{"gene":"TG_254120","gene_symbol":"ATG8","run_date":"2026-09-08T12:58:25","timeline":{"discoveries":[{"year":2011,"finding":"TgATG8 serves as an autophagosome marker in T. gondii; autophagosomes are induced by amino acid starvation and also form during normal intracellular development. TgAtg3 is required for conjugation of TgAtg8 to the autophagosomal membrane, and TgAtg3-depleted parasites exhibit mitochondrial fragmentation and severe growth defects, indicating TgAtg3-dependent autophagy regulates mitochondrial homeostasis during cell division.","method":"Conditional knockdown of TgAtg3; TgATG8 used as autophagosome marker; fluorescence microscopy; growth assays","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Moderate — conditional knockout with multiple orthogonal readouts (autophagosome marker, mitochondrial morphology, growth phenotype), single lab","pmids":["22144900"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2013,"finding":"TgATG4 is required for recycling of membrane-bound TgATG8 (delipidation). TgATG4-depleted parasites are defective in recycling membrane-associated TgATG8 and show mitochondrial fragmentation and loss of the apicoplast, demonstrating that TgATG4 regulates TgATG8 membrane association/dissociation and organelle homeostasis. TgATG8's C-terminus does not require processing prior to membrane association in T. gondii, unlike most eukaryotes.","method":"Conditional expression mutant of TgATG4; Western blotting; fluorescence microscopy; growth assays","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 2 / Moderate — conditional knockdown with multiple organellar phenotypes and biochemical readout for ATG8 lipidation, single lab","pmids":["23748741"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2015,"finding":"TgATG8 localizes to the outermost membrane of the apicoplast under normal intracellular growth conditions (not just to autophagosomes). Conditional knockdown of TgATG8 causes rapid loss of the apicoplast and intracellular replication defects due to abnormal apicoplast segregation into daughter cells, linked to loss of physical interactions between the apicoplast and centrosomes. This reveals a non-canonical, non-catabolic role for TgATG8 in apicoplast inheritance.","method":"Superresolution microscopy; biochemical fractionation; conditional knockdown; live imaging; growth assays","journal":"mBio","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional knockdown with superresolution microscopy, biochemical localization, and multiple cellular phenotypes; replicated in subsequent studies","pmids":["26507233"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2015,"finding":"TgATG8 and TgATG3 interact directly with high affinity (KD = 34.9 nM) as demonstrated by co-immunoprecipitation from parasite lysates and surface plasmon resonance. TgATG8 partially colocalizes with TgATG3 in parasites.","method":"Tandem affinity purification with anti-GFP antibody; Western blot; tandem mass spectrometry; surface plasmon resonance (BIAcore); immunofluorescence assay","journal":"Acta tropica","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — direct in vitro binding assay (SPR) plus pulldown from parasite lysate, single lab, two orthogonal methods","pmids":["26407821"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2012,"finding":"Monensin treatment induces autophagy in T. gondii as evidenced by translocation of ATG8 to autophagosomes. The autophagy inhibitor 3-methyladenine blocks ATG8 translocation and enhances parasite survival, establishing autophagy as a mechanism of monensin-induced parasite death.","method":"ATG8 localization by fluorescence microscopy; pharmacological inhibition with 3-methyladenine; survival assays","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — ATG8 as autophagy readout with pharmacological modulation, single lab, two supporting methods","pmids":["22848721"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2018,"finding":"The TgATG8-TgATG3 interaction interface was molecularly characterized: the core Atg8-family interacting motif (AIM) in TgATG3 is 239FADI242, distinct from the Plasmodium Atg3 AIM (105WLLP108). Substitution of conserved TgATG8 residues at the AIM-docking site disrupts TgATG8-TgATG3 interaction and reduces TgATG8 lipidation and autophagosome formation. Surrounding residues N238, D243, and C244 in TgATG3 also contribute to binding.","method":"Mutagenesis (alanine-scanning); peptide assay; AlphaScreen assay; lipidation assay; in vitro binding","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — active-site mutagenesis combined with multiple in vitro binding and functional assays (AlphaScreen, peptide, lipidation), single lab","pmids":["30026233"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"finding":"In Toxoplasma and Plasmodium, ATG12 lacks the C-terminal glycine required for covalent conjugation and ATG10 (the E2-like enzyme for ATG12 conjugation) is absent; instead, ATG12 forms a non-covalent complex with ATG5. This non-covalent ATG12-ATG5 complex retains the ability to facilitate ATG8-phosphatidylethanolamine conjugation (ATG8 lipidation).","method":"Biochemical reconstitution; binding assays; in vitro ATG8 lipidation assay; comparative genomics","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution of ATG8 lipidation in vitro with non-covalent ATG12-ATG5 complex, replicated across organisms including Toxoplasma and Plasmodium","pmids":["30911187"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2017,"finding":"TgATG18 regulates membrane association and apicoplast localization of TgATG8. TgATG18 interacts with PI3P, and this interaction is critical for apicoplast inheritance. Conditional knockdown of TgATG18 causes loss of the apicoplast and impairs TgATG8 localization to it.","method":"Conditional knockdown; lipid-binding assays; fluorescence microscopy; co-localization","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional knockdown with functional readout for ATG8 localization, lipid-binding assay, single lab","pmids":["29089429"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"finding":"The TgATG12-TgATG5-TgATG16L complex exists in T. gondii and localizes to isolated structures at the periphery of the apicoplast dependent on TgATG16L. Inducible depletion of TgATG12, TgATG5, or TgATG16L causes loss of the apicoplast and affects parasite growth. TgATG8 is translocated to the apicoplast via vesicles in a SNARE-dependent manner, as TgSNAP29 depletion disrupts TgATG8 apicoplast localization. A putative ubiquitin-interacting motif-docking site (UDS) in TgATG8 is required for its apicoplast