identifier: traitmech:000305 label: JukAB system definition: A phage defense system in which an organism possesses a two-gene jukAB locus encoding a JukA sensor that binds a PhiKZ-like gp241 early phage protein at the EPI vesicle and directly recruits the pore-forming-toxin-like JukB effector to destabilize the vesicle, suppress early phage gene expression, and prevent phage DNA replication and nucleus assembly. definition_source: DOI:10.1016/j.cell.2025.02.016 trait_category: GENOMICS term_kind: CLASS mapping_status: PROPOSED parent_traits: - traitmech:000209 synonyms: - synonym_text: JukAB synonym_type: RELATED_SYNONYM source: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md - synonym_text: jumbo phage killer synonym_type: RELATED_SYNONYM source: DOI:10.1016/j.cell.2025.02.016 evidence: - reference: DOI:10.1016/j.cell.2025.02.016 snippet: a two-component immune system that terminates infection of φKZ-like phages notes: Li et al. define Juk as a two-component immune system that terminates PhiKZ-like jumbo-phage infection. - reference: DOI:10.1101/2022.09.17.508391 snippet: jukA and jukB together, but not either gene alone, conferred resistance against notes: Li et al. show that the JukA sensor and JukB effector are jointly required for heterologous PhiKZ resistance. - reference: DOI:10.1016/j.cell.2025.02.016 snippet: JukA (formerly YaaW) rapidly senses the EPI vesicle by binding to an early-expressed phage protein, gp241, and then directly recruits JukB notes: Li et al. identify JukA binding to the PhiKZ-like early phage protein gp241 at the EPI vesicle as the JukAB input that recruits JukB. - reference: DOI:10.1016/j.cell.2025.02.016 snippet: The JukB effector structurally resembles a pore-forming toxin and destabilizes the EPI vesicle notes: Li et al. connect the recruited JukB effector to destabilization of the early phage infection vesicle. - reference: DOI:10.1016/j.cell.2025.02.016 snippet: suppressing the expression of early phage genes and preventing phage DNA replication and phage nucleus assembly while saving the cell notes: Li et al. describe the downstream anti-phage outcome of two-component Juk immunity. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: JukAB | 10\.1101/2022\.09\.17\.508391 | A family of novel immune systems targets early infection of nucleus-forming jumbo phages notes: The DefenseFinder article registry maps the named JukAB system to the Li et al. Juk immune-system preprint. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv snippet: "JukAB\tJukAB\t2\t2\tJukAB__JukA, JukAB__JukB" notes: The DefenseFinder rules table models JukAB as a two-component system requiring JukAB__JukA and JukAB__JukB profiles. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md snippet: '| JukAB__JukA | JukAB__JukA | JukAB | Custom | 20 |' notes: The DefenseFinder HMM inventory records JukAB__JukA under the JukAB model namespace. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md snippet: '| JukAB__JukB | JukAB__JukB | JukAB | Custom | 20 |' notes: The DefenseFinder HMM inventory records JukAB__JukB under the JukAB model namespace. canonical_examples: - taxon_id: NCBITaxon:287 taxon_label: Pseudomonas aeruginosa note: Li et al. discovered the native jukA-jukB operon in Pseudomonas aeruginosa PA14 and showed that the two-gene Juk locus provides immunity against PhiKZ-related nucleus-forming jumbo phages. reference: DOI:10.1101/2022.09.17.508391 causal_graphs: - graph_id: jukab_recruits_effector_to_block_jumbo_phage title: JukAB blocks early jumbo-phage infection description: Conservative system-level sketch linking a jukAB locus to gp241/EPI-vesicle sensing by JukA, JukB recruitment, JukB-mediated EPI-vesicle destabilization, suppression of early PhiKZ-like jumbo-phage development, and JukAB system possession. scope_status: NONMECHANISTIC scope_notes: The graph captures JukAB as a named DefenseFinder two-profile system in which JukA binds the PhiKZ gp241 early phage protein at the EPI vesicle and recruits JukB to destabilize that vesicle. It summarizes the direct two-component system without minting separate sequence feature traits for jukA, jukB, gp241, or other JukA-associated effector families. nodes: - node_id: jukab_locus label: jukAB locus node_type: GENETIC_ELEMENT description: A two-gene locus encoding JukA and JukB and represented by the DefenseFinder JukAB rule. - node_id: jukA_phage_ejected_factor_sensing label: JukA gp241 EPI-vesicle sensing node_type: BIOLOGICAL_PROCESS description: Binding of the JukA sensor to PhiKZ-like gp241 at the early phage infection vesicle. - node_id: jukB_effector_recruitment label: JukB effector recruitment node_type: BIOLOGICAL_PROCESS description: JukA-dependent recruitment of the JukB effector to the phage infection site. - node_id: early_jumbo_phage_progression