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Mol Cell. 2016 Dec 1;64(5):926-939. doi: 10.1016/j.molcel.2016.10.020. Epub 2016 Nov 17.

A Polar and Nucleotide-Dependent Mechanism of Action for RAD51 Paralogs in RAD51 Filament Remodeling.

Author information

1
Clare Hall Laboratory, The Francis Crick Institute, South Mimms EN6 3LD, UK.
2
Department of Biology, Masaryk University, 62500 Brno, Czech Republic; International Clinical Research Center, St. Anne's University Hospital in Brno, 62500 Brno, Czech Republic.
3
Department of Biochemistry and Molecular Biophysics, Columbia University Medical Center, New York City, NY 10032, USA.
4
Electron Microscopy Science Technology Platform, Lincoln's Inn Fields Laboratory, The Francis Crick Institute, London WC2A 3LY, UK.
5
Department of Biology, Masaryk University, 62500 Brno, Czech Republic; International Clinical Research Center, St. Anne's University Hospital in Brno, 62500 Brno, Czech Republic; National Centre for Biomolecular Research, Masaryk University, 62500 Brno, Czech Republic. Electronic address: lkrejci@chemi.muni.cz.
6
Clare Hall Laboratory, The Francis Crick Institute, South Mimms EN6 3LD, UK. Electronic address: simon.boulton@crick.ac.uk.

Abstract

Central to homologous recombination in eukaryotes is the RAD51 recombinase, which forms helical nucleoprotein filaments on single-stranded DNA (ssDNA) and catalyzes strand invasion with homologous duplex DNA. Various regulatory proteins assist this reaction including the RAD51 paralogs. We recently discovered that a RAD51 paralog complex from C. elegans, RFS-1/RIP-1, functions predominantly downstream of filament assembly by binding and remodeling RAD-51-ssDNA filaments to a conformation more proficient for strand exchange. Here, we demonstrate that RFS-1/RIP-1 acts by shutting down RAD-51 dissociation from ssDNA. Using stopped-flow experiments, we show that RFS-1/RIP-1 confers this dramatic stabilization by capping the 5' end of RAD-51-ssDNA filaments. Filament end capping propagates a stabilizing effect with a 5'→3' polarity approximately 40 nucleotides along individual filaments. Finally, we discover that filament capping and stabilization are dependent on nucleotide binding, but not hydrolysis by RFS-1/RIP-1. These data define the mechanism of RAD51 filament remodeling by RAD51 paralogs.

KEYWORDS:

DNA repair; Rad51; Rad51 paralogs; filaments; genome stability; homologous recombination

PMID:
27867009
PMCID:
PMC5145814
DOI:
10.1016/j.molcel.2016.10.020
[Indexed for MEDLINE]
Free PMC Article

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