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Hailong system

traitmech:000242 · CLASS · PROPOSED

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.

Trait evidence (7)

  • DOI:10.1038/s41586-025-09058-z
    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

    Tan et al. support Hailong as a named NTase-linked bacterial phage-defense family.

  • DOI:10.1038/s41586-025-09058-z
    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

    Tan et al. support curating the two core Hailong genes as a complete locus rather than as separate HalA or HalB protein traits.

  • DOI:10.1038/s41586-025-09058-z
    Hailong operons are widely conserved in defence islands across >70 genera of gram-positive and gram-negative bacteria

    Tan et al. support placing Hailong at a bacterial system level rather than curating only the assayed plasmid or species instances.

  • DOI:10.1038/s41586-025-09058-z
    Hailong protein B (HalB) is an NTase that converts deoxy-ATP into single-stranded DNA oligomers

    Tan et al. identify the HalB NTase signal-synthesis reaction inside the Hailong system.

  • DOI:10.1038/s41586-025-09058-z
    We show that HalB DNA signals bind to and repress activation of a partnering Hailong protein A (HalA) effector complex

    Tan et al. support repression of the HalA effector complex by HalB-derived DNA signals.

  • DOI:10.1038/s41586-025-09058-z
    viral DNA exonucleases required for phage replication trigger release of the primed HalA complex and induce protective host cell growth arrest

    Tan et al. support the phage-exonuclease trigger and growth-arrest output captured in the Hailong graph.

  • DOI:10.1016/j.molcel.2025.06.011
    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

    Kuehn and Pinilla-Redondo summarize Hailong as a bacterial anti-phage system gated by constitutive inhibitory DNA oligonucleotide signals.

Hailong DNA-signal gating couples phage exonuclease challenge to growth arrest

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.

NONMECHANISTIC · 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.

Hailong DNA-signal gating couples phage exonuclease challenge to growth arrest Interactive directed graph showing evidence-backed causal relationships for Hailong system.

Edge evidence

  • Hailong locus contributes to oligodeoxyadenylate signal synthesis RO:0002326

    The Hailong locus encodes HalB, an NTase that constitutively synthesizes oligodeoxyadenylate DNA signals.

    • DOI:10.1038/s41586-025-09058-z Hailong protein B (HalB) is an NTase that converts deoxy-ATP into single-stranded DNA oligomers Tan et al. identify HalB as the DNA-signal-synthesizing Hailong NTase.
  • oligodeoxyadenylate signal synthesis contributes to HalA-oligodeoxyadenylate repressed complex RO:0002326

    HalB-derived DNA signals bind the HalA effector complex and hold the complex in a primed, repressed state before phage infection.

    • DOI:10.1038/s41586-025-09058-z We show that HalB DNA signals bind to and repress activation of a partnering Hailong protein A (HalA) effector complex Tan et al. support formation of a repressed HalA effector complex by HalB-derived DNA signals.
  • HalA-oligodeoxyadenylate repressed complex negatively regulates HalA channel activation RO:0002212

    Oligodeoxyadenylate binding negatively regulates HalA channel function by locking the membrane effector in an inactive state.

    • DOI:10.1038/s41586-025-09058-z These results support that ODA-binding negatively regulates HalA channel function Tan et al. directly support negative regulation of HalA channel function by ODA binding.
  • phage exonuclease challenge activates HalA channel activation RO:0002213

    Viral DNA exonucleases degrade the inhibitory Hailong signal and trigger release of the primed HalA effector complex.

    • DOI:10.1038/s41586-025-09058-z viral DNA exonucleases required for phage replication trigger release of the primed HalA complex Tan et al. support viral DNA exonucleases as triggers for release of primed HalA.
  • HalA channel activation contributes to host cell growth arrest RO:0002326

    Release of HalA channel effector function links phage exonuclease sensing to protective host cell growth arrest.

    • DOI:10.1038/s41586-025-09058-z viral DNA replication enzymes that degrade ODA and trigger release of HalA ion channel effector function Tan et al. connect ODA degradation to release of HalA ion-channel effector function.
    • DOI:10.1038/s41586-025-09058-z viral DNA exonucleases required for phage replication trigger release of the primed HalA complex and induce protective host cell growth arrest Tan et al. support host cell growth arrest as a protective Hailong output after phage-exonuclease challenge.
  • host cell growth arrest confers Hailong system METPO:2007700

    Hailong-mediated host growth arrest is the phage-defense output that realizes the Hailong system trait.

    • DOI:10.1038/s41586-025-09058-z Hailong from the bacterium E. coli STEC 1178 providing >10,000-fold protection against dsDNA phages Tan et al. support Hailong-mediated growth arrest as part of a plasmid-borne system that protects E. coli against phage infection.
  • Hailong system is a phage defense system rdfs:subClassOf

    Hailong system possession is a phage-defense-system trait.

    • DOI:10.1038/s41586-025-09058-z Here we discover a family of bacterial defence systems, which we name Hailong Tan et al. place Hailong in the bacterial phage-defense system family.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1038/s41586-025-09058-z

Parent traits (1)

Synonyms (1)

  • Hailong anti-phage system EXACT_SYNONYM · DOI:10.1016/j.molcel.2025.06.011

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

Canonical examples (1)

Organisms cited as exemplars of this trait. Taxon ids are NCBITaxon and link out to the NCBI record.

  • Escherichia coli NCBITaxon:562 DOI:10.1038/s41586-025-09058-z 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.

Discussions and Knowledge Gaps (1)

Open questions attached to this trait. Seeded by just knowledge-gap-scan and curated; see the corpus-wide index.

Resolve Hailong ODA transfer, phage-trigger breadth, HalA ion specificity, and family architecture before minting narrower Hailong mechanism children.

KNOWLEDGE GAP OPEN hailong-mechanism-and-family-breadth-gap · raised by codex · 2026-09-18

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

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.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    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.