{"gene":"NDUFA9","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":2012,"finding":"TALEN-mediated knockout of NDUFA9 in HEK293T cells results in loss of NDUFA9 protein, impaired complex I assembly, and accumulation of a subcomplex containing only membrane arm subunits (lacking matrix arm marker subunits), demonstrating that NDUFA9 is required to stabilize the junction between the membrane and matrix arms of complex I as a late assembly step.","method":"TALEN gene knockout in HEK293T cells, blue-native PAGE complex I assembly analysis, galactose growth assay, re-expression rescue","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with defined assembly phenotype, rescue by re-expression, multiple orthogonal methods in a single rigorous study","pmids":["23223238"],"is_preprint":false},{"year":2011,"finding":"A homozygous missense mutation in NDUFA9 (Arg321Pro) causes complex I deficiency; lentiviral transduction with wild-type but not mutant NDUFA9 restored complex I activity in patient fibroblasts, establishing NDUFA9 as a functionally essential complex I subunit.","method":"Homozygosity mapping, candidate gene sequencing, lentiviral complementation in patient fibroblasts with wild-type vs. mutant NDUFA9","journal":"Journal of medical genetics","confidence":"High","confidence_rationale":"Tier 2 / Moderate — functional complementation with wild-type vs. mutant construct, direct enzymatic activity rescue in patient cells","pmids":["22114105"],"is_preprint":false},{"year":2017,"finding":"NDUFA9 is a Q-module subunit of complex I; patient fibroblasts with NDUFA9 variants show reduced complex I abundance and accumulation of Q-module subassemblies, while the more severe variant also causes P-module subassembly accumulation; both defects are rescued by lentiviral wild-type NDUFA9 complementation.","method":"Blue-native PAGE complex I assembly analysis in patient fibroblasts, lentiviral complementation with wild-type NDUFA9","journal":"Clinical genetics","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct assembly analysis in patient cells with rescue, two independent patient lines, orthogonal complementation","pmids":["28671271"],"is_preprint":false},{"year":2025,"finding":"Biallelic NDUFA9 variants reduce steady-state NDUFA9 protein levels, abolish fully assembled complex I, and decrease complex I activity in patient fibroblasts; protein modelling identifies Arg360 as a mutational hotspot predicted to cause NDUFA9 misfolding and/or disruption of binding interfaces.","method":"Patient fibroblast analysis (western blot, BN-PAGE, enzyme activity), protein structural modelling","journal":"Brain communications","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct biochemical analysis in fibroblasts from three patients, but structural modelling is computational and single-lab","pmids":["41069424"],"is_preprint":false},{"year":2024,"finding":"NDUFA9 crotonylation (induced by SAHA + sodium crotonate treatment) promotes browning of white adipocytes by enhancing mitochondrial complex I activity, ATP synthesis, and mitochondrial respiration, whereas NDUFA9 acetylation inhibits adipocyte browning; the two modifications compete at the same sites.","method":"Chemical induction of crotonylation/acetylation in cultured white adipocytes, NDUFA9 overexpression, mitochondrial respiration assays (Seahorse), complex I activity assay, in vivo fat browning mouse model","journal":"The international journal of biochemistry & cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional assays with multiple readouts in vitro and in vivo, but single lab and post-translational modification identity of crotonylation sites not structurally confirmed","pmids":["38657899"],"is_preprint":false},{"year":2026,"finding":"YY1 transcription factor directly binds the NDUFA9 promoter and upregulates NDUFA9 expression in NSCLC cells; NDUFA9 depletion reduces complex I activity, oxygen consumption rate, ATP production, and inhibits Akt-mTOR signaling (reduced mTOR kinase activity and phosphorylation of Akt and S6K), while NDUFA9 overexpression enhances these activities.","method":"ChIP/reporter assays for YY1 binding, shRNA/KO and overexpression in NSCLC cells, Seahorse mitochondrial assay, complex I activity assay, phospho-protein western blot, xenograft tumor model","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — multiple functional readouts and in vivo validation, but single lab