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SAP domain forms a flexible part of DNA aperture in Ku70/80.

Published version
Peer-reviewed

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Authors

Tesina, Petr 
Nguyen, Thanh-Binh 
Kukačka, Zdeněk 
Kater, Lukas 

Abstract

Nonhomologous end joining (NHEJ) is a DNA repair mechanism that religates double-strand DNA breaks to maintain genomic integrity during the entire cell cycle. The Ku70/80 complex recognizes DNA breaks and serves as an essential hub for recruitment of NHEJ components. Here, we describe intramolecular interactions of the Ku70 C-terminal domain, known as the SAP domain. Using single-particle cryo-electron microscopy, mass spectrometric analysis of intermolecular cross-linking and molecular modelling simulations, we captured variable positions of the SAP domain depending on DNA binding. The first position was localized at the DNA aperture in the Ku70/80 apo form but was not observed in the DNA-bound state. The second position, which was observed in both apo and DNA-bound states, was found below the DNA aperture, close to the helical arm of Ku70. The localization of the SAP domain in the DNA aperture suggests a function as a flexible entry gate for broken DNA. DATABASES: EM maps have been deposited in EMDB (EMD-11933). Coordinates have been deposited in Protein Data Bank (PDB 7AXZ). Other data are available from corresponding authors upon a request.

Description

Funder: Victorian Government


Funder: BBSRC

Keywords

DNA double-strand break, Ku70/80, SAP domain, integrative structural biology, nonhomologous end joining, DNA, DNA Breaks, Double-Stranded, DNA End-Joining Repair, Humans, Ku Autoantigen, Protein Conformation, Protein Domains

Journal Title

FEBS J

Conference Name

Journal ISSN

1742-464X
1742-4658

Volume Title

288

Publisher

Wiley
Sponsorship
Wellcome Trust (200814/Z/16/Z)