Fig. 3.

Schematic of CRISPR-Cas12a and CRISPR-Cas13a functions. A Cas12a nuclease recognizes DNA targets complementary to the crRNA spacer. Target recognition results in cleavage activities which leads to a staggering DNA double-strand break. In addition, activated Cas12a could nonspecifically cleave nearby ssDNA. B Cas13a is a crRNA-guided RNA-targeting nuclease. Upon binding to the target RNA, it could perform the target cleavage downstream of the protospacer flanking site (PFS, pink). In addition, activated Cas13a also possesses a nonspecific ribonuclease activity. The cleavage sites are marked by red arrows