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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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Caffeine inhibits gene conversion by displacing Rad51 from ssDNA
Michael Tsabar1, Jennifer M Mason2, Yuen-Ling Chan2
1Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA.
Nucleic Acids Research
|May 29, 2015
Summary
Caffeine disrupts gene conversion by interfering with Rad51 filament formation on DNA. This study shows caffeine causes Rad51 protein to detach from single-stranded DNA, impairing DNA repair.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- Homologous recombination repairs DNA double-strand breaks (DSBs) via Rad51 filament formation on single-stranded DNA (ssDNA).
- Caffeine has been observed to impede gene targeting in mammalian cells by promoting aberrant Rad51 interactions.
Purpose of the Study:
- To investigate caffeine's effect on gene conversion in yeast.
- To determine the mechanism by which caffeine impacts Rad51 filament formation and function during DNA repair.
Main Methods:
- Yeast gene conversion assays were performed with varying caffeine concentrations.
- Rad51 localization and filament integrity were assessed using microscopy and biochemical assays.
- Experiments were conducted on both yeast and irradiated human HeLa cells.
Main Results:
- Caffeine treatment prevented gene conversion in yeast, independent of DNA damage response pathways or DNA resection inhibition.
- Caffeine induced a dosage-dependent eviction of Rad51 from ssDNA, impairing gene conversion even at low doses.
- Rad51 filament disruption occurred without affecting Srs2 activity or Rad51's ATPase function, and was observed in human cells as well.
Conclusions:
- Caffeine disrupts gene conversion by destabilizing Rad51 filaments on ssDNA.
- The findings reveal a novel mechanism for caffeine's interference with DNA repair pathways.
- Caffeine's impact on Rad51 filament integrity is conserved across yeast and human cells.
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