Oligomerisation of Ku from Mycobacterium tuberculosis promotes DNA synapsis

Abstract

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is estimated to infect nearly one-quarter of the global population. A key factor in its resilience and persistence is its robust DNA repair capacity. Non-homologous end joining (NHEJ) is the primary pathway for repairing DNA double-strand breaks (DSBs) in many organisms, including Mtb, where it is mediated by the Ku protein and the multifunctional LigD enzyme. In this study, we demonstrate that Ku is essential for mycobacterial survival under DNA-damaging conditions. Using cryogenic electron microscopy (cryo-EM), we solved high-resolution structures of both the apo and DNA-bound forms of the Ku-Mtb homodimer. Our structural and biophysical analyses reveal that Ku forms an extended proteo-filament upon binding DNA. We identify critical residues involved in filament formation and DNA synapsis and show that their mutation severely impairs bacterial viability. Furthermore, we propose a model in which the C-terminus of Ku regulates DNA binding and loading and facilitates subsequent recruitment of LigD. These findings provide unique insights into bacterial DNA repair and guide future therapeutics.

Metadata

Item Type:	Article
Authors/Creators:	Zahid, S. https://orcid.org/0000-0002-1354-9209 Baconnais, S. Smith, H. Atwal, S. Bates, L. Read, H. https://orcid.org/0009-0001-9068-8720 Chadda, A. Morati, F. https://orcid.org/0000-0001-7512-9501 Bedwell, T. Stender, E.G.P. https://orcid.org/0000-0003-2011-7452 Walter, J. Hardwick, S.W. https://orcid.org/0000-0001-9246-1864 Westerlund, F. https://orcid.org/0000-0002-4767-4868 Galburt, E. https://orcid.org/0000-0003-4314-3215 Le Cam, E. https://orcid.org/0000-0002-6832-6117 Pyne, A. https://orcid.org/0000-0002-2658-8987 Mukamolova, G.V. https://orcid.org/0000-0001-5697-2018 Chaplin, A.K. https://orcid.org/0000-0002-9606-8346
Copyright, Publisher and Additional Information:	© The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Keywords:	Mycobacterium tuberculosis; Ku Autoantigen; DNA, Bacterial; Cryoelectron Microscopy; DNA End-Joining Repair; Bacterial Proteins; DNA Breaks, Double-Stranded; Protein Multimerization; Protein Binding; Models, Molecular; Mutation; DNA Repair
Dates:	Submitted: 11 March 2025 Accepted: 17 October 2025 Published (online): 26 November 2025 Published: 26 November 2025
Institution:	The University of Sheffield
Academic Units:	The University of Sheffield > Faculty of Engineering (Sheffield) > School of Chemical, Materials and Biological Engineering
Funding Information:	Funder Grant number Engineering and Physical Sciences Research Council EP/P02470X/1 Engineering and Physical Sciences Research Council EP/P025285/1 Engineering and Physical Sciences Research Council EP/S019367/1 Engineering and Physical Sciences Research Council EP/R00661X/1 UK RESEARCH AND INNOVATION MR/W00738X/1
Date Deposited:	05 Dec 2025 12:53
Last Modified:	05 Dec 2025 12:53
Status:	Published
Publisher:	Springer Science and Business Media LLC
Refereed:	Yes
Identification Number:	10.1038/s41467-025-65609-y
Related URLs:	PubMed URL
Sustainable Development Goals:
Open Archives Initiative ID (OAI ID):	oai:eprints.whiterose.ac.uk:235134

Download

Published Version

Filename: s41467-025-65609-y.pdf

Licence: CC-BY 4.0

CLICK TO DOWNLOAD

CORE (COnnecting REpositories)

Oligomerisation of Ku from Mycobacterium tuberculosis promotes DNA synapsis

Abstract

Metadata

Download

Published Version

Export

Statistics