identifier: traitmech:000503 label: ENDPaCF1 system definition: A phage defense system in which an organism possesses an ENDPaCF1 Type IIS restriction endonuclease-like locus with an inactive Endonuclease III sensing domain that can recognize diverse DNA hypermodifications and protect bacteria from hypermodified phages. definition_source: DOI:10.1101/2025.03.31.646159 trait_category: GENOMICS term_kind: CLASS mapping_status: PROPOSED parent_traits: - traitmech:000209 synonyms: - synonym_text: ENDPaCF1 synonym_type: EXACT_SYNONYM source: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md evidence: - reference: DOI:10.1101/2025.03.31.646159 snippet: The causal defense system is a Type IIS restriction endonuclease-like protein (ENDPaCF1), common in Pseudomonads, however it lacks an associated methyltransferase typical Type IIS R-M systems. notes: Yee et al. identify ENDPaCF1 as the causal Pseudomonas antiphage system and distinguish it from canonical Type IIS restriction-modification systems. - reference: DOI:10.1101/2025.03.31.646159 snippet: ENDPaCF1 protects bacteria against phages with hypermodified DNA and is surprisingly agnostic to the specific structure of the modification, which is unlike typical type IV restriction endonucleases. notes: Yee et al. connect ENDPaCF1 to protection against phages with multiple hypermodified-DNA chemistries. - reference: DOI:10.1101/2025.03.31.646159 snippet: Here, we employed the CRISPR-based Cascade-Cas3 system to delete defense islands in a Pseudomonas aeruginosa clinical isolate to identify mechanisms of lytic phage antagonism. Deletion of one island in a cystic fibrosis-derived clinical isolate sensitized the strain to phages from the Pbunavirus family, which are commonly used as therapeutics. notes: Yee et al. identified the ENDPaCF1 island as an endogenous Pseudomonas aeruginosa phage-defense determinant. - reference: DOI:10.1101/2025.03.31.646159 snippet: In ENDPaCF1, the endonuclease domain is fused to a catalytically inactive Endonuclease III (iEndoIII), a domain that recognizes non-canonical bases to repair DNA in prokaryotes and eukaryotes. notes: Yee et al. describe the ENDPaCF1 endonuclease plus inactive Endonuclease III domain architecture. - reference: DOI:10.1101/2025.03.31.646159 snippet: We therefore propose that nucleases containing an iEndoIII domain (END nucleases) can sense diverse DNA hypermodifications. notes: Yee et al. propose the END nuclease family around the iEndoIII domain's ability to sense diverse DNA modifications. - reference: DOI:10.1101/2025.03.31.646159 snippet: We further show that some hypermodified phages, including Pbunavirus family members and Wrowclawvirus family (Pa5oct-like) of jumbo phages, encode END nuclease inhibitors that directly bind to the nuclease, likely via the iEndoIII domain. notes: Yee et al. support direct phage inhibitor binding to END nucleases while leaving ENDPaCF1 inhibitor breadth unresolved. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: '| ENDPaCF1 | 10\.1101/2025\.03\.31\.646159 | END nucleases: Antiphage defense systems targeting multiple hypermodified phage genomes | ' notes: The pinned DefenseFinder article registry maps the ENDPaCF1 source key to the Yee et al. bioRxiv preprint. canonical_examples: - taxon_id: NCBITaxon:287 taxon_label: Pseudomonas aeruginosa note: Yee et al. identified ENDPaCF1 in the cystic-fibrosis-derived clinical isolate CF040 and showed that deleting the ENDPaCF1-bearing defense island sensitized the native Pseudomonas aeruginosa strain to Pbunavirus phages. reference: DOI:10.1101/2025.03.31.646159 causal_graphs: - graph_id: endpacf1_targets_hypermodified_phage_dna title: ENDPaCF1 targets hypermodified phage DNA description: Conservative system-level sketch linking an ENDPaCF1 locus to iEndoIII-linked sensing of hypermodified phage DNA, modification-dependent endonuclease targeting, phage restriction, and ENDPaCF1 system possession. scope_status: NONMECHANISTIC scope_notes: The graph captures ENDPaCF1 as a named single-protein phage-defense system with Type IIS restriction endonuclease-like and iEndoIII domains while leaving Pseudomonas natural host breadth, complete DNA-modification breadth, direct domain coupling, phage-inhibitor specificity, and DefenseFinder HMM/rules detection criteria unresolved. nodes: - node_id: endpacf1_locus label: ENDPaCF1 locus node_type: GENETIC_ELEMENT description: An ENDPaCF1 anti-phage locus encoding a Type IIS restriction endonuclease-like protein fused to an inactive Endonuclease III domain. - node_id: hypermodified_phage_dna_sensing label: hypermodified phage DNA sensing node_type: BIOLOGICAL_PROCESS description: Recognition of diverse DNA hypermodifications by ENDPaCF1-family END nuclease systems. - node_id: modification_dependent_phage_dna_cleavage label: modification-dependent