and Akt-mTOR pathway link is mechanistically indirect","pmids":["42014681"],"is_preprint":false}],"current_model":"NDUFA9 is a Q-module subunit of mitochondrial respiratory chain complex I that is essential for stabilizing the junction between the membrane and matrix arms of complex I during a late assembly step; loss-of-function (knockout, patient mutations) causes accumulation of membrane-arm subcomplexes, loss of fully assembled complex I, and abolished complex I enzymatic activity, while its function is regulated post-translationally by competing crotonylation (activating) and acetylation (inhibitory) modifications, and transcriptionally by the YY1 transcription factor."},"narrative":{"mechanistic_narrative":"NDUFA9 is a Q-module subunit of mitochondrial respiratory chain complex I that is required during a late assembly step to stabilize the junction between the membrane and matrix arms of the complex [PMID:23223238, PMID:28671271]. Loss of NDUFA9 by gene knockout blocks complex I assembly and leaves an accumulating membrane-arm subcomplex lacking matrix-arm subunits, with re-expression restoring assembly [PMID:23223238]; in patients, biallelic and homozygous NDUFA9 variants reduce steady-state protein, abolish fully assembled complex I, and abrogate complex I enzymatic activity, with the defect rescued by wild-type but not mutant complementation, establishing NDUFA9 as a functionally essential subunit [PMID:22114105, PMID:28671271, PMID:41069424]. Structural modelling places mutational hotspots (Arg321, Arg360) at positions predicted to destabilize the protein or disrupt binding interfaces [PMID:22114105, PMID:41069424]. Beyond its structural assembly role, NDUFA9 activity is tuned post-translationally by competing acyl modifications—crotonylation enhancing and acetylation inhibiting complex I activity, mitochondrial respiration, and ATP synthesis [PMID:38657899]—and its expression is driven transcriptionally by direct YY1 binding to the NDUFA9 promoter, with NDUFA9 levels in turn supporting oxidative phosphorylation and downstream Akt-mTOR signaling [PMID:42014681].","teleology":[{"year":2011,"claim":"Established that NDUFA9 is a functionally essential complex I subunit by showing a patient missense mutation causes complex I deficiency reversible by wild-type protein.","evidence":"Homozygosity mapping and lentiviral complementation (wild-type vs. Arg321Pro mutant) with enzymatic rescue in patient fibroblasts","pmids":["22114105"],"confidence":"High","gaps":["Did not define the assembly step at which NDUFA9 acts","Single mutation; allelic spectrum unknown"]},{"year":2012,"claim":"Defined the mechanistic role of NDUFA9 as stabilizing the membrane arm–matrix arm junction during a late assembly step, explaining why its loss yields a membrane-arm subcomplex.","evidence":"TALEN knockout in HEK293T, BN-PAGE assembly analysis, galactose growth assay, and re-expression rescue","pmids":["23223238"],"confidence":"High","gaps":["Did not map atomic contacts NDUFA9 makes at the arm junction","Did not place NDUFA9 within the Q-module specifically"]},{"year":2017,"claim":"Localized NDUFA9 to the Q-module and linked variant severity to the spectrum of subassemblies that accumulate, refining the assembly defect.","evidence":"BN-PAGE assembly analysis in two patient fibroblast lines with lentiviral wild-type complementation","pmids":["28671271"],"confidence":"High","gaps":["Mechanism linking severe variants to P-module subassembly accumulation unresolved","No structural model of variant effects"]},{"year":2024,"claim":"Revealed post-translational regulation of NDUFA9 by competing crotonylation (activating) and acetylation (inhibitory) modifications that tune complex I activity and adipocyte browning.","evidence":"Chemical induction of acyl modifications and overexpression in white adipocytes, Seahorse respiration, complex I activity assay, and in vivo fat browning mouse model","pmids":["38657899"],"confidence":"Medium","gaps":["Crotonylation/acetylation site identities not structurally confirmed","Enzymes adding/removing the modifications not identified","Single lab"]},{"year":2025,"claim":"Extended the patient mutation spectrum and used structural modelling to nominate Arg360 as a misfolding/interface-disrupting hotspot.","evidence":"Western blot, BN-PAGE, and enzyme activity in fibroblasts from three patients plus computational protein modelling","pmids":["41069424"],"confidence":"Medium","gaps":["Structural predictions are computational and not experimentally validated","Single-lab modelling"]},{"year":2026,"claim":"Identified transcriptional control of NDUFA9 by YY1 and connected NDUFA9-dependent oxidative phosphorylation to Akt-mTOR signaling in lung cancer cells.","evidence":"ChIP/reporter assays for YY1 binding, shRNA/KO and overexpression in NSCLC cells, Seahorse and complex I assays, phospho-western blot, and xenograft model","pmids":["42014681"],"confidence":"Medium","gaps":["Akt-mTOR link is mechanistically indirect","Single lab","Generality beyond NSCLC unknown"]},{"year":null,"claim":"How NDUFA9's structural assembly role, acyl-modification regulation, and YY1-driven transcription are integrated to control complex I activity across tissues remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No atomic-resolution map of NDUFA9 contacts at the arm junction","Modifying enzymes and crotonylation/acetylation site identities undefined","Tissue-specific integration of regulation uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,2]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0,4]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,4,5]}],"complexes":["mitochondrial respiratory chain complex I"],"partners":[],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q16795","full_name":"NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 9, mitochondrial","aliases":["Complex I-39kD","CI-39kD","NADH-ubiquinone oxidoreductase 39 kDa subunit"],"length_aa":377,"mass_kda":42.5,"function":"Accessory subunit of the mitochondrial membrane respiratory chain NADH dehydrogenase (Complex I), that is believed not to be involved in catalysis. Required for proper complex I assembly (PubMed:28671271). Complex I functions in the transfer of electrons from NADH to the respiratory chain. The immediate electron acceptor for the enzyme is believed to be ubiquinone","subcellular_location":"Mitochondrion matrix","url":"https://www.uniprot.org/uniprotkb/Q16795/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/NDUFA9","classification":"Not Classified","n_dependent_lines":337,"n_total_lines":1208,"dependency_fraction":0.27897350993377484},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/NDUFA9","total_profiled":1310},"omim":[{"mim_id":"618251","title":"MITOCHONDRIAL COMPLEX I DEFICIENCY, NUCLEAR TYPE 31; MC1DN31","url":"https://www.omim.org/entry/618251"},{"mim_id":"618247","title":"MITOCHONDRIAL COMPLEX I DEFICIENCY, NUCLEAR TYPE 26; MC1DN26","url":"https://www.omim.org/entry/618247"},{"mim_id":"615898","title":"NADH DEHYDROGENASE (UBIQUINONE) COMPLEX I, ASSEMBLY FACTOR 7; NDUFAF7","url":"https://www.omim.org/entry/615898"},{"mim_id":"615534","title":"TRANSLOCASE OF INNER MITOCHONDRIAL MEMBRANE DOMAIN-CONTAINING PROTEIN 1; TIMMDC1","url":"https://www.omim.org/entry/615534"},{"mim_id":"614919","title":"NITRIC OXIDE-ASSOCIATED PROTEIN 1; NOA1","url":"https://www.omim.org/entry/614919"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Mitochondria","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/NDUFA9"},"hgnc":{"alias_symbol":["SDR22E1","CI-39k","COQ11"],"prev_symbol":["NDUFS2L"]},"alphafold":{"accession":"Q16795","domains":[{"cath_id":"3.40.50.720","chopping":"40-204","consensus_level":"medium","plddt":95.9328,"start":40,"end":204},{"cath_id":"3.90.25","chopping":"209-238_269-331_344-377","consensus_level":"medium","plddt":93.6212,"start":209,"end":377}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q16795","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q16795-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q16795-F1-predicted_aligned_error_v6.png","plddt_mean":89.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=NDUFA9","jax_strain_url":"https://www.jax.org/strain/search?query=NDUFA9"},"sequence":{"accession":"Q16795","fasta_url":"https://rest.uniprot.org/uniprotkb/Q16795.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q16795/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q16795"}},"corpus_meta":[{"pmid":"23223238","id":"PMC_23223238","title":"Gene knockout using transcription activator-like effector nucleases (TALENs) reveals that human NDUFA9 protein is essential for stabilizing the junction between membrane and matrix arms of complex I.