| APIS families | APIS genes | Immune system | CLAN ID | Phages/MGEs | References | Description |
|---|---|---|---|---|---|---|
| APIS001 | Apyc1 | pyrimidine cyclase system for antiphage resistance (Pycsar) | CLAN001 | 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. |
| APIS002 | vs.4 | cyclic oligonucleotide-based antiphage signaling system (CBASS) | CLAN002 | T4 of E. coli | PMID:36848932 | Vs.4 antagonized cGAS signaling by binding tightly to cGAMP (dissociation constant of approximately 30 nM) and sequestering it; Bioinformatic analyses identified 198 homologues of Vs.4 in diverse phages; belongs to PHROG 717. |
| APIS003 | ArdA | restriction-modification (RM) | CLAN003 | plasmid pKM101 of E. coli | PMID:2989658 | DNA mimetics, i.e. structurally and electrostatically imitate the B-form of DNA and thus function as competitive inhibitors of restriction enzymes. |
| APIS004 | Acb2 | cyclic oligonucleotide-based antiphage signaling system (CBASS) | CLAN002 | PaMx33 of Pseudomonas aeruginosa | PMID:36750095 | Anti-CBASS protein ("Acb2") that forms a hexamer with three 3',3'-cGAMP molecules and reduces phospholipase activity. |
| APIS005 | Gad1 | Gabija | CLAN004 | 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. |
| APIS006 | abc1 | RecBCD | CLAN005 | Salmonella phage S149 | Silas et al., 2023 | Trigger programmed cell death (PCD) by P4 prophage. |
| APIS007 | KlcA | restriction-modification (RM) | CLAN006 | IncP-1b plasmid of Bordetella pertussis | PMID:20007596 | ArdB and KlcA act as anti-restriction proteins and inhibit the four main families of Type I RM systems in vivo. |
| APIS008 | Gad2 | Gabija | CLAN007 | 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. |
| APIS009 | Ral | restriction-modification (RM) | CLAN008 | Lambda of E. coli | PMID:3023633 | Ral of phage λ can activate the activity of the MTase and thereby accelerate protection of the phage DNA. |
| APIS010 | Ocr | restriction-modification (RM);bacteriophage exclusion (BREX) | CLAN009 | T7 of E. coli | PMID:32338761 329108 12235377 11804597 | Ocr physically associates with BrxX methyltransferase to neutralizes their ability to both methylate and exclude incoming phage DNA. Ocr structurally mimics the DNA phosphate backbone and interacts directly with EcoKI (both the MTase and REase domain of this type I R–M enzyme), thereby interfering with the activity of this system. |