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

Hnizda, Ales; Tesina, Petr; Nguyen, Thanh-Binh; Kukacka, Zdenek; Kater, Lukas; Chaplin, Amanda; Beckmann, Roland; Ascher, David B.; Novak, Petr und Blundell, Tom L. (2021): SAP domain forms a flexible part of DNA aperture in Ku70/80. In: Febs Journal, Bd. 288, Nr. 14: S. 4382-4393

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 ). Other data are available from corresponding authors upon a request.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Chemie und Pharmazie > Department Biochemie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 540 Chemie
• ISSN: 1742-464X
• Sprache: Englisch