{"id":"390fa482-b7ec-5e77-9edb-6138db349a60","stable_key":"d17caac5-7018-5ca8-9e96-95afeb384bc4:pectin-galactan-surface","predicate":"depolymerizes","statement":"Surface BT4668 supports galactan utilization; its deletion prevented growth on this substrate.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"2eb17663-d347-5859-a3d4-5d6fdf7d31a9","mechanism_event_label":"Galactan side chains need their own cutting machinery.","subject":{"id":"4e4e3fe9-03ef-5bd7-9f8c-5336d041afaa","slug":"bt-bt4668","display_name":"Bacteroides thetaiotaomicron BT4668, surface galactanase","entity_type_key":"protein"},"object":{"id":"fe63daec-e68f-5d3f-89da-f004e2165a98","slug":"pectic-galactan","display_name":"Pectic galactan side chains","entity_type_key":"chemical_species"},"evidence_count":1,"mechanism_event":{"id":"2eb17663-d347-5859-a3d4-5d6fdf7d31a9","stable_key":"d17caac5-7018-5ca8-9e96-95afeb384bc4:pectin-galactan-surface-event","event_type":"biochemical_relationship","label":"Galactan side chains need their own cutting machinery.","description":"Surface BT4668 supports galactan utilization; its deletion prevented growth on this substrate.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"4e4e3fe9-03ef-5bd7-9f8c-5336d041afaa","slug":"bt-bt4668","display_name":"Bacteroides thetaiotaomicron BT4668, surface galactanase","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"fe63daec-e68f-5d3f-89da-f004e2165a98","slug":"pectic-galactan","display_name":"Pectic galactan side chains","entity_type_key":"chemical_species"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/pectin-research/29255254.fulltext.txt\", \"locator\": \"Primary full-text span; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"514f1ffe2924a1c555e3ecea968fb7260d0f55aa1b22c057697dbc59676c5796\", \"start_char\": 3594, \"end_char\": 6987, \"text_sha256\": \"73cf8a91e0bec8b92fd78e4630a68e5b8f3e0fe9202fad389959e3de9259167c\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Purified enzymes, structural biology and targeted bacterial deletions","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Defined pectic substrates; growth media and recombinant-enzyme assays","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Bacterial machinery, not human digestive enzymes. Gene dependence is substrate- and strain-specific; no clinical microbiome threshold follows.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Pectin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"pectin","display_name":"Pectin, structurally heterogeneous plant polysaccharides","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Bacteroides thetaiotaomicron","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Galactan side chains need their own cutting machinery.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[pectin-p29255254] Dietary pectic glycans are degraded by coordinated enzyme pathways in human colonic Bacteroides. (2018). https://pubmed.ncbi.nlm.nih.gov/29255254/ DOI: 10.1038/s41564-017-0079-1","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Cell surface and periplasm","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"5a5e6cb9-095c-57fe-8f0e-b9b6a25dd13f","evidence_kind":"source_excerpt","locator":"Lines 100-111","start_line":100,"end_line":111,"excerpt":"### pectin-galactan-surface\nSurface BT4668 supports galactan utilization; its deletion prevented growth on this substrate.\nCondition category: normal\nnutrient_topic: Pectin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Galactan side chains need their own cutting machinery.\norganism: Bacteroides thetaiotaomicron\ntissue_or_cell_type: Cell surface and periplasm\nexperimental_model: Purified enzymes, structural biology and targeted bacterial deletions\nlimitations: Bacterial machinery, not human digestive enzymes. Gene dependence is substrate- and strain-specific; no clinical microbiome threshold follows.\nexposure: Defined pectic substrates; growth media and recombinant-enzyme assays\nevidence_span: {\"source_cache\": \"artifacts/pectin-research/29255254.fulltext.txt\", \"locator\": \"Primary full-text span; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"514f1ffe2924a1c555e3ecea968fb7260d0f55aa1b22c057697dbc59676c5796\", \"start_char\": 3594, \"end_char\": 6987, \"text_sha256\": \"73cf8a91e0bec8b92fd78e4630a68e5b8f3e0fe9202fad389959e3de9259167c\"}\n[pectin-p29255254] Dietary pectic glycans are degraded by coordinated enzyme pathways in human colonic Bacteroides. (2018). https://pubmed.ncbi.nlm.nih.gov/29255254/ DOI: 10.1038/s41564-017-0079-1","model_system":"Purified enzymes, structural biology and targeted bacterial deletions","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [pectin-p29255254] Dietary pectic glycans are degraded by coordinated enzyme pathways in human colonic Bacteroides. (2018). https://pubmed.ncbi.nlm.nih.gov/29255254/ DOI: 10.1038/s41564-017-0079-1","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"13c3aae7-702f-5bc9-9fca-a57d141882ce","stable_key":"import-d17caac5-7018-5ca8-9e96-95afeb384bc4","title":"Pectin: metabolism, signaling and nutrient connections (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"ff07001bc37d008a1e23fbba37146d0b0d33cc8c0bf42a75f1e1a7ef0aaeb489","revision_id":"76f1a2c5-02d0-511b-bde5-33079d7af6a0","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}