Bacterial virus anti-defence systems · sequence & structure resource

Encyclopaedia of Bacterial Virus Anti-Defence Systems

Available Proteins

Protein Name Mode of Action (MoA) Pfam ID Defence Subtype DOI PDB ID Protein Source
Polynucleotide_kinase Adds a 5'-phosphate group to the 3'-OH end of the tRNA fragment cleaved by PrrC, making it ready for ligation. PF13238, PF13671, PF24694 Escherichia coli PrrC 10.1002/j.1460-2075.1987.tb02532.x 1LY1 Enterobacteria phage T4
RNA_ligase_1 Ligates the broken ends of tRNA (a 5'-phosphate and 3'-OH). PF20819, PF09511 Escherichia coli PrrC 10.1002/j.1460-2075.1987.tb02532.x 5TT6 Enterobacteria phage T4
DNA modifying beta-glucosyltransferase Glucosylates hydroxymethyl-dCMP residues PF09198 Escherichia coli RM 10.1002/j.1460-2075.1994.tb06646.x 2BGT_A Enterobacteria phage T4
Stp Expression of Stp alleviates the restriction, and it is proposed that it binds to EcoPrrI. It triggers PrrC defence, and both inhibition and activation depend on the same residues within the N-proximal 18-residue region of Stp. PF08133 Escherichia coli type IC RM 10.1006/jmbi.1995.0343 - Enterobacteria phage T4
Abc2 Binds to the RecC subunit of RecBCD and promotes its recombination activity. PF11043 Escherichia coli RecBCD 10.1006/jmbi.1999.3486 - Bacteriophage P22
Ral Enables bacteriophage λ to utilize the host EcoK methyltransferase to methylate its own genome, thereby enhancing modification and alleviating restriction. Ral likely interacts with the HsdM or HsdS subunits of the EcoK complex, altering their conformation to increase methylation efficiency. PF11058 Escherichia coli type I RM 10.1016/0022-2836(86)90071-9 - Phage λreverse
Methylcarbamoylase_mom Recognises the sequence 5'-(C or G)-A-(C or G)-N-(C or T)-3' and performs methylcarbamoylation of adenine, preventing recognition of phage DNA by type I (EcoKI and EcoBI) restriction nucleases. - Escherichia coli type I and II RM 10.1016/0042-6822(76)90232-4, 10.1016/0378-1119(85)90108-8, 10.1093/nar/gkaa319 8BV8_A Escherichia phage Mu
Abc1 - PF08281, PF04545 Salmonella Typhimurium RecBCD 10.1016/0042-6822(87)90017-1 - Bacteriophage P22
DarA binds and protects phage DNA. PF18789, PF18788 Escherichia coli type I RM 10.1016/0042-6822(87)90324-2, 10.1111/mmi.13705 - Enterobacteria phage P1
DarB contains a methyltransferase domain, likely modifying phage. PF07669, PF00271, PF02384, PF04851, PF00176 Escherichia coli type I RM 10.1016/0042-6822(87)90324-2, 10.1111/mmi.13705 - Enterobacteria phage P1
DdrA binds and protects phage DNA. - Escherichia coli type I RM 10.1016/0042-6822(87)90324-2, 10.1111/mmi.13705 - Enterobacteria phage P1
Ddrb negative regulator of the P1 antirestriction system. PF18763 Escherichia coli type I RM 10.1111/mmi.13705 - Enterobacteria phage P1
Ulx binds and protects phage DNA. - Escherichia coli type I RM 10.1111/mmi.13705 - Enterobacteria phage P1
Hdf binds and protects phage DNA. PF18788 Escherichia coli type I RM 10.1016/0042-6822(87)90324-2, 10.1111/mmi.13705 - Enterobacteria phage P1
DNA adenine methylase recognises the sequence 5'-GATC-3' and methylates adenine, preventing recognition of phage DNA by the MboI restriction nuclease. Triggers Dazbog and retron Sen2 defences. PF02086 Escherichia coli RM 10.1016/0378-1119(83)90098-7 1YFJ_A Enterobacteria phage T4
Aca3 - PF12844, PF01381 - 10.1016/j.cell.2016.11.017 - -
AcrIIC1 binds to the Cas9 HNH nuclease domain and prevents cleavage of the nucleic acid sequence (allows DNA binding, blocks DNA cleavage). - Neisseria meningitidis type II-C CRISPR-Cas 10.1016/j.cell.2016.11.017, 10.1016/j.cell.2017.07.037 5VGB_B MGE in Brackiella oedipodis and Neisseria meningitidis
AcrIIC2 binds Cas9 through interactions with the positively charged bridge helix, thereby preventing crRNA loading. - Neisseria meningitidis type II-C CRISPR-Cas 10.1016/j.cell.2016.11.017 6J9M_B MGE in Neisseria meningitidis
AcrIIC3 interacts with the HNH domain of Cas9 and induces Cas9 dimerisation (hindering DNA binding). - Neisseria meningitidis type II-C CRISPR-Cas 10.1016/j.cell.2016.11.017, 10.1016/j.cell.2017.07.037 6JHV_A Prophages in Neisseria meningitidis
AcrIIA1 binds Cas9, triggering its degradation during lysogeny. PF13443 Listeria monocytogenes type II-A and type II-C CRISPR-Cas 10.1016/j.cell.2016.12.009, 10.1093/nar/gkx1181 5Y6A Listeria monocytogenes prophage 10403S
AcrIIA2 prevents Cas9 binding to DNA by occluding the protein residues required for DNA binding. - Listeria monocytogenes type II-A and type II-C 10.1016/j.cell.2016.12.009, 10.1016/j.molcel.2018.11.011 6MCB_C Listeria monocytogenes prophage 10403S
AcrIIA3 AlphaFold 3 predicts a direct interaction between Cas2 (https://www.ncbi.nlm.nih.gov/protein/ALU77912.1) and AcrIIA3 (ipTM = 0.7, pTM = 0.72). - Listeria monocytogenes type II-A CRISPR-Cas 10.1016/j.cell.2016.12.009 - Listeria monocytogenes prophage ΦSLCC2482
AcrIIA4 inhibits Cas9 enzymatic activity and DNA unwinding, and blocks the movement of HNH, thereby preventing DNA binding. PF24304 Listeria monocytogenes type II-A CRISPR-Cas 10.1016/j.cell.2016.12.009, 10.1038/nature22377 5XN4 Listeria monocytogenes prophage ΦJ0161b
AcrIIIB1 Directly interacts with the Cmr-a complex - Sulfolobus islandicus LAL14/1 type III-B CRISPR-Cas 10.1016/j.cell.2019.09.003 - Sulfolobus islandicus rod-shaped virus 2
Acb2 binds and sequesters CBASS signalling molecules (3′,3′-cGAMP, c-di-AMP, 3′,3′-c-di-UMP, 3′,3′-cUA and 3′,3′-cUG). Triggers the Panoptes defence system (DOI: 10.1038/s41586-025-09557-z) by binding 2′,3′-c-di-AMP, a signalling molecule synthesised by the defence system to keep it inactive. PF24729 Pseudomonas aeruginosa type II CBASS system 10.1016/j.cell.2022.12.041 8H2X_A Pseudomonas phage PaMx33
T5_ORF015 - - Escherichia coli type bNACHT01 NLR/bNACHT 10.1016/j.cell.2023.04.015 - Escherichia phage T5
Acb3 binds to the bacterial CD-NTase enzyme, which is involved in the synthesis of cyclic nucleotides in the CBASS response; also inhibits the human cGAS protein, a key component of the innate immune response to viral infections. - E. coli KTE188 type III CBASS 10.1016/j.cell.2024.12.035 - Ga0194137_1000084820 (IMG/VR)
Tad3 binds to ThsB (Thoeris type I) - Bacillus cereus MSX-D12 type I Thoeris 10.1016/j.cell.2024.12.035 9B7D Ga0172379_1000020175 (IMG/VR)
