identifier: traitmech:000242 label: Hailong system definition: A phage defense system in which an organism possesses a Hailong locus encoding a HalB NTase DNA-signal enzyme and a HalA membrane effector complex that can be held inactive by HalB-derived oligodeoxyadenylate until viral DNA exonucleases release the primed HalA complex and induce protective host cell growth arrest. definition_source: DOI:10.1038/s41586-025-09058-z trait_category: GENOMICS term_kind: CLASS mapping_status: PROPOSED parent_traits: - traitmech:000209 synonyms: - synonym_text: Hailong anti-phage system synonym_type: EXACT_SYNONYM source: DOI:10.1016/j.molcel.2025.06.011 evidence: - reference: DOI:10.1038/s41586-025-09058-z snippet: Here we discover a family of bacterial defence systems, which we name Hailong, that use NTase enzymes to constitutively synthesize DNA signals and guard against phage infection notes: Tan et al. support Hailong as a named NTase-linked bacterial phage-defense family. - reference: DOI:10.1038/s41586-025-09058-z snippet: Hailong is a two-gene operon that encodes Hailong protein A (HalA), a transmembrane protein of unknown function, and Hailong protein B (HalB), the predicted NTase enzyme notes: Tan et al. support curating the two core Hailong genes as a complete locus rather than as separate HalA or HalB protein traits. - reference: DOI:10.1038/s41586-025-09058-z snippet: Hailong operons are widely conserved in defence islands across >70 genera of gram-positive and gram-negative bacteria notes: Tan et al. support placing Hailong at a bacterial system level rather than curating only the assayed plasmid or species instances. - reference: DOI:10.1038/s41586-025-09058-z snippet: Hailong protein B (HalB) is an NTase that converts deoxy-ATP into single-stranded DNA oligomers notes: Tan et al. identify the HalB NTase signal-synthesis reaction inside the Hailong system. - reference: DOI:10.1038/s41586-025-09058-z snippet: We show that HalB DNA signals bind to and repress activation of a partnering Hailong protein A (HalA) effector complex notes: Tan et al. support repression of the HalA effector complex by HalB-derived DNA signals. - reference: DOI:10.1038/s41586-025-09058-z snippet: viral DNA exonucleases required for phage replication trigger release of the primed HalA complex and induce protective host cell growth arrest notes: Tan et al. support the phage-exonuclease trigger and growth-arrest output captured in the Hailong graph. - reference: DOI:10.1016/j.molcel.2025.06.011 snippet: the bacterial Hailong anti-phage system, in which constitutively synthesized DNA oligonucleotides inhibit a toxic ion channel-a molecular booby trap primed for activation by phage exonucleases notes: Kuehn and Pinilla-Redondo summarize Hailong as a bacterial anti-phage system gated by constitutive inhibitory DNA oligonucleotide signals. canonical_examples: - taxon_id: NCBITaxon:562 taxon_label: Escherichia coli note: Tan et al. showed that an Escherichia coli STEC 1178 Hailong system gave more than 10,000-fold protection against dsDNA phages in E. coli challenge assays. reference: DOI:10.1038/s41586-025-09058-z causal_graphs: - graph_id: hailong_dna_gated_growth_arrest title: Hailong DNA-signal gating couples phage exonuclease challenge to growth arrest description: Evidence-backed process sketch linking a Hailong locus to HalB oligodeoxyadenylate signal synthesis, HalA effector repression, viral DNA exonuclease challenge, HalA channel activation, and host cell growth arrest. scope_status: NONMECHANISTIC scope_notes: The graph captures Tan et al. Hailong oligodeoxyadenylate-gated phage-exonuclease-response evidence without asserting one universal ODA-transfer mechanism, phage trigger, HalA ion specificity, ancillary gene architecture, or host-processing factor across all Hailong homologs. nodes: - node_id: hailong_locus label: Hailong locus node_type: GENETIC_ELEMENT description: A Hailong phage-defense locus encoding a HalA membrane effector and a HalB NTase signal enzyme. - node_id: oda_signal_synthesis label: oligodeoxyadenylate signal synthesis node_type: BIOLOGICAL_PROCESS description: Constitutive synthesis of single-stranded DNA oligodeoxyadenylate signals by the Hailong HalB NTase. - node_id: hala_oda_repressed_complex label: HalA-oligodeoxyadenylate repressed complex node_type: STATE description: A primed, repressed HalA effector complex bound to HalB-derived oligodeoxyadenylate. - node_id: phage_exonuclease_challenge label: phage exonuclease challenge node_type: BIOLOGICAL_PROCESS description: Viral DNA exonuclease activity encountered during phage replication that degrades the Hailong inhibitory DNA signal. - node_id: hala_channel_activation label: HalA channel activation node_type: MOLECULAR_FUNCTION description: Release of Hailong HalA ion-channel effector function after inhibitory oligodeoxyadenylate is removed. - node_id: host_cell_growth_arrest label: host cell growth arrest node_type: STATE description: Protective arrest of