{"id":"d8d7cd03-9df3-5763-a0e8-f2a251b572bf","stable_key":"649e861b-265a-5912-bc36-3a73e53ef892:l-serine-shmt2-translation","predicate":"supports","statement":"Catalytic SHMT2 loss in human cells impaired mitochondrial tRNA modification and caused preferential ribosome stalling at AAG lysine and UUG leucine codons.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"8c2b3c03-f772-51cf-aaa0-cce352aca5de","mechanism_event_label":"Serine-linked folate chemistry helps mitochondria read particular codons.","subject":{"id":"2559e210-62e5-5cd8-bc77-538a9aecd7c8","slug":"shmt2","display_name":"SHMT2","entity_type_key":"protein"},"object":{"id":"70e959f9-8358-5acd-89d1-c83d5062e505","slug":"human-mitochondrial-codon-translation","display_name":"Human mitochondrial translation at lysine and leucine codons","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"8c2b3c03-f772-51cf-aaa0-cce352aca5de","stable_key":"649e861b-265a-5912-bc36-3a73e53ef892:l-serine-shmt2-translation-event","event_type":"observed_relationship","label":"Serine-linked folate chemistry helps mitochondria read particular codons.","description":"Catalytic SHMT2 loss in human cells impaired mitochondrial tRNA modification and caused preferential ribosome stalling at AAG lysine and UUG leucine codons.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"2559e210-62e5-5cd8-bc77-538a9aecd7c8","slug":"shmt2","display_name":"SHMT2","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"70e959f9-8358-5acd-89d1-c83d5062e505","slug":"human-mitochondrial-codon-translation","display_name":"Human mitochondrial translation at lysine and leucine codons","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"c882cd0b-9d83-5b07-bd1c-fe4d45657dcb","slug":"l-serine","display_name":"L-Serine","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"0413b195-325e-5757-a72b-f445d65c17bc","slug":"5-10-methylenetetrahydrofolate","display_name":"5,10-Methylenetetrahydrofolate","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"dd968147-5f93-56d5-bc83-7fa01f9b0e42","slug":"mt-trna-taurinomethyluridine","display_name":"Mitochondrial tRNA 5-taurinomethyluridine / tau-m5U34","entity_type_key":"rna_modification"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; 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unverified.","entity":null}],"evidence":[{"id":"637ecd03-0032-500a-9446-35e70fbf50b8","evidence_kind":"source_excerpt","locator":"Lines 174-180","start_line":174,"end_line":180,"excerpt":"## l-serine-shmt2-translation\nSerine-linked folate chemistry helps mitochondria read particular codons.\nCatalytic SHMT2 loss in human cells impaired mitochondrial tRNA modification and caused preferential ribosome stalling at AAG lysine and UUG leucine codons.\nModel: Human SHMT2 knockout and mitochondrial ribosome profiling.\nLimitations: The methyl-donor route was mechanistically inferred alongside measured modification and translation defects.\nEvidence access: Primary abstract\nMitochondrial translation requires folate-dependent tRNA methylation. · 2018 · https://pubmed.ncbi.nlm.nih.gov/29364879/ · DOI 10.1038/nature25460","model_system":"Human SHMT2 knockout and mitochondrial ribosome profiling.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"70bcf57a-36bb-563f-9073-2d616e5f155a","stable_key":"import-649e861b-265a-5912-bc36-3a73e53ef892","title":"L-Serine: synthesis, one-carbon metabolism, lipids and cross-nutrient mechanisms (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. 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