localization but not for lipidation.","method":"Auxin-inducible degron (AID) system; conditional knockdown; Co-immunoprecipitation; fluorescence microscopy; mutagenesis of UDS site","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 2 / Moderate — inducible depletion of multiple components with orthogonal readouts (complex co-IP, localization, growth), mutagenesis, single lab","pmids":["36095096"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"finding":"TgATG8-TgATG3 interaction, mediated by the AIM (239FADI242 in TgAtg3) and R27 in TgATG8, is required for TgATG8 lipidation, apicoplast localization, and apicoplast inheritance. Complemented lines with AIM or R27 mutations show loss of TgATG8 lipidation and apicoplast inheritance defects, resulting in delayed death and growth defects. The TgAtg3-TgATG8 interaction also contributes to maintenance of mitochondrial network integrity.","method":"Conditional knockdown complementation; site-directed mutagenesis; fluorescence microscopy; growth assays","journal":"Microbiology spectrum","confidence":"High","confidence_rationale":"Tier 2 / Moderate — mutagenesis complementation in conditional knockdown background with multiple phenotypic readouts (lipidation, apicoplast, mitochondria, growth), single lab","pmids":["35196797"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"TgATG7 is required for TgATG8 lipidation and apicoplast localization via its E1-type enzyme activity (catalytic cysteine C1133). TgATG7 also stabilizes the unlipidated pool of TgATG8 by direct interaction through its C-terminal domain (residues 1281–1290), preventing multi-monoubiquitination and proteasome-dependent degradation of TgATG8. Depletion of TgATG7 causes mitochondrial fragmentation and apicoplast loss.","method":"Conditional knockdown; catalytic point mutant (C1133S) complementation; co-immunoprecipitation; proteasome inhibition assay; ubiquitination assay; fluorescence microscopy; growth assays","journal":"Biochimica et biophysica acta. Molecular basis of disease","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — enzymatic mutagenesis, direct binding assay, ubiquitination/proteasome assay, and functional knockdown with multiple phenotypes, single lab","pmids":["37739091"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"finding":"TgVPS15 promotes PI3P generation, which regulates trafficking and conjugation of TgATG8 to the apicoplast and to autophagosomes (under nutrient stress) via PI3P-binding protein TgATG18. Depletion of TgVPS15 impairs apicoplast inheritance and TgATG8 apicoplast localization.","method":"Conditional knockdown; PI3P lipid assays; fluorescence microscopy; epistasis with TgATG18","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis (TgVPS15→TgATG18→TgATG8) supported by PI3P biochemical assay and localization readout, single lab","pmids":["36318587"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"The LIR docking site (LDS) of PfAtg8 is required for apicoplast localization and function (likely via lipidation), whereas the N-terminal helix is dispensable for apicoplast-specific function. An apicomplexan-specific loop previously implicated in membrane conjugation machinery interaction is not required for membrane conjugation or apicoplast function in either P. falciparum or T. gondii, indicating the effector function uses distinct structural features from canonical autophagy.","method":"Functional complementation; mutagenesis; fluorescence microscopy in P. falciparum and T. gondii","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional complementation with mutagenesis in two apicomplexan species, single lab","pmids":["36625582"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2016,"finding":"Autophagy, monitored by TgATG8 puncta formation, is downregulated in bradyzoites compared to tachyzoites. Rapamycin-induced autophagy reduces bradyzoite-specific gene BAG1 expression, while 3-MA inhibition of autophagy increases BAG1 expression, indicating that TgATG8-dependent autophagy is involved in the regulation of tachyzoite-to-bradyzoite transformation.","method":"Fluorescence microscopy (TgATG8 puncta); pharmacological induction/inhibition; RT-PCR for stage-specific markers; transgenic strains","journal":"Parasitology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, pharmacological approach with indirect readouts, no genetic manipulation of ATG8 itself","pmids":["26928609"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"Pru"}]}],"current_model":"TgATG8 is a central autophagy-related protein in Toxoplasma gondii that is lipidated (conjugated to phosphatidylethanolamine) via an E1 (TgATG7)–E2 (TgATG3) cascade regulated by TgATG4 (for delipidation/recycling) and facilitated by a non-covalent TgATG12-TgATG5-TgATG16L complex; under normal intracellular growth, TgATG8 is primarily targeted to the outermost membrane of the apicoplast—dependent on its LIR docking site, a ubiquitin-interacting motif-docking site (UDS), SNARE protein TgSNAP29-mediated vesicular trafficking, and the TgATG18/PI3P/TgVPS15 signaling axis—where it plays an essential non-canonical, non-catabolic role in centrosome-coupled apicoplast inheritance during cell division, while under stress conditions it relocates to autophagosomes to mediate canonical autophagy important for parasite survival in immune cells and in vivo virulence."},"narrative":{"mechanistic_narrative":"TgATG8 is the central ubiquitin-like conjugation protein of the Toxoplasma gondii autophagy machinery that functions in two distinct capacities: a non-canonical, non-catabolic role in apicoplast inheritance during normal intracellular growth and a canonical role in stress-induced autophagy [PMID:22144900, PMID:26507233]. TgATG8 is activated and conjugated to phosphatidylethanolamine through a conjugation cascade in which the E1-type enzyme TgATG7 (catalytic C1133) charges TgATG8 and the E2-type enzyme TgATG3 catalyzes lipidation, with the reaction facilitated by a non-covalent TgATG12-TgATG5-TgATG16L complex—an arrangement unique to apicomplexans, in which TgATG12 lacks the C-terminal glycine and the ATG10 enzyme is absent [PMID:30911187, PMID:36095096, PMID:37739091]. The TgATG8-TgATG3 interaction is high-affinity and depends on the AIM motif 239FADI242 in TgATG3 docking against the AIM-docking site of TgATG8 (including R27), and this interaction is required for lipidation, autophagosome formation, and apicoplast inheritance [PMID:26407821, PMID:30026233, PMID:35196797]. TgATG4 recycles membrane-bound TgATG8 by delipidation, and notably the TgATG8 C-terminus does not require processing prior to membrane association [PMID:23748741]. Under normal growth, TgATG8 is targeted to the outermost apicoplast membrane, where it mediates centrosome-coupled apicoplast segregation to daughter cells; this targeting requires the LIR docking site, a ubiquitin-interacting-motif docking site (UDS), TgSNAP29-dependent vesicular trafficking, and the TgVPS15/PI3P/TgATG18 signaling axis, and its loss causes apicoplast loss, mitochondrial fragmentation, and severe replication defects [PMID:26507233, PMID:29089429, PMID:36095096, PMID:37739091, PMID:36318587, PMID:36625582]. Under nutrient stress or drug treatment, TgATG8 relocalizes to autophagosomes to mediate canonical autophagy [PMID:22144900, PMID:22848721].","teleology":[{"year":2011,"claim":"Establishing TgATG8 as an autophagosome marker showed that Toxoplasma possesses a functional autophagy pathway operating both under starvation and during normal development, and linked its conjugation machinery to organelle homeostasis.","evidence":"Conditional knockdown of TgATG3 with TgATG8 as autophagosome marker, fluorescence microscopy, and growth assays","pmids":["22144900"],"confidence":"High","gaps":["Did not resolve whether the growth defect reflects catabolic autophagy or a non-autophagic role","No direct biochemistry of TgATG8 lipidation"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2012,"claim":"Pharmacological induction demonstrated that TgATG8-marked autophagy can drive parasite death, framing autophagy as a druggable vulnerability.","evidence":"Monensin treatment with ATG8 relocalization readout, 3-methyladenine inhibition, and survival assays","pmids":["22848721"],"confidence":"Medium","gaps":["Relies on pharmacological readouts without genetic manipulation of ATG8","Mechanism connecting monensin to autophagy induction unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2013,"claim":"Identifying TgATG4 as the delipidating protease clarified that TgATG8 cycles on and off membranes, and revealed the apicomplexan peculiarity that the TgATG8 C-terminus needs no processing before membrane association.","evidence":"Conditional expression mutant of TgATG4 with Western blotting of lipidated ATG8, fluorescence microscopy, and growth assays","pmids":["23748741"],"confidence":"High","gaps":["Did not distinguish autophagic from apicoplast-related pools of TgATG8","Structural basis of processing-independence not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2015,"claim":"Discovery that TgATG8 localizes to the apicoplast outer membrane and is required for its segregation established a non-canonical, non-catabolic role for the protein in organelle inheritance coupled to the centrosome.","evidence":"Superresolution microscopy, biochemical fractionation, conditional knockdown, and live imaging","pmids":["26507233"],"confidence":"High","gaps":["Molecular effectors linking TgATG8 to the centrosome not identified","How the same protein partitions between apicoplast and autophagosome unclear"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2015,"claim":"Quantifying the direct high-affinity TgATG8-TgATG3 interaction provided the biochemical basis for TgATG8 lipidation by the E2 enzyme.","evidence":"Tandem affinity purification, mass spectrometry, and surface plasmon resonance (KD = 34.9 nM)","pmids":["26407821"],"confidence":"Medium","gaps":["Interaction interface not yet mapped at residue resolution","Functional consequence of disrupting the interaction not tested here"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2016,"claim":"Correlating TgATG8 puncta with stage conversion implicated autophagy in the tachyzoite-to-bradyzoite transition.","evidence":"TgATG8 puncta microscopy with rapamycin/3-MA modulation and stage-marker RT-PCR in the Pru strain","pmids":["26928609"],"confidence":"Low","gaps":["Pharmacological only, with no genetic manipulation of ATG8 itself","Causal role of TgATG8 in differentiation not established","Indirect BAG1 readout"],"attribution":[{"species":"Toxoplasma gondii","strain":"Pru"}]},{"year":2017,"claim":"Placing TgATG18 and PI3P upstream of TgATG8 defined a lipid-signaling axis controlling TgATG8 membrane targeting to the apicoplast.","evidence":"Conditional knockdown of TgATG18, lipid-binding assays, and colocalization microscopy","pmids":["29089429"],"confidence":"Medium","gaps":["Source of PI3P at the apicoplast membrane not identified","How PI3P/ATG18 recruits ATG8 mechanistically unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2018,"claim":"Mapping the AIM in TgATG3 (239FADI242) and the TgATG8 AIM-docking site defined the molecular determinants of lipidation and distinguished the Toxoplasma motif from the Plasmodium ortholog.","evidence":"Alanine-scanning mutagenesis, peptide and AlphaScreen binding assays, and in vitro lipidation","pmids":["30026233"],"confidence":"High","gaps":["In vivo consequences of AIM disruption not shown in this study","Whether the same docking site serves the apicoplast role not addressed here"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"claim":"Reconstituting lipidation with a non-covalent ATG12-ATG5 complex revealed that apicomplexans have lost the canonical covalent ATG12 conjugation yet retain E3-like facilitation of ATG8-PE conjugation.","evidence":"Biochemical reconstitution, in vitro ATG8 lipidation, and comparative genomics across Toxoplasma and Plasmodium","pmids":["30911187"],"confidence":"High","gaps":["In vivo requirement of the complex for apicoplast targeting not tested here","Structural basis of non-covalent ATG12-ATG5 assembly not fully defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"claim":"Genetic dissection of the TgATG12-TgATG5-TgATG16L complex, TgSNAP29-dependent vesicular delivery, and a UDS in TgATG8 assembled the trafficking route by which TgATG8 reaches the apicoplast, separating apicoplast targeting from lipidation.","evidence":"Auxin-inducible degron depletion, co-immunoprecipitation, UDS mutagenesis, and fluorescence microscopy","pmids":["36095096"],"confidence":"High","gaps":["Identity of the ubiquitinated ligand engaging the UDS unknown","Cargo of TgSNAP29 vesicles not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"claim":"Complementation with AIM and TgATG8 R27 mutants demonstrated in vivo that the TgATG3-TgATG8 interaction drives lipidation, apicoplast inheritance, and mitochondrial integrity, tying the biochemical interface to organellar phenotypes.","evidence":"Conditional knockdown complementation with site-directed mutants and phenotypic microscopy/growth assays","pmids":["35196797"],"confidence":"High","gaps":["Whether mitochondrial and apicoplast defects share a