identifier: traitmech:000243
label: DarTG system
definition: A phage defense system in which an organism possesses a DarTG toxin-antitoxin
  locus whose DarT toxin can be released during bacteriophage infection to ADP-ribosylate
  viral DNA, block phage genome replication, and prevent production of mature virions.
definition_source: DOI:10.1038/s41564-022-01153-5
trait_category: GENOMICS
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- traitmech:000209
synonyms:
- synonym_text: DarTG toxin-antitoxin system
  synonym_type: EXACT_SYNONYM
  source: DOI:10.1038/s41564-022-01153-5
evidence:
- reference: DOI:10.1038/s41564-022-01153-5
  snippet: Representatives from two different subfamilies, DarTG1 and DarTG2, strongly
    protected E. coli MG1655 against different phages.
  notes: LeRoux et al. support DarTG as a two-subfamily phage-defense system with
    experimental activity in E. coli MG1655 challenge assays.
- reference: DOI:10.1038/s41564-022-01153-5
  snippet: infection with either RB69 or T5 phage, respectively, triggers release
    of the DarT toxin, a DNA ADP-ribosyltransferase, that then modifies viral DNA
    and prevents replication, thereby blocking the production of mature virions
  notes: LeRoux et al. support the DarT release, viral-DNA ADP-ribosylation, phage-genome-replication
    blockade, and mature-virion-production blockade captured in the causal graph.
- reference: DOI:10.1038/s41564-022-01153-5
  snippet: Collectively, our results indicate that phage defence may be a common function
    for TA systems and reveal the mechanism by which DarTG systems inhibit phage infection.
  notes: LeRoux et al. support DarTG as an experimentally resolved toxin-antitoxin
    phage-defense system.
- reference: DOI:10.1128/mbio.00111-24
  snippet: we identify clinical isolates of the global pathogen Vibrio cholerae harboring
    a novel genetic element encoding the bacterial immune system DarTG and reveal
    the immune system's impact on the co-circulating lytic phage ICP1.
  notes: Patel and Seed independently support DarTG as a bacterial immune system in
    V. cholerae clinical isolates and connect the system to defense against ICP1 phage.
- reference: DOI:10.1128/mbio.00111-24
  snippet: We show that DarTG inhibits ICP1 genome replication, thus preventing ICP1
    plaquing.
  notes: Patel and Seed support phage-genome-replication blockade as an output of
    the V. cholerae DarTG system.
- reference: DOI:10.1128/mbio.00111-24
  snippet: we probe clinical V. cholerae isolates for novel anti-phage immune systems
    that can inhibit ICP1 and discover the toxin-antitoxin system DarTG as a potent
    inhibitor.
  notes: Patel and Seed support the DarTG toxin-antitoxin system as a potent inhibitor
    of the co-circulating phage ICP1.
canonical_examples:
- taxon_id: NCBITaxon:666
  taxon_label: Vibrio cholerae
  note: Patel and Seed characterized a phage defense element encoding DarTG in 2008-2009
    clinical V. cholerae isolates and showed DarTG was responsible for ICP1 inhibition.
  reference: DOI:10.1128/mbio.00111-24
causal_graphs:
- graph_id: dartg_dna_adp_ribosylation_defense
  title: DarTG loci couple phage infection to viral-DNA ADP-ribosylation
  description: Evidence-backed process sketch linking sensitive phage infection to
    DarT toxin release, viral DNA ADP-ribosylation, inhibition of phage genome replication,
    restricted phage propagation, and the DarTG system trait.
  scope_status: NONMECHANISTIC
  scope_notes: The graph captures LeRoux and Patel DarTG phage-defense evidence without
    claiming a universal phage trigger, DarT release mechanism, viral target scope,
    or phage-encoded anti-DarT factor across all DarTG systems.
  nodes:
  - node_id: sensitive_phage_infection
    label: sensitive phage infection
    node_type: BIOLOGICAL_PROCESS
    description: Infection by a phage whose propagation can be inhibited by an active
      DarTG system.
  - node_id: darT_toxin_release
    label: DarT toxin release
    node_type: BIOLOGICAL_PROCESS
    description: Release of the DNA ADP-ribosyltransferase DarT toxin from inhibition
      during phage infection.
  - node_id: viral_dna_adp_ribosylation
    label: viral DNA ADP-ribosylation
    node_type: BIOLOGICAL_PROCESS
    description: DarT-mediated ADP-ribosylation of bacteriophage DNA after DarT is
      released from antitoxin control.
  - node_id: inhibited_phage_genome_replication
    label: inhibited phage genome replication
    node_type: STATE
    description: Reduced or blocked replication of the infecting phage genome downstream
      of DarT activity.
  - node_id: restricted_phage_propagation
    label: restricted phage propagation
    node_type: BIOLOGICAL_PROCESS
    description: Blocked mature-virion production or plaquing after DarTG inhibits
      the infecting phage.
  - node_id: dartg_system_trait
    label: DarTG system
    node_type: TRAIT
    grounding: traitmech:000243
    description: Possession of a genome-encoded DarTG 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: sensitive_phage_infection
    predicate: triggers
    object: darT_toxin_release
    description: Infection by RB69 or T5 phage triggers release of the DarT toxin
      in the tested DarTG subfamily systems.
    evidence:
    - reference: DOI:10.1038/s41564-022-01153-5
      snippet: infection with either RB69 or T5 phage, respectively, triggers release
        of the DarT toxin
      notes: LeRoux et al. identify phage infection as the upstream trigger for DarT
        toxin release.
  - subject: darT_toxin_release
    predicate: contributes to
    predicate_id: RO:0002326
    object: viral_dna_adp_ribosylation
    description: Released DarT ADP-ribosylates viral DNA after phage infection.
    evidence:
    - reference: DOI:10.1038/s41564-022-01153-5
      snippet: triggers release of the DarT toxin, a DNA ADP-ribosyltransferase, that
        then modifies viral DNA
      notes: LeRoux et al. support DarT release leading to viral-DNA ADP-ribosylation.
  - subject: viral_dna_adp_ribosylation
    predicate: contributes to
    predicate_id: RO:0002326
    object: inhibited_phage_genome_replication
    description: DarT-dependent viral-DNA modification blocks replication of the infecting
      phage genome.
    evidence:
    - reference: DOI:10.1038/s41564-022-01153-5
      snippet: then modifies viral DNA and prevents replication, thereby blocking
        the production of mature virions
      notes: LeRoux et al. directly connect viral-DNA modification to blocked phage
        replication.
    - reference: DOI:10.1128/mbio.00111-24
      snippet: We show that DarTG inhibits ICP1 genome replication, thus preventing
        ICP1 plaquing.
      notes: Patel and Seed show that V. cholerae DarTG also blocks ICP1 genome replication.
  - subject: inhibited_phage_genome_replication
    predicate: contributes to
    predicate_id: RO:0002326
    object: restricted_phage_propagation
    description: Inhibition of genome replication restricts mature virion production
      and phage plaquing.
    evidence:
    - reference: DOI:10.1038/s41564-022-01153-5
      snippet: prevents replication, thereby blocking the production of mature virions
      notes: LeRoux et al. support mature-virion blockade as a downstream effect of
        blocked phage replication.
    - reference: DOI:10.1128/mbio.00111-24
      snippet: DarTG inhibits ICP1 genome replication, thus preventing ICP1 plaquing
      notes: Patel and Seed support plaquing prevention as a downstream effect of
        ICP1 genome-replication blockade.
  - subject: restricted_phage_propagation
    predicate: confers
    predicate_id: METPO:2007700
    object: dartg_system_trait
    description: The DarTG system trait is realized by inhibition of phage replication
      and propagation.
    evidence:
    - reference: DOI:10.1038/s41564-022-01153-5
      snippet: reveal the mechanism by which DarTG systems inhibit phage infection
      notes: LeRoux et al. place the DNA ADP-ribosylation mechanism in the broader
        DarTG phage-infection-inhibition trait.
  - subject: dartg_system_trait
    predicate: is a
    predicate_id: rdfs:subClassOf
    object: phage_defense_system
    description: DarTG system possession is a phage-defense-system trait.
    evidence:
    - reference: DOI:10.1128/mbio.00111-24
      snippet: we probe clinical V. cholerae isolates for novel anti-phage immune
        systems that can inhibit ICP1 and discover the toxin-antitoxin system DarTG
        as a potent inhibitor.
      notes: Patel and Seed support DarTG as an anti-phage immune system.
curation_history:
- timestamp: '2026-09-18T14:18:08Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: Minted DarTG 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_v120.
  llm_assisted: true