identifier: traitmech:000325 label: SpbK system definition: An abortive infection system in which an organism possesses a SpbK-family locus represented by the DefenseFinder SpbK__SpbK profile and exemplified by the ICEBs1 spbK gene whose SPβ-YonE-dependent activity inhibits SPβ production and kills infected cells. definition_source: DOI:10.1371/journal.pgen.1010065 trait_category: GENOMICS term_kind: CLASS mapping_status: PROPOSED parent_traits: - traitmech:000214 synonyms: - synonym_text: SpbK synonym_type: RELATED_SYNONYM source: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md evidence: - reference: DOI:10.1371/journal.pgen.1010065 snippet: The ICEBs1 gene spbK, although dispensable for conjugation, was necessary and sufficient for the inhibition of SPß. notes: Johnson et al. support spbK as the ICEBs1 locus sufficient for SPβ inhibition. - reference: DOI:10.1371/journal.pgen.1010065 snippet: The anti-SPß phenotype (abortive infection) caused by spbK was dependent on the SPß gene yonE. notes: Johnson et al. support yonE-dependent abortive infection as the phage-specific SpbK output. - reference: DOI:10.1371/journal.pgen.1010065 snippet: Co-expression of spbK and yonE inhibited host cell growth and caused a drop in cell viability, even in the absence of any other ICEBs1 or SPß genes. notes: Johnson et al. support SpbK/YonE-associated host growth inhibition and cell death. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: 'SpbK | 10\.1371/journal\.pgen\.1010065 | Interactions between mobile genetic elements: An anti-phage gene in an integrative and conjugative element protects host cells from predation by a temperate bacteriophage' notes: The DefenseFinder article registry maps the named SpbK model namespace to the ICEBs1 SpbK anti-phage paper. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv snippet: "SpbK\tSpbK\t1\t1\tSpbK__SpbK" notes: The DefenseFinder rules table models SpbK as a single-profile system requiring the SpbK__SpbK profile. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md snippet: '| SpbK__SpbK | SpbK__SpbK | SpbK | Custom | 80 |' notes: The DefenseFinder HMM inventory records SpbK__SpbK under SpbK. canonical_examples: - taxon_id: NCBITaxon:1423 taxon_label: Bacillus subtilis note: Johnson et al. showed that ICEBs1 encodes an SpbK-dependent abortive infection system that protects B. subtilis host populations from SPβ. reference: DOI:10.1371/journal.pgen.1010065 causal_graphs: - graph_id: spbk_locus_mediates_spb_defense title: SpbK loci mediate SPβ abortive defense description: Conservative system-level sketch linking SpbK-family locus possession to SPβ YonE-dependent abortive infection and the SpbK system trait without asserting the direct SpbK-YonE coupling event or TIR-domain effector chemistry. scope_status: NONMECHANISTIC scope_notes: The graph captures SpbK as a named DefenseFinder single-profile abortive-infection system whose Bacillus ICEBs1 prototype requires the SPβ YonE trigger. It leaves the direct SpbK-YonE coupling, TIR-domain output, essential host target, and homolog breadth unresolved. nodes: - node_id: spbk_locus label: SpbK locus node_type: GENETIC_ELEMENT description: An ICEBs1-like abortive-infection locus represented by the DefenseFinder SpbK__SpbK profile. - node_id: spbk_yone_abortive_infection label: SpbK/YonE-dependent abortive infection node_type: BIOLOGICAL_PROCESS description: Abortive infection in which SpbK activity depends on the SPβ YonE gene and causes host growth inhibition and cell death. - node_id: spbk_system_trait label: SpbK system node_type: TRAIT grounding: traitmech:000325 description: Possession of a genome-encoded SpbK abortive-infection phage-defense system. edges: - subject: spbk_locus predicate: contributes to predicate_id: RO:0002326 object: spbk_yone_abortive_infection description: The ICEBs1 spbK locus is necessary and sufficient for YonE-dependent SPβ abortive infection, and DefenseFinder represents SpbK with a required SpbK profile. evidence: - reference: DOI:10.1371/journal.pgen.1010065 snippet: The ICEBs1 gene spbK, although dispensable for conjugation, was necessary and sufficient for the inhibition of SPß. notes: Johnson et al. connect the ICEBs1 spbK gene to SPβ inhibition. - reference: DOI:10.1371/journal.pgen.1010065 snippet: The anti-SPß phenotype (abortive infection) caused by spbK was dependent on the SPß gene yonE. notes: Johnson et al. support YonE dependence of SpbK-mediated abortive infection. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv snippet: "SpbK\tSpbK\t1\t1\tSpbK__SpbK" notes: The DefenseFinder rules table models SpbK as a single-profile system requiring the SpbK__SpbK profile. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md snippet: '| SpbK__SpbK | SpbK__SpbK | SpbK | Custom | 80 |' notes: The DefenseFinder HMM inventory records SpbK__SpbK under SpbK. - subject: spbk_yone_abortive_infection predicate: confers predicate_id: METPO:2007700 object: spbk_system_trait description: SpbK/YonE-dependent abortive infection realizes the SpbK system trait. evidence: - reference: DOI:10.1371/journal.pgen.1010065 snippet: Whatever the mechanism, we conclude that ICEBs1 encodes an abortive infection system that protects its host from predation by SPß. notes: Johnson et al. classify ICEBs1 spbK activity as an abortive infection system that protects its host from SPβ predation. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: 'SpbK | 10\.1371/journal\.pgen\.1010065 | Interactions between mobile genetic elements: An anti-phage gene in an integrative and conjugative element protects host cells from predation by a temperate bacteriophage' notes: The DefenseFinder article registry maps the named SpbK model namespace to the ICEBs1 SpbK anti-phage paper. discussions: - discussion_id: spbk-mechanism-gap prompt: Resolve the direct SPβ YonE trigger, SpbK TIR-domain output, essential host target, and broader SpbK homolog scope before minting narrower SpbK mechanism children. kind: KNOWLEDGE_GAP status: OPEN rationale: Johnson et al. support ICEBs1 spbK as a YonE-dependent abortive infection gene that inhibits SPβ and causes cell death, and DefenseFinder maps SpbK to the SpbK__SpbK profile. The direct SpbK-YonE coupling event, TIR-domain output, essential host target, and homolog breadth remain unresolved. attaches_to: - causal_graphs#spbk_locus_mediates_spb_defense posed_by: codex posed_date: '2026-09-21' curation_history: - timestamp: '2026-09-21T03:22:00Z' curator: codex action: MINTED_TRAITMECH_ID changes: Minted SpbK system as a DOI-backed GENOMICS TraitRecord under the abortive infection system parent after an ignored-and-hidden duplicate review found no exact live TraitMech, METPO, history, or prior proposal record; the replacement placeholder is reserved in proposals/metpo_traitmech_v202. llm_assisted: true - timestamp: '2026-09-21T03:45:00Z' curator: codex action: REVISED_TEXT changes: Standardized curator-written SPβ phage mentions to the canonical Greek beta spelling while preserving Johnson et al. evidence snippets exactly as exposed by the PLOS XML. llm_assisted: true