Tad4 binds to the bacterial ThsB (Thoeris type I) and also inhibits plant (Brachypodium distachyon, BdTIR) and human (Sterile alpha and TIR motif containing 1, SARM1) TIR proteins involved in the innate immune response. - Bacillus cereus MSX-D12 type I Thoeris 10.1016/j.cell.2024.12.035 - Ga0307375_1001427612 (IMG/VR)
Tad5 binds to ThsB (Thoeris type I) - Bacillus cereus MSX-D12 type I Thoeris 10.1016/j.cell.2024.12.035 - Ga0224422_1102149568 (IMG/VR)
Tad6 binds to ThsB (Thoeris type I) - Bacillus cereus MSX-D12 type I Thoeris 10.1016/j.cell.2024.12.035 - Ga0105013_100020934 (IMG/VR)
Tad7 binds to the bacterial type II Thoeris protein, ThsB - Bacillus amyloliquefaciens Y2 type II Thoeris 10.1016/j.cell.2024.12.035 - Ga0114343_100093911 (IMG/VR)
Tad8 binds to the bacterial type II Thoeris protein, ThsA - Bacillus amyloliquefaciens Y2 type II Thoeris 10.1016/j.cell.2024.12.035 - Ga0080708_10004799 (IMG/VR)
AriS suppresses the SOS response by targeting RecA, - Listeria monocytogenes strain 10403S SOS response 10.1016/j.celrep.2022.110723 - Prophage in listeria monocytogenes strain 10403S
NTase synthesises cyclic dinucleotides that bind to and competitively inhibit host STING immune sensors. - Sphingobacterium faecium TIR-STING effector 10.1016/j.celrep.2023.112305 - Bacillus phage Bcp1
Atd1 depletes the starvation alarmones (p)ppGpp. - TIR response (in vitro) 10.1016/j.celrep.2023.112305 - Pectobacterium phage PcCB7V
AcrIIA10 binding affinity to SpCas9 was demonstrated using biolayer interferometry, but detailed MoA is unknown. - Streptococcus pyogenes type II-A CRISPR-Cas 10.1016/j.chom.2019.01.003 - Metagenome
AcrIIA8 binding affinity to SpCas9 was demonstrated using biolayer interferometry, but detailed MoA is unknown. - Streptococcus pyogenes type II-A CRISPR-Cas 10.1016/j.chom.2019.01.003 - Metagenome
AcrIIA9 binding affinity to SpCas9 was demonstrated using biolayer interferometry, but detailed MoA is unknown. PF14058 Streptococcus pyogenes type II-A CRISPR-Cas 10.1016/j.chom.2019.01.003 - Metagenome
HgmTad2 sequesters cyclic dinucleotides and gcADPR. PF11195 Pseudomonas aeruginosa strain PAO1 type I (ThsA with SIR2) Thoeris 10.1016/j.chom.2019.01.003, 10.1038/s41586-024-08122-4 8KBI Metagenome
AcrIIA12 - - Listeria monocytogenes type II-A CRISPR-Cas 10.1016/j.chom.2020.04.001 - Listeria monocytogenes prophage φA006
AcrIIIB2 blocks the dissociation of cleaved target RNA from Cmr-α, inhibiting Cmr-α turnover and thereby suppressing Cas10 activities. - Sulfolobus islandicus type III-B CRISPR-Cas 10.1016/j.chom.2023.10.003 - Sulfolobus islandicus rod-shaped virus 3 isolate SIRV3
ZadI-1 - - Zorya type I 10.1016/j.chom.2025.06.010 - Pseudomonas phage vB_PaeM_FBPa35
DadIII-1 - - Druantia type III 10.1016/j.chom.2025.06.010 - Pseudomonas phage vB_PaeM_FBPa21
TadIII-1 AF3 predicts an interaction between TadIII-1 molecules and the ThcB1 dimer, but the co-purification experiment did not detect it - Thoeris type III 10.1016/j.chom.2025.06.010 - Pseudomonas phage vB_PaeM_FBPa12
Bdi1 inhibit a broad range of nucleic-acid-targeting defense systems, but MoA is unknown - Druantia type I;Zorya type I;Hypnos;RADAR 10.1016/j.chom.2025.06.010 - Pseudomonas phage Nemo
Bdi2 inhibit a broad range of nucleic-acid-targeting defense systems, but MoA is unknown - Druantia type I;Zorya type I;Hypnos;RADAR 10.1016/j.chom.2025.06.010 - Pseudomonas phage vB_PaeM_FBPa10
IPI* binds and inhibits the GmrS/GmrD complex (glucose-modified hydroxymethylcytosine restriction endonuclease). PF11634 Escherichia coli type IV RM 10.1016/j.jmb.2007.10.064 2JUB Enterobacteria phage T4
Gp4.5 inhibits the Lon Protease activity (it degrades the antitoxin) PF17574 Escherichia coli type II TA SanaTA 10.1016/j.molcel.2013.02.002 - Escherichia phage T7
AcrVIA1+ binds to Cas13a. - Leptotrichia wadei type VI-A CRISPR-Cas 10.1016/j.molcel.2020.03.033 - MGE in Leptotrichia wadei
AcrVIA2+ binds to the Leptotrichia wadei Cas13-crRNA, inhibiting its activity. - Leptotrichia buccalis type VI-A CRISPR-Cas 10.1016/j.molcel.2020.03.033 7XMW MGE in Leptotrichia wadei
AcrVIA3+ binds to the Leptotrichia wadei Cas13-crRNA, inhibiting its activity. - Leptotrichia wadei type VI-A CRISPR-Cas 10.1016/j.molcel.2020.03.033 - MGE in Leptotrichia wadei
AcrVIA4+ binds to the Leptotrichia wadei Cas13a. - Leptotrichia buccalis and Leptotrichia wadei type VI-A CRISPR-Cas 10.1016/j.molcel.2020.03.033 - MGE in Leptotrichia wadei
AcrVIA5+ binds to the Leptotrichia wadei Cas13a. - Leptotrichia buccalis type VI-A CRISPR-Cas 10.1016/j.molcel.2020.03.033 - MGE in Leptotrichia wadei
AcrVIA6+ binds to the Leptotrichia wadei Cas13a. - Leptotrichia wadei type VI-A CRISPR-Cas 10.1016/j.molcel.2020.03.033 - MGE in Rhodobacter capsulat R121
AcrVIA7+ - - Leptotrichia wadei type VI-A CRISPR-Cas 10.1016/j.molcel.2020.03.033 - MGE in Leptotrichia buccalis
U56 - PF08719 Escherichia coli type II Retron (Eco1) 10.1016/j.molcel.2024.05.001 - Escherichia phage ukendt
AcrVIB1 binds to the Riemerella anatipestifer Cas13b. - Prevotella buccae type VI-B CRISPR-Cas 10.1016/j.molcel.2022.05.003, 10.1016/j.molcel.2025.01.020 - MGE in Riemerella anatipestifer
Ugi binds specifically and reversibly to the host uracil-DNA glycosylase, preventing removal of uracil residues from PBS2 DNA by the host uracil-excision repair system. PF18880 Bacillus subtilis uracil-DNA glycosylase 10.1016/S0021-9258(19)70472-4 - Bacillus phage PBS2
Ocr binds to the DNA-binding groove of the type I DNA restriction/modification complex with higher affinity than DNA and blocks it. Triggers Paris defence. PF08684 Escherichia coli type I RM and type I BREX 10.1016/0022-2836(75)90083-2, 10.1016/s1097-2765(02)00435-5, 10.1093/nar/gkaa290, 10.1038/s41467-025-57006-2 1S7Z Escherichia phage T7
Arn binds and inhibits the Rgl enzyme (restriction of non-glucosylated DNA) through DNA mimicry. Triggers Paris defence PF22134 Escherichia coli type IV RM 10.1038/260454a0, 10.1074/jbc.M114.590851 3WX4 Enterobacteria phage T4
Aca1 - - - 10.1038/nature11723 7FA3_A -
AcrIF1 directly binds Cas7, sterically occluding target DNA and preventing its hybridisation to the crRNA. PF20829 Pseudomonas aeruginosa PA14 type I-F CRISPR-Cas 10.1038/nature11723 5uz9_I Pseudomonas phage JBD30
AcrIF3 binds to the Cas3 nuclease and locks it in the ADP-bound form, thus preventing it from binding to the effector-DNA complex and cleaving the target DNA. PF21401 Pseudomonas aeruginosa PA14 type I-F CRISPR-Cas 10.1038/nature11723 5GQH_B Pseudomonas phage JBD5
AcrIF4 binds to Cascade, the RNA-guided Csy complex, blocking DNA binding. - Pseudomonas aeruginosa PA14 type I-F CRISPR-Cas 10.1038/nature11723 7YHS_J Pseudomonas phage JBD24
AcrIF5 binds to the Csy–dsDNA complex, destabilising the helical bundle domain of Cas8f and thus preventing subsequent Cas2/3 recruitment. - Pseudomonas aeruginosa PA14 type I-F CRISPR-Cas 10.1038/nature11723 7F45 Pseudomonas phage JBD5
Gp54 - - Mycobacterium phage Phrann gp29/gp30 10.1038/nmicrobiol.2016.251 - Mycobacterium phage Tweety
Aca2 - PF08965, PF13560 - 10.1038/nmicrobiol.2016.85 7EZY_A -
AcrIF10 binds to Cas5f and Cas8f, occupying the DNA duplex binding site. - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1038/nmicrobiol.2016.85 6ANW MGE in Vibrio cyclitrophicus
AcrIF6 binds at the junction between Cas7.6f and Cas8f to inhibit DNA duplex splitting. - Pseudomonas aeruginosa type I-F and I-E CRISPR-Cas 10.1038/nmicrobiol.2016.85 6vqx_A MGE in Pseudomonas aeruginosa
AcrIF8 binds to the Csy spiral backbone, occupying the cavity surrounded by Cas5f, Cas7.4–7.6f, and Cas8f, to prevent DNA hybridisation. - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1038/nmicrobiol.2016.85 6VQW_A Pectobacterium phage ZF40
AcrIF9 binds to the effector complex, triggering sequence-non-specific dsDNA binding. - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1038/nmicrobiol.2016.85 7C78 MGE in Vibrio parahaemolyticus
AcrIIA6 binds allosteric centre of the Cas9 protein inducing its dimerisation and reducing its DNA binding affinity - Lactococcus lactis type II-A CRISPR-Cas 10.1038/s41467-018-05092-w 6EYX Streptococcus phage D4276
DpdA inserts the 7-deazaguanine base into phage genomic DNA, with 2′-deoxy-7-deazaguanine modifications protecting phage DNA from host restriction enzymes. - Type II RM (in vitro) 10.1038/s41467-019-13384-y - Enterobacteria phage 9g
FolE converts GTP into dihydroneopterin triphosphate (the first step of synthesis of 7-cyano-7-deazaguanine, a precursor in the pathway that leads to various DNA modifications found in phages). PF01227 Type II RM (in vitro) 10.1038/s41467-019-13384-y - Enterobacteria phage 9g
QueC catalyses the ATP-dependent conversion of 7-cyano-7-deazaguanine (preQ0) into 7-carboxy-7-deazaguanine (CDG). PF06508 Type II RM (in vitro) 10.1038/s41467-019-13384-y - Enterobacteria phage 9g
QueD converts dihydroneopterin triphosphate (H2NTP) into 6-carboxy-5,6,7,8-tetrahydropterin (CPH4) (the second step of synthesis of 7-cyano-7-deazaguanine, a precursor in the pathway that leads to various DNA modifications found in phages). PF01242 Type II RM (in vitro) 10.1038/s41467-019-13384-y - Enterobacteria phage 9g
QueE catalyses the conversion of 6-carboxy-5,6,7,8-tetrahydropterin (CPH4) into 7-cyano-7-deazaguanine (preQ0) (the third step of synthesis of 7-cyano-7-deazaguanine, a precursor in the pathway that leads to various DNA modifications found in phages). PF13353, PF04055 Type II RM (in vitro) 10.1038/s41467-019-13384-y - Enterobacteria phage 9g
AcrIC10 AlphaFold 3 predicts a direct interaction between Cas7c (https://www.ncbi.nlm.nih.gov/protein/UEM35122.1) and AcrIC10 (ipTM = 0.75, pTM = 0.78). - P. aeruginosa strains LL77 type I-C CRISPR-Cas system 10.1038/s41467-020-17652-0 - MGE in Xanthomonas translucens
AcrIC9 mimics the shape and charge distribution of double-stranded DNA (dsDNA), effectively occupying the site where the PAM interacts with the Cascade. - Pseudomonas aeruginosa strains LL77 type I-C CRISPR-Cas system 10.1038/s41467-020-17652-0, /10.1016/j.molcel.2023.12.034 8G9T_A Rhodobacter phage RcNL1
Aca9 - PF13560, PF01381 - 10.1038/s41467-020-19415-3 - -
AcrIE8 AlphaFold 3 predicts a high-confidence interactions between CasB (https://www.ncbi.nlm.nih.gov/protein/QZE32572.1) and AcrIE8 (ipTM = 0.85, pTM = 0.87). - Pseudomonas aeruginosa type I-E CRISPR-Cas 10.1038/s41467-020-19415-3 - MGE in Klebsiella pneumoniae
AcrIF15 AlphaFold 3 predicts a direct interaction between Cas8f/Csy1 (AHH51210.1) and AcrIF15 (ipTM = 0.70, pTM = 0.61). - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1038/s41467-020-19415-3 - MGE in Klebsiella michiganensis
AcrIF16 - - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1038/s41467-020-19415-3 - MGE in Pectobacterium parmentieri
AcrIF17 - - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1038/s41467-020-19415-3 - MGE in Pectobacterium carotovorum
AcrIF18* AlphaFold 3 predicts a direct interaction between Cas8f/Csy1 (AHH51210.1) and AcrIF18* (ipTM = 0.71, pTM = 0.61). - Pseudomonas aeruginosa type I-F and I-E CRISPR-Cas 10.1038/s41467-020-19415-3 - MGE in Serratia marcescens
AcrIF19 - - Pectobacterium and Serratia type I-F CRISPR-Cas 10.1038/s41467-020-19415-3 - MGE in Pectobacterium carotovorum
AcrIF20 - - Pectobacterium and Serratia type I-F CRISPR-Cas 10.1038/s41467-020-19415-3 - MGE in Pectobacterium parmentieri
AcrIF21 - - Pectobacterium and Serratia type I-F CRISPR-Cas 10.1038/s41467-020-19415-3 - MGE in Pectobacterium carotovorum
AcrIF22* - - Pectobacterium and Serratia type I-F CRISPR-Cas 10.1038/s41467-020-19415-3 - MGE in Pectobacterium parmentieri
AcrIF23 interacts with the Cas2/3 helicase-nuclease in the type I-F CRISPR-Cas system, inhibiting its DNA cleavage activity. - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1038/s41467-020-19415-3 7FIA Prophage in Pseudomonas aeruginosa
AcrIF24 forms a dimer that binds to the Csy complex in the type I-F CRISPR-Cas system, blocking target DNA hybridisation to crRNA and inducing the binding of non-sequence-specific dsDNA, which interferes with the CRISPR-mediated DNA cleavage process. - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1038/s41467-020-19415-3 7XI1 Prophage in Pseudomonas aeruginosa
AcrVA5Bsp inhibits Cas12a via acetylation, similar to its remote structural homolog, AcrVA5. - Lachnospiraceae bacterium type V-A CRISPR-Cas 10.1038/s41467-024-45068-7 - Bacteroidota phage (IMG_VR genome, ID: Ga0247610_10000168)
ADG.17 acts as a Phd-like antitoxin, binding to and inhibiting the Doc toxin (a kinase that targets EF-Tu) - Sulfolobus islandicus type II TA system PhD-Doc 10.1038/s41467-024-48074-x - Sulfolobus islandicus rod-shaped virus
SIFV2 gp15 AlphaFold 3 predicts a direct interaction between the helicase Cas3 (https://www.ncbi.nlm.nih.gov/protein/WP_014513746.1) and SIFV2 gp15 (ipTM = 0.79, pTM = 0.81). - Sulfolobus islandicus CRISPR-Cas subtype I-A 10.1038/s41467-024-48074-x - Sulfolobus islandicus filamentous virus 2
AcrIIA5 binds Cas9, inhibiting its activity. - Streptococcus thermophilus type II-A CRISPR-Cas 10.1038/s41564-017-0004-7, 10.1016/j.celrep.2019.10.078 6LKF Streptococcus phage D4276
Aca8 - - - 10.1038/s41564-018-0120-z - -
AcrID1 binds as a dimer to the Cas10d. PF07118 Sulfolobus islandicus LAL14/1 type I-D CRISPR-Cas system 10.1038/s41564-018-0120-z 6EXP Sulfolobus islandicus rudivirus 3 isolate SIRV3
AcrIIA16 - - Streptococcus pyogenes type II-A CRISPR-Cas 10.1038/s41564-020-0692-2 - Prophage in Listeria monocytogenes
AcrIIA17 - - Streptococcus pyogenes type II-A CRISPR-Cas 10.1038/s41564-020-0692-2 - MGE in Enterococcus faecalis
AcrIIA18 cleaves the single guide RNA (sgRNA), disrupting the ability of Cas9 to target DNA. - Streptococcus pyogenes type II-A CRISPR-Cas 10.1038/s41564-020-0692-2 7VLM MGE in Streptococcus macedonicus
AcrIIA19 - - Streptococcus pyogenes type II-A CRISPR-Cas 10.1038/s41564-020-0692-2 - MGE in Staphylococcus simulans
AcrIIA23 - - Streptococcus pyogenes type II-A CRISPR-Cas 10.1038/s41564-021-00996-8 - Streptococcus phage phiAp1.1
AdfA (anti-DarT factor A) - PF23813 Escherichia coli type IV TA system DarTG 10.1038/s41564-022-01153-5 - Enterobacteria phage RB69
mga47 (DNA polymerase) mutated DNA polymerase capable of replicating DNA modified (ADP-ribosylated) by the host DarTG system. - Escherichia coli type IV TA system DarTG 10.1038/s41564-022-01153-5 - Phage SECϕ18
P0020 - - Vibrio crassostreae type ABCDEFGH Dnd 10.1038/s41564-022-01157-1 - Vibrio phage 44E38.1
P0021 - - Vibrio crassostreae type ABCDEFGH Dnd 10.1038/s41564-022-01157-1 - Vibrio phage 44E38.1
DSR anti-defence 1 competes with the tail tube protein, DSR2's trigger, by binding DSR2 and inhibiting its NADase activity. - Bacillus subtilis 29R type II DSR 10.1038/s41564-022-01207-8 - Bacillus phages SP-beta and phi3T
JSS1_004 phosphorylates Dnd, CRISPR-Cas, QatABCD, SIR2+HerA and DUF4297+HerA defence systems. - Salmonella enterica type ABCDEFGH Dnd, the type I-E CRISPR-Cas system, QatABCD, SIR2+HerA and DUF4297+HerA. 10.1038/s41564-024-01851-2 - Salmonella phage JSS1
AcrIII-1 binds to cyclic tetra-adenylate and cleaves it into two linear diadenylates. PF08960 Sulfolobus islandicus M.16.4 type III-B CRISPR-Cas 10.1038/s41586-019-1909-5 2X4I_A Sulfolobus islandicus rudivirus 1
Acb1 serves as a metal-independent phosphodiesterase and hydrolyses the host's cyclic di- and trinucleotide CBASS signals, such as 3'3'-cGAMP, 3'3'-cUA and 3'3'3'-cAAA. PF23474 Escherichia coli KTE188 type III CBASS 10.1038/s41586-022-04716-y 7T26 Escherichia phage T4
Apyc1 serves as a metal-dependent cyclic NMP phosphodiesterase, degrading cyclic pyrimidines used in signalling. PF23023 E. coli KTE188 type III CBASS 10.1038/s41586-022-04716-y 7T28 Bacillus phage SBSphiJ
RacC - - Salmonella enterica type II Retron (Sen2) 10.1038/s41586-022-05091-4 - Metagenome
Tad1 binds the signalling molecule (1′′–3′ gcADPR) PF24729 Bacillus subtilis BEST7003 type I Thoeris;Pseudomonas aeruginosa type II-A and type III-C CBASS 10.1038/s41586-022-05375-9 7UAV_A Bacillus phage SBSphiJ7
Vs.4 binds the signalling molecule cGAMP. PF24729 Escherichia coli type II CBASS 10.1038/s41586-023-05862-7 7UQ2_A Enterobacteria phage T4
Gad1 binds the GajAB complex, forming an octameric web around it that inhibits DNA recognition and cleavage. - Bacillus cereus VD045 Gabija 10.1038/s41586-023-06855-2 8U7I_E Bacillus phage phi3T
Gad2 - - Bacillus cereus VD045 Gabija 10.1038/s41586-023-06869-w - Bacillus phage SPbetaL6 and SPbetaL7
Had1 - - Bacillus cereus B4087 Hachiman 10.1038/s41586-023-06869-w 8TTO_A Bacillus phage SBSphiJ4
Tad2 sequesters gcADPR PF11195 Bacillus subtilis type I Thoeris 10.1038/s41586-023-06869-w 8SME Bacillus phage SPO1
AcrIB3 replaces Cas5 (shares sequence similarity to Cas proteins) in a defective Cascade interference complex that fails to engage target DNA. PF09704 Listeria seeligeri type I-B CRISPR-Cas 10.1038/s41586-024-07923-x - MGE and prophages in Listeria genomes
AcrIB4 AlphaFold 3 predicts a direct interaction between Cas8a1 (https://www.ncbi.nlm.nih.gov/protein/WWV39459.1) and AcrIB4 (ipTM = 0.91, pTM = 0.76). - Listeria seeligeri type I-B CRISPR-Cas 10.1038/s41586-024-07923-x - MGE and prophages in Listeria genomes
AcrIB5 - PF24304 Listeria seeligeri type I-B CRISPR-Cas 10.1038/s41586-024-07923-x - MGE and prophages in Listeria genomes
AcrIB6 - - Listeria seeligeri type I-B CRISPR-Cas 10.1038/s41586-024-07923-x - MGE and prophages in Listeria genomes
AcrIB7 AlphaFold 3 predicts a direct interaction between Cas5b (https://www.ncbi.nlm.nih.gov/protein/WWV39457.1) and AcrIB7 (ipTM = 0.79, pTM = 0.78). - Listeria seeligeri type I-B CRISPR-Cas 10.1038/s41586-024-07923-x - MGE and prophages in Listeria genomes
AcrIB8 AlphaFold 3 predicts a direct interaction between the endonuclease Cas2 (https://www.ncbi.nlm.nih.gov/protein/WWV39453.1) and AcrIB8 (ipTM = 0.77, pTM = 0.77). - Listeria seeligeri type I-B CRISPR-Cas 10.1038/s41586-024-07923-x - MGE and prophages in Listeria genomes
AcrIB9 AlphaFold 3 predicts a direct interaction between Cas8a1 (https://www.ncbi.nlm.nih.gov/protein/WWV39459.1) and AcrIB9 (ipTM = 0.81, pTM = 0.8). - Listeria seeligeri type I-B CRISPR-Cas 10.1038/s41586-024-07923-x - MGE and prophages in Listeria genomes
AcrIIC7 - PF13443, PF01381 Listeria seeligeri type II-C CRISPR-Cas 10.1038/s41586-024-07923-x - MGE in Listeria seeligeri
AcrIIC8 - - Listeria seeligeri type II-C CRISPR-Cas 10.1038/s41586-024-07923-x - MGE in Listeria seeligeri
AcrIIC9 - - Listeria seeligeri type II-C CRISPR-Cas 10.1038/s41586-024-07923-x - Prophage in Listeria
AcrVIA2 inhibits type VI-A CRISPR immunity by causing crRNA degradation (may degrade crRNAs directly, but there is a possibility that AcrVIA2 prevents loading of crRNAs into Cas13). PF22590, PF00270, PF00271, PF04851 Listeria seeligeri type VI-A CRISPR-Cas 10.1038/s41586-024-07923-x - MGE in Listeria seeligeri
NARP1_Adps (ADPR-PP synthetase) adds a pyrophosphate group from ATP to ADPR to create ADPR-PP PF14572, PF00156 Bacillus subtilis type I Thoeris, DSR1, DSR2 and SEFIR. Escherichia coli SIR2–HerA 10.1038/s41586-024-07986-w - Escherichia phage JohannRWettstein (Bas63)
NARP1_Namat (nicotinamide ADPR transferase) synthesises NAD+ from ADPR-PP and nicotinamide - Bacillus subtilis type I Thoeris, DSR1, DSR2 and SEFIR. Escherichia coli SIR2–HerA 10.1038/s41586-024-07986-w - Escherichia phage JohannRWettstein (Bas63)
NARP2_nampt (nicotinamide phosphoribosyltransferase) synthesises nicotinamide mononucleotide from nicotinamide and phosphoribosyl pyrophosphate PF18127 Bacillus subtilis type I Thoeris, DSR1, DSR2 and SEFIR. Escherichia coli SIR2–HerA 10.1038/s41586-024-07986-w - Vibrio phage KVP40
NARP2_nmnat (nicotinamide mononucleotide adenylyltransferase) transfers adenyl group from ATP to nicotinamide mononucleotide and form NAD+ PF01467, PF00293 Bacillus subtilis type I Thoeris, DSR1, DSR2 and SEFIR. Escherichia coli SIR2–HerA 10.1038/s41586-024-07986-w - Vibrio phage KVP40
CARD domain-containing protein disrupts the interaction between the inflammasome complex and caspase, preventing activation of the caspase. - Lysobacter Enzymogenes Gasdermins 10.1038/s41586-024-08498-3 - Acinetobacter phage 133
ORF35 - - Escherichia coli Tmn 10.1038/s42003-025-07730-8 - Phage ΦSMS22
AcrIIA13 AlphaFold 3 predicts a direct interaction between SauCas9 and AcrIIA13 (ipTM = 0.9, pTM = 0.79), which is supported by a PDB entry without a corresponding publication (https://www.rcsb.org/structure/7ENI). - Staphylococcus aureus type II-A CRISPR-Cas 10.1073/pnas.1917668117 8K4M MGE in Staphylococcus schleiferi
AcrIIA14 - - Staphylococcus aureus type II-A CRISPR-Cas 10.1073/pnas.1917668117 7ENM MGE in Staphylococcus simulans
AcrIIA15 binds to Cas9, blocking the PAM recognition sites. - Staphylococcus aureus type II-A CRISPR-Cas 10.1073/pnas.1917668117 8JFO_B MGE in Staphylococcus delphini
Gp1.2 binds and inhibits Dgt - Escherichia coli dGTPase 10.1073/pnas.2123092119 7U66 Escherichia phage T7
Gam binds to the RecBCD complex and may bind to KiwaB. triggers retrons Se72 and Ec48, as well as Old nuclease. PF06064 Escherichia coli RecBCD and Kiwa 10.1073/pnas.70.8.2215, 10.1016/j.cell.2025.07.002 2UUZ Enterobacteria phage lambda
RexB stabilises the antitoxin MazE by affecting the ClpP proteases responsible for its degradation. - Escherichia coli type II TA system MazEF 10.1073/pnas.95.26.15481 - Enterobacteria phage lambda
PinA binds to the Lon protease, which degrage some antitoxins PF10465 Escherichia coli RM Lon Protease 10.1074/jbc.273.1.518 - Enterobacteria phage T4
Deoxycytidylate hydroxymethylase converts 2′-deoxycytidylate (or 2′-deoxycytidine-5′-monophosphate, dCMP) into 5-hydroxymethyl-dCMP (a step in DNA hypermodification). PF00303 Escherichia coli RM 10.1093/emboj/18.5.1104 1B5E_A Enterobacteria phage T4
PsiA - - Escherichia coli SOS response 10.1093/nar/18.15.4597 - Escherichia coli plasmid
AcrIIA20 - - Streptococcus iniae type II-A CRISPR-Cas 10.1093/nar/gkaa219 - MGE in Streptococcus iniae
AcrIIA21 - PF13545, PF01047, PF06970 Streptococcus pyogenes, Streptococcus aureus, and Streptococcus iniae type II-A CRISPR-Cas 10.1093/nar/gkaa219 - MGE in Streptococcus agalactiae GB00548
Vcrx091 (SSB) involved in repairing double-strand DNA breaks via recombination between short sequence repeats (single-strand-binding protein). PF00436 Vibrio cholerae type I CRISPR-Cas 10.1093/nar/gkaa518 - Plasmid pVCR94
Vcrx092 (Bet) involved in repairing double-strand DNA breaks via recombination between short sequence repeats (single-strand-annealing recombinase). PF03837 Vibrio cholerae type I CRISPR-Cas 10.1093/nar/gkaa518 - Plasmid pVCR94
Vcrx093 (Exo) involved in repairing double-strand DNA breaks via recombination between short sequence repeats (double-strand exonuclease). PF09588 Vibrio cholerae type I CRISPR-Cas 10.1093/nar/gkaa518 - Plasmid pVCR94
Vcrx089 - PF07728, PF08406, PF00437 Vibrio cholerae type I CRISPR-Cas 10.1093/nar/gkaa518 - Plasmid pVCR94
Vcrx090 - - Vibrio cholerae type I CRISPR-Cas 10.1093/nar/gkaa518 - Plasmid pVCR94
AcrIF7 binds to the target DNA-binding site of Cas8f. - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1038/nmicrobiol.2016.85, 10.1093/nar/gkaa690 6M3N Pseudomonas phage LPB1
Aca10 - PF13560 - 10.1093/nar/gkab006 7XI5_A -
AcrIC3 AlphaFold 3 predicts a high confidence interaction between helicase/endonuclease Cas3 (https://www.ncbi.nlm.nih.gov/protein/UEM35119.1) and AcrIC3 (ipTM = 0.91, pTM = 0.90) and a moderate confidence interaction between Cas2 (https://www.ncbi.nlm.nih.gov/protein/UEM35125.1) and AcrIC3 (ipTM = 0.7, pTM = 0.56). - Pseudomonas aeruginosa type I-C CRISPR-Cas system 10.1093/nar/gkab006 - MGE in Pseudomonas aeruginosa
AcrIC4 interacts with both the Cas7c and Cas8c subunits and inhibits dsDNA binding by acting as a negatively charged structural blockade at the PAM recognition site. - Pseudomonas aeruginosa type I-C CRISPR-Cas system 10.1093/nar/gkab006, 10.1016/j.molcel.2023.01.024 8DFO_M MGE in Pseudomonas aeruginosa
AcrIC5 AlphaFold 3 predicts a direct interaction between Cas8c (https://www.ncbi.nlm.nih.gov/protein/UEM35121.1) and AcrIC5 (ipTM = 0.92, pTM = 0.85). PF22147 Pseudomonas aeruginosa type I-C CRISPR-Cas system 10.1093/nar/gkab006 - MGE in Pseudomonas delhiensis
AcrIC6 - - Pseudomonas aeruginosa type I-C CRISPR-Cas system 10.1093/nar/gkab006 - MGE in Pseudomonas phragmitis
AcrIC7 - - Pseudomonas aeruginosa type I-C CRISPR-Cas system 10.1093/nar/gkab006 - MGE in Pseudomonas stutzeri
AcrIC8 inactivates Cascade by trapping the PAM-recognising Cas8 subunit in a non-productive conformation, incapable of performing PAM recognition. - Pseudomonas aeruginosa type I-C CRISPR-Cas system 10.1093/nar/gkab006 8g9s_A MGE in Pseudomonas aeruginosa
AcrIE9 - - Pseudomonas aeruginosa type I-E CRISPR-Cas system 10.1093/nar/gkab006 - MGE in Pseudomonas aeruginosa
AcrIF2/C2 acts as a dsDNA mimic that blocks target recognition by competing for a critical DNA-binding site on Cas7 and Cas8. - Pseudomonas aeruginosa type I-F and I-C CRISPR-Cas system 10.1093/nar/gkab006 5uz9_J Pseudomonas aeruginosa phages D3112
Aca11 - - - 10.1093/nar/gkac099 - -
Aca12 - PF13443 - 10.1093/nar/gkac099 - -
Aca13 - - - 10.1093/nar/gkac099 - -
AcrIIA24 - - Streptococcus thermophilus and Streptococcus pyogenes type II-A CRISPR-Cas 10.1093/nar/gkac099 - Streptococcus phage CHPC930
AcrIIA25 - - Streptococcus thermophilus and Streptococcus pyogenes type II-A CRISPR-Cas 10.1093/nar/gkac099 - Streptococcus phage P7602
AcrIIA26 AlphaFold 3 predicts a high confidence interaction between Cas9 (https://www.ncbi.nlm.nih.gov/protein/QHB64844.1) and AcrIIA26 (ipTM = 0.87, pTM = 0.79) - Streptococcus thermophilus and Streptococcus pyogenes type II-A CRISPR-Cas 10.1093/nar/gkac099 - MGE in Streptococcus sp.
AcrIIA27 - - Streptococcus thermophilus and Streptococcus pyogenes type II-A CRISPR-Cas 10.1093/nar/gkac099 - MGE in Streptococcus pyogenes K23866
AcrIIA28 binds to the REC3 domain of SpyCas9. - Streptococcus thermophilus and Streptococcus pyogenes type II-A CRISPR-Cas 10.1093/nar/gkac099 8WRX Streptococcus phage Javan128
AcrIIA29 binds to SpyCas9 via the REC3 domain, inhibiting DNA loading. - Streptococcus thermophilus and Streptococcus pyogenes type II-A CRISPR-Cas 10.1093/nar/gkac099 - MGE in Streptococcus pyogenes NS3335
AcrIIA30 - - Streptococcus thermophilus type II-A CRISPR-Cas 10.1093/nar/gkac099 - MGE in Streptococcus gordonii NCTC7870
AcrIIA31 AlphaFold 3 predicts a direct interaction between Cas9 (https://www.ncbi.nlm.nih.gov/protein/CAD0136979.1) and AcrIIA31 (ipTM = 0.87, pTM = 0.62). - Streptococcus thermophilus type II-A CRISPR-Cas 10.1093/nar/gkac099 - MGE in Streptococcus sp. SR1
AcrIIA32 interacts with the WED domain of SpyCas9, where it spatially obstructs conformational changes of the WED and PI domains, thereby inhibiting SpyCas9 from recognising the protospacer adjacent motif (PAM) and unwinding double-stranded DNA. - Streptococcus thermophilus and Streptococcus pyogenes type II-A CRISPR-Cas 10.1093/nar/gkac099, 10.1007/s11427-024-2607-8 8YE6_B MGE in Streptococcus uberis NZ01
AcrIC11 - PF03230 Xanthomonas albilineans CFBP7063 type I-C CRISPR-Cas system 10.1093/nar/gkad1097 - MGE in Xanthomonas albilineans
AcrIIA33 - - Streptococcus pyogenes type II-A CRISPR-Cas 10.1093/nar/gkad995 - MGE in Streptococcus equi DSM 20561
AcrIIA34 - - Streptococcus pyogenes type II-A CRISPR-Cas 10.1093/nar/gkad995 - MGE in Streptococcus lutetiensis AM38-2
SAM-AMP lyase cleaves the signalling molecule SAM-AMP used by type III CRISPR systems - - 10.1093/nar/gkaf655 - Metagenome
ArdB - PF03230 Escherichia coli type I RM 10.1093/nar/gkp1144 2WJ9 Plasmid pKM101
KlcA - PF03230 Escherichia coli type I RM 10.1093/nar/gkp1144 2KMG Plasmid pBP136
Hia5 modifies adenine residues to N6-methyladenine. - Diverse set of REases from type I RMs 10.1093/nar/gkr1039 - Prophage in Haemophilus influenzae
Hin1523 modifies adenine residues to N6-methyladenine. PF02086 Diverse set of REases from type I RM systems 10.1093/nar/gkr1039 - Prophage in Haemophilus influenzae
Nma1821 modifies adenine residues to N6-methyladenine. PF02086 Diverse set of REases from type I RM systems 10.1093/nar/gkr1039 - Prophage in Haemophilus influenzae
Rad degrades msDNA and ncRNA of the retron. PF13155 Escherichia coli type 1A retron (Ec83) 10.1101/2023.03.15.532788, 10.1038/s41467-024-53789-y - Escherichia coli phage ΦSP15
ORF126 - - - 10.1101/2023.04.06.535777 - Enterobacteriophages
ORF148 - - - 10.1101/2023.04.06.535777 - Enterobacteriophages
Gnarl1 - - Escherichia coli O-antigen-based barrier 10.1101/2023.04.06.535777 - Klebsiella phage vB_KpnM_KpV79
Gnarl2 - - Escherichia coli O-antigen-based barrier 10.1101/2023.04.06.535777 - Escherichia phage Mu
Gnarl3 - - Escherichia coli O-antigen-based barrier 10.1101/2023.04.06.535777 - Escherichia phage Mangalitsa
Ipii - - Escherichia coli type IV RM 10.1101/2023.04.06.535777 - Binds and inhibits the gmrS/gmrD complex (glucose-modified hydroxymethylcytosine restriction endonuclease)
ORF55 predicted to act as a nick-sensing, ATP-dependent DNA ligase (ipTM = 0.95, pTM = 0.95) that reverses the effect of effector nucleases. PF01068, PF14743 Escherichia coli type III Avs 10.1101/2024.04.14.589459 - DruSM1 phage
ORF83 - PF10686 Escherichia coli type III Avs 10.1101/2024.04.14.589459 - DruSM1 phage
ORF46 - - Escherichia coli type I BREX 10.1101/2024.04.14.589459 - DruSM1 phage
ORF72 - - Escherichia coli type I BREX 10.1101/2024.04.14.589459 - DruSM1 phage
ORF71 (Druad1) - - Escherichia coli type I Druantia 10.1101/2024.04.14.589459 - DruSM1 phage
ORF65 - - Escherichia coli hhe 10.1101/2024.04.14.589459 - DruSM1 phage
ORF58 predicted to bind ATP and NAD as a dimer. Triggers retron Ec86. PF23791 Escherichia coli Sir2+HerA and DUF4297+HerA 10.1101/2024.04.14.589459 - DruSM1 phage
Tlaloc - - Vibrio cyclitrophicus superhost with AbiH 10.1101/2024.06.14.598830 - Vibrio phage 1.056.O.
Enki - - Vibrio cyclitrophicus superhost with AbiH and Retron type II (Ec86) 10.1101/2024.06.14.598830 - Vibrio phage 1.080.O.
Surt - PF10076 Vibrio cyclitrophicus superhost with AbiU 10.1101/2024.06.14.598830 - Vibrio phage 1.217.O.
ADS38* - - Vibrio cyclitrophicus superhost with type V Avs 10.1101/2024.06.14.598830 - Vibrio phage
Nergal - - Vibrio cyclitrophicus superhost with type I CBASS 10.1101/2024.06.14.598830 - Vibrio phage 1.209.O.
Hades - - Vibrio cyclitrophicus superhost with type I DRT 10.1101/2024.06.14.598830 - Vibrio phage 1.066.O.
Kali - - Vibrio cyclitrophicus superhost with type I DRT 10.1101/2024.06.14.598830 - Vibrio phage 1.139.B.
Anhur - - Vibrio cyclitrophicus superhost with Septu 10.1101/2024.06.14.598830 - Vibrio phage 1.196.O.
Svarog - - Vibrio cyclitrophicus superhost with Septu 10.1101/2024.06.14.598830 - Vibrio phage 1.066.O.
AdfN (anti-DarT factor NADAR) removes ADP-ribose modifications from phage DNA. PF08010 Escherichia coli type IV TA system DarTG 10.1101/2024.07.11.602962, 10.1038/s41467-025-56887-7 - T4-like phages
T7 protein kinase hyperphosphorylates E. coli early proteins, with a preference for DNA/RNA-binding proteins including DNA-targeting defence systems. - Escherichia coli type II Retron (Eco9) and type IV TA system DarTG 10.1101/2024.12.20.629319 - Enterobacteria phage T4
Acb4 sequesters the CBASS signalling molecule 3′3′-cGAMP. - Yersinia aleksiciae type I CBASS and Citrobacter portucalensis/Escherichia coli type II CBASS 10.1101/2024.12.30.630793 9E4W Bacillus phage SPO1
Oad1 (OLD-antidefense 1) binds to the OLD exonuclease. - Vibrio cholerae Class 1 OLD nucleases 10.1101/2025.01.06.631583 - Vibrio phage ICP1
Anti-TerI1 prophage encoded anti-defence protein counteracting self-encoded defence system, TerI. TerI targets the terminase complex of invading phages, and anti-TerI1 and anti-Terl2 counteract Terl through direct interaction during prophage induction to allow virion production. - Prophage ϕ10403S TerI defence system (active in Listeria monocytogenes) 10.1101/2025.02.27.640495 - Prophage ϕ10403S
Anti-TerI2 prophage encoded anti-defence protein counteracting self-encoded defence system, TerI. TerI targets the terminase complex of invading phages, and anti-TerI1 and anti-Terl2 counteract Terl through direct interaction during prophage induction to allow virion production. - Prophage ϕ10403S TerI defence system (active in Listeria monocytogenes) 10.1101/2025.02.27.640495 - Prophage ϕ10403S
Dap2 directly binds to the Lon protease to prevent the degradation of the phage-encoded HNH endonuclease. - Pseudomonas aeruginosa Lon-mediated antiviral defence 10.1101/2025.03.13.642734 - Pseudomonas phage PaoP5
Dap1 binds and shields the Lon-protease target, phage HNH endonuclease. - Pseudomonas aeruginosa Lon-mediated antiviral defence 10.1101/2025.03.13.642734, 10.1038/s41564-024-01719-5 - Pseudomonas phage PaoP5
Sequestin bind and sequester the TIR-produced signaling molecules 3′cADPR and His-ADPR - Bacillus cereus MSX-D12 type I Thoeris 10.1101/2025.07.12.664507 - Metagenomics data (IMG_VR ID: IMGVR_UViG_3300045988_056527)
LockinA bind and sequester the TIR-produced signaling molecules 3′cADPR and His-ADPR - Bacillus cereus MSX-D12 type I Thoeris and Bacillus amyloliquefaciens Y2 type II Thoeris 10.1101/2025.07.12.664507 - Metagenomics data (IMG_VR ID: IMGVR_UViG_3300014204_000177)
Acb5a cleave and inactivate 3′3′-cGAMP and related molecules - Escherichia albertii MOD1-EC1698 type I CBASS 10.1101/2025.07.12.664507 - Metagenomics data (IMG_VR ID: IMGVR_UViG_3300024284_000007)
Psib binds to RecA protein. PF06290 Escherichia coli SOS response 10.1111/j.1365-2958.1992.tb01539.x, 10.1016/j.molcel.2009.07.026 3NCT_A Escherichia coli plasmid
Lar - PF14354 Escherichia coli K-12 type 1 RM 10.1111/j.1365-2958.1995.tb02438.x - Enterobacteria phage lambda
Dmd binds toxins (LsoA and RnlA) and neutralises them. PF17587 Escherichia coli type II TA systems RnlA-RnlB and LsoA-LsoB 10.1111/j.1365-2958.2012.07975.x 5HY3_B Enterobacteria phage T4
Alt performs ADP-ribosylation of MazF, abolishing its toxicity. PF03496 Escherichia coli type II TA system MazEF 10.1111/mmi.13225 - Enterobacteria phage T4
AcrVA4 induces dimerisation of Cas12-crRNA, blocking dsDNA binding by the complex. - Moraxella bovoculi and Lachnospiraceae bacterium type V-A CRISPR-Cas 10.1126/science.aau5138 6NM9_A MGE in Moraxella bovoculi 22581
AcrVA5 functions as an acetyltransferase and modifies Cas12a. - Moraxella bovoculi and Lachnospiraceae bacterium type V-A CRISPR-Cas 10.1126/science.aau5138 6IUF_A MGE in Moraxella bovoculi 58069
Aca4 - PF16509 - 10.1126/science.aau5174 - -
Aca5 - PF15943 - 10.1126/science.aau5174 - -
Aca6 - PF13384, PF13560, PF01381 - 10.1126/science.aau5174 - -
Aca7 - - - 10.1126/science.aau5174 - -
AcrIC1 - - Moraxella bovoculi type I-C CRISPR-Cas 10.1126/science.aau5174, 10.1093/nar/gkab006 - Moraxella bovoculi
AcrIE4-IF7 its N-terminal domain targets the PAM interaction site of the Cas8e subunit, and the C-terminal domain disables target DNA recognition at the PAM interaction site in the Cas8f subunit. - Pseudomonas aeruginosa SMC4386 type I-E and I-F CRISPR-Cas 10.1126/science.aau5174, 10.1093/nar/gkac096 7VZM MGE in Pseudomonas aeruginosa SMC4386
AcrIE5 AlphaFold 3 predicts high-confidence interactions between Cas5e (https://www.ncbi.nlm.nih.gov/protein/QZE32570.1) and AcrIE5 (ipTM = 0.81, pTM = 0.86). - Pseudomonas aeruginosa SMC4386 type I-E CRISPR-Cas 10.1126/science.aau5174 - MGE in Pseudomonas aeruginosa SMC4386
AcrIE6 - - Pseudomonas aeruginosa SMC4386 type I-E CRISPR-Cas 10.1126/science.aau5174 - MGE in Pseudomonas aeruginosa SMC4386
AcrIE7 - - Pseudomonas aeruginosa SMC4386 type I-E CRISPR-Cas 10.1126/science.aau5174 - MGE in Pseudomonas aeruginosa SMC4386
AcrIF11 ADP-ribosylates N250 of the Cas8f subunit, a residue required to recognise the PAM, within the crRNA-guided surveillance (Csy) complex. - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1126/science.aau5174, 10.1016/j.molcel.2020.09.015 6KYF MGE in Pseudomonas aeruginosa
AcrIF12 - - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1126/science.aau5174 - MGE in Pseudomonas aeruginosa
AcrIF13 binds to the Cas5f-8f tail and Cas7.6f subunits of the Csy complex to block target DNA recognition. - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1126/science.aau5174, 10.1016/j.jbc.2022.101636 7FI4 Moraxella phage Mcat5
AcrIF14 binds to the Cas7.4/7.6f subunits of the Csy complex, inducing strong non-specific DNA binding activity. - Pseudomonas aeruginosa type I-F CRISPR-Cas 10.1126/science.aau5174 7DU0 Moraxella phage Mcat5