common downstream effector unclear"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"claim":"Positioning TgVPS15 upstream of PI3P generation and TgATG18 completed the signaling epistasis controlling TgATG8 delivery to both the apicoplast and autophagosomes.","evidence":"Conditional knockdown of TgVPS15, PI3P lipid assays, and epistasis with TgATG18","pmids":["36318587"],"confidence":"Medium","gaps":["Whether TgVPS15 acts through a canonical PI3-kinase not fully defined","Spatial regulation distinguishing apicoplast versus autophagosome pools unclear"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Establishing TgATG7 as the E1 enzyme and as a stabilizer of unlipidated TgATG8 showed that ATG7 both activates ATG8 and protects it from ubiquitin-dependent proteasomal degradation.","evidence":"Catalytic C1133S mutant complementation, co-IP, ubiquitination and proteasome-inhibition assays, and knockdown phenotyping","pmids":["37739091"],"confidence":"High","gaps":["Ubiquitin ligase responsible for TgATG8 multi-monoubiquitination not identified","How stabilization is coordinated with lipidation flux unclear"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Mutagenesis of ATG8 structural features across two apicomplexans showed that the LIR docking site drives apicoplast function while the N-terminal helix and the apicomplexan-specific loop are dispensable, indicating the effector role uses distinct determinants from canonical autophagy.","evidence":"Functional complementation and mutagenesis in P. falciparum and T. gondii","pmids":["36625582"],"confidence":"Medium","gaps":["Direct binding partners engaged by the LIR docking site at the apicoplast not identified","Whether the same determinants operate identically in both species not fully resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The molecular effectors that physically couple apicoplast-membrane TgATG8 to the centrosome to drive organelle inheritance, and the ubiquitinated ligand read by the TgATG8 UDS, remain unidentified.","evidence":"","pmids":[],"confidence":"High","gaps":["No identified centrosome-linking effector downstream of TgATG8","Ligand engaging the UDS unknown","Molecular switch partitioning TgATG8 between apicoplast and autophagosome undefined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Non-covalent TgATG12-TgATG5-TgATG16L complex (facilitates TgATG8-PE conjugation)"],"partners":["TGATG3 (E2-TYPE CONJUGATING ENZYME; DIRECT HIGH-AFFINITY BINDING VIA AIM 239FADI242 / TGATG8 R27)","TGATG7 (E1-TYPE ACTIVATING ENZYME; STABILIZES UNLIPIDATED TGATG8)","TGATG4 (DELIPIDATION/RECYCLING PROTEASE)","TGATG18 (PI3P-BINDING REGULATOR OF MEMBRANE/APICOPLAST TARGETING)","TGVPS15 (PI3P GENERATION UPSTREAM OF TGATG18)","TGSNAP29 (SNARE MEDIATING VESICULAR DELIVERY TO APICOPLAST)","TGATG12-TGATG5-TGATG16L COMPLEX"],"other_free_text":["TgATG8 C-terminus does not require processing prior to membrane association, unlike most eukaryotes.","TgATG12 lacks the C-terminal glycine for covalent conjugation and ATG10 is absent in apicomplexans.","Apicoplast targeting requires the LIR/AIM docking site and a ubiquitin-interacting-motif docking site (UDS); the UDS is dispensable for lipidation.","N-terminal helix and an apicomplexan-specific loop are dispensable for apicoplast function.","TgATG8 conjugation is coupled to apicoplast inheritance via physical apicoplast-centrosome interactions."]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"22144900","id":"PMC_22144900","title":"Autophagy protein Atg3 is essential for maintaining mitochondrial integrity and for normal intracellular development of Toxoplasma gondii tachyzoites.","date":"2011","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/22144900","citation_count":95,"is_preprint":false},{"pmid":"28604719","id":"PMC_28604719","title":"Essential role for GABARAP autophagy proteins in interferon-inducible GTPase-mediated host defense.","date":"2017","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/28604719","citation_count":84,"is_preprint":false},{"pmid":"24466199","id":"PMC_24466199","title":"The E2-like conjugation enzyme Atg3 promotes binding of IRG and Gbp proteins to Chlamydia- and Toxoplasma-containing vacuoles and host resistance.","date":"2014","source":"PloS 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conjugation to non-covalent interaction in the ubiquitin-like ATG12 system.","date":"2019","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/30911187","citation_count":45,"is_preprint":false},{"pmid":"29089429","id":"PMC_29089429","title":"Autophagy-Related Protein ATG18 Regulates Apicoplast Biogenesis in Apicomplexan Parasites.","date":"2017","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/29089429","citation_count":42,"is_preprint":false},{"pmid":"27992947","id":"PMC_27992947","title":"Toxoplasma gondii autophagy-related protein ATG9 is crucial for the survival of parasites in their host.","date":"2017","source":"Cellular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/27992947","citation_count":26,"is_preprint":false},{"pmid":"36095096","id":"PMC_36095096","title":"Apicoplast biogenesis mediated by ATG8 requires the ATG12-ATG5-ATG16L and SNAP29 complexes in Toxoplasma 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molecular mechanism of the autophagy-related Atg8-Atg3 protein interaction in Toxoplasma gondii.","date":"2018","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/30026233","citation_count":9,"is_preprint":false},{"pmid":"26928609","id":"PMC_26928609","title":"Induction of Autophagy interferes the tachyzoite to bradyzoite transformation of Toxoplasma gondii.","date":"2016","source":"Parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/26928609","citation_count":9,"is_preprint":false},{"pmid":"37739091","id":"PMC_37739091","title":"Toxoplasma gondii autophagy-related protein ATG7 maintains apicoplast inheritance by stabilizing and lipidating ATG8.","date":"2023","source":"Biochimica et biophysica acta. Molecular basis of disease","url":"https://pubmed.ncbi.nlm.nih.gov/37739091","citation_count":7,"is_preprint":false},{"pmid":"36318587","id":"PMC_36318587","title":"A VPS15-like kinase regulates apicoplast biogenesis and autophagy by promoting PI3P generation in Toxoplasma gondii.","date":"2022","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/36318587","citation_count":5,"is_preprint":false},{"pmid":"36625582","id":"PMC_36625582","title":"Structure-Function Relationship for a Divergent Atg8 Protein Required for a Nonautophagic Function in Apicomplexan