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

DOI: 10.1111/febs.15732 DOI Help

Authors: Ales Hnizda (University of Cambridge) , Petr Tesina (University of Munich) , Than-Binh Nguyen (University of Melbourne; Baker Heart and Diabetes Institute) , Zdeněk Kukačka (nstitute of Microbiology, Academy of Sciences of the Czech Republic) , Lukas Kater (University of Munich) , Amanda K. Chaplin (University of Cambridge) , Roland Beckmann (University of Munich) , David B. Ascher (University of Cambridge; University of Melbourne; Baker Heart and Diabetes Institute) , Petr Novák (Institute of Microbiology, Academy of Sciences of the Czech Republic) , Tom L. Blundell (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Febs Journal

State: Published (Approved)
Published: February 2021
Diamond Proposal Number(s): 17057

Open Access Open Access

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.

Journal Keywords: DNA double‐strand break; integrative structural biology; Ku70/80; nonhomologous end joining; SAP domain

Subject Areas: Biology and Bio-materials, Chemistry

Diamond Offline Facilities: Electron Bio-Imaging Centre (eBIC)
Instruments: Krios II-Titan Krios II at Diamond

Added On: 19/04/2021 15:15

Documents:
febs.15732.pdf

Discipline Tags:

Biochemistry Chemistry Structural biology Life Sciences & Biotech

Technical Tags:

Microscopy Electron Microscopy (EM) Cryo Electron Microscopy (Cryo EM)