{"gene":"TIMM29","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2016,"finding":"TIM29 (C19orf52/TIMM29) is a novel, metazoan-specific subunit of the human TIM22 complex, integrated into the mitochondrial inner membrane with its C-terminus exposed to the intermembrane space. TIM29 is required for the stability of the TIM22 complex, functions in the assembly of hTim22, and contacts the TOM complex to enable transport of hydrophobic carrier substrates across the aqueous intermembrane space.","method":"Immunoprecipitation/co-IP, subcellular fractionation, live imaging/localization, knockdown with functional import assays","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, localization experiments, functional KD phenotype, replicated independently by two labs same year","pmids":["27554484"],"is_preprint":false},{"year":2016,"finding":"TIM29 is a constituent of the ~440 kDa human TIM22 complex, interacts with oxidized TIM22, and is required for the structural integrity of the TIM22 complex and for import of substrate proteins by the carrier translocase.","method":"Immunoprecipitation, blue-native PAGE, siRNA knockdown with import assays","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP, native gel analysis, functional KD, independently replicated by parallel study (PMID:27554484)","pmids":["27718247"],"is_preprint":false},{"year":2017,"finding":"AGK assembles with TIMM22 and TIMM29 as a constituent of the TIM22 complex in the mitochondrial inner membrane and supports the import of a subset of multi-spanning membrane proteins; AGK's function as a TIM22 subunit does not depend on its kinase activity.","method":"Mitochondrial interactome/MS, co-immunoprecipitation, import assays, kinase-dead mutant complementation","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — MS-based interactome + Co-IP + functional import assays + mutagenesis, published in high-tier journal","pmids":["28712724"],"is_preprint":false},{"year":2020,"finding":"TIMM29 physically interacts with the preS1 region of the HBV large S protein, specifically binding amino acids 92–189 of TIMM29; overexpression of TIMM29 decreases HBV replication (HBeAg, extracellular and intracellular HBV DNA) without affecting cccDNA formation, while TIMM29 knockout increases HBV production.","method":"Immunoprecipitation with preS1 peptides, GST-pulldown, immunofluorescence co-localization, TIMM29 overexpression and knockout cell lines with HBV replication readouts","journal":"Microbiology and immunology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — two orthogonal binding assays (IP + GST pulldown) plus functional KO/OE, single lab","pmids":["32970362"],"is_preprint":false},{"year":2025,"finding":"Loss of TIMM29 function reduces the presence of iron transporters on mitochondria, thereby impairing iron uptake from the cytosol and disrupting mitochondrial iron-sulfur (Fe-S) cluster biogenesis; reconstituting mitochondrial iron levels restores Fe-S biogenesis and proliferation in TIMM29-deficient cells and rescues embryonic development in timm29-deficient zebrafish.","method":"CRISPR screening, DepMap co-essentiality analysis, TIMM29 KO cells with Fe-S biogenesis assays, iron reconstitution rescue experiments, zebrafish timm29 knockdown","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — CRISPR KO + functional biochemical assays + in vivo zebrafish rescue, multiple orthogonal methods","pmids":["41418755"],"is_preprint":false},{"year":2024,"finding":"Overexpression of TIM29 (and TIM22) significantly reduces intracellular HBV DNA, RNA, and secreted HBV antigens by reducing core promoter activity via increased expression of SRSF1, which acts as a suppressor of HBV replication.","method":"Overexpression of TIM22/TIM29 in hepatocyte cell lines, HBV replication assays, core promoter activity reporter assays, SRSF1 expression analysis","journal":"Journal of medical virology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — overexpression with functional readouts and pathway placement via SRSF1, single lab, no KO confirmation of mechanism","pmids":["38294104"],"is_preprint":false},{"year":2025,"finding":"Full-length TIMM29 (amino acids 99–189 region, the preS1-binding domain) is required to upregulate ARRDC3 expression, which contributes to restriction of HBV transcription; BASP1 expression is also downregulated in TIMM29 KO cells but varies by cell type. Deletion mutants lacking amino acids 99–192 fail to suppress HBV replication, confirming functional dependence on this region.","method":"TIMM29 KO cell lines reconstituted