Parasites.","date":"2023","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/36625582","citation_count":4,"is_preprint":false},{"pmid":"28807302","id":"PMC_28807302","title":"Targeted overexpression of cyclic AMP-dependent protein kinase subunit in Toxoplasma gondii promotes replication and virulence in host cells.","date":"2017","source":"Veterinary parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/28807302","citation_count":2,"is_preprint":false},{"pmid":"39000057","id":"PMC_39000057","title":"The Effects and Mechanism of ATM Kinase Inhibitors in Toxoplasma gondii.","date":"2024","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39000057","citation_count":1,"is_preprint":false},{"pmid":"25065213","id":"PMC_25065213","title":"[Preparation and application of the polyclonal antibody of Toxoplasma gondii autophagy protein 8 (TgAtg8)].","date":"2014","source":"Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases","url":"https://pubmed.ncbi.nlm.nih.gov/25065213","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15766,"output_tokens":4402,"usd":0.056664,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10591,"output_tokens":5724,"usd":0.098028,"stage2_stop_reason":"end_turn"},"total_usd":0.154692,"stage1_batch_id":"msgbatch_01TEPNZ4MCzJ7xtsNwosiDRk","stage2_batch_id":"msgbatch_01FQShM7n1sfCr4pWTDShmki","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"TgATG8 serves as an autophagosome marker in T. gondii; autophagosomes are induced by amino acid starvation and also form during normal intracellular development. TgAtg3 is required for conjugation of TgAtg8 to the autophagosomal membrane, and TgAtg3-depleted parasites exhibit mitochondrial fragmentation and severe growth defects, indicating TgAtg3-dependent autophagy regulates mitochondrial homeostasis during cell division.\",\n      \"method\": \"Conditional knockdown of TgAtg3; TgATG8 used as autophagosome marker; fluorescence microscopy; growth assays\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockout with multiple orthogonal readouts (autophagosome marker, mitochondrial morphology, growth phenotype), single lab\",\n      \"pmids\": [\"22144900\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"TgATG4 is required for recycling of membrane-bound TgATG8 (delipidation). TgATG4-depleted parasites are defective in recycling membrane-associated TgATG8 and show mitochondrial fragmentation and loss of the apicoplast, demonstrating that TgATG4 regulates TgATG8 membrane association/dissociation and organelle homeostasis. TgATG8's C-terminus does not require processing prior to membrane association in T. gondii, unlike most eukaryotes.\",\n      \"method\": \"Conditional expression mutant of TgATG4; Western blotting; fluorescence microscopy; growth assays\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockdown with multiple organellar phenotypes and biochemical readout for ATG8 lipidation, single lab\",\n      \"pmids\": [\"23748741\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TgATG8 localizes to the outermost membrane of the apicoplast under normal intracellular growth conditions (not just to autophagosomes). Conditional knockdown of TgATG8 causes rapid loss of the apicoplast and intracellular replication defects due to abnormal apicoplast segregation into daughter cells, linked to loss of physical interactions between the apicoplast and centrosomes. This reveals a non-canonical, non-catabolic role for TgATG8 in apicoplast inheritance.\",\n      \"method\": \"Superresolution microscopy; biochemical fractionation; conditional knockdown; live imaging; growth assays\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional knockdown with superresolution microscopy, biochemical localization, and multiple cellular phenotypes; replicated in subsequent studies\",\n      \"pmids\": [\"26507233\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TgATG8 and TgATG3 interact directly with high affinity (KD = 34.9 nM) as demonstrated by co-immunoprecipitation from parasite lysates and surface plasmon resonance. TgATG8 partially colocalizes with TgATG3 in parasites.\",\n      \"method\": \"Tandem affinity purification with anti-GFP antibody; Western blot; tandem mass spectrometry; surface plasmon resonance (BIAcore); immunofluorescence assay\",\n      \"journal\": \"Acta tropica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct in vitro binding assay (SPR) plus pulldown from parasite lysate, single lab, two orthogonal methods\",\n      \"pmids\": [\"26407821\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Monensin treatment induces autophagy in T. gondii as evidenced by translocation of ATG8 to autophagosomes. The autophagy inhibitor 3-methyladenine blocks ATG8 translocation and enhances parasite survival, establishing autophagy as a mechanism of monensin-induced parasite death.\",\n      \"method\": \"ATG8 localization by fluorescence microscopy; pharmacological inhibition with 3-methyladenine; survival assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — ATG8 as autophagy readout with pharmacological modulation, single lab, two supporting methods\",\n      \"pmids\": [\"22848721\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The TgATG8-TgATG3 interaction interface was molecularly characterized: the core Atg8-family interacting motif (AIM) in TgATG3 is 239FADI242, distinct from the Plasmodium Atg3 AIM (105WLLP108). Substitution of conserved TgATG8 residues at the AIM-docking site disrupts TgATG8-TgATG3 interaction and reduces TgATG8 lipidation and autophagosome formation. Surrounding residues N238, D243, and C244 in TgATG3 also contribute to binding.\",\n      \"method\": \"Mutagenesis (alanine-scanning); peptide assay; AlphaScreen assay; lipidation assay; in vitro binding\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — active-site mutagenesis combined with multiple in vitro binding and functional assays (AlphaScreen, peptide, lipidation), single lab\",\n      \"pmids\": [\"30026233\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In Toxoplasma and Plasmodium, ATG12 lacks the C-terminal glycine required for covalent conjugation and ATG10 (the E2-like enzyme for ATG12 conjugation) is absent; instead, ATG12 forms a non-covalent complex with ATG5. This non-covalent ATG12-ATG5 complex retains the ability to facilitate ATG8-phosphatidylethanolamine conjugation (ATG8 lipidation).