identifier: METPO:1000721 label: extreme hyperthermophilic definition: A temperature preference that grows optimally at temperatures above 90°C. definition_source: DOI:10.1007/s007920050010 trait_category: ENVIRONMENT term_kind: CLASS mapping_status: REVIEWED parent_traits: - METPO:1000613 synonyms: - synonym_text: extreme hyperthermophile synonym_type: RELATED_SYNONYM source: metpo.owl - synonym_text: extremely hyperthermophilic synonym_type: RELATED_SYNONYM source: metpo.owl evidence: - reference: DOI:10.1007/s007920050010 snippet: It grew at between 90 degrees C and 113 degrees C notes: 'Organism example: Pyrolobus fumarii grows in the extreme hyperthermophilic range.' - reference: DOI:10.1128/MMBR.65.1.1-43.2001 snippet: resistant to irreversible inactivation at high temperatures notes: Thermostable-protein review supports extreme protein and membrane stability as the basis of hyperthermophile physiology. canonical_examples: - taxon_id: NCBITaxon:54252 taxon_label: Pyrolobus fumarii note: "Highest optimal growth temperature known (106 C; range 90-113 C); cannot grow below 90 C." reference: DOI:10.1007/s007920050010 causal_graphs: - graph_id: extreme_hyperthermophilic_archaeal_adaptation title: Extreme-hyperthermophilic archaeal heat-adaptation mechanism description: DOI-backed graph linking extreme hyperthermophily to archaeal tetraether membrane lipids, hyperthermostable proteins, and bioenergetic adaptation at temperatures above 90 °C. nodes: - node_id: extreme_hyperthermophilic_trait label: extreme hyperthermophilic node_type: TRAIT grounding: METPO:1000721 description: Optimal growth at temperatures above 90 °C. - node_id: very_high_temperature label: very high temperature node_type: ENVIRONMENTAL_FACTOR description: Ambient temperature above 90 °C, typical of hydrothermal vents and geothermal springs. grounding: PATO:0001305 - node_id: tetraether_lipids label: archaeal tetraether membrane lipids node_type: CHEMICAL description: Glycerol-dibiphytanyl-glycerol-tetraether (GDGT) lipids forming heat-resistant monolayer membranes in hyperthermophilic archaea. - node_id: hyperthermostable_proteins label: hyperthermostable proteins node_type: GENE_OR_PROTEIN description: Proteins with extreme resistance to denaturation, including enzymes active at >90 °C. - node_id: hyperthermophile_bioenergetics label: hyperthermophile bioenergetics node_type: BIOLOGICAL_PROCESS description: Energy transduction tuned to function in very-high-temperature environments. - node_id: reverse_gyrase label: reverse gyrase node_type: GENE_OR_PROTEIN description: ATP-dependent topoisomerase that introduces positive supercoils into DNA; characteristic of hyperthermophiles. grounding: UniProtKB:A0A088E825 - node_id: dna_positive_supercoiling label: DNA positive supercoiling node_type: BIOLOGICAL_PROCESS description: Positive supercoiling of DNA topology that stabilizes the double helix at high temperature. - node_id: dna_thermal_denaturation label: DNA thermal denaturation node_type: BIOLOGICAL_PROCESS description: Heat-induced melting/denaturation of DNA, a threat to genome integrity at very high temperature. - node_id: thermally_damaged_dna label: thermally damaged DNA node_type: CHEMICAL description: Nicked or thermally damaged DNA subject to heat-driven strand breakage. - node_id: grs_cyclization_enzymes label: GrsA/GrsB GDGT cyclization enzymes node_type: GENE_OR_PROTEIN description: Enzymes that introduce ring cyclizations into GDGT tetraether lipids, increasing membrane packing. - node_id: membrane_integrity_high_temp label: membrane integrity at high temperature node_type: STATE description: Maintained structural integrity of the cell membrane under membrane-destabilizing heat. edges: - subject: very_high_temperature predicate: selects for object: extreme_hyperthermophilic_trait description: Very-high-temperature habitats select for extreme hyperthermophily. evidence: - reference: DOI:10.1007/s007920050010 snippet: It grew at between 90 degrees C and 113 degrees C notes: Supports growth above 90 °C in extreme hyperthermophiles. predicate_id: METPO:2007401 - subject: tetraether_lipids predicate: protects against object: very_high_temperature description: Archaeal tetraether lipids form heat-resistant membranes that protect against very-high-temperature membrane stress. evidence: - reference: DOI:10.1146/annurev-micro-091313-103612 snippet: membrane lipid composition notes: Membrane-adaptation review supports membrane lipid composition as the primary tunable mechanism for thermal adaptation; in hyperthermophilic archaea this is realized via tetraether (GDGT) monolayer membranes. - subject: hyperthermostable_proteins predicate: enables object: hyperthermophile_bioenergetics description: Hyperthermostable proteins enable continued energy conservation at very high temperature. evidence: - reference: DOI:10.1128/MMBR.65.1.1-43.2001 snippet: resistant to irreversible inactivation at high temperatures notes: Supports protein hyperthermostability as a hyperthermophile feature. predicate_id: RO:0002327 - subject: hyperthermophile_bioenergetics predicate: enables object: extreme_hyperthermophilic_trait description: Heat-adapted bioenergetics supports growth at extreme hyperthermophilic temperatures. evidence: - reference: DOI:10.1016/s0300-9629(97)00003-0 snippet: energy transducing enzymes notes: Supports temperature-adapted energy transduction as the basis of thermophile and hyperthermophile growth. predicate_id: RO:0002327 - subject: reverse_gyrase predicate: introduces positive supercoils into object: dna_positive_supercoiling description: Reverse gyrase introduces positive supercoils into DNA in hyperthermophiles. evidence: - reference: DOI:10.1264/jsme2.me23087 notes: reverse gyrase... introduces positive supercoils into DNA (review-supported mechanistic edge). - subject: dna_positive_supercoiling predicate: decreases risk of object: dna_thermal_denaturation description: Positive DNA supercoiling decreases the risk of thermal denaturation of DNA. evidence: - reference: DOI:10.1264/jsme2.me23087 notes: reverse gyrase prevents the thermal denaturation of DNA by introducing positive DNA supercoiling (widely accepted in review literature). - subject: reverse_gyrase predicate: protects object: thermally_damaged_dna description: Reverse gyrase has heat-protective DNA chaperone activity that reduces thermal DNA damage, independent of supercoiling. evidence: - reference: DOI:10.1093/nar/gkh683 notes: Reverse gyrase has heat-protective DNA chaperone activity, reducing double-stranded DNA breakage ~8-fold at 90 C (strong experimental support). - subject: tetraether_lipids predicate: maintains object: membrane_integrity_high_temp description: Archaeal ether/tetraether lipids maintain membrane integrity at high temperature. evidence: - reference: DOI:10.1186/2046-0481-57-6-348 notes: archaeal membranes contain tetraethers and diethers, enabling cells to withstand membrane-destroying temperatures (broad classic mechanism). - subject: grs_cyclization_enzymes predicate: increases object: membrane_integrity_high_temp description: GrsA/GrsB cyclization of GDGTs increases membrane packing and stability at high temperature. evidence: - reference: DOI:10.1007/s00792-023-01330-2 notes: cyclized GDGTs (introduced by GrsA/GrsB) increase membrane packing and stability (strong mechanistic membrane edge). predicate_id: RO:0002213 curation_history: - timestamp: '2026-05-05T01:35:46.909279+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 Pyrolobus fumarii organism example with PMID-backed evidence. llm_assisted: true - timestamp: '2026-05-13T11:30:00-07:00' curator: claude action: CURATED_CAUSAL_GRAPH changes: Added DOI-backed causal graph linking archaeal tetraether membrane lipids, hyperthermostable proteins, and hyperthermophile bioenergetics to extreme hyperthermophily. llm_assisted: true - timestamp: '2026-05-13T22:45:00-07:00' curator: codex action: IMPROVED_CAUSAL_GRAPH_EVIDENCE changes: Replaced Pyrolobus fumarii PMID fallback with the article DOI in definition, record evidence, and CausalEdge evidence. llm_assisted: true - timestamp: '2026-05-20T03:35:29Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×1). 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: supports → enables ×1.' llm_assisted: true - timestamp: '2026-05-24T04:13:20Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×1). 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: '2026-06-23T00:00:00Z' curator: claude action: ENRICH_CAUSAL_GRAPH changes: Added 5 evidence-backed generic edges (6 new nodes) from the deep-research report. llm_assisted: true - timestamp: '2026-06-24T17:21:09Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002213×1). llm_assisted: true - timestamp: '2026-06-24T17:21:16Z' 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