identifier: traitmech:000321 label: AbiU system definition: An abortive infection system in which an organism possesses an abiU-family locus represented by the DefenseFinder AbiU__AbiU profile and exemplified by the Lactococcus lactis LL51-1 AbiU determinant, whose abiU1 open reading frame is responsible for phage resistance, whose abiU2 region may downregulate 936/P335 resistance, and whose activity reduces c2, 936, and P335 lactococcal phage plaquing while delaying transcription of phages 712 and c2. definition_source: DOI:10.1128/AEM.67.11.5225-5232.2001 trait_category: GENOMICS term_kind: CLASS mapping_status: PROPOSED parent_traits: - traitmech:000214 synonyms: - synonym_text: AbiU synonym_type: RELATED_SYNONYM source: DOI:10.1128/AEM.67.11.5225-5232.2001 evidence: - reference: PMID:11679349 snippet: This study reports on the identification and characterization of a novel abortive infection system, AbiU, from Lactococcus lactis. notes: Dai et al. identify AbiU as a novel Lactococcus lactis abortive-infection system. - reference: PMID:11679349 snippet: 'AbiU confers resistance to phages from the three main industrially relevant lactococcal phage species: c2, 936, and P335.' notes: Dai et al. measured the AbiU activity spectrum across representative c2, 936, and P335 lactococcal phages. - reference: PMID:11679349 snippet: 'The presence of AbiU reduced the efficiency of plaquing against specific phage from each species as follows: 3.7 x 10(-1), 1.0 x 10(-2), and 1.0 x 10(-1), respectively.' notes: Dai et al. quantified phage-specific AbiU reductions in efficiency of plaquing against c2, 936, and P335 representatives. - reference: PMID:11679349 snippet: abiU involves two open reading frames, abiU1 (1,772 bp) and abiU2 (1,019 bp). notes: Dai et al. reported a two-ORF abiU locus rather than resolving AbiU as a single isolated protein trait. - reference: PMID:11679349 snippet: Evidence indicates that AbiU1 is responsible for phage resistance and that AbiU2 may downregulate phage resistance against 936 and P335 type phages but not c2 type phage. notes: Dai et al. connected AbiU1 to the phage-resistance phenotype and left AbiU2 as a likely regulator of a phage-species-specific resistance output. - reference: PMID:11679349 snippet: AbiU appeared to delay transcription of both phage 712 and c2, with the effect being more marked on phage c2. notes: Dai et al. linked AbiU to delayed phage transcription without resolving the direct phage trigger or AbiU1 target. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: 'AbiU | 10\.1016/j\.mib\.2005\.06\.006 | Phage abortive infection in lactococci: variations on a theme' notes: The DefenseFinder article registry maps the named AbiU model namespace to a lactococcal abortive-infection review. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv snippet: "AbiU\tAbiU\t1\t1\tAbiU__AbiU" notes: The DefenseFinder rules table models AbiU as a one-component system requiring the AbiU__AbiU profile. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md snippet: '| AbiU__AbiU | AbiU__AbiU | AbiU | Custom | 60 |' notes: The DefenseFinder HMM inventory records AbiU__AbiU under the AbiU model namespace. canonical_examples: - taxon_id: NCBITaxon:1358 taxon_label: Lactococcus lactis note: Dai et al. characterized AbiU from Lactococcus lactis LL51-1 and showed that AbiU confers resistance to c2, 936, and P335 lactococcal phages. reference: DOI:10.1128/AEM.67.11.5225-5232.2001 causal_graphs: - graph_id: abiu_locus_delays_lactococcal_phage_transcription title: AbiU activity delays lactococcal phage transcription description: Conservative system-level sketch linking an abiU-family locus to AbiU antiphage activity, reduced c2/936/P335 phage plaquing, delayed phage 712 and c2 transcription, and AbiU-system possession without asserting the unresolved phage trigger or AbiU1 molecular target. scope_status: NONMECHANISTIC scope_notes: The graph captures AbiU as a named DefenseFinder single-profile abortive-infection system whose LL51-1 prototype restricts c2, 936, and P335 lactococcal phages. It leaves the direct phage trigger, AbiU1 molecular function, AbiU2 downregulation route, natural locus breadth, and phage escape routes unresolved. nodes: - node_id: abiu_locus label: abiU locus node_type: GENETIC_ELEMENT description: An abiU-family abortive-infection locus represented by the DefenseFinder AbiU__AbiU profile. - node_id: abiu_antiphage_activity label: AbiU antiphage activity node_type: BIOLOGICAL_PROCESS description: Abortive-infection phage resistance mediated by the AbiU system. - node_id: lactococcal_phage_plaquing_reduction label: lactococcal phage plaquing reduction node_type: BIOLOGICAL_PROCESS description: Reduced plaquing of c2, 936, and P335 lactococcal phages by an AbiU-containing host. - node_id: phage_transcription_delay label: phage transcription delay node_type: BIOLOGICAL_PROCESS description: Delayed transcription of phages 712 and c2 in AbiU-containing Lactococcus lactis hosts. - node_id: abiu_system_trait label: AbiU system node_type: TRAIT grounding: traitmech:000321 description: Possession of a genome-encoded AbiU