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urease activity

traitmech:000077 · CLASS · REVIEWED

A physiological enzyme-activity phenotype in which a cell produces urease, which hydrolyzes urea to ammonia and carbon dioxide, typically raising local pH; it is the basis of the diagnostic urease test.

Urease-catalyzed urea hydrolysis

Evidence-backed causal sketch linking urease to hydrolysis of urea into ammonia, the basis of the urease test.

Urease-catalyzed urea hydrolysis Interactive directed graph showing evidence-backed causal relationships for urease activity.

Edge evidence

  • urease enables urease activity RO:0002327

    Urease carries out urea hydrolysis.

    • DOI:10.1128/mr.59.3.451-480.1995 Mobley, Island & Hausinger review microbial ureases.
  • urease activity consumes urea biolink:consumes

    The urease reaction consumes urea.

    • DOI:10.1128/mr.59.3.451-480.1995 Supports urea as the hydrolysis substrate.
  • urease activity has output ammonia RO:0002234

    Urea hydrolysis produces ammonia.

    • DOI:10.1128/mr.53.1.85-108.1989 Mobley & Hausinger support ammonia release from urea hydrolysis.
  • urease activity manifests as urease activity METPO:2007400

    Urease enzymatic activity manifests as the observable urease-activity phenotype scored by the diagnostic urease test.

    • DOI:10.1128/mr.59.3.451-480.1995 Urease activity (urea-to-ammonia hydrolysis raising local pH) is the assayable phenotype used to score urease-positive organisms.
  • urease activity has output hydroxide RO:0002234

    Urea hydrolysis produces hydroxide, mechanistically explaining alkalinization.

    • DOI:10.24263/2304-974x-2024-13-2-10 (NH2)2CO + 2H2O + urease -> 2 NH4+ + 2 OH- + CO2 + urease.
  • urease activity has output carbon dioxide RO:0002234

    Urea hydrolysis produces carbon dioxide.

    • DOI:10.24263/2304-974x-2024-13-2-10 (NH2)2CO + 2H2O + urease -> 2 NH4+ + 2 OH- + CO2 + urease.
  • urease activity increases pH RO:0002213

    Urea hydrolysis (NH4+/OH- production) increases local pH, the basis of the urease test color change.

    • DOI:10.1021/acs.est.3c06617 Urea hydrolysis produces NH4+ and OH-, causing a pH increase.
  • carbon dioxide is substrate of carbonic anhydrase activity

    CO2 from urea hydrolysis is hydrated by carbonic anhydrase.

    • DOI:10.1021/acs.est.3c06617 Hydration of CO2 to HCO3- by carbonic anhydrase.
  • carbonic anhydrase activity increases bicarbonate RO:0002213

    Carbonic anhydrase hydrates CO2, increasing bicarbonate.

    • DOI:10.1021/acs.est.3c06617 Increase in [HCO3-] following the hydration of CO2 to HCO3- by CA.
  • carbonic anhydrase activity affects calcium carbonate precipitation

    CA-driven buffering enhances solubility trapping and affects the CaCO3 phase formed.

    • DOI:10.1021/acs.est.3c06617 CA physiologically promotes buffering, which enhances solubility trapping and affects the phase of the CaCO3 mineral formed.

Provenance

Source
METPO (2025-11-25)
Definition source
DOI:10.1128/mr.59.3.451-480.1995

Parent traits (1)

Synonyms (1)

  • urease-positive RELATED_SYNONYM · DOI:10.1128/mr.59.3.451-480.1995

kg-microbe context

Matched 1 kg-microbe node via parent_proxy.

  • METPO:1000059 [-2.682, -2.070, -3.656, -0.652, …]

512-dim DeepWalkSkipGramEnsmallen embedding from kg-microbe (2026-04-25).

Nearest neighbors in embedding space

Top-8 cosine-similar METPO traits from the 2026-04-25 deepwalk (512-D).

Deep research

Generated by just research-trait; source: research/traits/physiology/urease_activity-deep-research-falcon.md

Unreviewed literature output — not curated TraitMech content Ontology identifiers suggested below have not been resolved against their ontologies, and some are known to be wrong. Check any CURIE against the source before using it. 
# Curation report: microbial urease activity

## Trait record and scope

- **Trait:** urease activity
- **Identifier:** `traitmech:000077`
- **Category / kind / status:** PHYSIOLOGY / CLASS / REVIEWED
- **Parent:** `METPO:1000059`
- **Synonym:** urease-positive

This trait should denote the **demonstrated physiological capacity of a microbial cell or preparation to produce active urease and hydrolyze urea**. The core reaction is commonly summarized as urea + water → ammonia + carbamate, followed by spontaneous carbamate decomposition to additional ammonia and carbon dioxide/bicarbonate. Urease is **EC 3.5.1.5**, generally a cytosolic, dinuclear nickel enzyme. Its ammonia output commonly raises local pH and is the basis of colorimetric diagnostic urease tests. (nim2019thematurationpathway pages 1-3, farrugia2013biosynthesisofthe pages 1-1)

### Recommended boundaries

Include:

1. Active enzyme formation, including structural urease subunits and nickel-dependent maturation.
2. Urea access when it is mechanistically necessary for expressed activity.
3. Urea hydrolysis and immediate products.
4. Direct assay observables such as ammonia release or indicator-detected alkalinization.

Treat as **downstream context-specific branches**, rather than defining features:

- acid resistance and gastric colonization in *Helicobacter pylori*;
- urea utilization as a nitrogen source;
- urinary struvite/carbonate-apatite formation;
- calcium-carbonate biocementation;
- host-cell injury from ammonia.