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23223238","citation_count":69,"is_preprint":false},{"pmid":"25631044","id":"PMC_25631044","title":"Identification of Coq11, a new coenzyme Q biosynthetic protein in the CoQ-synthome in Saccharomyces cerevisiae.","date":"2015","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25631044","citation_count":65,"is_preprint":false},{"pmid":"22114105","id":"PMC_22114105","title":"Defective NDUFA9 as a novel cause of neonatally fatal complex I disease.","date":"2011","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22114105","citation_count":45,"is_preprint":false},{"pmid":"28671271","id":"PMC_28671271","title":"NDUFA9 point mutations cause a variable mitochondrial complex I assembly defect.","date":"2017","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/28671271","citation_count":35,"is_preprint":false},{"pmid":"32205446","id":"PMC_32205446","title":"COQ11 deletion mitigates respiratory deficiency caused by mutations in the gene encoding the coenzyme Q chaperone protein Coq10.","date":"2020","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/32205446","citation_count":16,"is_preprint":false},{"pmid":"35892093","id":"PMC_35892093","title":"HIV-1 Tat and cocaine impact astrocytic energy reservoirs and epigenetic regulation by influencing the LINC01133-hsa-miR-4726-5p-NDUFA9 axis.","date":"2022","source":"Molecular therapy. Nucleic acids","url":"https://pubmed.ncbi.nlm.nih.gov/35892093","citation_count":11,"is_preprint":false},{"pmid":"38657899","id":"PMC_38657899","title":"NDUFA9 and its crotonylation modification promote browning of white adipocytes by activating mitochondrial function in mice.","date":"2024","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/38657899","citation_count":6,"is_preprint":false},{"pmid":"37156397","id":"PMC_37156397","title":"Identification of novel coenzyme Q10 biosynthetic proteins Coq11 and Coq12 in Schizosaccharomyces pombe.","date":"2023","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/37156397","citation_count":5,"is_preprint":false},{"pmid":"41069424","id":"PMC_41069424","title":"Biallelic NDUFA9 variants cause a progressive neurodevelopmental disorder with prominent dystonia and mitochondrial complex I deficiency.","date":"2025","source":"Brain communications","url":"https://pubmed.ncbi.nlm.nih.gov/41069424","citation_count":1,"is_preprint":false},{"pmid":"42014681","id":"PMC_42014681","title":"YY1-mediated NDUFA9 upregulation promotes NSCLC cell growth through mitochondrial and Akt-mTOR pathway modulation.","date":"2026","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/42014681","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7478,"output_tokens":1578,"usd":0.023052,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8379,"output_tokens":2210,"usd":0.048572,"stage2_stop_reason":"end_turn"},"total_usd":0.071624,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2012,\n      \"finding\": \"TALEN-mediated knockout of NDUFA9 in HEK293T cells results in loss of NDUFA9 protein, impaired complex I assembly, and accumulation of a subcomplex containing only membrane arm subunits (lacking matrix arm marker subunits), demonstrating that NDUFA9 is required to stabilize the junction between the membrane and matrix arms of complex I as a late assembly step.\",\n      \"method\": \"TALEN gene knockout in HEK293T cells, blue-native PAGE complex I assembly analysis, galactose growth assay, re-expression rescue\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with defined assembly phenotype, rescue by re-expression, multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"23223238\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"A homozygous missense mutation in NDUFA9 (Arg321Pro) causes complex I deficiency; lentiviral transduction with wild-type but not mutant NDUFA9 restored complex I activity in patient fibroblasts, establishing NDUFA9 as a functionally essential complex I subunit.\",\n      \"method\": \"Homozygosity mapping, candidate gene sequencing, lentiviral complementation in patient fibroblasts with wild-type vs. mutant NDUFA9\",\n      \"journal\": \"Journal of medical genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional complementation with wild-type vs. mutant construct, direct enzymatic activity rescue in patient cells\",\n      \"pmids\": [\"22114105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"NDUFA9 is a Q-module subunit of complex I; patient fibroblasts with NDUFA9 variants show reduced complex I abundance and accumulation of Q-module subassemblies, while the more severe variant also causes P-module subassembly accumulation; both defects are rescued by lentiviral wild-type NDUFA9 complementation.