Understanding the structure and role of DNA-PK in NHEJ: How X-ray diffraction and cryo-EM contribute in complementary ways. (October 2019)

• Record Type: Journal Article
• Authors: Wu, Qian; Liang, Shikang; Ochi, Takashi; Chirgadze, Dimitri Y.; Huiskonen, Juha T.; Blundell, Tom L.
• Is Part Of: Progress in biophysics and molecular biology. Volume 147(2019)
• Page Start: 26
• Page End: 32
• Publication Date: 2019-10
• Subjects: DNA-PK -- DNA-PKcs -- Ku70/80 -- NHEJ -- DSBs -- X-ray crystallography -- Cryo-EM -- DNA repair; Biophysics -- Periodicals; Biochemistry -- Periodicals; Biophysics -- Periodicals; Molecular Biology -- Periodicals; Biophysique -- Périodiques; Biochimie -- Périodiques; 571.4
• DOI: 10.1016/j.pbiomolbio.2019.03.007
• Languages: English
• ISSNs: 0079-6107

Abstract

Abstract: DNA double-strand breaks (DSBs), generated by ionizing radiation, reactive oxygen species and DNA replication across nicks, are the most severe DNA damage in eukaryotic cells. Non-Homologous End Joining repairs DNA double-strand breaks directly without a template and so can take place at any point in the cell cycle. Ku70/80 heterodimers rapidly assemble around broken DNA ends, allowing DNA-PKcs, the catalytic subunit of DNA-dependent protein kinase, to be recruited and facilitating synapsis of broken DNA ends. This then provides a stage for end-processing and ligation. Here we review progress leading in 2017 to the medium resolution X-ray structure of DNA-PKcs, a single polypeptide chain of 4128 amino acids. This was followed quickly by chain tracing of cryo-EM structures of DNA-PKcs in complex with Ku and DNA. We discuss how combination of structural information from X-ray and cryo-EM studies can produce a working model for complex multicomponent molecular assemblies such as those found in DNA-double-strand-break repair.