title: Rad51 polymerization reveals a new chromatin remodeling mechanism.
abstract: Rad51 protein is a well known protagonist of homologous recombination in eukaryotic cells. Rad51 polymerization on single-stranded DNA and its role in presynaptic filament formation have been extensively documented. Rad51 polymerizes also on double-stranded DNA but the significance of this filament formation remains unclear. We explored the behavior of Saccharomyces cerevisiae Rad51 on dsDNA and the influence of nucleosomes on Rad51 polymerization mechanism to investigate its putative role in chromatin accessibility to recombination machinery. We combined biochemical approaches, transmission electron microscopy (TEM) and atomic force microscopy (AFM) for analysis of the effects of the Rad51 filament on chromatinized templates. Quantitative analyses clearly demonstrated the occurrence of chromatin remodeling during nucleoprotein filament formation. During Rad51 polymerization, recombinase proteins moved all the nucleosomal arrays in front of the progressing filament. This polymerization process had a powerful remodeling effect, as Rad51 destabilized the nucleosomes along considerable stretches of DNA. Similar behavior was observed with RecA. Thus, recombinase polymerization is a powerful mechanism of chromatin remodeling. These remarkable features open up new possibilities for understanding DNA recombination and reveal new types of ATP-dependent chromatin dynamics.
authors.affiliation: CNRS, Laboratoire de Microscopie Moléculaire et Cellulaire, UMR 8126 Interactions Moléculaires et Cancer, Institut de Cancérologie Gustave Roussy, Villejuif, France.
authors.forename: Pauline
authors.initials: P
authors.lastname: Dupaigne
authors.forename: Christophe
authors.initials: C
authors.lastname: Lavelle
authors.forename: Anthony
authors.initials: A
authors.lastname: Justome
authors.forename: Sophie
authors.initials: S
authors.lastname: Lafosse
authors.forename: Gilles
authors.initials: G
authors.lastname: Mirambeau
authors.forename: Marc
authors.initials: M
authors.lastname: Lipinski
authors.forename: Olivier
authors.initials: O
authors.lastname: Piétrement
authors.forename: Eric
authors.initials: E
authors.lastname: Le Cam
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D042002:Chromatin Assembly and Disassembly; D018625:Microscopy, Atomic Force; D009707:Nucleosomes / Q000378:metabolism / Q000648:ultrastructure; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism*; D011938:Rec A Recombinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D002843:Chromatin; D009707:Nucleosomes; D029701:Saccharomyces cerevisiae Proteins; D000255:Adenosine Triphosphate; D051135:Rad51 Recombinase; D011938:Rec A Recombinases