title: Threonines 2638/2647 in DNA-PK are essential for cellular resistance to ionizing radiation.
abstract: DNA-dependent protein kinase (DNA-PK) is required for the repair of double-stranded DNA breaks through the nonhomologous DNA end joining pathway. DNA-PK activity is required for DNA repair, but kinase activity also appears to be attenuated through an autoregulatory feedback loop. We show that autophosphorylation of DNA-PK catalytic subunit occurs in trans at least three sites NH(2) terminal to the catalytic domain and that two sites, threonine 2638 and 2647, determine DNA-PK autophosphorylation in vitro. Thr2638/2647ala substitution in DNA-PK catalytic subunit compromised cellular resistance to ionizing radiation without affecting DNA end joining, suggesting a requirement for DNA-PK inactivation for cell survival at a step after the rejoining of double-stranded DNA breaks.
authors.affiliation: Department of Medicine, University of Ottawa, the Ottawa Health Research Institute, Ottawa, Ontario, K1Y 4E9 Canada.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Soubeyrand
authors.forename: Louise
authors.initials: L
authors.lastname: Pope
authors.forename: Benjamin
authors.initials: B
authors.lastname: Pakuts
authors.forename: Robert J G
authors.initials: RJ
authors.lastname: Haché
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D004249:DNA Damage; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D004789:Enzyme Activation; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011836:Radiation Tolerance / Q000502:physiology*; D013912:Threonine / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D013912:Threonine; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases