title: CK2 phosphorylation of XRCC1 facilitates dissociation from DNA and single-strand break formation during base excision repair.
abstract: CK2 phosphorylates the scaffold protein XRCC1, which is required for efficient DNA single-strand break (SSB) repair. Here, we express an XRCC1 protein (XRCC1(ckm)) that cannot be phosphorylated by CK2 in XRCC1 mutated EM9 cells and show that the role of this post-translational modification gives distinct phenotypes in SSB repair and base excision repair (BER). Interestingly, we find that fewer SSBs are formed during BER after treatment with the alkylating agent dimethyl sulfate (DMS) in EM9 cells expressing XRCC1(ckm) (CKM cells) or following inhibition with the CK2 inhibitor 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT). We also show that XRCC1(ckm) protein has a higher affinity for DNA than wild type XRCC1 protein and resides in an immobile fraction on DNA, in particular after damage. We propose a model whereby the increased affinity for DNA sequesters XRCC1(ckm) and the repair enzymes associated with it, at the repair site, which retards kinetics of BER. In conclusion, our results indicate that phosphorylation of XRCC1 by CK2 facilitates the BER incision step, likely by promoting dissociation from DNA.
authors.affiliation: Department of Genetics, Microbiology and Toxicology, Stockholm University, S-106 91 Stockholm, Sweden.
authors.forename: Cecilia E
authors.initials: CE
authors.lastname: Ström
authors.forename: Oliver
authors.initials: O
authors.lastname: Mortusewicz
authors.forename: David
authors.initials: D
authors.lastname: Finch
authors.forename: Jason L
authors.initials: JL
authors.lastname: Parsons
authors.forename: Anne
authors.initials: A
authors.lastname: Lagerqvist
authors.forename: Fredrik
authors.initials: F
authors.lastname: Johansson
authors.forename: Niklas
authors.initials: N
authors.lastname: Schultz
authors.forename: Klaus
authors.initials: K
authors.lastname: Erixon
authors.forename: Grigory L
authors.initials: GL
authors.lastname: Dianov
authors.forename: Thomas
authors.initials: T
authors.lastname: Helleday
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology; D000818:Animals; D016466:CHO Cells; D047390:Casein Kinase II / Q000378:metabolism*; D002470:Cell Survival / Q000235:genetics; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000187:drug effects / Q000378:metabolism*; D053904:DNA Breaks, Single-Stranded / Q000187:drug effects*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D059645:Mutation Rate; D010766:Phosphorylation / Q000187:drug effects; D051135:Rad51 Recombinase / Q000378:metabolism; D013463:Sulfuric Acid Esters / Q000494:pharmacology; D013997:Time Factors; D000076105:X-ray Repair Cross Complementing Protein 1
chemical_list: D000477:Alkylating Agents; D004268:DNA-Binding Proteins; D013463:Sulfuric Acid Esters; D000076105:X-ray Repair Cross Complementing Protein 1; D004247:DNA; D047390:Casein Kinase II; D051135:Rad51 Recombinase; C007482:dimethyl sulfate