label: early jumbo-phage progression node_type: BIOLOGICAL_PROCESS description: Early phage transcription, DNA replication, and nucleus assembly during infection by a nucleus-forming jumbo phage. - node_id: epi_vesicle_destabilization label: EPI vesicle destabilization node_type: BIOLOGICAL_PROCESS description: JukB-associated destabilization of the lipid-based early phage infection vesicle. - node_id: jukab_system_trait label: JukAB system node_type: TRAIT grounding: traitmech:000305 description: Possession of a genome-encoded JukAB 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: jukab_locus predicate: contributes to predicate_id: RO:0002326 object: jukA_phage_ejected_factor_sensing description: The JukAB locus encodes JukA, the sensor that binds the early phage protein gp241 at the EPI vesicle. evidence: - reference: DOI:10.1016/j.cell.2025.02.016 snippet: JukA (formerly YaaW) rapidly senses the EPI vesicle by binding to an early-expressed phage protein, gp241 notes: Li et al. identify gp241/EPI-vesicle binding by JukA as the characterized JukAB sensor input. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv snippet: "JukAB\tJukAB\t2\t2\tJukAB__JukA, JukAB__JukB" notes: DefenseFinder requires the JukA profile in its JukAB system rule. - subject: jukA_phage_ejected_factor_sensing predicate: contributes to predicate_id: RO:0002326 object: jukB_effector_recruitment description: JukA sensing of gp241 at the EPI vesicle directly recruits the JukB effector. evidence: - reference: DOI:10.1016/j.cell.2025.02.016 snippet: JukA (formerly YaaW) rapidly senses the EPI vesicle by binding to an early-expressed phage protein, gp241, and then directly recruits JukB notes: Li et al. place direct JukB recruitment downstream of JukA-gp241 binding at the EPI vesicle. - subject: jukB_effector_recruitment predicate: contributes to predicate_id: RO:0002326 object: epi_vesicle_destabilization description: Recruited JukB is a pore-forming-toxin-like effector that destabilizes the EPI vesicle. evidence: - reference: DOI:10.1016/j.cell.2025.02.016 snippet: The JukB effector structurally resembles a pore-forming toxin and destabilizes the EPI vesicle notes: Li et al. connect JukB to the vesicle destabilization step of JukAB immunity. - subject: epi_vesicle_destabilization predicate: mitigates predicate_id: METPO:2007407 object: early_jumbo_phage_progression description: EPI-vesicle destabilization by the JukAB response blocks early jumbo-phage gene expression, DNA replication, and nucleus assembly. evidence: - reference: DOI:10.1016/j.cell.2025.02.016 snippet: suppressing the expression of early phage genes and preventing phage DNA replication and phage nucleus assembly while saving the cell notes: Li et al. define the anti-phage output of the two-component Juk system. - subject: epi_vesicle_destabilization predicate: confers predicate_id: METPO:2007700 object: jukab_system_trait description: JukB-associated EPI-vesicle destabilization realizes the JukAB defense trait. evidence: - reference: DOI:10.1016/j.cell.2025.02.016 snippet: a two-component immune system that terminates infection of φKZ-like phages notes: Li et al. frame two-component Juk as an immune system that terminates PhiKZ-like phage infection. - subject: jukab_system_trait predicate: is a predicate_id: rdfs:subClassOf object: phage_defense_system description: JukAB system possession is a phage-defense-system trait. evidence: - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: JukAB | 10\.1101/2022\.09\.17\.508391 | A family of novel immune systems targets early infection of nucleus-forming jumbo phages notes: DefenseFinder associates JukAB with the Li et al. nucleus-forming-jumbo-phage immune system paper. discussions: - discussion_id: jukab-vesicle-effector-family-gap prompt: Resolve JukB vesicle-destabilization chemistry and the boundaries of other JukA-containing systems before minting narrower mechanism children. kind: KNOWLEDGE_GAP status: OPEN rationale: Li et al. resolve gp241/EPI-vesicle sensing by JukA and direct recruitment of JukB as a two-component JukAB strategy, but the exact chemistry of JukB-mediated vesicle destabilization and the relationship between canonical JukAB and JukA homologs paired with diverse other putative effectors still need narrower review. attaches_to: - causal_graphs#jukab_recruits_effector_to_block_jumbo_phage posed_by: codex posed_date: '2026-09-20' curation_history: - timestamp: '2026-09-20T08:47:10Z' curator: codex action: MINTED_TRAITMECH_ID changes: Minted JukAB system as a DOI-backed GENOMICS TraitRecord under phage defense system after an ignored-and-hidden duplicate review found no exact live TraitMech, METPO, or prior proposal record; the replacement placeholder is reserved in proposals/metpo_traitmech_v182. llm_assisted: true