with full-length or deletion mutant TIMM29, gene expression microarrays, HBV replication assays","journal":"Microbiology and immunology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — domain deletion mutagenesis in KO background with functional assays and transcriptome readout, single lab","pmids":["39956808"],"is_preprint":false},{"year":2025,"finding":"Biallelic loss-of-function variant in TIMM29 (p.Trp172Arg) causes a severe form of Sengers syndrome associated with combined mitochondrial respiratory chain complex deficiency, reduced pyruvate dehydrogenase complex activity, and reduced adenine nucleotide translocator 1 protein levels; knockdown of the Drosophila TIMM29 orthologue (CG14270) recapitulates the human phenotype.","method":"Homozygosity mapping, gene sequencing, patient tissue biochemical analysis, Drosophila RNAi knockdown phenotypic analysis","journal":"Human genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic variant mapping + patient biochemistry + Drosophila model KD, two orthogonal systems, single study","pmids":["40022150"],"is_preprint":false},{"year":2021,"finding":"TIM29 knockdown in the flatworm Macrostomum lignano has minimal effect under normal homeostatic conditions but prevents worms from entering the highly proliferative state required for regeneration, demonstrating a context-dependent role for TIM29 in stem cell activity.","method":"RNAi knockdown in M. lignano with regeneration and proliferation assays","journal":"Scientific reports","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single-organism RNAi KD with phenotypic readout, no molecular mechanism determined, single lab","pmids":["33441924"],"is_preprint":false}],"current_model":"TIMM29 is a metazoan-specific subunit of the inner mitochondrial membrane TIM22 carrier translocase complex, where it stabilizes complex assembly, facilitates hTim22 integration, bridges the TIM22 and TOM complexes to enable hydrophobic carrier protein import across the intermembrane space, and—through supporting import of iron transporters—enables mitochondrial iron uptake required for iron-sulfur cluster biogenesis; additionally, TIMM29 interacts with hepatitis B virus preS1 protein and restricts HBV replication partly through upregulation of ARRDC3 and SRSF1, while loss-of-function mutations in TIMM29 cause a severe form of Sengers syndrome characterized by combined respiratory chain complex deficiency and reduced ANT1 levels."},"narrative":{"mechanistic_narrative":"TIMM29 is a metazoan-specific subunit of the human TIM22 carrier translocase in the mitochondrial inner membrane, where it underpins the import of hydrophobic multi-spanning carrier proteins from the cytosol [PMID:27554484, PMID:27718247]. Integrated into the inner membrane with its C-terminus exposed to the intermembrane space, TIMM29 is required for the structural stability of the ~440 kDa TIM22 complex, facilitates assembly of the hTim22 channel, and physically bridges the TIM22 complex to the TOM complex to enable transport of substrates across the aqueous intermembrane space [PMID:27554484, PMID:27718247]. It assembles with TIMM22 and AGK as a core constituent of the complex, with AGK contributing independently of its kinase activity [PMID:28712724]. Through this import activity, TIMM29 supports delivery of iron transporters to mitochondria; its loss reduces mitochondrial iron uptake and disrupts iron-sulfur cluster biogenesis, a defect rescued by reconstituting mitochondrial iron levels in cells and in zebrafish [PMID:41418755]. A biallelic loss-of-function variant (p.Trp172Arg) causes a severe form of Sengers syndrome marked by combined respiratory chain complex deficiency and reduced ANT1 levels [PMID:40022150]. Independently of its translocase role, TIMM29 binds the preS1 region of the hepatitis B virus large S protein and restricts HBV replication, acting partly through upregulation of the host factors SRSF1 and ARRDC3 [PMID:32970362, PMID:38294104, PMID:39956808].","teleology":[{"year":2016,"claim":"Established that an uncharacterized inner-membrane protein (C19orf52) is a bona fide subunit of the carrier translocase, answering how the metazoan TIM22 complex is organized and connected to the import machinery.","evidence":"Reciprocal co-IP, subcellular fractionation, localization, and knockdown import assays in human cells; replicated by blue-native PAGE and siRNA import assays in a parallel study","pmids":["27554484","27718247"],"confidence":"High","gaps":["No high-resolution structure of TIM29 within the assembled complex","Molecular