Thanks to a single-molecule imaging technique, researchers have revealed the mechanisms of PcrA helicase, an important DNA-regulating enzyme. To prevent unwanted recombination of a damaged or degraded section of DNA, the enzyme binds at the point of the break, where the double- and single-stranded regions meet. Then, it uses its motor function to "reel in" the tail, like a fisherman pulling in a rope, knocking off recombination proteins along the way.