title: Phosphorylation of PNKP by ATM prevents its proteasomal degradation and enhances resistance to oxidative stress.
abstract: We examined the mechanism regulating the cellular levels of PNKP, the major kinase/phosphatase involved in the repair of oxidative DNA damage, and find that it is controlled by ATM phosphorylation and ubiquitylation-dependent proteasomal degradation. We discovered that ATM-dependent phosphorylation of PNKP at serines 114 and 126 in response to oxidative DNA damage inhibits ubiquitylation-dependent proteasomal degradation of PNKP, and consequently increases PNKP stability that is required for DNA repair. We have also purified a novel Cul4A-DDB1 ubiquitin ligase complex responsible for PNKP ubiquitylation and identify serine-threonine kinase receptor associated protein (STRAP) as the adaptor protein that provides specificity of the complex to PNKP. Strap(-/-) mouse embryonic fibroblasts subsequently contain elevated cellular levels of PNKP, and show elevated resistance to oxidative DNA damage. These data demonstrate an important role for ATM and the Cul4A-DDB1-STRAP ubiquitin ligase in the regulation of the cellular levels of PNKP, and consequently in the repair of oxidative DNA damage.
authors.affiliation: Gray Institute for Radiation Oncology and Biology, Department of Oncology, University of Oxford, Roosevelt Drive, Oxford OX3 7DQ, UK. jason.parsons@oncology.ox.ac.uk
authors.forename: Jason L
authors.initials: JL
authors.lastname: Parsons
authors.forename: Svetlana V
authors.initials: SV
authors.lastname: Khoronenkova
authors.forename: Irina I
authors.initials: II
authors.lastname: Dianova
authors.forename: Nicola
authors.initials: N
authors.lastname: Ternette
authors.forename: Benedikt M
authors.initials: BM
authors.lastname: Kessler
authors.forename: Pran K
authors.initials: PK
authors.lastname: Datta
authors.forename: Grigory L
authors.initials: GL
authors.lastname: Dianov
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism*; D044842:Cullin Proteins / Q000378:metabolism; D004249:DNA Damage; D045643:DNA Repair Enzymes / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004795:Enzyme Stability; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D018384:Oxidative Stress; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000302:isolation & purification / Q000378:metabolism; D054875:Ubiquitination
chemical_list: C114234:CUL4A protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D044842:Cullin Proteins; C091435:DDB1 protein, human; D004268:DNA-Binding Proteins; C434146:Strap protein; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; C530380:PNKP protein, human; D017853:Phosphotransferases (Alcohol Group Acceptor); C000619445:Pnkp protein, mouse; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases; D046988:Proteasome Endopeptidase Complex; D045643:DNA Repair Enzymes