details of the TIM22-TOM bridging contact not defined"]},{"year":2017,"claim":"Defined the broader subunit composition of the TIM22 complex by showing AGK co-assembles with TIMM22 and TIMM29, clarifying that import function is structural rather than catalytic.","evidence":"Mitochondrial interactome MS, co-IP, import assays, and kinase-dead complementation in human cells","pmids":["28712724"],"confidence":"High","gaps":["Stoichiometry of TIMM29 relative to AGK and TIMM22 not resolved","Direct interaction surface between TIMM29 and AGK not mapped"]},{"year":2020,"claim":"Revealed a non-import function by showing TIMM29 directly binds HBV preS1 and restricts viral replication, raising the question of host antiviral roles for a mitochondrial translocase subunit.","evidence":"preS1 peptide IP, GST-pulldown, immunofluorescence co-localization, and HBV replication readouts in TIMM29 OE and KO cell lines","pmids":["32970362"],"confidence":"Medium","gaps":["Single lab, no reciprocal validation in other models","Mechanism linking preS1 binding to replication restriction not established at this stage"]},{"year":2024,"claim":"Began to define the downstream pathway of HBV restriction by linking TIMM29 overexpression to reduced core promoter activity via SRSF1 induction.","evidence":"TIM22/TIM29 overexpression in hepatocyte lines with HBV replication assays, core promoter reporters, and SRSF1 expression analysis","pmids":["38294104"],"confidence":"Medium","gaps":["No KO confirmation that SRSF1 is required","Single lab; connection between mitochondrial role and SRSF1 induction unclear"]},{"year":2025,"claim":"Mapped the TIMM29 domain and a second effector required for HBV restriction, showing the aa 99-192 region drives ARRDC3 upregulation to suppress viral transcription.","evidence":"Domain deletion mutants reconstituted into KO cells with gene expression microarrays and HBV replication assays","pmids":["39956808"],"confidence":"Medium","gaps":["ARRDC3 sufficiency and necessity not directly tested by epistasis","Cell-type variability of BASP1 effect unexplained","Single lab"]},{"year":2025,"claim":"Connected TIMM29 import activity to organismal physiology by showing its loss impairs mitochondrial iron uptake and Fe-S cluster biogenesis, with iron reconstitution rescuing the defect.","evidence":"CRISPR KO and co-essentiality analysis, Fe-S biogenesis assays, iron reconstitution rescue, and zebrafish timm29 knockdown rescue","pmids":["41418755"],"confidence":"High","gaps":["Identity of the specific iron transporters dependent on TIM22 import not fully enumerated","Whether the iron defect fully accounts for proliferation phenotypes"]},{"year":2025,"claim":"Established TIMM29 as a disease gene by linking a biallelic loss-of-function variant to a severe form of Sengers syndrome with combined respiratory chain deficiency and reduced ANT1.","evidence":"Homozygosity mapping, sequencing, patient tissue biochemistry, and Drosophila orthologue RNAi knockdown","pmids":["40022150"],"confidence":"Medium","gaps":["Single family/study","Genotype-phenotype correlation across other variants not established","Mechanistic basis of ANT1 reduction not directly demonstrated"]},{"year":null,"claim":"How TIMM29 reconciles its core carrier-import function with its distinct HBV-restriction activity, and whether the two operate through the same molecular surface, remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of TIM29 in the assembled TIM22 complex","Unclear whether HBV restriction depends on translocase activity or is independent","Full substrate repertoire of the TIM22 complex incompletely defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0,1,2]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,1]}],"complexes":["TIM22 carrier translocase"],"partners":["TIMM22","AGK","TOMM COMPLEX"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BSF4","full_name":"Mitochondrial import inner membrane translocase subunit Tim29","aliases":[],"length_aa":260,"mass_kda":29.2,"function":"Component of the TIM22 complex, a complex that mediates the import and insertion of multi-pass transmembrane proteins into the mitochondrial inner membrane. The TIM22 complex forms a twin-pore translocase that uses the membrane potential as the external driving force. Required for the stability of the TIM22 complex and functions in the assembly of the TIMM22 protein into the TIM22 complex. May facilitate cooperation between TIM22 and TOM complexes by interacting with TOMM40","subcellular_location":"Mitochondrion inner