identifier: traitmech:000524 label: Brc23 system definition: A phage defense system in which an organism possesses a gcu23/Brc23 bacteriophage-resistance integron cassette that supports growth during bacteriophage challenge. definition_source: DOI:10.1126/science.ads0915 trait_category: GENOMICS term_kind: CLASS mapping_status: PROPOSED parent_traits: - traitmech:000209 synonyms: - synonym_text: gcu23 synonym_type: RELATED_SYNONYM source: DOI:10.1126/science.ads0915 - synonym_text: brc23 synonym_type: RELATED_SYNONYM source: DOI:10.1126/science.ads0915 evidence: - reference: DOI:10.1126/science.ads0915 snippet: gcu23 had a broader defense profile, including high resistance levels against G4, MS2, F1, and T4 notes: Kieffer et al. report that the former gcu23 cassette conferred a broader phage-defense profile with high G4, MS2, F1, and T4 resistance levels. - reference: DOI:10.1126/science.ads0915 snippet: We therefore redefined both cassettes as BRiCs (brc22 and brc23) notes: Kieffer et al. renamed gcu22 and gcu23 as Brc cassettes after phage-resistance testing. - reference: DOI:10.1126/science.ads0915 snippet: Predicted secondary structures of attC sites in identified BRiCs notes: Kieffer et al. identify BRiC bacteriophage-resistance integron cassettes and show their predicted attC secondary structures. - reference: DOI:10.1126/science.ads0915 snippet: 'brc113 brc217 brc76 brcWGS21 brc22 brc23' notes: Kieffer et al. include brc23 among identified BRiCs with predicted attC secondary structures. - reference: https://www.science.org/doi/suppl/10.1126/science.ads0915/suppl_file/science.ads0915_sm.pdf snippet: 'D279 pMBA PcW brc23 E. coli IJ1862' notes: Kieffer et al.'s supplementary construct table lists pMBA PcW brc23 in E. coli IJ1862 under naturally occurring defense island constructs. - reference: https://www.science.org/doi/suppl/10.1126/science.ads0915/suppl_file/science.ads0915_sm.pdf snippet: 'D284 pMBA PcW brc23 K. pneumoniae KP5' notes: Kieffer et al.'s supplementary construct table lists pMBA PcW brc23 in Klebsiella pneumoniae KP5 under naturally occurring defense island constructs. causal_graphs: - graph_id: brc23_integron_cassette_confers_phage_resistance title: Brc23 BRiCs confer phage resistance description: Conservative system-level sketch linking a gcu23/Brc23 bacteriophage-resistance integron cassette to phage resistance and Brc23 system possession. scope_status: NONMECHANISTIC scope_notes: The graph captures Brc23 at the integron-cassette and phage-resistance-output level without asserting the native host range, exact sensitive-phage breadth outside the reported panels, direct molecular substrate, whether Brc22 and Brc23 are variants of one Tragantia family, or a DefenseFinder article/HMM/rules profile absent from the pinned snapshot. nodes: - node_id: brc23_integron_cassette label: Brc23 integron cassette node_type: GENETIC_ELEMENT description: A mobile integron gene cassette curated here as gcu23/Brc23. - node_id: brc23_phage_resistance label: Brc23 phage resistance node_type: BIOLOGICAL_PROCESS description: Reduced phage inhibition in cells carrying the gcu23/Brc23 integron cassette. - node_id: brc23_system_trait label: Brc23 system node_type: TRAIT grounding: traitmech:000524 description: Possession of a genome-encoded Brc23 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: brc23_integron_cassette predicate: contributes to predicate_id: RO:0002326 object: brc23_phage_resistance description: The gcu23/Brc23 integron cassette contributes to G4, MS2, F1, and T4 phage resistance during phage-panel assays. evidence: - reference: DOI:10.1126/science.ads0915 snippet: gcu23 had a broader defense profile, including high resistance levels against G4, MS2, F1, and T4 notes: Kieffer et al. report that the former gcu23 cassette conferred a broader phage-defense profile with high G4, MS2, F1, and T4 resistance levels. - subject: brc23_phage_resistance predicate: confers predicate_id: METPO:2007700 object: brc23_system_trait description: Brc23-linked phage resistance realizes the Brc23 system possession trait. evidence: - reference: DOI:10.1126/science.ads0915 snippet: gcu23 had a broader defense profile, including high resistance levels against G4, MS2, F1, and T4 notes: Kieffer et al. report that the former gcu23 cassette conferred a broader phage-defense profile with high G4, MS2, F1, and T4 resistance levels. - reference: DOI:10.1126/science.ads0915 snippet: We therefore redefined both cassettes as