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Real-time Observation of the DNA Strand Exchange Reaction Mediated by Rad51
06:24

Real-time Observation of the DNA Strand Exchange Reaction Mediated by Rad51

Published on: February 13, 2019

The F-Box DNA helicase Fbh1 prevents Rhp51-dependent recombination without mediator proteins

Fekret Osman1, Julie Dixon, Alexis R Barr

  • 1Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom.

Molecular and Cellular Biology
|September 2, 2005
PubMed

Insights

Mediator proteins are essential for Rad51 (Rhp51) to function with the F-box DNA helicase Fbh1 in DNA repair. Deleting Fbh1 bypasses the need for mediators, suggesting an interplay controls Rhp51 activity.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Rad51 nucleoprotein filament formation is crucial for homologous recombination and DNA repair.
  • Mediator proteins (e.g., Rad52) facilitate Rad51 loading by overcoming inhibitory factors like replication protein A.
  • The F-box DNA helicase Fbh1's role in regulating Rad51 activity is not fully understood.

Purpose of the Study:

  • To investigate the role of mediator proteins in the function of fission yeast Rad51 (Rhp51) in the presence of Fbh1.
  • To elucidate the interplay between Fbh1 and mediator proteins in controlling Rhp51-mediated DNA repair.

Main Methods:

  • Genetic analysis involving gene deletions (fbh1, rad22, rhp55, swi5) in fission yeast.
  • Assessment of Rhp51-dependent recombination and DNA repair.
  • Analysis of cell growth, viability, and DNA damage sensitivity.
  • Colocalization studies of Fbh1 and Rhp51 at damage-induced foci.
  • Functional analysis of different fbh1 mutant alleles.

Main Results:

  • Deletion of fbh1 largely circumvents the requirement for the mediator Rad22 (Rhp51 orthologue) in recombination and DNA repair.
  • Loss of Fbh1 function suppresses the growth defects and DNA damage sensitivity of mediator mutants (rad22, rhp55, swi5).
  • Fbh1 colocalizes with Rhp51 at DNA damage sites, indicating a physical interaction.
  • Both F-box and helicase activities of Fbh1 are implicated in controlling Rhp51.

Conclusions:

  • Mediator proteins are required for Rhp51 function in the presence of Fbh1, highlighting a regulatory interplay.
  • Fbh1 acts antagonistically to mediator proteins in controlling Rhp51-mediated DNA repair.
  • The interaction between Fbh1 and mediators likely occurs at sites of nucleoprotein filament assembly.

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