\",\n      \"method\": \"Blue-native PAGE complex I assembly analysis in patient fibroblasts, lentiviral complementation with wild-type NDUFA9\",\n      \"journal\": \"Clinical genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct assembly analysis in patient cells with rescue, two independent patient lines, orthogonal complementation\",\n      \"pmids\": [\"28671271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Biallelic NDUFA9 variants reduce steady-state NDUFA9 protein levels, abolish fully assembled complex I, and decrease complex I activity in patient fibroblasts; protein modelling identifies Arg360 as a mutational hotspot predicted to cause NDUFA9 misfolding and/or disruption of binding interfaces.\",\n      \"method\": \"Patient fibroblast analysis (western blot, BN-PAGE, enzyme activity), protein structural modelling\",\n      \"journal\": \"Brain communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct biochemical analysis in fibroblasts from three patients, but structural modelling is computational and single-lab\",\n      \"pmids\": [\"41069424\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"NDUFA9 crotonylation (induced by SAHA + sodium crotonate treatment) promotes browning of white adipocytes by enhancing mitochondrial complex I activity, ATP synthesis, and mitochondrial respiration, whereas NDUFA9 acetylation inhibits adipocyte browning; the two modifications compete at the same sites.\",\n      \"method\": \"Chemical induction of crotonylation/acetylation in cultured white adipocytes, NDUFA9 overexpression, mitochondrial respiration assays (Seahorse), complex I activity assay, in vivo fat browning mouse model\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional assays with multiple readouts in vitro and in vivo, but single lab and post-translational modification identity of crotonylation sites not structurally confirmed\",\n      \"pmids\": [\"38657899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"YY1 transcription factor directly binds the NDUFA9 promoter and upregulates NDUFA9 expression in NSCLC cells; NDUFA9 depletion reduces complex I activity, oxygen consumption rate, ATP production, and inhibits Akt-mTOR signaling (reduced mTOR kinase activity and phosphorylation of Akt and S6K), while NDUFA9 overexpression enhances these activities.\",\n      \"method\": \"ChIP/reporter assays for YY1 binding, shRNA/KO and overexpression in NSCLC cells, Seahorse mitochondrial assay, complex I activity assay, phospho-protein western blot, xenograft tumor model\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — multiple functional readouts and in vivo validation, but single lab and Akt-mTOR pathway link is mechanistically indirect\",\n      \"pmids\": [\"42014681\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"NDUFA9 is a Q-module subunit of mitochondrial respiratory chain complex I that is essential for stabilizing the junction between the membrane and matrix arms of complex I during a late assembly step; loss-of-function (knockout, patient mutations) causes accumulation of membrane-arm subcomplexes, loss of fully assembled complex I, and abolished complex I enzymatic activity, while its function is regulated post-translationally by competing crotonylation (activating) and acetylation (inhibitory) modifications, and transcriptionally by the YY1 transcription factor.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"NDUFA9 is a Q-module subunit of mitochondrial respiratory chain complex I that is required during a late assembly step to stabilize the junction between the membrane and matrix arms of the complex [#0, #2]. Loss of NDUFA9 by gene knockout blocks complex I assembly and leaves an accumulating membrane-arm subcomplex lacking matrix-arm subunits, with re-expression restoring assembly [#0]; in patients, biallelic and homozygous NDUFA9 variants reduce steady-state protein, abolish fully assembled complex I, and abrogate complex I enzymatic activity, with the defect rescued by wild-type but not mutant complementation, establishing NDUFA9 as a functionally essential subunit [#1, #2, #3]. Structural modelling places mutational hotspots (Arg321, Arg360) at positions predicted to destabilize the protein or disrupt binding interfaces [#1, #3]. Beyond its structural assembly role, NDUFA9 activity is tuned post-translationally by competing acyl modifications—crotonylation enhancing and acetylation inhibiting complex I activity, mitochondrial respiration, and ATP synthesis [#4]—and its expression is driven transcriptionally by direct YY1 binding to the NDUFA9 promoter, with NDUFA9 levels in turn supporting oxidative phosphorylation and downstream Akt-mTOR signaling [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Established that NDUFA9 is a functionally essential complex I subunit by showing a patient missense mutation causes complex I deficiency reversible by wild-type protein.