Fig. 5. Model for Cas12a target search and cleavage. Cas12a binds DNA at a random location and undergoes 1D diffusion to locate its target. The PID recognizes the target's PAM sequence, which triggers a cascade of conformational changes to unwind the DNA duplex and form the R-loop. The NTS interacts with the RuvC domain triggering the first cleavage event. A rate limiting conformational change brings the TS into the RuvC active site enabling staggered TS cleavage. The DSB is complete and Cas12a is recycled for another round of catalysis.
