Competition between PARP-1 and Ku70 control the decision between high-fidelity and mutagenic DNA repair.
Affinity maturation of antibodies requires a unique process of targeted mutation that allows changes to accumulate in the antibody genes while the rest of the genome is protected from off-target mutations that can be oncogenic. This targeting requires that the same deamination event be repaired either by a mutagenic or a high-fidelity pathway depending on the genomic location. We have previously shown that the BRCT domain of the DNA-damage sensor PARP-1 is required for mutagenic repair occurring in the context of IgH and IgL diversification in the chicken B cell line DT40. Here we show that immunoprecipitation of the BRCT domain of PARP-1 pulls down Ku70 and the DNA-PK complex although the BRCT domain of PARP-1 does not bind DNA, suggesting that this interaction is not DNA dependent. Through sequencing the IgL variable region in PARP-1(-/-) cells that also lack Ku70 or Lig4, we show that Ku70 or Lig4 deficiency restores GCV to PARP-1(-/-) cells and conclude that the mechanism by which PARP-1 is promoting mutagenic repair is by inhibiting high-fidelity repair which would otherwise be mediated by Ku70 and Lig4.
Seattle Children's Hospital Research Institute, 1900 9th Ave., Seattle, WA 98101, USA.
M N
MN
Paddock
A T
AT
Bauman
R
R
Higdon
E
E
Kolker
S
S
Takeda
A M
AM
Scharenberg
D000818:Animals; D034961:Antigens, Nuclear / Q000378:metabolism*; D055162:Biocatalysis; D002460:Cell Line; D004249:DNA Damage; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics*; D051747:DNA-Activated Protein Kinase / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005785:Gene Conversion; D006801:Humans; D000072200:Ku Autoantigen; D016296:Mutagenesis / Q000235:genetics*; D009687:Nuclear Proteins / Q000378:metabolism; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; C000607893:LIG4 protein, human; D009687:Nuclear Proteins; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen; D011088:DNA Ligases; D000072481:DNA Ligase ATP
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