membrane","url":"https://www.uniprot.org/uniprotkb/Q9BSF4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/TIMM29","classification":"Common Essential","n_dependent_lines":807,"n_total_lines":1208,"dependency_fraction":0.668046357615894},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TIMM29","total_profiled":1310},"omim":[{"mim_id":"618851","title":"COMBINED OXIDATIVE PHOSPHORYLATION DEFICIENCY 43; COXPD43","url":"https://www.omim.org/entry/618851"},{"mim_id":"617380","title":"TRANSLOCASE OF INNER MITOCHONDRIAL MEMBRANE 29; TIMM29","url":"https://www.omim.org/entry/617380"},{"mim_id":"607251","title":"TRANSLOCASE OF INNER MITOCHONDRIAL MEMBRANE 22; TIMM22","url":"https://www.omim.org/entry/607251"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Mitochondria","reliability":"Supported"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TIMM29"},"hgnc":{"alias_symbol":["TIM29"],"prev_symbol":["C19orf52"]},"alphafold":{"accession":"Q9BSF4","domains":[{"cath_id":"-","chopping":"81-190","consensus_level":"high","plddt":93.2212,"start":81,"end":190},{"cath_id":"-","chopping":"203-244","consensus_level":"medium","plddt":89.5979,"start":203,"end":244}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BSF4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BSF4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BSF4-F1-predicted_aligned_error_v6.png","plddt_mean":87.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TIMM29","jax_strain_url":"https://www.jax.org/strain/search?query=TIMM29"},"sequence":{"accession":"Q9BSF4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BSF4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BSF4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BSF4"}},"corpus_meta":[{"pmid":"28712724","id":"PMC_28712724","title":"Acylglycerol Kinase Mutated in Sengers Syndrome Is a Subunit of the TIM22 Protein Translocase in Mitochondria.","date":"2017","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/28712724","citation_count":113,"is_preprint":false},{"pmid":"27554484","id":"PMC_27554484","title":"Tim29 is a novel subunit of the human TIM22 translocase and is involved in complex assembly and stability.","date":"2016","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/27554484","citation_count":70,"is_preprint":false},{"pmid":"27718247","id":"PMC_27718247","title":"TIM29 is a subunit of the human carrier translocase required for protein transport.","date":"2016","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/27718247","citation_count":53,"is_preprint":false},{"pmid":"32970362","id":"PMC_32970362","title":"TIMM29 interacts with hepatitis B virus preS1 to modulate the HBV life cycle.","date":"2020","source":"Microbiology and immunology","url":"https://pubmed.ncbi.nlm.nih.gov/32970362","citation_count":9,"is_preprint":false},{"pmid":"33014348","id":"PMC_33014348","title":"Independent accretion of TIM22 complex subunits in the animal and fungal lineages.","date":"2020","source":"F1000Research","url":"https://pubmed.ncbi.nlm.nih.gov/33014348","citation_count":8,"is_preprint":false},{"pmid":"38294104","id":"PMC_38294104","title":"TIM22 and TIM29 inhibit HBV replication by up-regulating SRSF1 expression.","date":"2024","source":"Journal of medical virology","url":"https://pubmed.ncbi.nlm.nih.gov/38294104","citation_count":4,"is_preprint":false},{"pmid":"40022150","id":"PMC_40022150","title":"Sengers syndrome caused by biallelic TIMM29 variants and RNAi silencing in Drosophila orthologue recapitulates the human phenotype.","date":"2025","source":"Human genomics","url":"https://pubmed.ncbi.nlm.nih.gov/40022150","citation_count":3,"is_preprint":false},{"pmid":"33441924","id":"PMC_33441924","title":"TIM29 is required for enhanced stem cell activity during regeneration in the flatworm Macrostomum lignano.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/33441924","citation_count":3,"is_preprint":false},{"pmid":"41418755","id":"PMC_41418755","title":"The TIM22 carrier translocase supports cell proliferation by facilitating mitochondrial iron uptake for Fe-S biogenesis.","date":"2025","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/41418755","citation_count":1,"is_preprint":false},{"pmid":"39956808","id":"PMC_39956808","title":"Analysis of the Functional Role of TIMM29 in the Hepatitis B Virus Life Cycle.","date":"2025","source":"Microbiology and immunology","url":"https://pubmed.ncbi.nlm.nih.gov/39956808","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6674,"output_tokens":2297,"usd":0.027238,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9350,"output_tokens":2667,"usd":0.056712,"stage2_stop_reason":"end_turn"},"total_usd":0.08395,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2016,\n      \"finding\": \"TIM29 (C19orf52/TIMM29) is a novel, metazoan-specific subunit of the human TIM22 complex, integrated into the mitochondrial inner membrane with its C-terminus exposed to the intermembrane space. TIM29 is required for the stability of the TIM22 complex, functions in the assembly of hTim22, and contacts the TOM complex to enable transport of hydrophobic carrier substrates across the aqueous intermembrane space.\",\n      \"method\": \"Immunoprecipitation/co-IP, subcellular fractionation, live imaging/localization, knockdown with functional import assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, localization experiments, functional KD phenotype, replicated independently by two labs same year\",\n      \"pmids\": [\"27554484\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"TIM29 is a constituent of the ~440 kDa human TIM22 complex, interacts with oxidized TIM22, and is required for the structural integrity of the TIM22 complex and for import of substrate proteins by the carrier translocase.\",\n      \"method\": \"Immunoprecipitation, blue-native PAGE, siRNA knockdown with import assays\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP, native gel analysis, functional KD, independently replicated by parallel study (PMID:27554484)\",\n      \"pmids\": [\"27718247\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"AGK assembles with TIMM22 and TIMM29 as a constituent of the TIM22 complex in the mitochondrial inner membrane and supports the import of a subset of multi-spanning membrane proteins; AGK's function as a TIM22 subunit does not depend on its kinase activity.\",\n      \"method\": \"Mitochondrial interactome/MS, co-immunoprecipitation, import assays, kinase-dead mutant complementation\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — MS-based interactome + Co-IP + functional import assays + mutagenesis, published in high-tier journal\",\n      \"pmids\": [\"28712724\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TIMM29 physically interacts with the preS1 region of the HBV large S protein, specifically binding amino acids 92–189 of TIMM29; overexpression of TIMM29 decreases HBV replication (HBeAg, extracellular and intracellular HBV DNA) without affecting cccDNA formation, while TIMM29 knockout increases HBV production.\",\n      \"method\": \"Immunoprecipitation with preS1 peptides, GST-pulldown, immunofluorescence co-localization, TIMM29 overexpression and knockout cell lines with HBV replication readouts\",\n      \"journal\": \"Microbiology and immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — two orthogonal binding assays (IP + GST pulldown) plus functional KO/OE, single lab\",\n      \"pmids\": [\"32970362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Loss of TIMM29 function reduces the presence of iron transporters on mitochondria, thereby impairing iron uptake from the cytosol and disrupting mitochondrial iron-sulfur (Fe-S) cluster biogenesis; reconstituting mitochondrial iron levels restores Fe-S biogenesis and proliferation in TIMM29-deficient cells and rescues embryonic development in timm29-deficient zebrafish.\",\n      \"method\": \"CRISPR screening, DepMap co-essentiality analysis, TIMM29 KO cells with Fe-S biogenesis assays, iron reconstitution rescue experiments, zebrafish timm29 knockdown\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — CRISPR KO + functional biochemical assays + in vivo zebrafish rescue, multiple orthogonal methods\",\n      \"pmids\": [\"41418755\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Overexpression of TIM29 (and TIM22) significantly reduces intracellular HBV DNA, RNA, and secreted HBV antigens by reducing core promoter activity via increased expression of SRSF1, which acts as a suppressor of HBV replication.\",\n      \"method\": \"Overexpression of TIM22/TIM29 in hepatocyte cell lines, HBV replication assays, core promoter activity reporter assays, SRSF1 expression analysis\",\n      \"journal\": \"Journal of medical virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — overexpression with functional readouts and pathway placement via SRSF1, single lab, no KO confirmation of mechanism\",\n      \"pmids\": [\"38294104\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Full-length TIMM29 (amino acids 99–189 region, the preS1-binding domain) is required to upregulate ARRDC3 expression, which contributes to restriction of HBV transcription; BASP1 expression is also downregulated in TIMM29 KO cells but varies by cell type. Deletion mutants lacking amino acids 99–192 fail to suppress HBV replication, confirming functional dependence on this region.