Do not equate urease activity with merely possessing `ure` genes. Activity additionally depends on expression, assembly, nickel availability, accessory proteins, and assay conditions. Conversely, a negative pH-indicator assay does not necessarily prove absence of urease if substrate uptake, nickel, cell density, incubation time, buffering, or enzyme expression is limiting.

Nearby but distinct traits include urea transport, nickel uptake/homeostasis, acid tolerance, ammonia production by other pathways, nitrogen-source utilization, carbonate precipitation, urinary-stone formation, and urea amidolyase activity.

## Candidate nodes

### Trait and process nodes

- urease activity — `traitmech:000077`
- urease activity / urea amidohydrolase activity — `GO:0009039`; `EC:3.5.1.5`
- urea catabolic process — `GO:0019627`
- urease maturation / nickel insertion — label-only candidate pending exact ontology review
- alkalinization, acid resistance, biomineralization, and diagnostic urease-test positivity — label-only or separately grounded downstream nodes

### Genes, proteins, and complexes

- `ureA`, `ureB`, `ureC`: structural genes/subunits. In the canonical bacterial architecture, UreA/γ, UreB/β, and catalytic UreC/α form `(UreABC)3`; *Helicobacter* uses a fused/two-subunit variant, so one universal stoichiometry should not be asserted. (nim2019thematurationpathway pages 1-3, farrugia2013biosynthesisofthe pages 1-1)
- UreD, or its homolog UreH; UreE; UreF; UreG: urease-accessory maturation proteins.
- UreG: P-loop GTPase involved in nickel delivery.
- UreE: nickel-binding metallochaperone.
- apo-urease and mature holo-urease complexes.
- UreI: acid-gated urea channel; **taxon-specific to the *H. pylori* mechanistic branch**, not a generic requirement.

Use label-only nodes in the initial YAML unless a taxon is fixed; UniProt identifiers differ among organisms and should not be generalized.

### Chemicals and cofactors

High-confidence candidates include urea, water, ammonia/ammonium, carbamate, carbon dioxide, bicarbonate/carbonate, Ni²⁺, GTP/GDP, and a carbamylated active-site lysine. The mature active site contains two nickel ions coordinated around a carbamylated lysine and other ligands. (nim2019thematurationpathway pages 1-3, farrugia2013biosynthesisofthe pages 1-1)

Context-specific candidates include Ca²⁺, Mg²⁺, phosphate, calcium carbonate, struvite, and carbonate apatite. Candidate inhibitors include acetohydroxamic acid, 2-mercaptoacetamide, lactic acid, bismuth compounds, and noncognate metal ions. These should not all be represented as universal physiological regulators. (burne2000bacterialureasesin pages 4-6, nim2019thematurationpathway pages 8-10, szczerbiec2024antibacterialpropertiesand pages 5-7)

Showing the first 60 of 191 lines of findings; the linked file also carries the run's front matter and the prompt it was given — read the full report.

Curation history

  1. · PROPOSED_FROM_RESEARCH · claude

    Proposed candidate PHYSIOLOGY trait (urease activity) from literature research to fill the enzyme-activity-phenotype gap.

  2. · CURATED_CAUSAL_GRAPH · claude

    Added evidence-backed causal graph (urease urea hydrolysis) with GO/CHEBI node groundings and RO/METPO/biolink predicate groundings; promoted PROPOSED to REVIEWED.

  3. · GROUND_CAUSAL_NODES · claude

    Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (UniProtKB:A0A090IGX8×1).

  4. · FIX_ORPHAN_NODE · claude

    Connected the previously-orphaned urease_activity_trait node via a 'manifests as' (METPO:2007400) edge from urease_function, so the molecular function links to the observable trait.

  5. · ENRICH_CAUSAL_GRAPH · claude

    Added 6 evidence-backed generic edges (6 new nodes) from the deep-research report.

  6. · GROUND_CAUSAL_PREDICATES · claude

    Grounded 4 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (METPO:2000202×2, RO:0002213×2).

  7. · GROUND_CAUSAL_NODES · claude

    Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (CHEBI:16526×1).

  8. · GROUND_CAUSAL_NODES · claude

    Grounded 3 causal-node grounding field(s) via mappings/node_grounding.tsv (CHEBI:16234×1, GO:0004089×1, CHEBI:17544×1).

  9. · RETRACT_DEAD_UNIPROT_GROUNDINGS · claude

    Retracted 1 UniProtKB grounding(s) whose accessions are deleted from UniProt; nodes demoted to label-only pending re-grounding (docs/GROUNDING_POLICY.md)

  10. · GROUND_CAUSAL_NODES · claude

    Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (GO:0009039×1).

  11. · MIGRATE_MICROBE_DOMAIN_EDGES · claude

    Re-grounded 3 causal edge(s) off microbe-domain METPO predicates (3 to has output), issue 301. The previous predicates are transitively rdfs:subPropertyOf METPO:2000001, whose rdfs:domain is METPO:1000525 (microbe), so a causal-graph subject entailed that the subject IS a microbe; CausalNodeTypeEnum has no organism member, so no such edge could ever satisfy the domain. Edge directions are unchanged - this pass only relabels and re-grounds. RO:0002234 (has output) is used where the subject is an activity, since biolink gives it the domain 'biological process or activity'; the METPO replacements are proposed in proposals/metpo_traitmech_v8 and v9 and are placeholder ids until METPO mints them.

  12. · UNGROUND_CAUSAL_NODE · claude

    Dropped the grounding GO:0009039 from node urease. Issue 352. GO:0009039 is 'urease ACTIVITY'. Same as catalase: kept on urease_function, dropped from the protein that enables it.