Martínez‐García, B. orcid.org/0000-0001-9530-3271, Dyson, S. orcid.org/0000-0002-0126-3633, Segura, J. orcid.org/0000-0002-2170-2701 et al. (5 more authors) (2023) Condensin pinches a short negatively supercoiled DNA loop during each round of ATP usage. The EMBO Journal, 42 (3). e111913. ISSN 0261-4189
Abstract
Condensin, an SMC (structural maintenance of chromosomes) protein complex, extrudes DNA loops using an ATP‐dependent mechanism that remains to be elucidated. Here, we show how condensin activity alters the topology of the interacting DNA. High condensin concentrations restrain positive DNA supercoils. However, in experimental conditions of DNA loop extrusion, condensin restrains negative supercoils. Namely, following ATP‐mediated loading onto DNA, each condensin complex constrains a DNA linking number difference (∆Lk) of −0.4. This ∆Lk increases to −0.8 during ATP binding and resets to −0.4 upon ATP hydrolysis. These changes in DNA topology do not involve DNA unwinding, do not spread outside the condensin‐DNA complex and can occur in the absence of the condensin subunit Ycg1. These findings indicate that during ATP binding, a short DNA domain delimited by condensin is pinched into a negatively supercoiled loop. We propose that this loop is the feeding segment of DNA that is subsequently merged to enlarge an extruding loop. Such a “pinch and merge” mechanism implies that two DNA‐binding sites produce the feeding loop, while a third site, plausibly involving Ycg1, might anchor the extruding loop.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2022 The Authors. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | DNA supercoil; DNA topology; SMC complex; condensin; loop extrusion; DNA, Superhelical; Chromosomes; DNA; Adenosine Triphosphate; Cell Cycle Proteins |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 23 Jan 2025 10:24 |
Last Modified: | 23 Jan 2025 10:24 |
Published Version: | https://doi.org/10.15252/embj.2022111913 |
Status: | Published |
Publisher: | Springer Science and Business Media LLC |
Refereed: | Yes |
Identification Number: | 10.15252/embj.2022111913 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:221961 |