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Lookup NU author(s): Dr Adam WollmanORCiD
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
© 2018 The Author(s). Bacterial DNA gyrase introduces negative supercoils into chromosomal DNA and relaxes positive supercoils introduced by replication and transiently by transcription. Removal of these positive supercoils is essential for replication fork progression and for the overall unlinking of the two duplex DNA strands, as well as for ongoing transcription. To address how gyrase copes with these topological challenges, we used high-speed single-molecule fluorescence imaging in live Escherichia coli cells. We demonstrate that at least 300 gyrase molecules are stably bound to the chromosome at any time, with ∼12 enzymes enriched near each replication fork. Trapping of reaction intermediates with ciprofloxacin revealed complexes undergoing catalysis. Dwell times of ∼2 s were observed for the dispersed gyrase molecules, which we propose maintain steady-state levels of negative supercoiling of the chromosome. In contrast, the dwell time of replisome-proximal molecules was ∼8 s, consistent with these catalyzing processive positive supercoil relaxation in front of the progressing replisome.
Author(s): Stracy M, Wollman AJM, Kaja E, Gapinski J, Lee J-E, Leek VA, McKie SJ, Mitchenall LA, Maxwell A, Sherratt DJ, Leake MC, Zawadzki P
Publication type: Article
Publication status: Published
Journal: Nucleic Acids Research
Year: 2019
Volume: 47
Issue: 1
Pages: 210-220
Print publication date: 10/01/2019
Online publication date: 16/11/2018
Acceptance date: 07/11/2018
Date deposited: 10/02/2020
ISSN (print): 0305-1048
ISSN (electronic): 1362-4962
Publisher: Oxford University Press
URL: https://doi.org/10.1093/nar/gky1143
DOI: 10.1093/nar/gky1143
PubMed id: 30445553
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