Oligomerisation of Ku from Mycobacterium tuberculosis promotes DNA synapsis
Journal article, 2025
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.
Author
Sayma Zahid
University Of Leicester
Sonia Baconnais
Stabilité génétique et oncogenèse
Henrietta Smith
University of Sheffield
Saseela Atwal
University Of Leicester
Lucy Bates
University Of Leicester
Harriet Read
University of Sheffield
Ankita Chadda
Washington University in St. Louis
Salk Institute for Biological Studies
Florian Morati
Chalmers, Life Sciences, Chemical Biology
Tom Bedwell
1st
Emil G.P. Stender
1st
Joanne Walter
1st
Steven W. Hardwick
University of Cambridge
Fredrik Westerlund
Chalmers, Life Sciences, Chemical Biology
Eric Galburt
Washington University in St. Louis
Eric Le Cam
Stabilité génétique et oncogenèse
Alice Pyne
University of Sheffield
Galina V. Mukamolova
University Of Leicester
Amanda K. Chaplin
University Of Leicester
Nature Communications
2041-1723 (ISSN) 20411723 (eISSN)
Vol. 16 1 10568Next Generation Nanofluidic Devices for Single Molecule Analysis of DNA Repair Dynamics
European Commission (EC) (EC/H2020/866238), 2020-04-01 -- 2025-03-31.
Subject Categories (SSIF 2025)
Molecular Biology
Medical Biotechnology
Biophysics
DOI
10.1038/s41467-025-65609-y