of UvrD at the fork is dependent on UvrD's function. Our findings show that UvrD is recruited to sites of nucleoprotein blocks via different mechanisms to Rep and plays a multi-faceted role in ensuring successful DNA replication.

摘要

所有生物的 DNA 复制都必须克服核蛋白块以完成基因组复制。大肠杆菌中的辅助复制解旋酶 Rep 和 UvrD 有助于去除这些块并辅助复制的重新起始。最近的活细胞研究揭示了 Rep 功能的机制细节;然而,UvrD 在 DNA 修复中的作用与其作为辅助解旋酶的功能之间的分工在活细胞中仍不清楚。通过将超分辨单分子荧光显微镜与生化分析相结合,我们发现 UvrD 自身组装成四聚体组装体,与 Rep 不同,尽管在大约 80%的复制叉处发现,但它不会被招募到特定的复制体蛋白上。相反,其与叉的共定位可能是由于由 DNA 结合蛋白组成的复制块的频率非常高,包括 RNA 聚合酶和参与修复 DNA 损伤的因子。删除 rep 和 DNA 修复因子基因 mutS 和 uvrA,以及通过 RNA 聚合酶突变和抗生素抑制抑制转录,表明叉处的 UvrD 水平取决于 UvrD 的功能。我们的发现表明,UvrD 通过与 Rep 不同的机制被招募到核蛋白块的位点,并在确保成功的 DNA 复制中发挥多方面的作用。

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