A novel function of Rad54 protein. Stabilization of the Rad51 nucleoprotein filament.

Homologous recombination is important for the repair of double-stranded DNA breaks in all organisms. Rad51 and Rad54 proteins are two key components of the homologous recombination machinery in eukaryotes. In vitro, Rad51 protein assembles with single-stranded DNA to form the helical nucleoprotein filament that promotes DNA strand exchange, a basic ...
step of homologous recombination. Rad54 protein interacts with this Rad51 nucleoprotein filament and stimulates its DNA pairing activity, suggesting that Rad54 protein is a component of the nucleoprotein complex involved in the DNA homology search. Here, using physical criteria, we demonstrate directly the formation of Rad54-Rad51-DNA nucleoprotein co-complexes that contain equimolar amounts of each protein. The binding of Rad54 protein significantly stabilizes the Rad51 nucleoprotein filament formed on either single-stranded DNA or double-stranded DNA. The Rad54-stabilized nucleoprotein filament is more competent in DNA strand exchange and acts over a broader range of solution conditions. Thus, the co-assembly of an interacting partner with the Rad51 nucleoprotein filament represents a novel means of stabilizing the biochemical entity central to homologous recombination, and reveals a new function of Rad54 protein.
Mesh Terms:
Adenosine Triphosphatases, Biotinylation, DNA, DNA Repair Enzymes, DNA Restriction Enzymes, DNA, Single-Stranded, DNA-Binding Proteins, Dose-Response Relationship, Drug, Electrophoresis, Polyacrylamide Gel, Models, Biological, Nucleoproteins, Polystyrenes, Protein Binding, Protein Structure, Tertiary, Protein Transport, Rad51 Recombinase, Recombination, Genetic, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Salts, Sodium Chloride, Streptavidin
J. Biol. Chem.
Date: Apr. 18, 2003
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