Ku and DNA-dependent protein kinase dynamic conformations and assembly regulate DNA binding and the initial non-homologous end joining complex.
DNA double strand break (DSB) repair by non-homologous end joining (NHEJ) is initiated by DSB detection by Ku70/80 (Ku) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) recruitment, which promotes pathway progression through poorly defined mechanisms. Here, Ku and DNA-PKcs solution structures alone and in complex with DNA, defined by x-ray scattering, reveal major structural reorganizations that choreograph NHEJ initiation. The Ku80 C-terminal region forms a flexible arm that extends from the DNA-binding core to recruit and retain DNA-PKcs at DSBs. Furthermore, Ku- and DNA-promoted assembly of a DNA-PKcs dimer facilitates trans-autophosphorylation at the DSB. The resulting site-specific autophosphorylation induces a large conformational change that opens DNA-PKcs and promotes its release from DNA ends. These results show how protein and DNA interactions initiate large Ku and DNA-PKcs rearrangements to control DNA-PK biological functions as a macromolecular machine orchestrating assembly and disassembly of the initial NHEJ complex on DNA.
Hammel
Michal
M
Physical Biosciences Division, Department of Molecular Biology, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. mhammel@lbl.gov
Yu
Yaping
Y
Mahaney
Brandi L
BL
Cai
Brandon
B
Ye
Ruiqiong
R
Phipps
Barry M
BM
Rambo
Robert P
RP
Hura
Greg L
GL
Pelikan
Martin
M
So
Sairei
S
Abolfath
Ramin M
RM
Chen
David J
DJ
Lees-Miller
Susan P
SP
Tainer
John A
JA
D034961:Antigens, Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D000072200:Ku Autoantigen; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D004247:DNA; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen