Browse anti-prokaryotic immune system families by Host order

AD families AD genes Defense system CLAN ID Phages/MGEs References Description
APIS001 Apyc1 pyrimidine cyclase system for antiphage resistance (Pycsar) CLAN008 Bsp38 of Bacillus subtilis PMID:35395152 SBSphiJ Apyc1 efficiently hydrolyses a wide range of cyclic mononucleotides; 273 Acb1 and 107 Apyc1 phage proteins were identified.
APIS005 Gad1 Gabija CLAN009 phi3T of B. subtilis Yirmiya et al., 2023 Antine et al., 2023 Gad1 forms an octameric web that encases the GajAB complex and inhibits DNA recognition and cleavage.
APIS008 Gad2 Gabija CLAN023 SPbetaL7 of B. subtilis Yirmiya et al., 2023 Alphafold2 predicted that Gad2 is an enzyme with a nucleotidyltransferase protein domain, suggesting that it inhibits Gabija via a mechanism of action different than Gad1.
APIS024 Tad1 Thoeris CLAN001 SBSphiJ7 of B. subtilis PMID:36174646 Tad1 proteins are not an enzymes, but are 'sponges' that bind and sequester the immune signaling molecule (cyclic ADP-ribose or gcADPR) produced by TIR-domain proteins, thus decoupling phage sensing from immune effector activation and rendering Thoeris inactive.
APIS025 Had1 Hachiman CLAN068 SBSphiJ4 of B. subtilis Yirmiya et al., 2023 Had1 (Hachiman anti-defense 1) is a Hachiman-inhibiting family of phage proteins. The mechanism of Hachiman defense is unknown.
APIS027 DSAD1 defence-associated sirtuin (DSR) CLAN070 SPbeta phages of B. subtilis PMID:36192536 DSAD1 is a phage anti-DSR2 protein that binds and inhibits Defence-associated sirtuins (DSR2). In bacteria, N-terminal sirtuin (SIR2) domains within DSR2 were shown to participate in defence systems including prokaryotic argonautes (pAgo), Thoeris, AVAST, defence-associated sirtuin (DSR), etc.
APIS029 Tad2 Thoeris CLAN001 Bacillus phage SPO1 Yirmiya et al., 2023 Tad2 is a "sponge" that sequesters the immune signaling molecules produced by Thoeris TIR-domain proteins in response to phage.
APIS041 CLAN008
APIS044 CLAN008 Bacillus phage W.Ph.
APIS101 ugi DNA repair CLAN077 Bacillus phage AR9 PMID: 6776115 Uracil-DNA-glycosylase inhibitor.
APIS102 CLAN029
APIS132 MpaR SOS response CLAN029 prophage of Listeria monocytogenes 10403S PMID:31754112 MpaR plays a critical role in the de-repression (induction) of the two phage elements and is sufficient for ϕ10403S induction.
APIS178 AriS SOS response CLAN047 prophage of Listeria monocytogenes 10403S PMID:35443160 LMRG_02920 (AriS) encodes in prophage L. monocytogenes strain 10403S. It acts as a RecA inhibitor and inhibits the bacterial SOS response.
APIS181 CLAN029
APIS192 CLAN026
anti_TerI2 anti_TerI2 TerI CLAN110 Listeria monocytogenes 10403S Azulay et al., 2025 Anti-TerI2 counteract TerI during prophage induction to allow virion production.
APIS265 anti_TerI1 TerI CLAN053 Listeria monocytogenes 10403S Azulay et al., 2025 Anti-TerI1 counteract TerI during prophage induction to allow virion production.
APIS224 acb4 cyclic oligonucleotide-based antiphage signalling system (CBASS) CLAN093 Bacillus phage SPO1 PMID:40845805 Acb4 proteins bind nucleotide signals and inhibit a broad range of CBASS operons.
APIS288 LockinA Type I Thoeris,Type II Thoeris CLAN003 B. subtilis phage SBSphiJ PMID:41785351 act as nucleotide “sponges,” binding 1′′–3′ glycocyclic adenosine diphosphate–ribose (3′caDPr) and histidine conjugated to aDPr (his- aDPr)
APIS240 Tad6 type I Thoeris CLAN016 PMID:39855193 Tad3, Tad4, and Tad6 each have a conserved loop that blocks the active site pocket and interacts with the catalytic E85 residue of the type I ThsB
APIS242 Tad7 type II Thoeris CLAN033 PMID:39855193 The conserved loop of Tad7 binds the catalytic E99 residue of type II ThsB via a hydrogen bond.
APIS258 Tad4 type I Thoeris CLAN015 PMID:39855193 Tad3, Tad4, and Tad6 each have a conserved loop that blocks the active site pocket and interacts with the catalytic E85 residue of the type I ThsB.
APIS270 Tad8 type II Thoeris CLAN034 PMID:39855193 The conserved loops in Tad8 occupy the pocket within ThsA responsible for His-ADPR binding.
APIS351 Tad3 type I Thoeris CLAN014 PMID:39855193 Tad3, Tad4, and Tad6 each have a conserved loop that blocks the active site pocket and interacts with the catalytic E85 residue of the type I ThsB.
Tad5 Tad5 type I Thoeris CLAN052 PMID:39855193 Tad5 can interact with E85 and other active site residues in ThsB but does not completely block the active site pocket.