identifier: METPO:1000617
label: hyperthermophilic
definition: A temperature preference in which growth is favored at very high temperatures,
  typically ≥80 °C.
definition_source: DOI:10.1111/j.1574-6976.1996.tb00233.x
trait_category: ENVIRONMENT
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000613
synonyms:
- synonym_text: extreme thermophilic
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
evidence:
- reference: DOI:10.1111/j.1574-6976.1996.tb00233.x
  snippet: optimal growth temperatures between 80°C and 110°C
  notes: Supports hyperthermophile growth at very high temperatures.
- reference: PMID:9348040
  snippet: hyperthermophilic archaeon, Pyrococcus furiosus
  notes: 'Organism example: Pyrococcus furiosus is described as hyperthermophilic.'
canonical_examples:
- taxon_id: NCBITaxon:2261
  taxon_label: Pyrococcus furiosus
  note: "Model hyperthermophilic archaeon (growth optimum ~100 C)."
  reference: DOI:10.1007/BF00413027
causal_graphs:
- graph_id: hyperthermophilic_thermostability
  title: Hyperthermophilic thermostability mechanism
  description: Evidence-backed causal sketch linking hyperthermophily to very high
    temperature, thermostable enzymes, reverse gyrase, archaeal chaperonins, and membrane
    adaptation.
  nodes:
  - node_id: hyperthermophilic_trait
    label: hyperthermophilic
    node_type: TRAIT
    grounding: METPO:1000617
    description: Growth is favored at very high temperatures, typically at or above
      80 degrees C.
  - node_id: very_high_temperature
    label: very high temperature
    node_type: ENVIRONMENTAL_FACTOR
    description: Growth condition around 80 degrees C or hotter.
    grounding: PATO:0001305
  - node_id: thermostable_enzymes
    label: thermostable enzymes
    node_type: GENE_OR_PROTEIN
    description: Enzymes resistant to irreversible inactivation at high temperatures.
  - node_id: reverse_gyrase
    label: reverse gyrase
    node_type: GENE_OR_PROTEIN
    description: Topoisomerase associated with hyperthermophiles and positive DNA
      supercoiling.
    grounding: UniProtKB:A0A088E825
  - node_id: molecular_chaperonins
    label: archaeal molecular chaperonins
    node_type: GENE_OR_PROTEIN
    description: Protein-folding systems in hyperthermophilic archaea.
  - node_id: membrane_lipid_composition
    label: membrane lipid composition
    node_type: CELLULAR_LOCALIZATION
    description: Membrane lipid features supporting stability at very high temperature.
  - node_id: cdpg
    label: cyclic 2,3-diphosphoglycerate (cDPG)
    node_type: CHEMICAL
    description: Extremolyte/compatible solute found in hyperthermophilic archaea
      that confers thermoprotection.
  - node_id: archaeal_proteins
    label: archaeal proteins
    node_type: GENE_OR_PROTEIN
    description: Cellular proteins whose thermostability is enhanced by protective
      solutes.
  - node_id: dna_oxidative_damage
    label: DNA oxidative damage by hydroxyl radicals
    node_type: BIOLOGICAL_PROCESS
    description: Oxidative damage to DNA caused by hydroxyl radicals under high-temperature
      stress.
  - node_id: gmgt_lipids
    label: glycerol monoalkyl glycerol tetraether (GMGT) lipids
    node_type: CHEMICAL
    description: Cross-linked tetraether membrane lipids whose abundance increases
      at high growth temperature.
  - node_id: gms_synthase
    label: Gms (GMGT synthase)
    node_type: GENE_OR_PROTEIN
    description: Enzyme required to form the bridging cross-link of GMGT lipids.
  - node_id: membrane_rigidity
    label: membrane rigidity at high temperature
    node_type: QUALITY
    description: Increased rigidity/reduced fluidity of the membrane supporting stability
      at high temperature.
  - node_id: macrocyclic_archaeol
    label: macrocyclic archaeol
    node_type: CHEMICAL
    description: Macrocyclized archaeal membrane lipid that increases membrane stability
      and rigidity.
    grounding: CHEBI:193595
  edges:
  - subject: very_high_temperature
    predicate: selects for
    object: hyperthermophilic_trait
    description: Very high-temperature environments select for hyperthermophilic growth
      capacity.
    evidence:
    - reference: DOI:10.1111/j.1574-6976.1996.tb00233.x
      snippet: optimal growth temperatures between 80°C and 110°C
      notes: Review supports hyperthermophile growth temperature range.
    predicate_id: METPO:2007401
  - subject: thermostable_enzymes
    predicate: enables
    object: hyperthermophilic_trait
    description: Thermostable enzymes support metabolism at very high temperature.
    evidence:
    - reference: DOI:10.1128/MMBR.65.1.1-43.2001
      snippet: thermostable ... optimally active at high temperatures
      notes: Supports enzyme thermostability in hyperthermophiles.
    predicate_id: RO:0002327
  - subject: reverse_gyrase
    predicate: contributes to
    object: hyperthermophilic_trait
    description: Reverse gyrase is associated with DNA stabilization in hyperthermophiles.
    evidence:
    - reference: DOI:10.3389/fmicb.2021.661411
      snippet: reverse gyrase is present in all the hyperthermophiles
      notes: Review supports the strong association of reverse gyrase with hyperthermophily.
