title: Inhibition of homologous recombination by DNA-dependent protein kinase requires kinase activity, is titratable, and is modulated by autophosphorylation.
abstract: How a cell chooses between nonhomologous end joining (NHEJ) and homologous recombination (HR) to repair a double-strand break (DSB) is a central and largely unanswered question. Although there is evidence of competition between HR and NHEJ, because of the DNA-dependent protein kinase (DNA-PK)'s cellular abundance, it seems that there must be more to the repair pathway choice than direct competition. Both a mutational approach and chemical inhibition were utilized to address how DNA-PK affects HR. We find that DNA-PK's ability to repress HR is both titratable and entirely dependent on its enzymatic activity. Still, although requisite, robust enzymatic activity is not sufficient to inhibit HR. Emerging data (including the data presented here) document the functional complexities of DNA-PK's extensive phosphorylations that likely occur on more than 40 sites. Even more, we show here that certain phosphorylations of the DNA-PK large catalytic subunit (DNA-PKcs) clearly promote HR while inhibiting NHEJ, and we conclude that the phosphorylation status of DNA-PK impacts how a cell chooses to repair a DSB.
authors.affiliation: College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Neal
authors.forename: Van
authors.initials: V
authors.lastname: Dang
authors.forename: Pauline
authors.initials: P
authors.lastname: Douglas
authors.forename: Marc S
authors.initials: MS
authors.lastname: Wold
authors.forename: Susan P
authors.initials: SP
authors.lastname: Lees-Miller
authors.forename: Katheryn
authors.initials: K
authors.lastname: Meek
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D055162:Biocatalysis; D020134:Catalytic Domain; D002460:Cell Line; D053903:DNA Breaks, Double-Stranded; D051747:DNA-Activated Protein Kinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D011994:Recombinant Proteins; D051747:DNA-Activated Protein Kinase