identifier: traitmech:000007
label: radiotolerant
definition: An environmental tolerance in which an organism survives doses of ionizing
  and/or ultraviolet radiation that are lethal to most microorganisms, typically via
  efficient DNA repair and oxidative-damage protection.
definition_source: DOI:10.1101/cshperspect.a012765
trait_category: ENVIRONMENT
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000059
synonyms:
- synonym_text: radioresistant
  synonym_type: RELATED_SYNONYM
  source: DOI:10.1101/cshperspect.a012765
evidence:
- reference: DOI:10.1101/cshperspect.a012765
  snippet: A strong correlation has been shown between intracellular Mn/Fe concentration
    ratios and bacterial resistance to radiation
  notes: Review of extreme radiation resistance supports manganese-antioxidant protection
    of the proteome as a core radiotolerance mechanism in Deinococcus radiodurans,
    "a champion of extreme radiation resistance".
- reference: DOI:10.3390/genes14091803
  snippet: Deinococcus radiodurans, a Gram-positive extremophilic bacterium, is a
    remarkable example of such an organism, showcasing an impressive resistance to
    a wide array of stressors, including ionizing radiation, desiccation, UV radiation,
    and oxidizing agents
  notes: 'Organism example: Deinococcus radiodurans tolerates ionizing radiation,
    UV radiation, and desiccation.'
canonical_examples:
- taxon_id: NCBITaxon:1299
  taxon_label: Deinococcus radiodurans
  note: "Most radiation-resistant model organism; survives >15 kGy acute gamma (type strain R1)."
  reference: https://pubmed.ncbi.nlm.nih.gov/11238985/
causal_graphs:
- graph_id: radiotolerance_repair_antioxidant
  title: Radiotolerance via DNA repair and Mn-antioxidant proteome protection
  description: Evidence-backed causal sketch linking efficient DNA-damage repair and
    manganese-antioxidant protection to survival of lethal radiation doses.
  nodes:
  - node_id: radiotolerant_trait
    label: radiotolerant
    node_type: TRAIT
    grounding: traitmech:000007
    description: Survival of ionizing and/or UV radiation doses lethal to most microbes.
  - node_id: radiation_exposure
    label: ionizing or UV radiation exposure
    node_type: ENVIRONMENTAL_FACTOR
    description: High dose of ionizing or ultraviolet radiation.
  - node_id: dna_damage_repair
    label: DNA repair
    node_type: BIOLOGICAL_PROCESS
    grounding: GO:0006281
    description: Repair of radiation-induced DNA lesions (double-strand breaks, adducts,
      dimers).
  - node_id: mn_antioxidant_protection
    label: manganese-antioxidant proteome protection
    node_type: BIOLOGICAL_PROCESS
    description: Mn-driven protection of repair proteins from oxidative damage.
  - node_id: reactive_oxygen_species
    label: reactive oxygen species (ROS)
    node_type: CHEMICAL
    description: Reactive oxygen species generated as an aftermath of irradiation
      that damage DNA and proteins.
  - node_id: mn2_ion
    label: manganese(II) ion
    node_type: CHEMICAL
    description: Intracellular Mn2+ that acts as an antioxidant scavenging ROS.
  - node_id: fe2_ion
    label: iron(II) ion
    node_type: CHEMICAL
    description: Intracellular Fe2+ that propagates ROS through Fenton chemistry.
  - node_id: reca_protein
    label: RecA recombinase
    node_type: GENE_OR_PROTEIN
    description: RecA recombinase central to homologous-recombination repair of radiation-induced
      double-strand breaks.
  - node_id: homologous_recombination
    label: homologous recombination
    node_type: BIOLOGICAL_PROCESS
    description: Homologous recombination repair of DNA double-strand breaks.
    grounding: GO:0035825
  - node_id: ner_uvrabc
    label: nucleotide excision repair (UvrABC)
    node_type: BIOLOGICAL_PROCESS
    description: UvrABC excinuclease-mediated nucleotide excision repair of UV-induced
      helix-distorting lesions.
