identifier: traitmech:000345 label: MazEF system definition: A phage defense system in which an organism possesses a two-component MazEF toxin-antitoxin locus whose MazE antitoxin and MazF endoribonuclease can protect Escherichia coli against RNA phages and that DefenseFinder represents with mandatory MazEF__MazE and MazEF__MazF profiles. definition_source: DOI:10.1098/rsbl.2025.0080 trait_category: GENOMICS term_kind: CLASS mapping_status: PROPOSED parent_traits: - traitmech:000209 synonyms: - synonym_text: MazEF synonym_type: EXACT_SYNONYM source: PMID:40494395 - synonym_text: mazEF synonym_type: RELATED_SYNONYM source: PMID:40494395 - synonym_text: MazEF__MazE synonym_type: RELATED_SYNONYM source: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md - synonym_text: MazEF__MazF synonym_type: RELATED_SYNONYM source: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md evidence: - reference: PMID:40494395 snippet: we investigated the role of a model toxin-antitoxin system, MazEF, in protecting Escherichia coli against two RNA phage species notes: Nikolic et al. directly tested MazEF as an Escherichia coli toxin-antitoxin module protecting against RNA phages. - reference: PMID:40494395 snippet: the native presence of mazEF moderately reduced population susceptibility and increased the survival of individual E. coli cells notes: Nikolic et al. support native mazEF as a moderate RNA phage defense determinant in Escherichia coli. - reference: PMID:40494395 snippet: Genomic analysis further revealed an underrepresentation of the MazF cleavage site in genomes of RNA phages infecting E. coli notes: Nikolic et al. support selection against MazF ACA cleavage sites in RNA phages that infect E. coli. - reference: https://pmc.ncbi.nlm.nih.gov/articles/PMC12151602/ snippet: MazEF interferes with RNA phage replication within already infected cells notes: Nikolic et al. interpret the mazEF deletion phenotype as intracellular interference with RNA phage replication, not an adsorption defect. - reference: https://pmc.ncbi.nlm.nih.gov/articles/PMC12151602/ snippet: direct interference, rather than abortive infection, plays the predominant role in the case of MazEF notes: Nikolic et al. caution that the main MazEF effect in their RNA phage assays appears to be direct interference rather than abortive infection. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: MazEF | 10\.1098/rsbl\.2025\.0080 | A bacterial toxin-antitoxin system as a native defence element against RNA phages notes: The DefenseFinder article registry maps the named MazEF system to the Nikolic et al. RNA-phage defense paper. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv snippet: "MazEF\tMazEF\t2\t2\tMazEF__MazE, MazEF__MazF" notes: The DefenseFinder rules table models MazEF as a two-profile system requiring MazE and MazF profiles. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md snippet: '| MazEF__MazE | MazEF__MazE | MazEF | Custom | 20 |' notes: The DefenseFinder HMM inventory records the MazE profile in the MazEF model namespace. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/Liste_hmm_system.md snippet: '| MazEF__MazF | MazEF__MazF | MazEF | Custom | 20 |' notes: The DefenseFinder HMM inventory records the MazF profile in the MazEF model namespace. canonical_examples: - taxon_id: NCBITaxon:562 taxon_label: Escherichia coli note: Nikolic et al. compared Escherichia coli K-12 MG1655 derivatives carrying or lacking the native mazEF locus and found moderate but measurable native mazEF protection against the MS2 and Qbeta RNA phages. reference: DOI:10.1098/rsbl.2025.0080 causal_graphs: - graph_id: mazef_rna_phage_defense title: MazEF loci reduce RNA phage susceptibility description: Conservative system-level sketch linking a MazEF locus to native RNA phage defense and the MazEF system possession trait. scope_status: NONMECHANISTIC scope_notes: The graph captures native MazEF protection against RNA phages without asserting a phage-triggered MazF activation route, a resolved direct phage-RNA cleavage event, MazEF-mediated DNA-phage defense breadth, or a generic abortive-infection output. nodes: - node_id: mazef_locus label: MazEF locus node_type: GENETIC_ELEMENT description: A two-component toxin-antitoxin locus represented by MazE and MazF profiles. - node_id: rna_phage_replication_interference label: RNA phage replication interference node_type: BIOLOGICAL_PROCESS description: Reduced RNA phage replication or survival of RNA phage-infected cells associated with native mazEF. - node_id: mazef_system_trait label: MazEF system node_type: TRAIT grounding: traitmech:000345 description: Possession of a genome-encoded MazEF toxin-antitoxin 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: mazef_locus predicate: contributes to predicate_id: RO:0002326 object: rna_phage_replication_interference description: Native mazEF contributes to reduced Escherichia coli susceptibility to the MS2 and Qbeta RNA phages. evidence: - reference: PMID:40494395 snippet: the native presence of mazEF moderately reduced population susceptibility notes: Nikolic et al. connect native mazEF presence to reduced RNA phage susceptibility. - reference: https://pmc.ncbi.nlm.nih.gov/articles/PMC12151602/ snippet: MazEF interferes with RNA phage replication within already infected cells notes: Nikolic et al. distinguish MazEF-mediated intracellular interference from blocked RNA phage adsorption. - subject: rna_phage_replication_interference predicate: confers predicate_id: METPO:2007700 object: mazef_system_trait description: MazEF-associated reduction of RNA phage susceptibility realizes the MazEF system trait. evidence: - reference: PMID:40494395 snippet: RNA-degrading toxin-antitoxin systems may also help defend against RNA phages notes: Nikolic et al. frame the MazEF result as support for RNA-degrading toxin-antitoxin systems as RNA phage defense elements. - subject: mazef_system_trait predicate: is a predicate_id: rdfs:subClassOf object: phage_defense_system description: MazEF system possession is a phage-defense-system trait. evidence: - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/List_system_article.md snippet: MazEF | 10\.1098/rsbl\.2025\.0080 | A bacterial toxin-antitoxin system as a native defence element against RNA phages notes: DefenseFinder associates MazEF with the Nikolic et al. RNA-phage defense paper. - reference: https://raw.githubusercontent.com/mdmparis/defense-finder-models/afb0e5a8b466be53586b13266f5d38d98c3ac268/DefenseFinder_rules.tsv snippet: "MazEF\tMazEF\t2\t2\tMazEF__MazE, MazEF__MazF" notes: The DefenseFinder rules table models MazEF as a two-profile system requiring MazE and MazF profiles. discussions: - discussion_id: mazef-activation-breadth-gap prompt: Resolve MazEF activation, direct MazF RNA targets, and RNA- versus DNA-phage breadth before minting narrower MazEF mechanism children. kind: KNOWLEDGE_GAP status: OPEN rationale: Nikolic et al. support native MazEF protection against RNA phages and argue that direct interference predominates in those assays, but the phage-induced route to active MazF, the relative contributions of phage-RNA cleavage and host-RNA degradation, the breadth of MazEF DNA-phage defense, and the DefenseFinder MazEF model boundaries remain unresolved. attaches_to: - causal_graphs#mazef_rna_phage_defense posed_by: codex posed_date: '2026-09-21' curation_history: - timestamp: '2026-09-21T21:03:46Z' curator: codex action: MINTED_TRAITMECH_ID changes: Minted MazEF 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_v222. llm_assisted: true