title: Bloom syndrome helicase stimulates RAD51 DNA strand exchange activity through a novel mechanism.
abstract: Loss or inactivation of BLM, a helicase of the RecQ family, causes Bloom syndrome, a genetic disorder with a strong predisposition to cancer. Although the precise function of BLM remains unknown, genetic data has implicated BLM in the process of genetic recombination and DNA repair. Previously, we demonstrated that BLM can disrupt the RAD51-single-stranded DNA filament that promotes the initial steps of homologous recombination. However, this disruption occurs only if RAD51 is present in an inactive ADP-bound form. Here, we investigate interactions of BLM with the active ATP-bound form of the RAD51-single-stranded DNA filament. Surprisingly, we found that BLM stimulates DNA strand exchange activity of RAD51. In contrast to the helicase activity of BLM, this stimulation does not require ATP hydrolysis. These data suggest a novel BLM function that is stimulation of the RAD51 DNA pairing. Our results demonstrate the important role of the RAD51 nucleoprotein filament conformation in stimulation of DNA pairing by BLM.
authors.affiliation: Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102-1192, USA.
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Bugreev
authors.forename: Olga M
authors.initials: OM
authors.lastname: Mazina
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Mazin
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D020029:Base Pairing / Q000187:drug effects; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D004247:DNA; D004265:DNA Helicases; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins; D006801:Humans; D008957:Models, Genetic; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D009690:Nucleic Acid Conformation / Q000187:drug effects; D051135:Rad51 Recombinase / Q000378:metabolism*; D053484:RecQ Helicases / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic / Q000187:drug effects
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D051135:Rad51 Recombinase; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; C103532:RAD54L protein, human; D053484:RecQ Helicases; D002118:Calcium