Human DNA-dependent protein kinase activation mechanism

Shikang Liang, Tom Blundell

OAI: oai:www.repository.cam.ac.uk:1810/346618 • DOI: 10.17863/CAM.94034

DNA-dependent protein kinase (DNA-PK), a multicomponent complex including DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and Ku70/80 heterodimer together with DNA, is central to human DNA damage response and repair. However, the structural mechanism of its activation remains unclear. Using DNA-PK selective inhibitor (M3814), we identified from one dataset two cryo-EM structures of the human DNA-PK complex in different states, the intermediate state and the active state. Here we show that the kinase activation is regulated through conformational changes caused by the binding ligand and the string region (residues 802-846) of DNA-PKcs, particularly the helix-hairpin-helix (HhH) motif (residues 816-836) that interacts with DNA. These observations demonstrate the regulatory role of the ligand and why DNA-PK is DNA dependent. The cooperation and coordination among binding partners, disordered flexible regions, and mechanically flexible HEAT repeats modulate the kinase activation. Together with previous work, we now have a better molecular understanding of DNA-PK catalysis.

Humans DNA-Activated Protein Kinase Protein Serine-Threonine Kinases DNA-Binding Proteins Phosphorylation Ligands Nuclear Proteins Protein Kinases DNA DNA Repair Antigens Nuclear