A polar and nucleotide-dependent mechanism of action for RAD51 paralogs in RAD51 filament remodeling
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Martin RG Taylor Mário Špírek Chu Jian Ma Raffaella Carzaniga Tohru Takaki Lucy Collinson Eric C Greene Lumir Krejci Simon BoultonAbstract
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.
Journal details
Journal Molecular Cell
Volume 64
Issue number 5
Pages 926-939
Available online
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Publisher website (DOI) 10.1016/j.molcel.2016.10.020
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Europe PubMed Central 27867009
Pubmed 27867009
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