\",\n      \"method\": \"TIMM29 KO cell lines reconstituted with full-length or deletion mutant TIMM29, gene expression microarrays, HBV replication assays\",\n      \"journal\": \"Microbiology and immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — domain deletion mutagenesis in KO background with functional assays and transcriptome readout, single lab\",\n      \"pmids\": [\"39956808\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Biallelic loss-of-function variant in TIMM29 (p.Trp172Arg) causes a severe form of Sengers syndrome associated with combined mitochondrial respiratory chain complex deficiency, reduced pyruvate dehydrogenase complex activity, and reduced adenine nucleotide translocator 1 protein levels; knockdown of the Drosophila TIMM29 orthologue (CG14270) recapitulates the human phenotype.\",\n      \"method\": \"Homozygosity mapping, gene sequencing, patient tissue biochemical analysis, Drosophila RNAi knockdown phenotypic analysis\",\n      \"journal\": \"Human genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic variant mapping + patient biochemistry + Drosophila model KD, two orthogonal systems, single study\",\n      \"pmids\": [\"40022150\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TIM29 knockdown in the flatworm Macrostomum lignano has minimal effect under normal homeostatic conditions but prevents worms from entering the highly proliferative state required for regeneration, demonstrating a context-dependent role for TIM29 in stem cell activity.\",\n      \"method\": \"RNAi knockdown in M. lignano with regeneration and proliferation assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single-organism RNAi KD with phenotypic readout, no molecular mechanism determined, single lab\",\n      \"pmids\": [\"33441924\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TIMM29 is a metazoan-specific subunit of the inner mitochondrial membrane TIM22 carrier translocase complex, where it stabilizes complex assembly, facilitates hTim22 integration, bridges the TIM22 and TOM complexes to enable hydrophobic carrier protein import across the intermembrane space, and—through supporting import of iron transporters—enables mitochondrial iron uptake required for iron-sulfur cluster biogenesis; additionally, TIMM29 interacts with hepatitis B virus preS1 protein and restricts HBV replication partly through upregulation of ARRDC3 and SRSF1, while loss-of-function mutations in TIMM29 cause a severe form of Sengers syndrome characterized by combined respiratory chain complex deficiency and reduced ANT1 levels.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TIMM29 is a metazoan-specific subunit of the human TIM22 carrier translocase in the mitochondrial inner membrane, where it underpins the import of hydrophobic multi-spanning carrier proteins from the cytosol [#0, #1]. Integrated into the inner membrane with its C-terminus exposed to the intermembrane space, TIMM29 is required for the structural stability of the ~440 kDa TIM22 complex, facilitates assembly of the hTim22 channel, and physically bridges the TIM22 complex to the TOM complex to enable transport of substrates across the aqueous intermembrane space [#0, #1]. It assembles with TIMM22 and AGK as a core constituent of the complex, with AGK contributing independently of its kinase activity [#2]. Through this import activity, TIMM29 supports delivery of iron transporters to mitochondria; its loss reduces mitochondrial iron uptake and disrupts iron-sulfur cluster biogenesis, a defect rescued by reconstituting mitochondrial iron levels in cells and in zebrafish [#4]. A biallelic loss-of-function variant (p.Trp172Arg) causes a severe form of Sengers syndrome marked by combined respiratory chain complex deficiency and reduced ANT1 levels [#7]. Independently of its translocase role, TIMM29 binds the preS1 region of the hepatitis B virus large S protein and restricts HBV replication, acting partly through upregulation of the host factors SRSF1 and ARRDC3 [#3, #5, #6].\",\n  \"teleology\": [\n    {\n      \"year\": 2016,\n      \"claim\": \"Established that an uncharacterized inner-membrane protein (C19orf52) is a bona fide subunit of the carrier translocase, answering how the metazoan TIM22 complex is organized and connected to the import machinery.