Native Cas9 (SpCas9) |
Streptococcus pyrogenes |
NGG |
100 nt long gRNA |
Introduce double stranded breaks; create blunt ends |
Mojica et al., 2005 |
Cas9 nickase (Cas9n) |
Engineered from S. pyrogenes
|
NGG |
Mutation in native Cas9 (RuvC or HNH D10, aspartate to alanine substitution) |
Generate single stranded break; efficient HDR repair mechanism |
Cong et al., 2013; Fauser et al., 2014
|
dCas9 |
Engineered from S. pyrogenes
|
NGG |
Mutated Cas9 |
RNA guided transcription regulation (CRISPRi, CRISPRa); delivers GFP enabling visualization of genetic element dynamics |
Hilton et al., 2015 |
Dimeric RNA-guided FokI nucleases (RFNs) |
Engineered from S. pyrogenes
|
NGG |
Fusion of dCas9 protein and FokI nuclease domain |
High genome editing frequency and reduced off-target mutations |
Tsai et al., 2014; Bortesi and Fischer, 2015
|
NmCas9 |
Neisseria meningitidis |
NNNNGATT |
Longer crRNA component (24 nt) |
Reduced off-target effects |
Hou et al., 2013 |
StCas9 |
Streptococcus thermophilus |
NNAGAAW |
On target cleavage activities |
Reduced off-target effects |
Horvath et al., 2008; |
SaCas9 |
Staphylococcus aureus |
NNGRRT or NNGRR(N) |
On target cleavage activities |
Reduced off-target effects |
Esvelt et al., 2013 |
Cas9-DD (Destabilized Cas9) |
Engineered from S. pyrogenes |
NGG |
Conjugation of destabilized domain to Cas9 |
Temporal, spatial and locus-specific control of gene expression; Increased NHEJ- mediated gene insertion efficiency |
Geisinger et al., 2016; Senturk et al., 2015
|
Cpf1 |
Prevoltella and Francisella1
|
NTT |
Contain a RuvC-like endonuclease domain, lack HNH endonuclease domain; 42 nt long gRNA |
Require one RNA (crRNA); Produce staggered cut ends; easier to deliver in low capacity vectors ex. AAV |
Zetsche et al., 2015a |