W. Rathmell
Last active: 11/27/2019

Failure of hairpin-ended and nicked DNA To activate DNA-dependent protein kinase: implications for V(D)J recombination.

Smider V, Rathmell WK, Brown G, Lewis S, Chu G
Mol Cell Biol. 1998 18 (11): 6853-8

PMID: 9774698 · PMCID: PMC109268 · DOI:10.1128/mcb.18.11.6853

V(D)J recombination is initiated by a coordinated cleavage reaction that nicks DNA at two sites and then forms a hairpin coding end and blunt signal end at each site. Following cleavage, the DNA ends are joined by a process that is incompletely understood but nevertheless depends on DNA-dependent protein kinase (DNA-PK), which consists of Ku and a 460-kDa catalytic subunit (DNA-PKCS or p460). Ku directs DNA-PKCS to DNA ends to efficiently activate the kinase. In vivo, the mouse SCID mutation in DNA-PKCS disrupts joining of the hairpin coding ends but spares joining of the open signal ends. To better understand the mechanism of V(D)J recombination, we measured the activation of DNA-PK by the three DNA structures formed during the cleavage reaction: open ends, DNA nicks, and hairpin ends. Although open DNA ends strongly activated DNA-PK, nicked DNA substrates and hairpin-ended DNA did not. Therefore, even though efficient processing of hairpin coding ends requires DNA-PKCS, this may occur by activation of the kinase bound to the cogenerated open signal end rather than to the hairpin end itself.

MeSH Terms (13)

Animals DNA DNA-Activated Protein Kinase DNA-Binding Proteins DNA Nucleotidyltransferases Enzyme Activation Mice Mice, SCID Mutation Nucleic Acid Conformation Protein-Serine-Threonine Kinases Recombination, Genetic VDJ Recombinases

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