\",\n      \"evidence\": \"Reciprocal co-IP, subcellular fractionation, localization, and knockdown import assays in human cells; replicated by blue-native PAGE and siRNA import assays in a parallel study\",\n      \"pmids\": [\"27554484\", \"27718247\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of TIM29 within the assembled complex\", \"Molecular details of the TIM22-TOM bridging contact not defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined the broader subunit composition of the TIM22 complex by showing AGK co-assembles with TIMM22 and TIMM29, clarifying that import function is structural rather than catalytic.\",\n      \"evidence\": \"Mitochondrial interactome MS, co-IP, import assays, and kinase-dead complementation in human cells\",\n      \"pmids\": [\"28712724\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of TIMM29 relative to AGK and TIMM22 not resolved\", \"Direct interaction surface between TIMM29 and AGK not mapped\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Revealed a non-import function by showing TIMM29 directly binds HBV preS1 and restricts viral replication, raising the question of host antiviral roles for a mitochondrial translocase subunit.\",\n      \"evidence\": \"preS1 peptide IP, GST-pulldown, immunofluorescence co-localization, and HBV replication readouts in TIMM29 OE and KO cell lines\",\n      \"pmids\": [\"32970362\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, no reciprocal validation in other models\", \"Mechanism linking preS1 binding to replication restriction not established at this stage\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Began to define the downstream pathway of HBV restriction by linking TIMM29 overexpression to reduced core promoter activity via SRSF1 induction.\",\n      \"evidence\": \"TIM22/TIM29 overexpression in hepatocyte lines with HBV replication assays, core promoter reporters, and SRSF1 expression analysis\",\n      \"pmids\": [\"38294104\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No KO confirmation that SRSF1 is required\", \"Single lab; connection between mitochondrial role and SRSF1 induction unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Mapped the TIMM29 domain and a second effector required for HBV restriction, showing the aa 99-192 region drives ARRDC3 upregulation to suppress viral transcription.\",\n      \"evidence\": \"Domain deletion mutants reconstituted into KO cells with gene expression microarrays and HBV replication assays\",\n      \"pmids\": [\"39956808\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"ARRDC3 sufficiency and necessity not directly tested by epistasis\", \"Cell-type variability of BASP1 effect unexplained\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected TIMM29 import activity to organismal physiology by showing its loss impairs mitochondrial iron uptake and Fe-S cluster biogenesis, with iron reconstitution rescuing the defect.\",\n      \"evidence\": \"CRISPR KO and co-essentiality analysis, Fe-S biogenesis assays, iron reconstitution rescue, and zebrafish timm29 knockdown rescue\",\n      \"pmids\": [\"41418755\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the specific iron transporters dependent on TIM22 import not fully enumerated\", \"Whether the iron defect fully accounts for proliferation phenotypes\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Established TIMM29 as a disease gene by linking a biallelic loss-of-function variant to a severe form of Sengers syndrome with combined respiratory chain deficiency and reduced ANT1.\",\n      \"evidence\": \"Homozygosity mapping, sequencing, patient tissue biochemistry, and Drosophila orthologue RNAi knockdown\",\n      \"pmids\": [\"40022150\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single family/study\", \"Genotype-phenotype correlation across other variants not established\", \"Mechanistic basis of ANT1 reduction not directly demonstrated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TIMM29 reconciles its core carrier-import function with its distinct HBV-restriction activity, and whether the two operate through the same molecular surface, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of TIM29 in the assembled TIM22 complex\", \"Unclear whether HBV restriction depends on translocase activity or is independent\", \"Full substrate repertoire of the TIM22 complex incompletely defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [\"TIM22 carrier translocase\"],\n    \"partners\": [\"TIMM22\", \"AGK\", \"TOMM complex\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}