Related Experiment Video
Updated: May 2, 2026

Real-time Observation of the DNA Strand Exchange Reaction Mediated by Rad51
Published on: February 13, 2019
Context-dependent remodeling of Rad51-DNA complexes by Srs2 is mediated by a specific protein-protein interaction
Anna K Lytle1, Sofia S Origanti1, Yupeng Qiu2
1Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA.
Abstract:
The yeast Srs2 helicase removes Rad51 nucleoprotein filaments from single-stranded DNA (ssDNA), preventing DNA strand invasion and exchange by homologous recombination. This activity requires a physical interaction between Srs2 and Rad51, which stimulates ATP turnover in the Rad51 nucleoprotein filament and causes dissociation of Rad51 from ssDNA. Srs2 also possesses a DNA unwinding activity and here we show that assembly of more than one Srs2 molecule on the 3' ssDNA overhang is required to initiate DNA unwinding. When Rad51 is bound on the double-stranded DNA, its interaction with Srs2 blocks the helicase (DNA unwinding) activity of Srs2. Thus, in different DNA contexts, the physical interaction of Rad51 with Srs2 can either stimulate or inhibit the remodeling functions of Srs2, providing a means for tailoring DNA strand exchange activities to enhance the fidelity of recombination.
Related Concept Videos
Homologous Recombination
Homologous Recombination
Single-Strand DNA Binding Proteins
Restarting Stalled Replication Forks
Conservative Site-specific Recombination and Phase Variation
The recognition sites for Cre recombinase called LoxP...
Fixing Double-strand Breaks

