Table 1 Differences between type I, II, III, and V CRISPR/Cas systems
From: Application of different types of CRISPR/Cas-based systems in bacteria
Classification | Type I | Type II | Type III | Type V |
|---|---|---|---|---|
Signature protein | Cas3 (or Cas3′) | Cas9 (1368 amino acids) | Csm (III-A) or Cmr (III-B) | Cas12a (1200–1300 amino acids) |
Effector | Cascade | crRNA and tracrRNA (sgRNA) | Cascade | crRNA |
PAM sequence | 3-nt | G-rich sequence, 5′-NGG-3′ | Without PAM | 5′-YTN-3′(FnCas12a), 5′-TTTN-3′(AsCas12a, LbCas12a) |
Cleavage product | SSBs | DSB (flat end) | SSBs at every 6-nt | DSB (Sticky end with 5 nucleotides protruding) |