Rad54 oligomers translocate and cross-bridge double-stranded DNA to stimulate synapsis.
Rad54 is a key component of the eukaryotic recombination machinery. Its presence in DNA strand-exchange reactions in vitro results in a significant stimulation of the overall reaction rate. Using untagged Rad54, we show that this stimulation can be attributed to enhancement of the formation of a key reaction intermediate known as DNA networks. Using a novel, single DNA molecule, dual-optical tweezers approach we show how Rad54 stimulates DNA network formation. We discovered that Rad54 oligomers possess a unique ability to cross-bridge or bind double-stranded DNA molecules positioned in close proximity. Further, Rad54 oligomers rapidly translocate double-stranded DNA while simultaneously inducing topological loops in the DNA at the locus of the oligomer. The combination of the cross-bridging and double-stranded DNA translocation activities of Rad54 stimulates the formation of DNA networks, leading to rapid and efficient DNA strand exchange by Rad51.
Bianco
Piero R
PR
Department of Microbiology and Immunology, Centre for Single Molecule Biophysics, 321 Cary Hall, University at Buffalo, SUNY, Buffalo, NY 14214, USA. pbianco@buffalo.edu
Bradfield
Justin J
JJ
Castanza
Lauren R
LR
Donnelly
Andrea N
AN
D000255:Adenosine Triphosphate / Q000378:metabolism; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism*; D023902:Chromosome Pairing; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases; D004268:DNA-Binding Proteins; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D008856:Microscopy, Fluorescence; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport
D001704:Biopolymers; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D005982:Glutathione Transferase; D004265:DNA Helicases; C103532:RAD54L protein, human