host-cell growth downstream of Hailong HalA effector activation. - node_id: hailong_system_trait label: Hailong system node_type: TRAIT grounding: traitmech:000242 description: Possession of a genome-encoded Hailong 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: hailong_locus predicate: contributes to predicate_id: RO:0002326 object: oda_signal_synthesis description: The Hailong locus encodes HalB, an NTase that constitutively synthesizes oligodeoxyadenylate DNA signals. evidence: - reference: DOI:10.1038/s41586-025-09058-z snippet: Hailong protein B (HalB) is an NTase that converts deoxy-ATP into single-stranded DNA oligomers notes: Tan et al. identify HalB as the DNA-signal-synthesizing Hailong NTase. - subject: oda_signal_synthesis predicate: contributes to predicate_id: RO:0002326 object: hala_oda_repressed_complex description: HalB-derived DNA signals bind the HalA effector complex and hold the complex in a primed, repressed state before phage infection. evidence: - reference: DOI:10.1038/s41586-025-09058-z snippet: We show that HalB DNA signals bind to and repress activation of a partnering Hailong protein A (HalA) effector complex notes: Tan et al. support formation of a repressed HalA effector complex by HalB-derived DNA signals. - subject: hala_oda_repressed_complex predicate: negatively regulates predicate_id: RO:0002212 object: hala_channel_activation description: Oligodeoxyadenylate binding negatively regulates HalA channel function by locking the membrane effector in an inactive state. evidence: - reference: DOI:10.1038/s41586-025-09058-z snippet: These results support that ODA-binding negatively regulates HalA channel function notes: Tan et al. directly support negative regulation of HalA channel function by ODA binding. - subject: phage_exonuclease_challenge predicate: activates predicate_id: RO:0002213 object: hala_channel_activation description: Viral DNA exonucleases degrade the inhibitory Hailong signal and trigger release of the primed HalA effector complex. evidence: - reference: DOI:10.1038/s41586-025-09058-z snippet: viral DNA exonucleases required for phage replication trigger release of the primed HalA complex notes: Tan et al. support viral DNA exonucleases as triggers for release of primed HalA. - subject: hala_channel_activation predicate: contributes to predicate_id: RO:0002326 object: host_cell_growth_arrest description: Release of HalA channel effector function links phage exonuclease sensing to protective host cell growth arrest. evidence: - reference: DOI:10.1038/s41586-025-09058-z snippet: viral DNA replication enzymes that degrade ODA and trigger release of HalA ion channel effector function notes: Tan et al. connect ODA degradation to release of HalA ion-channel effector function. - reference: DOI:10.1038/s41586-025-09058-z snippet: viral DNA exonucleases required for phage replication trigger release of the primed HalA complex and induce protective host cell growth arrest notes: Tan et al. support host cell growth arrest as a protective Hailong output after phage-exonuclease challenge. - subject: host_cell_growth_arrest predicate: confers predicate_id: METPO:2007700 object: hailong_system_trait description: Hailong-mediated host growth arrest is the phage-defense output that realizes the Hailong system trait. evidence: - reference: DOI:10.1038/s41586-025-09058-z snippet: Hailong from the bacterium E. coli STEC 1178 providing >10,000-fold protection against dsDNA phages notes: Tan et al. support Hailong-mediated growth arrest as part of a plasmid-borne system that protects E. coli against phage infection. - subject: hailong_system_trait predicate: is a predicate_id: rdfs:subClassOf object: phage_defense_system description: Hailong system possession is a phage-defense-system trait. evidence: - reference: DOI:10.1038/s41586-025-09058-z snippet: Here we discover a family of bacterial defence systems, which we name Hailong notes: Tan et al. place Hailong in the bacterial phage-defense system family. discussions: - discussion_id: hailong-mechanism-and-family-breadth-gap prompt: Resolve Hailong ODA transfer, phage-trigger breadth, HalA ion specificity, and family architecture before minting narrower Hailong mechanism children. kind: KNOWLEDGE_GAP status: OPEN rationale: Tan et al. support HalB oligodeoxyadenylate synthesis, HalA repression by inhibitory DNA signals, and viral DNA-exonuclease-triggered release of HalA effector function, but Hailong homologs need separate review before TraitMech asserts one complete ODA-transfer pathway, phage nuclease trigger, HalA ion selectivity, host-processing factor, or ancillary-gene architecture across the full Hailong family. posed_by: codex posed_date: '2026-09-18' curation_history: - timestamp: '2026-09-18T13:27:00Z' curator: codex action: MINTED_TRAITMECH_ID changes: Minted Hailong system as a DOI-backed GENOMICS TraitRecord under the phage defense system parent 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_v119. llm_assisted: true