Table 1 Anti-CRISPR proteins and their mechanisms of action

AcrE1 (P. aeruginosa)

100

Type I-E

–

–

[31]

AcrE2 (P. aeruginosa)

84

Type I-E

–

–

[31]

AcrE3 (P. aeruginosa)

68

Type I-E

–

–

[31]

AcrE4 (P. aeruginosa)

52

Type I-E

–

–

[31]

AcrF1 (P. aeruginosa)

78

Type I-F

Inhibits DNA binding

2LW5,5UZ9,6ANV,6B46

[30, 36,37,38,39]

AcrF2 (P. aeruginosa)

90

Type I-F

Partially overlaps with the binding site of dsDNA

5UZ9,6B47

[30, 36, 39]

AcrF3 (P. aeruginosa)

139

Type I-F

Blocks the entrance of the DNA binding tunnel; blocks new sequence acquisition

5GNF,5GQH,5B7I

[30, 40,41,42]

AcrF4 (P. aeruginosa)

100

Type I-F

–

–

[30]

AcrF5 (P. aeruginosa)

79

Type I-F

–

–

[30]

AcrF6 (P. aeruginosa)

100

Type I-E/F

–

–

[32]

AcrF7 (P. aeruginosa)

67

Type I-F

–

–

[32]

AcrF8 (P. atrosepticum)

92

Type I-F

–

–

[32]

AcrF9 (V. parahaemolyticus)

68

Type I-F

–

–

[32]

AcrF10 (S. xiamenensis)

97

Type I-F

DNA mimic, blocks DNA binding

6ANW,6B48

[32, 39]

AcrIIA1 (L. monocytogenes)

149

Type II-A

–

5Y6A

[51, 60]

AcrIIA2 (L. monocytogenes)

123

Type II-A

Inhibits DNA binding

–

[51]

AcrIIA3 (L. monocytogenes)

125

Type II-A

–

–

[51]

AcrIIA4 (L. monocytogenes)

87

Type II-A

PAM mimic, inhibits DNA binding; interacts with active site within the RuvC domain; hinders the conformation change of the HNH domain

5XBL,5VW1,5VZL

[51, 55,56,57]

AcrIIA5 (S. thermophilus)

140

Type II-A

–

–

[54]

AcrIIC1 (N. meningitidis)

85

Type II-C

Binds the HNH domain; shields the catalytic center

5VGB

[50, 59]

AcrIIC2 (N. meningitidis)

123

Type II-C

–

–

[50]

AcrIIC3 (N. meningitidis)

116

Type II-C

Induces Cas9 dimerization; inhibits DNA binding

–

[50, 59]