title: Reconstitution of DNA repair synthesis in vitro and the role of polymerase and helicase activities.
abstract: The error-free repair of double-strand DNA breaks by homologous recombination (HR) ensures genomic stability using undamaged homologous sequence to copy genetic information. While some of the aspects of the initial steps of HR are understood, the molecular mechanisms underlying events downstream of the D-loop formation remain unclear. Therefore, we have reconstituted D-loop-based in vitro recombination-associated DNA repair synthesis assay and tested the efficacy of polymerases Pol δ and Pol η to extend invaded primer, and the ability of three helicases (Mph1, Srs2 and Sgs1) to displace this extended primer. Both Pol δ and Pol η extended up to 50% of the D-loop substrate, but differed in product length and dependency on proliferating cell nuclear antigen (PCNA). Mph1, but not Srs2 or Sgs1, displaced the extended primer very efficiently, supporting putative role of Mph1 in promoting the synthesis-dependent strand-annealing pathway. The experimental system described here can be employed to increase our understanding of HR events following D-loop formation, as well as the regulatory mechanisms involved.
authors.affiliation: Department of Biology, Masaryk University, Kamenice 5/A7, 625 00 Brno, Czech Republic.
authors.forename: Marek
authors.initials: M
authors.lastname: Sebesta
authors.forename: Peter
authors.initials: P
authors.lastname: Burkovics
authors.forename: Lajos
authors.initials: L
authors.lastname: Haracska
authors.forename: Lumir
authors.initials: L
authors.lastname: Krejci
mesh_terms: D004265:DNA Helicases / Q000378:metabolism*; D004258:DNA Polymerase III / Q000378:metabolism*; D004260:DNA Repair; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D011995:Recombination, Genetic; D013379:Substrate Specificity
chemical_list: D004258:DNA Polymerase III; D004259:DNA-Directed DNA Polymerase; D004265:DNA Helicases