1. Competition between PARP-1 and Ku70 control the decision between high-fidelity and mutagenic DNA repair.
- Author
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Paddock MN, Bauman AT, Higdon R, Kolker E, Takeda S, and Scharenberg AM
- Subjects
- Animals, Biocatalysis, Cell Line, DNA Damage, DNA Ligase ATP, DNA Ligases metabolism, DNA-Activated Protein Kinase metabolism, Gene Conversion, Humans, Ku Autoantigen, Nuclear Proteins metabolism, Poly (ADP-Ribose) Polymerase-1, Poly(ADP-ribose) Polymerases chemistry, Protein Structure, Tertiary, Antigens, Nuclear metabolism, DNA Repair genetics, DNA-Binding Proteins metabolism, Mutagenesis genetics, Poly(ADP-ribose) Polymerases metabolism
- Abstract
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., (Copyright © 2010 Elsevier B.V. All rights reserved.)
- Published
- 2011
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