abortive-infection phage-defense system. - node_id: abortive_infection_system_trait label: abortive infection system node_type: TRAIT grounding: traitmech:000214 description: Possession of a genome-encoded abortive-infection phage-defense system. edges: - subject: abiu_locus predicate: contributes to predicate_id: RO:0002326 object: abiu_antiphage_activity description: The abiU-family locus encodes AbiU antiphage activity, and DefenseFinder models AbiU as a one-profile system. evidence: - reference: PMID:11679349 snippet: abiU involves two open reading frames, abiU1 (1,772 bp) and abiU2 (1,019 bp). notes: Dai et al. identified the two ORFs in the AbiU determinant. - reference: PMID:11679349 snippet: Evidence indicates that AbiU1 is responsible for phage resistance notes: Dai et al. connected AbiU1 to the phage-resistance phenotype. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv snippet: "AbiU\tAbiU\t1\t1\tAbiU__AbiU" notes: The DefenseFinder rules table models AbiU as a one-component system requiring the AbiU__AbiU profile. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md snippet: '| AbiU__AbiU | AbiU__AbiU | AbiU | Custom | 60 |' notes: The DefenseFinder HMM inventory records AbiU__AbiU under the AbiU model namespace. - subject: abiu_antiphage_activity predicate: contributes to predicate_id: RO:0002326 object: lactococcal_phage_plaquing_reduction description: AbiU activity reduces plaquing of c2, 936, and P335 lactococcal phages. evidence: - reference: PMID:11679349 snippet: 'AbiU confers resistance to phages from the three main industrially relevant lactococcal phage species: c2, 936, and P335.' notes: Dai et al. measured AbiU activity against c2, 936, and P335 phages. - reference: PMID:11679349 snippet: 'The presence of AbiU reduced the efficiency of plaquing against specific phage from each species as follows: 3.7 x 10(-1), 1.0 x 10(-2), and 1.0 x 10(-1), respectively.' notes: Dai et al. quantified phage-specific AbiU EOP reductions. - subject: abiu_antiphage_activity predicate: contributes to predicate_id: RO:0002326 object: phage_transcription_delay description: AbiU activity delays transcription of lactococcal phages 712 and c2. evidence: - reference: PMID:11679349 snippet: AbiU appeared to delay transcription of both phage 712 and c2 notes: Dai et al. detected delayed phage 712 and c2 transcription in the presence of AbiU. - subject: lactococcal_phage_plaquing_reduction predicate: confers predicate_id: METPO:2007700 object: abiu_system_trait description: Reduced c2/936/P335 lactococcal phage plaquing realizes the AbiU abortive-infection trait. evidence: - reference: PMID:11679349 snippet: This study reports on the identification and characterization of a novel abortive infection system, AbiU, from Lactococcus lactis. notes: Dai et al. place AbiU in the abortive-infection class of phage defense. - reference: PMID:11679349 snippet: The presence of AbiU reduced the efficiency of plaquing against specific phage from each species notes: Dai et al. linked AbiU to reduced lactococcal phage plaquing. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: 'AbiU | 10\.1016/j\.mib\.2005\.06\.006 | Phage abortive infection in lactococci: variations on a theme' notes: The DefenseFinder article registry maps the named AbiU model namespace to a lactococcal abortive-infection review. - subject: phage_transcription_delay predicate: contributes to predicate_id: RO:0002326 object: abiu_system_trait description: Delayed 712/c2 phage transcription contributes to the AbiU abortive-infection trait. evidence: - reference: PMID:11679349 snippet: AbiU appeared to delay transcription of both phage 712 and c2 notes: Dai et al. identified delayed phage transcription as an AbiU-associated output. - subject: abiu_system_trait predicate: is a predicate_id: rdfs:subClassOf object: abortive_infection_system_trait description: AbiU system possession is an abortive-infection-system trait. evidence: - reference: PMID:11679349 snippet: This study reports on the identification and characterization of a novel abortive infection system, AbiU notes: Dai et al. place AbiU in the abortive-infection class of phage defense. discussions: - discussion_id: abiu-orf-and-transcription-gap prompt: Resolve the AbiU phage trigger, direct AbiU1 and AbiU2 functions, and phage-transcription-delay route before minting narrower AbiU mechanism children. kind: KNOWLEDGE_GAP status: OPEN rationale: Dai et al. support AbiU as a named lactococcal abortive-infection system that reduces plaquing of c2, 936, and P335 phages and delays 712 and c2 phage transcription. DefenseFinder represents AbiU with a one-profile rule, but this first system-level record leaves the phage trigger, AbiU1 molecular function, AbiU2 downregulation route, natural locus breadth, and phage escape routes unresolved. attaches_to: - causal_graphs#abiu_locus_delays_lactococcal_phage_transcription posed_by: codex posed_date: '2026-09-20' curation_history: - timestamp: '2026-09-20T22:48:12Z' curator: codex action: MINTED_TRAITMECH_ID changes: Minted AbiU 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_v198. llm_assisted: true