Fig. 1
From: Applications of CRISPR technology in studying plant-pathogen interactions: overview and perspective
Diagrammatic representation of the cleavage site architecture of different CRISPR system. sgRNA consists of a spacer (light blue), crRNA (purple) and tracrRNA (dark orange). Optimal PAMs (orange) and PFSs (red) are important for recognizing target of these corresponding systems. Cas12a, Cas12b, and Cas14 are validated subtypes in type V and each shows a distinct architecture. Only crRNA is required for Cas12a, while the other subtypes require an additional tracrRNA. Cas14 cleaves ssDNA without PAM specificity. Cas13a and Cas13b belong to subtype VI with recognition of the PFS sequence, the crRNA-Cas13 complex induces ssRNA cleavage activity. Cas9, CRISPR associated protein 9; crRNA, CRISPR RNA; sgRNA, single guide RNA; tracrRNA, transactivating CRISPR RNA; PAM, protospacer adjacent motif; PFS, protospacer flanking sites