phage DNA cleavage node_type: BIOLOGICAL_PROCESS description: Cleavage of phage DNA by a nuclease after hypermodified DNA is detected. - node_id: hypermodified_phage_infection label: hypermodified phage infection node_type: BIOLOGICAL_PROCESS description: Infection by bacteriophages that carry hypermodified genomes. - node_id: endpacf1_system_trait label: ENDPaCF1 system node_type: TRAIT grounding: traitmech:000503 description: Possession of a genome-encoded ENDPaCF1 phage-defense system. - node_id: phage_defense_system label: phage defense system node_type: TRAIT grounding: traitmech:000209 description: Possession of one or more genome-encoded immune systems that inhibit bacteriophage infection. edges: - subject: endpacf1_locus predicate: enables predicate_id: RO:0002327 object: hypermodified_phage_dna_sensing description: An ENDPaCF1 locus enables sensing of diverse hypermodified phage genomes. evidence: - reference: DOI:10.1101/2025.03.31.646159 snippet: The causal defense system is a Type IIS restriction endonuclease-like protein (ENDPaCF1), common in Pseudomonads, however it lacks an associated methyltransferase typical Type IIS R-M systems. notes: Yee et al. identify ENDPaCF1 as the causal Pseudomonas antiphage system and distinguish it from canonical Type IIS restriction-modification systems. - reference: DOI:10.1101/2025.03.31.646159 snippet: In ENDPaCF1, the endonuclease domain is fused to a catalytically inactive Endonuclease III (iEndoIII), a domain that recognizes non-canonical bases to repair DNA in prokaryotes and eukaryotes. notes: Yee et al. describe the ENDPaCF1 endonuclease plus inactive Endonuclease III domain architecture. - reference: DOI:10.1101/2025.03.31.646159 snippet: We therefore propose that nucleases containing an iEndoIII domain (END nucleases) can sense diverse DNA hypermodifications. notes: Yee et al. propose the END nuclease family around the iEndoIII domain's ability to sense diverse DNA modifications. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: '| ENDPaCF1 | 10\.1101/2025\.03\.31\.646159 | END nucleases: Antiphage defense systems targeting multiple hypermodified phage genomes | ' notes: The pinned DefenseFinder article registry maps the ENDPaCF1 source key to the Yee et al. bioRxiv preprint. - subject: hypermodified_phage_infection predicate: contributes to predicate_id: RO:0002326 object: hypermodified_phage_dna_sensing description: Hypermodified phage genomes provide the substrate recognized by ENDPaCF1-family END nucleases. evidence: - reference: DOI:10.1101/2025.03.31.646159 snippet: ENDPaCF1 protects bacteria against phages with hypermodified DNA and is surprisingly agnostic to the specific structure of the modification, which is unlike typical type IV restriction endonucleases. notes: Yee et al. connect ENDPaCF1 to protection against phages with multiple hypermodified-DNA chemistries. - subject: modification_dependent_phage_dna_cleavage predicate: mitigates predicate_id: METPO:2007407 object: hypermodified_phage_infection description: Modification-dependent phage DNA cleavage protects bacteria against phages with hypermodified DNA. evidence: - reference: DOI:10.1101/2025.03.31.646159 snippet: ENDPaCF1 protects bacteria against phages with hypermodified DNA and is surprisingly agnostic to the specific structure of the modification, which is unlike typical type IV restriction endonucleases. notes: Yee et al. connect ENDPaCF1 to protection against phages with multiple hypermodified-DNA chemistries. - subject: modification_dependent_phage_dna_cleavage predicate: confers predicate_id: METPO:2007700 object: endpacf1_system_trait description: ENDPaCF1-family targeting of hypermodified phage DNA realizes the ENDPaCF1 system trait. evidence: - reference: DOI:10.1101/2025.03.31.646159 snippet: Our findings reveal modularity of the sensing and cleavage domains, as expected of a modification-dependent endonucleases. notes: Yee et al. frame END nuclease activity as modification-dependent coupling between sensing and cleavage domains. - subject: endpacf1_system_trait predicate: is a predicate_id: rdfs:subClassOf object: phage_defense_system description: ENDPaCF1 system possession is a phage-defense-system trait. evidence: - reference: DOI:10.1101/2025.03.31.646159 snippet: The causal defense system is a Type IIS restriction endonuclease-like protein (ENDPaCF1), common in Pseudomonads, however it lacks an associated methyltransferase typical Type IIS R-M systems. notes: Yee et al. identify ENDPaCF1 as the causal Pseudomonas antiphage system and distinguish it from canonical Type IIS restriction-modification systems. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: '| ENDPaCF1 | 10\.1101/2025\.03\.31\.646159 | END nucleases: Antiphage defense systems targeting multiple hypermodified phage genomes | ' notes: The pinned DefenseFinder article registry maps the ENDPaCF1 source key to the Yee et al. bioRxiv preprint. discussions: - discussion_id: endpacf1-host-modification-and-model-gap prompt: Resolve ENDPaCF1 Pseudomonas host breadth, complete phage-DNA hypermodification breadth, direct iEndoIII sensing-to-cleavage coupling, phage inhibitor specificity, and DefenseFinder HMM/rules coverage before minting narrower END nuclease mechanism or component traits. kind: KNOWLEDGE_GAP status: OPEN rationale: Yee et al. support ENDPaCF1 as a Type IIS restriction endonuclease-like Pseudomonas phage-defense system that can recognize diverse hypermodified phage genomes, and the pinned DefenseFinder article registry maps the ENDPaCF1 source key to the Yee et al. preprint. The pinned HMM inventory and rules table have no exact ENDPaCF1 rows. This first-pass record therefore does not resolve a complete profile model, the direct domain coupling between iEndoIII sensing and cleavage, or the full natural host, phage, and inhibitor breadth. evidence: - reference: DOI:10.1101/2025.03.31.646159 snippet: The causal defense system is a Type IIS restriction endonuclease-like protein (ENDPaCF1), common in Pseudomonads, however it lacks an associated methyltransferase typical Type IIS R-M systems. notes: Yee et al. identify ENDPaCF1 as the causal Pseudomonas antiphage system and distinguish it from canonical Type IIS restriction-modification systems. - reference: DOI:10.1101/2025.03.31.646159 snippet: ENDPaCF1 protects bacteria against phages with hypermodified DNA and is surprisingly agnostic to the specific structure of the modification, which is unlike typical type IV restriction endonucleases. notes: Yee et al. connect ENDPaCF1 to protection against phages with multiple hypermodified-DNA chemistries. - reference: DOI:10.1101/2025.03.31.646159 snippet: In ENDPaCF1, the endonuclease domain is fused to a catalytically inactive Endonuclease III (iEndoIII), a domain that recognizes non-canonical bases to repair DNA in prokaryotes and eukaryotes. notes: Yee et al. describe the ENDPaCF1 endonuclease plus inactive Endonuclease III domain architecture. - reference: DOI:10.1101/2025.03.31.646159 snippet: We further show that some hypermodified phages, including Pbunavirus family members and Wrowclawvirus family (Pa5oct-like) of jumbo phages, encode END nuclease inhibitors that directly bind to the nuclease, likely via the iEndoIII domain. notes: Yee et al. support direct phage inhibitor binding to END nucleases while leaving ENDPaCF1 inhibitor breadth unresolved. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: '| ENDPaCF1 | 10\.1101/2025\.03\.31\.646159 | END nucleases: Antiphage defense systems targeting multiple hypermodified phage genomes | ' notes: The pinned DefenseFinder article registry maps the ENDPaCF1 source key to the Yee et al. bioRxiv preprint. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md notes: A structured first-pass search of the pinned DefenseFinder HMM inventory found no exact ENDPaCF1 row. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv notes: A structured first-pass search of the pinned DefenseFinder rules table found no exact ENDPaCF1 system row. attaches_to: - causal_graphs#endpacf1_targets_hypermodified_phage_dna posed_by: codex posed_date: '2026-09-30' curation_history: - timestamp: '2026-09-30T23:39:24Z' curator: codex action: MINTED_TRAITMECH_ID changes: Minted ENDPaCF1 system as a bioRxiv- and DefenseFinder-backed GENOMICS TraitRecord under phage defense system after an ignored-and-hidden duplicate review found no exact live TraitMech, METPO, history, research, generated, or prior proposal record; kept the graph at Type IIS restriction-endonuclease-like system level because the pinned DefenseFinder article row is not backed by pinned HMM or rules rows; the replacement placeholder is reserved in proposals/metpo_traitmech_v380. llm_assisted: true - timestamp: '2026-09-30T23:39:25Z' curator: codex action: REVIEW_CANONICAL_EXAMPLE_EVIDENCE_GAP changes: Reviewed ENDPaCF1 system canonical_examples and left them empty because public preprint and DefenseFinder evidence supports the named phage-defense system but not a direct named native microbial isolate exemplar with experimentally verified endogenous ENDPaCF1 activity. No paid research was used. llm_assisted: true - timestamp: '2026-10-01T00:24:07Z' curator: codex action: ADDRESS_ENDPACF1_REVIEW_FINDINGS changes: 'Addressed Copilot review issues #1501, #1502, and #1503: added Pseudomonas aeruginosa (NCBITaxon:287) as a DOI-backed native ENDPaCF1 canonical example, removed the unsupported direct hypermodified-phage-DNA-sensing to modification-dependent-phage-DNA-cleavage causal edge, and included the discussions block in the repository CREATE history sections.' llm_assisted: true