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Synapsis of DNA ends by DNA‐dependent protein kinase
Author(s) -
DeFazio Lisa G.,
Stansel Rachel M.,
Griffith Jack D.,
Chu Gilbert
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdf299
Subject(s) - synapsis , biology , dna pkcs , dna , dna clamp , microbiology and biotechnology , dna repair , biophysics , biochemistry , homologous chromosome , gene , reverse transcriptase , rna
The catalytic subunit of DNA‐dependent protein kinase (DNA‐PK CS ) is required for a non‐homologous end‐joining pathway that repairs DNA double‐strand breaks produced by ionizing radiation or V(D)J recombination; however, its role in this pathway has remained obscure. Using a neutravidin pull‐down assay, we found that DNA‐PK CS mediates formation of a synaptic complex containing two DNA molecules. Furthermore, kinase activity was cooperative with respect to DNA concentration, suggesting that activation of the kinase occurs only after DNA synapsis. Electron microscopy revealed complexes of two DNA ends brought together by two DNA‐PK CS molecules. Our results suggest that DNA‐PK CS brings DNA ends together and then undergoes activation of its kinase, presumably to regulate subsequent steps for processing and ligation of the ends.