\",\n      \"method\": \"Biochemical reconstitution; binding assays; in vitro ATG8 lipidation assay; comparative genomics\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution of ATG8 lipidation in vitro with non-covalent ATG12-ATG5 complex, replicated across organisms including Toxoplasma and Plasmodium\",\n      \"pmids\": [\"30911187\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"TgATG18 regulates membrane association and apicoplast localization of TgATG8. TgATG18 interacts with PI3P, and this interaction is critical for apicoplast inheritance. Conditional knockdown of TgATG18 causes loss of the apicoplast and impairs TgATG8 localization to it.\",\n      \"method\": \"Conditional knockdown; lipid-binding assays; fluorescence microscopy; co-localization\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional knockdown with functional readout for ATG8 localization, lipid-binding assay, single lab\",\n      \"pmids\": [\"29089429\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The TgATG12-TgATG5-TgATG16L complex exists in T. gondii and localizes to isolated structures at the periphery of the apicoplast dependent on TgATG16L. Inducible depletion of TgATG12, TgATG5, or TgATG16L causes loss of the apicoplast and affects parasite growth. TgATG8 is translocated to the apicoplast via vesicles in a SNARE-dependent manner, as TgSNAP29 depletion disrupts TgATG8 apicoplast localization. A putative ubiquitin-interacting motif-docking site (UDS) in TgATG8 is required for its apicoplast localization but not for lipidation.\",\n      \"method\": \"Auxin-inducible degron (AID) system; conditional knockdown; Co-immunoprecipitation; fluorescence microscopy; mutagenesis of UDS site\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — inducible depletion of multiple components with orthogonal readouts (complex co-IP, localization, growth), mutagenesis, single lab\",\n      \"pmids\": [\"36095096\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TgATG8-TgATG3 interaction, mediated by the AIM (239FADI242 in TgAtg3) and R27 in TgATG8, is required for TgATG8 lipidation, apicoplast localization, and apicoplast inheritance. Complemented lines with AIM or R27 mutations show loss of TgATG8 lipidation and apicoplast inheritance defects, resulting in delayed death and growth defects. The TgAtg3-TgATG8 interaction also contributes to maintenance of mitochondrial network integrity.\",\n      \"method\": \"Conditional knockdown complementation; site-directed mutagenesis; fluorescence microscopy; growth assays\",\n      \"journal\": \"Microbiology spectrum\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis complementation in conditional knockdown background with multiple phenotypic readouts (lipidation, apicoplast, mitochondria, growth), single lab\",\n      \"pmids\": [\"35196797\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TgATG7 is required for TgATG8 lipidation and apicoplast localization via its E1-type enzyme activity (catalytic cysteine C1133). TgATG7 also stabilizes the unlipidated pool of TgATG8 by direct interaction through its C-terminal domain (residues 1281–1290), preventing multi-monoubiquitination and proteasome-dependent degradation of TgATG8. Depletion of TgATG7 causes mitochondrial fragmentation and apicoplast loss.\",\n      \"method\": \"Conditional knockdown; catalytic point mutant (C1133S) complementation; co-immunoprecipitation; proteasome inhibition assay; ubiquitination assay; fluorescence microscopy; growth assays\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular basis of disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — enzymatic mutagenesis, direct binding assay, ubiquitination/proteasome assay, and functional knockdown with multiple phenotypes, single lab\",\n      \"pmids\": [\"37739091\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TgVPS15 promotes PI3P generation, which regulates trafficking and conjugation of TgATG8 to the apicoplast and to autophagosomes (under nutrient stress) via PI3P-binding protein TgATG18. Depletion of TgVPS15 impairs apicoplast inheritance and TgATG8 apicoplast localization.\",\n      \"method\": \"Conditional knockdown; PI3P lipid assays; fluorescence microscopy; epistasis with TgATG18\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis (TgVPS15→TgATG18→TgATG8) supported by PI3P biochemical assay and localization readout, single lab\",\n      \"pmids\": [\"36318587\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The LIR docking site (LDS) of PfAtg8 is required for apicoplast localization and function (likely via lipidation), whereas the N-terminal helix is dispensable for apicoplast-specific function. An apicomplexan-specific loop previously implicated in membrane conjugation machinery interaction is not required for membrane conjugation or apicoplast function in either P. falciparum or T. gondii, indicating the effector function uses distinct structural features from canonical autophagy.\",\n      \"method\": \"Functional complementation; mutagenesis; fluorescence microscopy in P. falciparum and T. gondii\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional complementation with mutagenesis in two apicomplexan species, single lab\",\n      \"pmids\": [\"36625582\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Autophagy, monitored by TgATG8 puncta formation, is downregulated in bradyzoites compared to tachyzoites. Rapamycin-induced autophagy reduces bradyzoite-specific gene BAG1 expression, while 3-MA inhibition of autophagy increases BAG1 expression, indicating that TgATG8-dependent autophagy is involved in the regulation of tachyzoite-to-bradyzoite transformation.\",\n      \"method\": \"Fluorescence microscopy (TgATG8 puncta); pharmacological induction/inhibition; RT-PCR for stage-specific markers; transgenic strains\",\n      \"journal\": \"Parasitology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, pharmacological approach with indirect readouts, no genetic manipulation of ATG8 itself\",\n      \"pmids\": [\"26928609\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"Pru\"}]\n    }\n  ],\n  \"current_model\": \"TgATG8 is a central autophagy-related protein in Toxoplasma gondii that is lipidated (conjugated to phosphatidylethanolamine) via an E1 (TgATG7)–E2 (TgATG3) cascade regulated by TgATG4 (for delipidation/recycling) and facilitated by a non-covalent TgATG12-TgATG5-TgATG16L complex; under normal intracellular growth, TgATG8 is primarily targeted to the outermost membrane of the apicoplast—dependent on its LIR docking site, a ubiquitin-interacting motif-docking site (UDS), SNARE protein TgSNAP29-mediated vesicular trafficking, and the TgATG18/PI3P/TgVPS15 signaling axis—where it plays an essential non-canonical, non-catabolic role in centrosome-coupled apicoplast inheritance during cell division, while under stress conditions it relocates to autophagosomes to mediate canonical autophagy important for parasite survival in immune cells and in vivo virulence.