BRiCs (brc22 and brc23) notes: Kieffer et al. renamed gcu22 and gcu23 as Brc cassettes after phage-resistance testing. - subject: brc23_system_trait predicate: is a predicate_id: rdfs:subClassOf object: phage_defense_system description: Brc23 system possession is a phage-defense-system trait. evidence: - reference: DOI:10.1126/science.ads0915 snippet: Predicted secondary structures of attC sites in identified BRiCs notes: Kieffer et al. identify BRiC bacteriophage-resistance integron cassettes and show their predicted attC secondary structures. - reference: DOI:10.1126/science.ads0915 snippet: 'brc113 brc217 brc76 brcWGS21 brc22 brc23' notes: Kieffer et al. include brc23 among identified BRiCs with predicted attC secondary structures. discussions: - discussion_id: brc23-defensefinder-model-gap prompt: Resolve Brc23 native host breadth, exact sensitive-phage breadth, molecular output, Tragantia-family boundaries, and DefenseFinder article/HMM/rules coverage before minting narrower Brc23 mechanism children. kind: KNOWLEDGE_GAP status: OPEN rationale: Kieffer et al. identify brc23 as a bacteriophage-resistance integron cassette. The pinned DefenseFinder article registry, HMM inventory, and rules table have no exact gcu23 or Brc23 row, so the first-pass record leaves native-host breadth, profile boundaries, exact phage target breadth, direct molecular output, and Brc22/Brc23 Tragantia-family scope unresolved. evidence: - reference: DOI:10.1126/science.ads0915 snippet: gcu23 had a broader defense profile, including high resistance levels against G4, MS2, F1, and T4 notes: Kieffer et al. report that the former gcu23 cassette conferred a broader phage-defense profile with high G4, MS2, F1, and T4 resistance levels. - reference: DOI:10.1126/science.ads0915 snippet: We therefore redefined both cassettes as BRiCs (brc22 and brc23) notes: Kieffer et al. renamed gcu22 and gcu23 as Brc cassettes after phage-resistance testing. - reference: DOI:10.1126/science.ads0915 snippet: Predicted secondary structures of attC sites in identified BRiCs notes: Kieffer et al. identify BRiC bacteriophage-resistance integron cassettes and show their predicted attC secondary structures. - reference: DOI:10.1126/science.ads0915 snippet: 'brc113 brc217 brc76 brcWGS21 brc22 brc23' notes: Kieffer et al. include brc23 among identified BRiCs with predicted attC secondary structures. - reference: https://www.science.org/doi/suppl/10.1126/science.ads0915/suppl_file/science.ads0915_sm.pdf snippet: 'D279 pMBA PcW brc23 E. coli IJ1862' notes: Kieffer et al.'s supplementary construct table lists pMBA PcW brc23 in E. coli IJ1862 under naturally occurring defense island constructs. - reference: https://www.science.org/doi/suppl/10.1126/science.ads0915/suppl_file/science.ads0915_sm.pdf snippet: 'D284 pMBA PcW brc23 K. pneumoniae KP5' notes: Kieffer et al.'s supplementary construct table lists pMBA PcW brc23 in Klebsiella pneumoniae KP5 under naturally occurring defense island constructs. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md notes: A structured first-pass search of the pinned DefenseFinder article registry found no exact gcu23, brc23, or Brc23 row. - 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 gcu23, brc23, or Brc23 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 gcu23, brc23, or Brc23 system row. attaches_to: - causal_graphs#brc23_integron_cassette_confers_phage_resistance posed_by: codex posed_date: '2026-10-01' curation_history: - timestamp: '2026-10-01T20:08:00Z' curator: codex action: MINTED_TRAITMECH_ID changes: Minted Brc23 system as a DOI-backed GENOMICS TraitRecord under phage defense system after an ignored-and-hidden duplicate review ruled out same-scope live TraitMech, METPO, history, and prior proposal collisions after reviewing exact Brc23/brc23/gcu23 hits; kept the graph at BRiC integron-cassette level because the pinned DefenseFinder article registry, HMM inventory, and rules table have no exact Brc23 row; the replacement placeholder is reserved in proposals/metpo_traitmech_v401. llm_assisted: true - timestamp: '2026-10-01T20:08:01Z' curator: codex action: REVIEW_CANONICAL_EXAMPLE_EVIDENCE_GAP changes: Reviewed Brc23 system during initial curation and left canonical_examples empty because the sources support heterologous gcu23/Brc23 phage-resistance assays but not a direct named native microbial isolate exemplar with experimentally verified endogenous Brc23 activity. No paid research was used. llm_assisted: true