identifier: METPO:1000464 label: pH range high definition: A pH range phenotype in which the growth-supporting external pH range spans approximately 10–14, characteristic of extreme-alkaliphile physiology. definition_source: DOI:10.1038/nrmicro2549 trait_category: ENVIRONMENT term_kind: CLASS mapping_status: REVIEWED parent_traits: - METPO:1000332 synonyms: - synonym_text: Alkali Tolerant synonym_type: EXACT_SYNONYM source: metpo.owl - synonym_text: Alkaliphile synonym_type: EXACT_SYNONYM source: metpo.owl - synonym_text: Extreme Alkaliphile synonym_type: EXACT_SYNONYM source: metpo.owl - synonym_text: 10_to_14 synonym_type: RELATED_SYNONYM source: metpo.owl evidence: - reference: DOI:10.1038/nrmicro2549 snippet: alkaliphiles notes: pH-homeostasis review supports extreme-alkaliphile physiology growing at external pH above 10. - reference: DOI:10.1016/j.tim.2007.02.005 snippet: proton motive force notes: pH-homeostasis review supports robust Na+/H+ antiporter activity as the extreme-alkaliphile mechanism sustaining the proton motive force above pH 10. causal_graphs: - graph_id: ph_range_high_extreme_alkaliphile title: pH-range-high extreme-alkaliphile range description: DOI-backed graph linking extreme-alkaliphile Na+/H+ antiporter activity to a pH growth range extending above 10. nodes: - node_id: ph_range_high_trait label: pH range high node_type: TRAIT grounding: METPO:1000464 description: pH growth-supporting range extending above ~10. - node_id: ph_range label: pH range node_type: TRAIT grounding: METPO:1000332 description: Span of external pH values supporting growth. - node_id: extreme_alkaliphile_antiport label: extreme-alkaliphile Na+/H+ antiport node_type: BIOLOGICAL_PROCESS description: Robust Na+/H+ antiporter activity importing H+ at strongly alkaline external pH. - node_id: mrp_antiporter_complex label: Mrp Na+/H+ antiporter complex node_type: GENE_OR_PROTEIN description: Hetero-oligomeric CPA3-family Na+/H+ antiporter complex essential at high external pH. - node_id: mrp_operon label: mrpA-G operon node_type: GENE_OR_PROTEIN description: Operon encoding the seven hydrophobic Mrp proteins that form the antiporter complex. - node_id: membrane_potential label: transmembrane potential (delta-psi) node_type: QUALITY description: Large transmembrane electrical potential energizing electrogenic cation/H+ antiport. - node_id: na_solute_symporters label: Na+/solute symporters node_type: GENE_OR_PROTEIN description: Symporters re-importing Na+ with solutes to supply cytoplasmic Na+ for antiport. - node_id: cytoplasmic_na label: cytoplasmic Na+ node_type: CHEMICAL description: Intracellular sodium pool required to sustain alkaliphile antiport activity. - node_id: f1fo_atp_synthase label: F1Fo-ATP synthase node_type: GENE_OR_PROTEIN description: Proton-translocating ATP synthase whose proton uptake contributes to pH homeostasis. - node_id: alkaline_ph_homeostasis label: alkaline pH homeostasis node_type: BIOLOGICAL_PROCESS description: Maintenance of a near-neutral cytoplasmic pH against a strongly alkaline exterior. - node_id: external_ph_high label: external pH > 10.3 node_type: ENVIRONMENTAL_FACTOR description: Strongly alkaline external pH above ~10.3. - node_id: carbonate_speciation label: carbonate (CO3 2-) speciation node_type: CHEMICAL description: Shift of dissolved inorganic carbon toward carbonate at high pH. edges: - subject: extreme_alkaliphile_antiport predicate: enables object: ph_range_high_trait description: Robust Na+/H+ antiport enables growth at pH > 10. evidence: - reference: DOI:10.1016/j.tim.2007.02.005 snippet: proton motive force notes: Supports antiporter-driven proton re-import as the extreme-alkaliphile mechanism. predicate_id: RO:0002327 - subject: ph_range_high_trait predicate: is a object: ph_range description: pH range high is a quantitative bin of the pH-range phenotype. evidence: - reference: DOI:10.1038/nrmicro2549 snippet: alkaliphiles notes: Supports the pH 10–14 range as a value within the pH-range distribution. predicate_id: rdfs:subClassOf - subject: mrp_antiporter_complex predicate: enables object: ph_range_high_trait description: The hetero-oligomeric Mrp antiporter has an indispensable role in growth at high pH. evidence: - reference: DOI:10.1038/nrmicro2549 notes: The unusual hetero-oligomeric Mrp antiporter has an indispensable role at high pH. predicate_id: RO:0002327 - subject: mrp_operon predicate: encodes object: mrp_antiporter_complex description: The mrpA-G operon encodes the seven proteins forming the hetero-oligomeric Mrp complex. evidence: - reference: DOI:10.1038/nrmicro2549 notes: Mrp antiporters are encoded in operons containing genes for seven hydrophobic proteins; all required to form the hetero-oligomeric complex. predicate_id: biolink:encodes - subject: membrane_potential predicate: drives object: mrp_antiporter_complex description: A large transmembrane potential drives electrogenic Na+/H+ antiport that imports H+. evidence: - reference: DOI:10.1038/nrmicro2549 notes: A large transmembrane potential is essential to drive electrogenic Na+/H+ and K+/H+ antiporters that import H+. - subject: na_solute_symporters predicate: supplies object: cytoplasmic_na description: Na+/solute symporters supply the cytoplasmic Na+ required to sustain antiport activity. evidence: - reference: DOI:10.1038/nrmicro2549 notes: The ongoing requirement for cytoplasmic Na+ to support high levels of alkaliphile antiport activity is met by numerous Na+/solute symporters. - subject: cytoplasmic_na predicate: enables object: mrp_antiporter_complex description: Cytoplasmic Na+ is the substrate that sustains high levels of alkaliphile antiport activity. evidence: - reference: DOI:10.1038/nrmicro2549 notes: Cytoplasmic Na+ is required to support high levels of alkaliphile antiport activity. predicate_id: RO:0002327 - subject: f1fo_atp_synthase predicate: contributes to object: alkaline_ph_homeostasis description: Proton uptake accompanying ATP synthesis contributes to alkaliphile pH homeostasis. evidence: - reference: DOI:10.1038/nrmicro2549 notes: The proton uptake that accompanies ATP synthesis by the F1Fo-ATP synthase contributes to alkaliphile pH homeostasis. predicate_id: RO:0002326 - subject: alkaline_ph_homeostasis predicate: enables object: ph_range_high_trait description: Maintenance of cytoplasmic pH homeostasis enables growth at strongly alkaline external pH. evidence: - reference: DOI:10.1038/nrmicro2549 notes: Alkaline pH homeostasis underlies extreme-alkaliphile growth above pH 10. predicate_id: RO:0002327 - subject: external_ph_high predicate: shifts speciation toward object: carbonate_speciation description: External pH above ~10.3 shifts dissolved inorganic carbon speciation toward carbonate. evidence: - reference: DOI:10.1128/AEM.01557-23 notes: DIC speciation shifts strongly with pH, toward CO3= above ~10.3. curation_history: - timestamp: '2026-05-05T01:35:46.832881+00:00' curator: seed_from_metpo action: SEEDED_FROM_METPO changes: imported from data/raw/metpo.owl (CLASS) llm_assisted: false - timestamp: '2026-05-13T10:00:00-07:00' curator: claude action: CURATED_CAUSAL_GRAPH changes: Added DOI-backed definition and causal graph linking extreme-alkaliphile Na+/H+ antiport to the pH-range-high bin. llm_assisted: true - timestamp: '2026-05-20T03:35:30Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×1, rdfs:subClassOf×1). llm_assisted: true - timestamp: '2026-06-23T00:00:00Z' curator: claude action: ENRICH_CAUSAL_GRAPH changes: Added 8 evidence-backed generic edges (9 new nodes) from the deep-research report. llm_assisted: true - timestamp: '2026-06-24T17:21:10Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 5 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×3, biolink:encodes×1, RO:0002326×1). llm_assisted: true