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TgATG8 is the central ubiquitin-like conjugation protein of the Toxoplasma gondii autophagy machinery that functions in two distinct capacities: a non-canonical, non-catabolic role in apicoplast inheritance during normal intracellular growth and a canonical role in stress-induced autophagy [#0, #2]. TgATG8 is activated and conjugated to phosphatidylethanolamine through a conjugation cascade in which the E1-type enzyme TgATG7 (catalytic C1133) charges TgATG8 and the E2-type enzyme TgATG3 catalyzes lipidation, with the reaction facilitated by a non-covalent TgATG12-TgATG5-TgATG16L complex\\u2014an arrangement unique to apicomplexans, in which TgATG12 lacks the C-terminal glycine and the ATG10 enzyme is absent [#6, #8, #10]. The TgATG8-TgATG3 interaction is high-affinity and depends on the AIM motif 239FADI242 in TgATG3 docking against the AIM-docking site of TgATG8 (including R27), and this interaction is required for lipidation, autophagosome formation, and apicoplast inheritance [#3, #5, #9]. TgATG4 recycles membrane-bound TgATG8 by delipidation, and notably the TgATG8 C-terminus does not require processing prior to membrane association [#1]. Under normal growth, TgATG8 is targeted to the outermost apicoplast membrane, where it mediates centrosome-coupled apicoplast segregation to daughter cells; this targeting requires the LIR docking site, a ubiquitin-interacting-motif docking site (UDS), TgSNAP29-dependent vesicular trafficking, and the TgVPS15/PI3P/TgATG18 signaling axis, and its loss causes apicoplast loss, mitochondrial fragmentation, and severe replication defects [#2, #7, #8, #10, #11, #12]. Under nutrient stress or drug treatment, TgATG8 relocalizes to autophagosomes to mediate canonical autophagy [#0, #4].\"\n  ,\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Establishing TgATG8 as an autophagosome marker showed that Toxoplasma possesses a functional autophagy pathway operating both under starvation and during normal development, and linked its conjugation machinery to organelle homeostasis.\",\n      \"evidence\": \"Conditional knockdown of TgATG3 with TgATG8 as autophagosome marker, fluorescence microscopy, and growth assays\",\n      \"pmids\": [\"22144900\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve whether the growth defect reflects catabolic autophagy or a non-autophagic role\", \"No direct biochemistry of TgATG8 lipidation\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Pharmacological induction demonstrated that TgATG8-marked autophagy can drive parasite death, framing autophagy as a druggable vulnerability.\",\n      \"evidence\": \"Monensin treatment with ATG8 relocalization readout, 3-methyladenine inhibition, and survival assays\",\n      \"pmids\": [\"22848721\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relies on pharmacological readouts without genetic manipulation of ATG8\", \"Mechanism connecting monensin to autophagy induction unresolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identifying TgATG4 as the delipidating protease clarified that TgATG8 cycles on and off membranes, and revealed the apicomplexan peculiarity that the TgATG8 C-terminus needs no processing before membrane association.\",\n      \"evidence\": \"Conditional expression mutant of TgATG4 with Western blotting of lipidated ATG8, fluorescence microscopy, and growth assays\",\n      \"pmids\": [\"23748741\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not distinguish autophagic from apicoplast-related pools of TgATG8\", \"Structural basis of processing-independence not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Discovery that TgATG8 localizes to the apicoplast outer membrane and is required for its segregation established a non-canonical, non-catabolic role for the protein in organelle inheritance coupled to the centrosome.\",\n      \"evidence\": \"Superresolution microscopy, biochemical fractionation, conditional knockdown, and live imaging\",\n      \"pmids\": [\"26507233\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular effectors linking TgATG8 to the centrosome not identified\", \"How the same protein partitions between apicoplast and autophagosome unclear\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Quantifying the direct high-affinity TgATG8-TgATG3 interaction provided the biochemical basis for TgATG8 lipidation by the E2 enzyme.\",\n      \"evidence\": \"Tandem affinity purification, mass spectrometry, and surface plasmon resonance (KD = 34.9 nM)\",\n      \"pmids\": [\"26407821\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Interaction interface not yet mapped at residue resolution\", \"Functional consequence of disrupting the interaction not tested here\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Correlating TgATG8 puncta with stage conversion implicated autophagy in the tachyzoite-to-bradyzoite transition.\",\n      \"evidence\": \"TgATG8 puncta microscopy with rapamycin/3-MA modulation and stage-marker RT-PCR in the Pru strain\",\n      \"pmids\": [\"26928609\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Pharmacological only, with no genetic manipulation of ATG8 itself\", \"Causal role of TgATG8 in differentiation not established\", \"Indirect BAG1 readout\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"Pru\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Placing TgATG18 and PI3P upstream of TgATG8 defined a lipid-signaling axis controlling TgATG8 membrane targeting to the apicoplast.\",\n      \"evidence\": \"Conditional knockdown of TgATG18, lipid-binding assays, and colocalization microscopy\",\n      \"pmids\": [\"29089429\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Source of PI3P at the apicoplast membrane not identified\", \"How PI3P/ATG18 recruits ATG8 mechanistically unresolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Mapping the AIM in TgATG3 (239FADI242) and the TgATG8 AIM-docking site defined the molecular determinants of lipidation and distinguished the Toxoplasma motif from the Plasmodium ortholog.\",\n      \"evidence\": \"Alanine-scanning mutagenesis, peptide and AlphaScreen binding assays, and in vitro lipidation\",\n      \"pmids\": [\"30026233\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo consequences of AIM disruption not shown in this study\", \"Whether the same docking site serves the apicoplast role not addressed here\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Reconstituting lipidation with a non-covalent ATG12-ATG5 complex revealed that apicomplexans have lost the canonical covalent ATG12 conjugation yet retain E3-like facilitation of ATG8-PE conjugation.