  - node_id: carotenoid_pigments
    label: carotenoid pigments
    node_type: CHEMICAL
    description: Carotenoid pigments (e.g. deinoxanthin) that scavenge ROS as non-enzymatic
      antioxidants.
  edges:
  - subject: radiation_exposure
    predicate: challenges
    object: radiotolerant_trait
    description: Radiation exposure is the environmental challenge the trait counters.
    evidence:
    - reference: DOI:10.3390/genes14091803
      notes: Deinococcus radiodurans is the reference organism for surviving ionizing
        radiation, UV, desiccation, and oxidizing agents.
    predicate_id: METPO:2007406
  - subject: dna_damage_repair
    predicate: enables
    object: radiotolerant_trait
    description: Efficient repair of radiation-induced DNA lesions enables survival.
    evidence:
    - reference: DOI:10.1101/cshperspect.a012765
      notes: Review of extreme radiation resistance highlights efficient DNA repair
        as a core radiotolerance mechanism.
    predicate_id: RO:0002327
  - subject: mn_antioxidant_protection
    predicate: enables
    object: radiotolerant_trait
    description: Mn-antioxidant protection of the proteome preserves repair capacity
      under irradiation.
    evidence:
    - reference: DOI:10.1101/cshperspect.a012765
      notes: Intracellular Mn/Fe ratio correlates with bacterial radiation resistance.
    predicate_id: RO:0002327
  - subject: radiation_exposure
    predicate: causes
    object: reactive_oxygen_species
    description: Ionizing/UV radiation produces reactive oxygen species.
    evidence:
    - reference: DOI:10.1371/journal.pone.0304810
      notes: Another aftermath of irradiation is the production of reactive oxygen
        species (ROS); general mechanism across microbes.
    predicate_id: biolink:causes
  - subject: mn2_ion
    predicate: acts as antioxidant against
    object: reactive_oxygen_species
    description: Mn2+ acts as an antioxidant that scavenges ROS.
    evidence:
    - reference: DOI:10.1128/spectrum.03838-23
      notes: Manganese is an antioxidant, acting as a sponge of ROS; general bacterial
        mechanism.
  - subject: fe2_ion
    predicate: promotes
    object: reactive_oxygen_species
    description: Fe2+ furthers the spread of ROS through Fenton chemistry.
    evidence:
    - reference: DOI:10.1128/spectrum.03838-23
      notes: Iron furthers the spread of ROS through Fenton chemistry; mechanistic
        basis of Mn/Fe ratio association with tolerance.
    predicate_id: RO:0002213
  - subject: mn2_ion
    predicate: part of
    object: mn_antioxidant_protection
    description: Mn2+ antioxidant activity is part of the Mn-antioxidant proteome
      protection process.
    evidence:
    - reference: DOI:10.1128/spectrum.03838-23
      notes: Intracellular Mn/Fe ratio is the best-understood predictor of IR tolerance;
        Mn acts as a ROS sponge protecting the proteome.
    predicate_id: biolink:part_of
  - subject: reca_protein
    predicate: mediates
    object: homologous_recombination
    description: RecA mediates homologous recombination repair of double-strand breaks.
    evidence:
    - reference: DOI:10.3390/su17177864
      notes: HR is central for double-strand break repair, with RecA abundant and
        RecA expression increasing eightfold after 15 kGy.
  - subject: homologous_recombination
    predicate: part of
    object: dna_damage_repair
    description: Homologous recombination is a component of radiation-induced DNA
      repair.
    evidence:
    - reference: DOI:10.3390/su17177864
      notes: HR is central for double-strand break repair of radiation-induced lesions.
    predicate_id: biolink:part_of
  - subject: ner_uvrabc
    predicate: part of
    object: dna_damage_repair
    description: UvrABC nucleotide excision repair repairs UV-induced helix-distorting
      lesions.
    evidence:
    - reference: DOI:10.3390/genes14091803
      notes: UvrA is the initial damage sensor in NER, recruiting UvrB and, with UvrC,
        performing dual-incision to remove UV-induced damaged DNA.
    predicate_id: biolink:part_of
  - subject: carotenoid_pigments
    predicate: scavenges
    object: reactive_oxygen_species
    description: Carotenoid pigments scavenge ROS as non-enzymatic antioxidants.
    evidence:
    - reference: DOI:10.3390/su17177864
      notes: The carotenoid deinoxanthin scavenges ROS quantitatively (removed up
        to 69.7% H2O2 and quenched singlet oxygen up to 99%).
curation_history:
- timestamp: '2026-05-28T00:00:00Z'
  curator: claude
  action: PROPOSED_FROM_RESEARCH
  changes: Proposed candidate ENVIRONMENT trait (general radiation tolerance) from
    literature research to fill the radiation-tolerance coverage gap. Parent of the
    ionizing- and UV-specific sub-variants.
  llm_assisted: true
- timestamp: '2026-06-09T14:00:00Z'
  curator: claude
  action: CURATED_CAUSAL_GRAPH
  changes: Added evidence-backed causal graph (radiotolerance via DNA repair + Mn-antioxidant)
    with GO node grounding and RO/METPO predicate groundings; promoted PROPOSED to
    REVIEWED.
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 8 evidence-backed generic edges (7 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:11Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 5 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (biolink:part_of×3, biolink:causes×1, RO:0002213×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:31Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (GO:0035825×1).
  llm_assisted: true