AcrVA1 binds to Cas12a by mimicking the PAM and triggers cleavage of the target-recognition sequence of the Cas12a-bound guide RNA to inactivate the Cas12a complex (blocks DNA binding). - Moraxella bovoculi, Acidaminococcus sp. and Lachnospiraceae bacterium type V-A CRISPR-Cas 10.1126/science.aau5174, 10.1016/j.chom.2019.05.004 6NMD_B MGE in Moraxella bovoculi 58069
AcrVA2 - - Moraxella bovoculi type V-A CRISPR-Cas 10.1126/science.aau5174 7CI1_A MGE in Moraxella bovoculi 58069
AcrVA3 - - Moraxella bovoculi type V-A CRISPR-Cas 10.1126/science.aau5174 - MGE in Moraxella bovoculi 58069
AcrVIA1 binds to the crRNA-exposed face of Cas13a, preventing access to the target RNA and the conformational changes required for nuclease activation. - Listeria seeligeri type VI-A CRISPR-Cas 10.1126/science.abb6151 6VRB_C Listeriaphage (fLS46)
OrbA directly binds the ATPase BrxC, disrupting its dimerisation - Vibrio cholerae type I BREX 10.1126/science.abg2166, 10.1128/jb.00206-24 - Vibrio phage ICP1
Forsur-7 AlphaFold 3 predicts a direct interaction between Avs3B (https://www.ncbi.nlm.nih.gov/protein/AZY97719.1) and Forsur-7 (ipTM = 0.72, pTM = 0.37). - Salmonella enterica type III Avs 10.1126/science.abm4096 - Escherichia phage forsur
Lidtsur-17 - - Salmonella enterica type III Avs 10.1126/science.abm4096 - Escherichia phage Lidtsur
Lidtsur-6 - - Salmonella enterica type III Avs 10.1126/science.abm4096 - Escherichia phage Lidtsur
ArdU shares high similarity to ArdA (PDB ID: 2w82), which binds to the MTase of the type I RM complex and blocks it. AlphaFold 3 predicts a moderate-confidence complex between MTase (https://www.ncbi.nlm.nih.gov/protein/WP_010883983.1) and ArdU (ipTM = 0.76, pTM = 0.76). PF07275 Deinococcus radiodurans RM systems 10.1128/AEM.66.9.3856-3867.2000 - Deinococcus radiopugnans plasmid pUE30
AcrIA1 abolishes spacer acquisition by the type I-A CRISPR/Cas system. PF01930, PF12705 Sulfolobus islandicus type I-A CRISPR-Cas 10.1128/jb.00747-18, 10.1016/j.jmb.2023.167996 - Sulfolobus spindle-shaped virus Ragged Hills
ArdA binds to the MTase of the type I RM complex and blocks it. Triggers Ronin defence. PF07275 Escherichia coli type I RM 10.1128/jb.174.15.5079-5085.1992 2W82_A Plasmid pKM101
ArdK the mechanism is not clear, apart from its role in regulating the expression of ardA and ardB. PF16509 Escherichia coli type I RM 10.1128/jb.175.15.4843-4850.1993 7BBQ Plasmid pKM101
ArdR the mechanism is not clear, apart from the role in regulating the expression of ardA and ardB. - Escherichia coli type I RM 10.1128/jb.175.15.4843-4850.1993 - Plasmid pKM101
S-adenosyl-methionine_lyase degrades S-adenosyl-methionine (SAM) and inhibits SAM synthase. SAM is believed to be a co-factor in BREX-mediated and RM-mediated exclusion. PF23780 Escherichia coli type I RM;Escherichia coli type I BREX 10.1128/JVI.19.1.136-145.1976, 10.1016/j.celrep.2023.112972 6ZNB Enterobacteria phage T3
RIIA - PF13589 Escherichia coli RexAB 10.1128/jvi.61.12.3790-3794.1987 - Enterobacteria phage T4
RIIB Triggers Gasdermin defence PF13518, PF13551, PF02796 Escherichia coli RexAB 10.1128/jvi.61.12.3790-3794.1987 - Enterobacteria phage T4
AdfB (anti-DarT factor B) binds the toxin, DarT. - Vibrio cholerae type IV TA system DarTG 10.1128/mbio.00111-24 - Vibrio phage ICP1
AcrIE1 binds as a dimer to Cas3 (blocks DNA cleavage). - Pseudomonas aeruginosa SMC4386 type I-E CRISPR-Cas 10.1128/mBio.00896-14 6AS4 Pseudomonas phage JBD5
AcrIE2 - - Pseudomonas aeruginosa SMC4386 type I-E CRISPR-Cas 10.1128/mBio.00896-14 - Pseudomonas phage JBD88a
AcrIE4 AlphaFold 3 predicts high-confidence interactions between CasA (Cas8e, https://www.ncbi.nlm.nih.gov/protein/QZE32573.1) and AcrIE4 (ipTM = 0.92, pTM = 0.89) and Cas6e (https://www.ncbi.nlm.nih.gov/protein/QZE32569.1) and AcrIE4 (ipTM = 0.8, pTM = 0.85). - Pseudomonas aeruginosa SMC4386 type I-E CRISPR-Cas 10.1128/mBio.00896-14 - Pseudomonas phage D3112
AcrIE3 primarily binds to Cas8e, but may interact with Cas5e and Cas7e. - Pseudomonas aeruginosa SMC4386 type I-E CRISPR-Cas 10.1128/mBio.00896-14, 10.1016/j.str.2024.10.024 - Pseudomonas phage DMS3
AcrIIC4 binds to Cas9, blocking DNA binding. - Neisseria meningitidis type II-C CRISPR-Cas 10.1128/mBio.02321-18 7F7P_A MGE in Haemophilus parainfluenza
AcrIIC5 binds to Cas9, blocking DNA binding - Neisseria meningitidis type II-C CRISPR-Cas 10.1128/mBio.02321-18 8JB9 MGE in Simonsiella muelleri
AcrIB2 hypothesised to act as a DNA mimic, with some tentative evidence that it binds Cas3. - Clostridioides difficile type I-B CRISPR-Cas 10.1128/msphere.00401-23 - Clostridium difficile phage φCD38-2
AcrIIA22 modifies MGE DNA topology. - Streptococcus pyogenes type II-A CRISPR-Cas 10.1371/journal.pbio.3001428 7JTA_A Metagenome
ArdC ssDNA-binding protein with a metalloprotease domain; the mechanism is not clear. PF08401 Pseudomonas putida type I RM (hsdRMS) 10.1371/journal.pgen.1008750 6SNA_A Plasmid R388
Nip binds directly to the TIR (NADase) domain of the anti-phage defense protein SpbK, inhibiting its NADase activity and thereby preventing abortive infection. - Bacillus subtilis SpbK 10.1371/journal.pgen.1011551 - Phage Φ3T
AcrIIA11 binds SpyCas9 to inhibit dsDNA cleavage. - Streptococcus pyogenes type II-A CRISPR-Cas 10.7554/eLife.46540 - Metagenome
Tifa may directly interact with the toxin, toxN. AlphaFold 3 predicts a direct interaction between ToxN (https://www.ncbi.nlm.nih.gov/protein/WP_012609144.1) and Tifa (ipTM = 0.72, pTM = 0.75). PF23945 Escherichia coli type III TA toxIN 10.7554/eLife.79549 - Enterobacteria phage T4
Gp5.9 mimics DNA and binds to the RecB subunit of RecBCD, competing sterically with DNA. Triggers retron Ec48 defence - Escherichia coli RecBCD 10.7554/eLife.83409 8B1R_P Enterobacteria phage T4
AcrIIC6 binds to sgRNA loaded Cas9 preventing the complex from binding target DNA - Neisseria meningitidis type II-C CRISPR-Cas No DOI, master thesis (Khan, A.N., 2021. Characterizing a Novel Type II-C Anti-CRISPR, AcrIIC6) - Prophages in Neisseria meningitidis and Pasteurella multocida
Deoxynucleoside monophosphate kinase synthesises hydroxymethyl-deoxycytidine triphosphate (Hm-dCTP) from Hm-dCMP. PF21448 Escherichia coli RM PMID: 8670851 (there is no DOI) 1DEK_A Enterobacteria phage T4