A bacterial resolvase first exploits, then constrains intrinsic dynamics of the Holliday junction to direct recombination

Homologous recombination forms and resolves an entangled DNA Holliday Junction (HJ) critical for achieving genome repair. We use single-molecule observation and cluster analysis to probe how prototypic bacterial resolvase RuvC selects two of four possible HJ strands for cleavage. RuvC first exploits, then constrains intrinsic HJ isomer exchange and branch migration dynamics to direct cleavage toward only a desired, catalytically competent HJ conformation, thus controlling recombination products.