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Updated: Jun 15, 2025
06:24
Real-time Observation of the DNA Strand Exchange Reaction Mediated by Rad51
Published on: February 13, 2019
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The human Shu complex promotes RAD51 activity by modulating RPA dynamics on ssDNA
Sarah R Hengel1,2, Katherine G Oppenheimer3, Chelsea M Smith3,4
1University of Pittsburgh, School of Medicine, Department of Pharmacology and Chemical Biology, UPMC-Hillman Cancer Center, Pittsburgh, PA, USA. sarah.hengel@tufts.edu.
Nature Communications
|August 21, 2024
Summary
The Shu complex, including SWSAP1-SWS1, stabilizes RAD51 filaments for DNA repair. This complex is crucial for high-fidelity repair and presents a potential cancer therapeutic target.
Area of Science:
- Molecular Biology
- DNA Repair Mechanisms
- Cancer Therapeutics
Background:
- Homologous recombination and replication stress rely on RAD51 for templated DNA repair.
- RAD51 activity is regulated by BRCA2 and RAD51 paralogs, including the Shu complex (SWSAP1, SWS1, SPIDR).
Purpose of the Study:
- To investigate the role of the SWSAP1-SWS1 complex in RAD51-mediated DNA repair.
- To determine the functional impact of SWSAP1-SWS1 on RAD51 filament stability and strand exchange.
- To explore the therapeutic potential of targeting the Shu complex in cancer.
Main Methods:
- Single-molecule confocal fluorescence microscopy and optical tweezers to analyze RAD51-SWSAP1-SWS1 interactions.
- Assessment of RAD51 filament stability and strand exchange activity.
- Analysis of human knockout cell lines (sgSWSAP1, sgSWS1) for sensitivity to PARP and APE1 inhibitors.
- Identification and characterization of cancer variants in SWSAP1.
Main Results:
- SWSAP1-SWS1 directly binds RAD51, enhancing filament stability and enabling strand exchange.
- SWSAP1-SWS1 decorates functional RAD51 filaments during homologous recombination.
- SWSAP1-SWS1 promotes RPA diffusion on single-stranded DNA (ssDNA).
- Knockout of SWSAP1 or SWS1 in human cells confers sensitivity to PARP and APE1 inhibitors.
- Cancer-associated variants in SWSAP1 disrupt Shu complex formation.
Conclusions:
- SWSAP1-SWS1 is a key stimulator of RAD51-dependent high-fidelity DNA repair.
- The Shu complex, particularly SWSAP1-SWS1, is a promising new target for cancer therapy.
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