title: AHNAK interacts with the DNA ligase IV-XRCC4 complex and stimulates DNA ligase IV-mediated double-stranded ligation.
abstract: AHNAK is a high molecular weight protein that is under-expressed in several radiosensitive neuroblastoma cell lines. Using immunoaffinity purification or purified proteins, we show that AHNAK interacts specifically with the DNA ligase IV-XRCC4 complex, a complex that functions in DNA non-homologous end-joining. Furthermore, AHNAK and the DNA ligase IV-XRCC4 complex co-immunoprecipitate demonstrating an in vivo interaction. This interaction is specific and is not observed with other DNA ligases nor with other components of the DNA non-homologous end-joining machinery. We characterised AHNAK as a protein that stimulates the double-stranded (DS) ligation activity of DNA ligase IV-XRCC4. We show that AHNAK has weak DNA-binding activity and forms a stable complex with the DNA ligase IV-XRCC4 complex on DNA. AHNAK is also able to link two DNA molecules to a similar extent to that previously reported for Ku. Together, these findings demonstrate new activities for AHNAK, and raise the possibility that it may function to modulate DNA non-homologous end-joining.
authors.affiliation: Genome Damage and Stability Centre, University of Sussex, Science Park Road, Falmer, Brighton BN1 9RQ, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Stiff
authors.forename: Emma
authors.initials: E
authors.lastname: Shtivelman
authors.forename: Penny
authors.initials: P
authors.lastname: Jeggo
authors.forename: Boris
authors.initials: B
authors.lastname: Kysela
mesh_terms: D015153:Blotting, Western; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D009943:Organophosphorus Compounds; D011233:Precipitin Tests; D020539:Sequence Analysis, Protein
chemical_list: C043517:2-(4-isothiocyanatophenoxy)-1,3,2-dioxaphosphinene 2-oxide; C075176:AHNAK protein, human; D004268:DNA-Binding Proteins; C000607893:LIG4 protein, human; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D009943:Organophosphorus Compounds; C101467:XRCC4 protein, human; D011088:DNA Ligases; D000072481:DNA Ligase ATP