identifier: traitmech:000580 label: thermotaxis definition: A motile phenotype in which an organism biases its active movement in response to a temperature gradient. definition_source: DOI:10.7554/eLife.26607 trait_category: PHYSIOLOGY term_kind: CLASS mapping_status: PROPOSED parent_traits: - METPO:1000702 evidence: - reference: DOI:10.7554/eLife.26607 snippet: detect and follow environmental temperature gradients notes: Paulick et al., Introduction; version 2, Version of Record dated 2017-08-31, https://cdn.elifesciences.org/articles/26607/elife-26607-v2.pdf. Figures 1-3 and their figure supplements distinguish behavioral gradients from FRET reporters and chemical adaptation. Temperature preference for movement is not a growth-temperature class. - reference: DOI:10.1073/pnas.0709903105 snippet: responds to changes in temperature by modifying its motor behavior notes: 'Paster and Ryu, Abstract and Results: thermal pulses changed tethered-cell motor bias. Their inversion temperatures are assay-specific, not universal trait thresholds. This assay measures motor output rather than spatial accumulation.' canonical_examples: - taxon_id: NCBITaxon:83333 taxon_label: Escherichia coli K-12 reference: DOI:10.7554/eLife.26607 note: 'AW405, a K-12 derivative carrying a GFP marker, showed thermal migration in microfluidic gradients (Figures 1C and 2D-E; Methods: Strains and plasmids). It is not the engineered VS223 FRET reporter or the MG1655 growth assay.' causal_graphs: - graph_id: thermotaxis_tar_response title: Tar-mediated control of thermal migration description: A receptor-modification-dependent thermal response changes swimming bias and realizes thermotaxis. scope_status: MECHANISTIC scope_notes: The E. coli Tar-mediated arm, not a universal microbial mechanism or a complete Tar/Tsr accumulation model. Engineered receptor experiments establish the Tar transitions. Interplay with Tsr and chemical adaptation changes the intact-cell response. nodes: - node_id: thermotaxis_temperature_change label: temperature change during movement node_type: ENVIRONMENTAL_FACTOR description: Temporal thermal stimulus encountered in a spatial gradient. - node_id: thermotaxis_tar_modification label: Tar covalent modification state node_type: STATE description: Deamidation and methylation of Tar adaptation sites; unprocessed, unmethylated and heavily methylated forms differ. - node_id: thermotaxis_tar_receptor label: Tar aspartate chemoreceptor node_type: GENE_OR_PROTEIN gene_symbols: - tar description: The full-length Tar receptor, including its thermal signaling role. grounding_status: REVIEWED_LABEL_ONLY grounding_notes: InterPro IPR003122 resolves to a Tar-related ligand-binding domain, not the full receptor; IPR004090 covers the broader MCP family. Neither is an exact whole-Tar grounding. The reviewed K-12 protein remains an instance example. protein_examples: - uniprot_id: UniProtKB:P07017 protein_label: Methyl-accepting chemotaxis protein II gene_symbol: tar taxon_id: NCBITaxon:83333 taxon_label: Escherichia coli K-12 entry_status: REVIEWED retrieved_on: '2026-10-03' entry_version: 208 sequence_version: 2 role: Tar component of the K-12 thermal response; not the entire receptor array. evidence: - reference: DOI:10.7554/eLife.26607 snippet: both Tar- and Tsr-only cells exhibited thermophilic responses notes: Results, Figure 3A and Methods identify K-12 Tar-only receptor experiments; UniProt verifies protein identity. - node_id: thermotaxis_swimming_control label: thermal control of run-and-tumble bias node_type: BIOLOGICAL_PROCESS description: Receptor signaling changes smooth-swimming versus tumbling; this is not merely a change in swimming speed. - node_id: thermotaxis_migration_process label: thermotaxis node_type: BIOLOGICAL_PROCESS grounding: GO:0043052 description: Directed migration in response to a temperature gradient. - node_id: thermotaxis_trait label: thermotaxis node_type: TRAIT grounding: traitmech:000580 description: Organism-level