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Updated: Jun 21, 2026

Real-time Observation of the DNA Strand Exchange Reaction Mediated by Rad51
Published on: February 13, 2019
Srs2 disassembles Rad51 filaments by a protein-protein interaction triggering ATP turnover and dissociation of Rad51
Edwin Antony1, Eric J Tomko, Qi Xiao
1Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA.
Abstract:
Rad51 is a DNA recombinase functioning in the repair of DNA double-strand breaks and the generation of genetic diversity by homologous recombination (HR). In the presence of ATP, Rad51 self-assembles into an extended polymer on single-stranded DNA to catalyze strand exchange. Inappropriate HR causes genomic instability, and it is normally prevented by remodeling enzymes that antagonize the activities of Rad51 nucleoprotein filaments. In yeast, the Srs2 helicase/translocase suppresses HR by clearing Rad51 polymers from single-stranded DNA. We have examined the mechanism of disassembly of Rad51 nucleoprotein filaments by Srs2 and find that a physical interaction between Rad51 and the C-terminal region of Srs2 triggers ATP hydrolysis within the Rad51 filament, causing Rad51 to dissociate from DNA. This allosteric mechanism explains the biological specialization of Srs2 as a DNA motor protein that antagonizes HR.
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