\",\n      \"evidence\": \"Homozygosity mapping and lentiviral complementation (wild-type vs. Arg321Pro mutant) with enzymatic rescue in patient fibroblasts\",\n      \"pmids\": [\"22114105\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the assembly step at which NDUFA9 acts\", \"Single mutation; allelic spectrum unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defined the mechanistic role of NDUFA9 as stabilizing the membrane arm–matrix arm junction during a late assembly step, explaining why its loss yields a membrane-arm subcomplex.\",\n      \"evidence\": \"TALEN knockout in HEK293T, BN-PAGE assembly analysis, galactose growth assay, and re-expression rescue\",\n      \"pmids\": [\"23223238\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not map atomic contacts NDUFA9 makes at the arm junction\", \"Did not place NDUFA9 within the Q-module specifically\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Localized NDUFA9 to the Q-module and linked variant severity to the spectrum of subassemblies that accumulate, refining the assembly defect.\",\n      \"evidence\": \"BN-PAGE assembly analysis in two patient fibroblast lines with lentiviral wild-type complementation\",\n      \"pmids\": [\"28671271\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking severe variants to P-module subassembly accumulation unresolved\", \"No structural model of variant effects\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Revealed post-translational regulation of NDUFA9 by competing crotonylation (activating) and acetylation (inhibitory) modifications that tune complex I activity and adipocyte browning.\",\n      \"evidence\": \"Chemical induction of acyl modifications and overexpression in white adipocytes, Seahorse respiration, complex I activity assay, and in vivo fat browning mouse model\",\n      \"pmids\": [\"38657899\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Crotonylation/acetylation site identities not structurally confirmed\", \"Enzymes adding/removing the modifications not identified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended the patient mutation spectrum and used structural modelling to nominate Arg360 as a misfolding/interface-disrupting hotspot.\",\n      \"evidence\": \"Western blot, BN-PAGE, and enzyme activity in fibroblasts from three patients plus computational protein modelling\",\n      \"pmids\": [\"41069424\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural predictions are computational and not experimentally validated\", \"Single-lab modelling\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Identified transcriptional control of NDUFA9 by YY1 and connected NDUFA9-dependent oxidative phosphorylation to Akt-mTOR signaling in lung cancer cells.\",\n      \"evidence\": \"ChIP/reporter assays for YY1 binding, shRNA/KO and overexpression in NSCLC cells, Seahorse and complex I assays, phospho-western blot, and xenograft model\",\n      \"pmids\": [\"42014681\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Akt-mTOR link is mechanistically indirect\", \"Single lab\", \"Generality beyond NSCLC unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How NDUFA9's structural assembly role, acyl-modification regulation, and YY1-driven transcription are integrated to control complex I activity across tissues remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No atomic-resolution map of NDUFA9 contacts at the arm junction\", \"Modifying enzymes and crotonylation/acetylation site identities undefined\", \"Tissue-specific integration of regulation uncharacterized\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 4, 5]}\n    ],\n    \"complexes\": [\"mitochondrial respiratory chain complex I\"],\n    \"partners\": [],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}