disposition for temperature-guided active movement. edges: - subject: thermotaxis_temperature_change predicate: modulates predicate_id: RO:0002211 object: thermotaxis_tar_receptor description: Temperature changes elicit a Tar response when its modification state permits thermosensing. evidence: - reference: DOI:10.1074/jbc.271.30.17932 snippet: Tar comes to function as a thermoreceptor notes: 'Abstract: deamidation enables the thermal response; the primary translational product is not a thermoreceptor.' - subject: thermotaxis_tar_modification predicate: modulates predicate_id: RO:0002211 object: thermotaxis_tar_receptor description: Covalent modification changes the receptor's warm, cold or null response state. evidence: - reference: DOI:10.1128/jb.179.21.6573-6580.1997 snippet: thermosensing function that is modulated by covalent modification of its four methylation sites notes: 'Abstract: the mutational study distinguishes deamidation from methylation and tests receptor thermosensing, not a universal preferred temperature.' - subject: thermotaxis_tar_receptor predicate: regulates predicate_id: RO:0002211 object: thermotaxis_swimming_control description: Tar-mediated signaling changes swimming bias, with the response sign depending on receptor modification. evidence: - reference: DOI:10.1074/jbc.271.30.17932 snippet: eliciting a smooth-swimming signal upon increase of temperature notes: 'Abstract: this warm response applies to deamidated, unmethylated Tar; the heavily methylated form instead signals smooth swimming on cooling. Intermediate phosphorelay steps are compressed, not bypassed.' - subject: thermotaxis_swimming_control predicate: contributes to predicate_id: RO:0002326 object: thermotaxis_migration_process description: Temperature-dependent run-and-tumble statistics bias migration along a thermal gradient. evidence: - reference: DOI:10.1073/pnas.0709903105 snippet: This stochastic strategy biases the cell's random walk notes: 'Introduction: temporal temperature sensing biases runs and tumbles, giving net movement along spatial gradients. The separate motor assay is not itself a migration measurement.' - subject: thermotaxis_migration_process predicate: confers predicate_id: METPO:2007700 object: thermotaxis_trait description: Temperature-guided migration realizes the organismal thermotaxis phenotype. evidence: - reference: DOI:10.7554/eLife.26607 snippet: cells accumulated towards the warmer side of the gradient notes: 'Results, Figure 1C: buffer-adapted swimming cells; chemical adaptation can alter the direction (Figure 2).' discussions: - discussion_id: thermotaxis-context-and-mapping-boundaries prompt: Resolve assay-dependent response inversion without imposing a universal temperature threshold. kind: KNOWLEDGE_GAP status: OPEN rationale: DOI:10.1073/pnas.0709903105 reports thermal-response inversion under its tethered-cell conditions. DOI:10.7554/eLife.26607 instead finds continued warm-seeking in buffer under flow; its Discussion suggests residual chemical stimulation as one explanation of earlier results, not a proven correction. Retain medium, adaptation, strain and assay context. Growth optima, passive thermophoresis and temperature-dependent speed alone do not establish thermotaxis. GO:0043052 is a biological process (QuickGO checked 2026-10-03), so it grounds the process node rather than an equivalent xref on the disposition. The Tar arm does not describe every thermotactic microbe. posed_by: codex posed_date: '2026-10-03' curation_history: - timestamp: '2026-10-03T22:20:00Z' curator: codex action: MINTED_TRAITMECH_ID changes: Added thermotaxis with four primary DOI sources, exact snippets, a K-12 behavioral example and a Tar-mediated causal graph. Verified P07017, NCBITaxon:83333 and GO:0043052 at authorities. Ignored-and-hidden searches found no exact record or METPO term; reserved METPO:1053400 in proposal v457. Kept assay-dependent inversion separate from growth-temperature preference. llm_assisted: true