title: Differential recruitment of DNA Ligase I and III to DNA repair sites.
abstract: DNA ligation is an essential step in DNA replication, repair and recombination. Mammalian cells contain three DNA Ligases that are not interchangeable although they use the same catalytic reaction mechanism. To compare the recruitment of the three eukaryotic DNA Ligases to repair sites in vivo we introduced DNA lesions in human cells by laser microirradiation. Time lapse microscopy of fluorescently tagged proteins showed that DNA Ligase III accumulated at microirradiated sites before DNA Ligase I, whereas we could detect only a faint accumulation of DNA Ligase IV. Recruitment of DNA Ligase I and III to repair sites was cell cycle independent. Mutational analysis and binding studies revealed that DNA Ligase I was recruited to DNA repair sites by interaction with PCNA while DNA Ligase III was recruited via its BRCT domain mediated interaction with XRCC1. Selective recruitment of specialized DNA Ligases may have evolved to accommodate the particular requirements of different repair pathways and may thus enhance efficiency of DNA repair.
authors.affiliation: Department of Biology II, Ludwig Maximilians University, Munich, 82152 Planegg-Martinsried, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Mortusewicz
authors.forename: Ulrich
authors.initials: U
authors.lastname: Rothbauer
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Cardoso
authors.forename: Heinrich
authors.initials: H
authors.lastname: Leonhardt
mesh_terms: D000818:Animals; D002460:Cell Line; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D051379:Mice; D000075223:Poly-ADP-Ribose Binding Proteins; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D021381:Protein Transport; D000076105:X-ray Repair Cross Complementing Protein 1; D029867:Xenopus Proteins
chemical_list: D004268:DNA-Binding Proteins; C000607892:LIG1 protein, human; C000607893:LIG4 protein, human; D000075223:Poly-ADP-Ribose Binding Proteins; D018809:Proliferating Cell Nuclear Antigen; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human; D029867:Xenopus Proteins; C000619352:Xrcc1 protein, mouse; D011088:DNA Ligases; D000072481:DNA Ligase ATP; C000618816:DNA ligase III alpha protein, Xenopus; C000618817:LIG3 protein, human; C000618818:Lig3 protein, mouse