Cas12a target search and cleavage on force-stretched DNA

Using optical tweezers, we investigate target search and cleavage by CRISPR–Cas12a on force-stretched k-DNA. Cas12a uses fast, one-dimensional hopping to locate its target. Binding and cleavage occur rapidly and specifically at low forces (r5 pN), with a 1.8 nm rate-limiting conformational change. Mechanical distortion slows diffusion, increases off-target binding but hinders cleavage.