\",\n      \"evidence\": \"Biochemical reconstitution, in vitro ATG8 lipidation, and comparative genomics across Toxoplasma and Plasmodium\",\n      \"pmids\": [\"30911187\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo requirement of the complex for apicoplast targeting not tested here\", \"Structural basis of non-covalent ATG12-ATG5 assembly not fully defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Genetic dissection of the TgATG12-TgATG5-TgATG16L complex, TgSNAP29-dependent vesicular delivery, and a UDS in TgATG8 assembled the trafficking route by which TgATG8 reaches the apicoplast, separating apicoplast targeting from lipidation.\",\n      \"evidence\": \"Auxin-inducible degron depletion, co-immunoprecipitation, UDS mutagenesis, and fluorescence microscopy\",\n      \"pmids\": [\"36095096\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the ubiquitinated ligand engaging the UDS unknown\", \"Cargo of TgSNAP29 vesicles not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Complementation with AIM and TgATG8 R27 mutants demonstrated in vivo that the TgATG3-TgATG8 interaction drives lipidation, apicoplast inheritance, and mitochondrial integrity, tying the biochemical interface to organellar phenotypes.\",\n      \"evidence\": \"Conditional knockdown complementation with site-directed mutants and phenotypic microscopy/growth assays\",\n      \"pmids\": [\"35196797\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether mitochondrial and apicoplast defects share a common downstream effector unclear\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Positioning TgVPS15 upstream of PI3P generation and TgATG18 completed the signaling epistasis controlling TgATG8 delivery to both the apicoplast and autophagosomes.\",\n      \"evidence\": \"Conditional knockdown of TgVPS15, PI3P lipid assays, and epistasis with TgATG18\",\n      \"pmids\": [\"36318587\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether TgVPS15 acts through a canonical PI3-kinase not fully defined\", \"Spatial regulation distinguishing apicoplast versus autophagosome pools unclear\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Establishing TgATG7 as the E1 enzyme and as a stabilizer of unlipidated TgATG8 showed that ATG7 both activates ATG8 and protects it from ubiquitin-dependent proteasomal degradation.\",\n      \"evidence\": \"Catalytic C1133S mutant complementation, co-IP, ubiquitination and proteasome-inhibition assays, and knockdown phenotyping\",\n      \"pmids\": [\"37739091\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitin ligase responsible for TgATG8 multi-monoubiquitination not identified\", \"How stabilization is coordinated with lipidation flux unclear\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Mutagenesis of ATG8 structural features across two apicomplexans showed that the LIR docking site drives apicoplast function while the N-terminal helix and the apicomplexan-specific loop are dispensable, indicating the effector role uses distinct determinants from canonical autophagy.\",\n      \"evidence\": \"Functional complementation and mutagenesis in P. falciparum and T. gondii\",\n      \"pmids\": [\"36625582\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding partners engaged by the LIR docking site at the apicoplast not identified\", \"Whether the same determinants operate identically in both species not fully resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The molecular effectors that physically couple apicoplast-membrane TgATG8 to the centrosome to drive organelle inheritance, and the ubiquitinated ligand read by the TgATG8 UDS, remain unidentified.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No identified centrosome-linking effector downstream of TgATG8\", \"Ligand engaging the UDS unknown\", \"Molecular switch partitioning TgATG8 between apicoplast and autophagosome undefined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0019776\", \"supporting_discovery_ids\": [6, 9, 10], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0035973\", \"supporting_discovery_ids\": [0, 2, 4], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005776\", \"supporting_discovery_ids\": [0, 4], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0020011\", \"supporting_discovery_ids\": [2, 7, 8, 12], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006914\", \"supporting_discovery_ids\": [0, 1, 4], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0048308\", \"supporting_discovery_ids\": [2, 8, 11], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\n      \"Non-covalent TgATG12-TgATG5-TgATG16L complex (facilitates TgATG8-PE conjugation)\"\n    ],\n    \"partners\": [\n      \"TgATG3 (E2-type conjugating enzyme; direct high-affinity binding via AIM 239FADI242 / TgATG8 R27)\",\n      \"TgATG7 (E1-type activating enzyme; stabilizes unlipidated TgATG8)\",\n      \"TgATG4 (delipidation/recycling protease)\",\n      \"TgATG18 (PI3P-binding regulator of membrane/apicoplast targeting)\",\n      \"TgVPS15 (PI3P generation upstream of TgATG18)\",\n      \"TgSNAP29 (SNARE mediating vesicular delivery to apicoplast)\",\n      \"TgATG12-TgATG5-TgATG16L complex\"\n    ],\n    \"other_free_text\": [\n      \"TgATG8 C-terminus does not require processing prior to membrane association, unlike most eukaryotes.\",\n      \"TgATG12 lacks the C-terminal glycine for covalent conjugation and ATG10 is absent in apicomplexans.\",\n      \"Apicoplast targeting requires the LIR/AIM docking site and a ubiquitin-interacting-motif docking site (UDS); the UDS is dispensable for lipidation.\",\n      \"N-terminal helix and an apicomplexan-specific loop are dispensable for apicoplast function.\",\n      \"TgATG8 conjugation is coupled to apicoplast inheritance via physical apicoplast-centrosome interactions.\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_254120","name":"ATG8","product":"autophagy-related protein ATG8","uniprot_acc":"A0A125YKY6","chromosome":"TGME49_chrIII","start_pos":1457767},{"strain":"GT1","gene_id":"TGGT1_254120","name":null,"product":"putative autophagy-related protein 8 atg8","uniprot_acc":null,"chromosome":"TGGT1_chrIII","start_pos":1439044},{"strain":"RH88","gene_id":"TGRH88_004240","name":null,"product":"putative autophagy-related protein 8 atg8","uniprot_acc":null,"chromosome":"CM023084","start_pos":1146784},{"strain":"VEG","gene_id":"TGVEG_254120","name":null,"product":"putative autophagy-related protein 8 atg8","uniprot_acc":"B9PWU8","chromosome":"TGVEG_chrIII","start_pos":1466167}]}