    predicate_id: RO:0002326
  - subject: molecular_chaperonins
    predicate: regulates
    object: thermostable_enzymes
    description: Chaperonin systems support protein folding under heat stress.
    evidence:
    - reference: DOI:10.1038/nrmicro866
      snippet: protein-folding system to cope with heat stress
      notes: Review supports archaeal chaperonins in hyperthermophile heat-stress
        protein folding.
    predicate_id: RO:0002211
  - subject: membrane_lipid_composition
    predicate: enables
    object: hyperthermophilic_trait
    description: Membrane lipid adaptation contributes to growth near the upper temperature
      range for life.
    evidence:
    - reference: DOI:10.1016/s0300-9629(97)00003-0
      snippet: changes in the membrane lipid composition
      notes: Supports membrane lipid changes as high-temperature adaptation.
    predicate_id: RO:0002327
  - subject: cdpg
    predicate: increases thermostability of
    object: archaeal_proteins
    description: cDPG increases the thermostability of archaeal proteins.
    evidence:
    - reference: DOI:10.3389/fmicb.2023.1267570
      notes: Its presence increases the thermostability of archaeal proteins.
  - subject: cdpg
    predicate: protects against
    object: dna_oxidative_damage
    description: cDPG protects DNA against oxidative damage caused by hydroxyl radicals.
    evidence:
    - reference: DOI:10.3389/fmicb.2023.1267570
      notes: Protects the DNA against oxidative damage caused by hydroxyl radicals.
  - subject: very_high_temperature
    predicate: increases production of
    object: gmgt_lipids
    description: Elevated growth temperature increases production of GMGT membrane
      lipids.
    evidence:
    - reference: DOI:10.1073/pnas.2318761121
      notes: GMGT production and methylation increases with elevated temperatures
        (broad conclusion across three cultured archaea).
  - subject: gms_synthase
    predicate: required for
    object: gmgt_lipids
    description: Gms is required to form the bridging cross-link of a GMGT.
    evidence:
    - reference: DOI:10.1073/pnas.2318761121
      notes: Gms, that is required to form the bridging cross-link of a GMGT.
  - subject: gmgt_lipids
    predicate: contributes to
    object: membrane_rigidity
    description: GMGTs contribute to increased membrane rigidity at high temperature.
    evidence:
    - reference: DOI:10.1038/s41467-024-49650-x
      notes: GMGTs are thought to contribute to increased membrane rigidity at high
        temperature.
    predicate_id: RO:0002326
  - subject: macrocyclic_archaeol
    predicate: increases
    object: membrane_rigidity
    description: Macrocyclic archaeol increases membrane stability and rigidity, reducing
      membrane fluidity.
    evidence:
    - reference: DOI:10.1128/msystems.01159-22
      notes: Could increase overall membrane stability and rigidity and reduce membrane
        fluidity.
    predicate_id: RO:0002213
curation_history:
- timestamp: '2026-05-05T01:35:46.858819+00:00'
  curator: seed_from_metpo
  action: SEEDED_FROM_METPO
  changes: imported from data/raw/metpo.owl (CLASS)
  llm_assisted: false
- timestamp: '2026-05-06T14:58:45-07:00'
  curator: codex
  action: CURATED_WITH_ORGANISM_EXAMPLE
  changes: Added Pyrococcus furiosus organism example with PMID-backed evidence.
  llm_assisted: true
- timestamp: '2026-05-11T00:00:00-07:00'
  curator: codex
  action: CURATED_WITH_LITERATURE
  changes: Added DOI-backed hyperthermophily causal graph for thermostable enzymes,
    reverse gyrase, chaperonins, and membrane adaptation.
  llm_assisted: true
- timestamp: '2026-05-20T03:35:29Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 3 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002327×2, RO:0002326×1).
  llm_assisted: true
- timestamp: '2026-05-23T21:30:06Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2007401×1).
  llm_assisted: true
- timestamp: '2026-05-24T04:13:18Z'
  curator: claude
  action: RENAME_PREDICATE_LABELS
  changes: 'Renamed 1 causal-edge predicate label(s) to align with existing groundings:
    maintains → regulates ×1.'
  llm_assisted: true
- timestamp: '2026-05-24T04:13:21Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002211×1).
  llm_assisted: true
- timestamp: '2026-05-24T05:05:14Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (UniProtKB:A0A088E825×1).
  llm_assisted: true
- timestamp: '2026-05-24T08:14:32Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (PATO:0001637×1).
  llm_assisted: true
- timestamp: '2026-06-15T07:19:08Z'
  curator: claude
  action: FIX_NODE_GROUNDING_CURIE
  changes: Overwrote 1 causal-node grounding(s) to corrected CURIEs (phase-2 id-label
    fix; verified vs OAK).
  llm_assisted: true
- timestamp: '2026-06-17T04:09:43Z'
  curator: claude
  action: REMOVE_REDUNDANT_SYNONYM
  changes: Removed 1 synonym(s) whose text duplicated the label (seeder redundancy;
    no information lost).
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 6 evidence-backed generic edges (7 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:10Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002326×1, RO:0002213×1).
  llm_assisted: true
- timestamp: '2026-06-24T17:23:30Z'
  curator: claude
  action: GROUND_CAUSAL_NODES
  changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv
    (CHEBI:193595×1).
  llm_assisted: true