identifier: traitmech:000328 label: ApsAB system definition: A genomics trait describing possession of an ApsAB anti-plasmid defense locus encoding the nuclease/helicase ApsA and Argonaute-like ApsB proteins that can destabilize high- and low-copy-number plasmids. definition_source: DOI:10.1038/s41467-024-48219-y trait_category: GENOMICS term_kind: CLASS mapping_status: PROPOSED parent_traits: - METPO:1000188 synonyms: - synonym_text: ApsAB synonym_type: EXACT_SYNONYM source: DOI:10.1038/s41467-024-48219-y - synonym_text: apsAB synonym_type: EXACT_SYNONYM source: DOI:10.1038/s41467-024-48219-y evidence: - reference: DOI:10.1038/s41467-024-48219-y snippet: a novel antiplasmid system ApsAB actively involved in pOXA-48 destabilization notes: Zongo et al. support ApsAB as a named anti-plasmid system involved in pOXA-48 destabilization. - reference: DOI:10.1038/s41467-024-48219-y snippet: We show that ApsAB targets high and low-copy number plasmids. notes: Zongo et al. support anti-plasmid activity against both high- and low-copy-number plasmids. - reference: DOI:10.1038/s41467-024-48219-y snippet: ApsAB combines a nuclease/helicase protein and a novel type of Argonaute-like protein. notes: Zongo et al. support a two-component ApsAB system combining ApsA nuclease/helicase and Argonaute-like ApsB proteins. - reference: DOI:10.1038/s41467-024-48219-y snippet: This confirmed that F3141-F3140 corresponds to a novel antiplasmid defense system that we renamed apsAB for antiplasmid system AB. notes: Zongo et al. support apsAB as the expanded name for the F3141-F3140 anti-plasmid defense locus. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: ApsAB | 10\.1038/s41467-024-48219-y | An antiplasmid system drives antibiotic resistance gene integration in carbapenemase-producing Escherichia coli lineages notes: The DefenseFinder article registry maps the named ApsAB system to the Zongo et al. Escherichia coli anti-plasmid-system paper; the pinned DefenseFinder HMM inventory and rules table do not list ApsAB, so this row is name-to-paper evidence rather than model-component evidence. canonical_examples: - taxon_id: NCBITaxon:562 taxon_label: Escherichia coli note: Zongo et al. identified ApsAB in ST38 Escherichia coli and found that homologous E. coli ApsAB-like systems also destabilized a ColE1 multicopy plasmid. reference: DOI:10.1038/s41467-024-48219-y causal_graphs: - graph_id: apsab_locus_destabilizes_plasmids title: ApsAB loci destabilize plasmids description: Conservative system-level sketch linking possession of an ApsAB locus to plasmid destabilization without asserting the unresolved guide source, recognition rule, or degradation chemistry. scope_status: NONMECHANISTIC scope_notes: The graph captures ApsAB as a named anti-plasmid defense system while leaving the direct ApsB guide source, the target-recognition rule, the exact plasmid-degradation chemistry, the natural plasmid substrate range, family breadth, and the absence of pinned DefenseFinder HMM or rule rows unresolved. nodes: - node_id: apsab_locus label: ApsAB locus node_type: GENETIC_ELEMENT description: An anti-plasmid defense locus encoding ApsA nuclease/helicase and Argonaute-like ApsB components. - node_id: plasmid_destabilization label: plasmid destabilization node_type: BIOLOGICAL_PROCESS description: Reduced maintenance or active elimination of plasmids in cells carrying ApsAB. - node_id: apsab_system_trait label: ApsAB system node_type: TRAIT grounding: traitmech:000328 description: Possession of a genome-encoded ApsAB anti-plasmid defense locus. edges: - subject: apsab_locus predicate: contributes to predicate_id: RO:0002326 object: plasmid_destabilization description: The F3141-F3140 locus was renamed apsAB and ApsAB expression promotes plasmid elimination. evidence: - reference: DOI:10.1038/s41467-024-48219-y snippet: This confirmed that F3141-F3140 corresponds to a novel antiplasmid defense system that we renamed apsAB for antiplasmid system AB. notes: Zongo et al. identify F3141-F3140 as the ApsAB anti-plasmid system. - reference: DOI:10.1038/s41467-024-48219-y snippet: These results indicate that ApsAB actively eliminates the plasmid, likely by promoting its degradation notes: Zongo et al. report active ApsAB-mediated plasmid elimination after arabinose induction. - reference: DOI:10.1038/s41467-024-48219-y snippet: Both systems were found to destabilize a ColE1 multicopy plasmid notes: Zongo et al. found that homologous E. coli ApsAB-like systems can destabilize a ColE1 multicopy plasmid. - subject: plasmid_destabilization predicate: confers predicate_id: METPO:2007700 object: apsab_system_trait description: ApsAB-mediated plasmid destabilization realizes the ApsAB system trait. evidence: - reference: DOI:10.1038/s41467-024-48219-y snippet: We show that ApsAB targets high and low-copy number plasmids. notes: Zongo et al. support the ApsAB anti-plasmid output against high- and low-copy-number plasmids. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: ApsAB | 10\.1038/s41467-024-48219-y | An antiplasmid system drives antibiotic resistance gene integration in carbapenemase-producing Escherichia coli lineages notes: The DefenseFinder article registry maps the named ApsAB system to the Zongo et al. Escherichia coli anti-plasmid-system paper; the pinned DefenseFinder HMM inventory and rules table do not list ApsAB, so this row is name-to-paper evidence rather than model-component evidence. discussions: - discussion_id: apsab-substrate-and-guide-source-gap prompt: Resolve ApsAB guide sources, plasmid substrates, and model coverage before minting narrower ApsAB mechanism children. kind: KNOWLEDGE_GAP status: OPEN rationale: Zongo et al. support ApsAB as a two-component E. coli anti-plasmid system and report activity against high- and low-copy-number plasmids, but the direct ApsB guide source, the target-recognition rule, exact plasmid-degradation chemistry, natural substrate range, family-level breadth, and profile-to-component model are not resolved enough here to assert narrower mechanistic or subtype traits. attaches_to: - causal_graphs#apsab_locus_destabilizes_plasmids posed_by: codex posed_date: '2026-09-21' curation_history: - timestamp: '2026-09-21T05:45:03Z' curator: codex action: MINTED_TRAITMECH_ID changes: Minted ApsAB system as a DOI-backed GENOMICS TraitRecord under the quality root 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_v205. llm_assisted: true