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Updated: Dec 16, 2025
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Real-time Observation of the DNA Strand Exchange Reaction Mediated by Rad51
Published on: February 13, 2019
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RADX condenses single-stranded DNA to antagonize RAD51 loading
Hongshan Zhang1, Jeffrey M Schaub1, Ilya J Finkelstein1,2
1Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
Nucleic Acids Research
|July 5, 2020
Summary
RADX protein condenses single-stranded DNA (ssDNA), even when coated by Replication Protein A (RPA). This action inhibits RAD51 binding, crucial for DNA replication integrity and homologous recombination regulation.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- RADX is a mammalian protein vital for stabilizing telomeres and replication forks.
- Maintaining balance between RADX and Replication Protein A (RPA) is essential for DNA replication integrity.
- RADX negatively regulates RAD51-mediated homologous recombination at stalled forks.
Purpose of the Study:
- To elucidate the mechanism by which RADX interacts with DNA.
- To investigate the interaction between RADX, RPA, and RAD51.
- To understand RADX's role in regulating homologous recombination.
Main Methods:
- Single-molecule imaging in vitro.
- Analysis of protein-DNA interactions.
- Investigating RADX's effect on RPA-coated ssDNA.
Main Results:
- RADX condenses RPA-coated single-stranded DNA (ssDNA) filaments, forming higher-order assemblies.
- RADX captures ssDNA in trans via these assemblies.
- RADX prevents RAD51 displacement of RPA and inhibits RAD51 loading onto ssDNA.
Conclusions:
- RADX functions as an ssDNA condensation protein.
- RADX inhibits RAD51 filament formation, antagonizing RAD51's role in homologous recombination.
- RADX may also antagonize other ssDNA-binding proteins on RPA-coated ssDNA.
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