title: Rad54 protein is targeted to pairing loci by the Rad51 nucleoprotein filament.
abstract: Rad51 and Rad54 proteins are important for the repair of double-stranded DNA (dsDNA) breaks by homologous recombination in eukaryotes. Rad51 assembles on single-stranded DNA (ssDNA) to form a helical nucleoprotein filament that performs homologous pairing with dsDNA; Rad54 stimulates this pairing substantially. Here, we demonstrate that Rad54 acts in concert with the mature Rad51-ssDNA filament. Enhancement of DNA pairing by Rad54 is greatest at an equimolar ratio relative to Rad51 within the filament. Reciprocally, the Rad51-ssDNA filament enhances both the dsDNA-dependent ATPase and the dsDNA unwinding activities of Rad54. We conclude that Rad54 participates in the DNA homology search as a component of the Rad51-nucleoprotein filament and that the filament delivers Rad54 to the dsDNA pairing locus, thereby linking the unwinding of potential target DNA with the homology search process.
authors.affiliation: Division of Biological Sciences, University of California, Davis 95616, USA.
authors.forename: A V
authors.initials: AV
authors.lastname: Mazin
authors.forename: C J
authors.initials: CJ
authors.lastname: Bornarth
authors.forename: J A
authors.initials: JA
authors.lastname: Solinger
authors.forename: W D
authors.initials: WD
authors.lastname: Heyer
authors.forename: S C
authors.initials: SC
authors.lastname: Kowalczykowski
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D004265:DNA Helicases; D004260:DNA Repair / Q000187:drug effects / Q000502:physiology*; D045643:DNA Repair Enzymes; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004278:DNA, Superhelical / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000494:pharmacology; D004926:Escherichia coli; D005656:Fungal Proteins / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D051135:Rad51 Recombinase; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D013045:Species Specificity
chemical_list: D004277:DNA, Single-Stranded; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C495151:RAD51 protein, S cerevisiae; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D000251:Adenosine Triphosphatases; C075468:RAD54 protein, S cerevisiae; D004265:DNA Helicases; D045643:DNA Repair Enzymes