{"gene":"PF3D7_1314600","run_date":"2026-09-08T14:19:06","timeline":{"discoveries":[{"year":2004,"finding":"LipL1 (lipoic acid protein ligase) localizes to the mitochondrion of P. falciparum, as established by GFP fusion of its N-terminal sequence expressed in intraerythrocytic parasites; functionality was confirmed by complementation of lipA/lipB-deficient bacteria.","method":"GFP fusion live imaging of N-terminal sequences; bacterial complementation assay","journal":"Molecular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by GFP fusion with functional validation by bacterial complementation, single lab","pmids":["15225307"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2007,"finding":"LipL1 restores lipoate scavenging in lipoylation-deficient bacteria, demonstrating it is a functional lipoate ligase. 8-bromo-octanoate inhibits LipL1 activity and arrests P. falciparum intraerythrocytic growth, decreasing incorporation of radiolabelled lipoate into parasite proteins; this growth inhibition is reversed by exogenous lipoate, consistent with specific interference with lipoate scavenging.","method":"Bacterial complementation assay; in vitro growth inhibition assay with radiolabelled lipoate incorporation; lipoate rescue experiment","journal":"Molecular microbiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (complementation, radiolabelled substrate incorporation, chemical inhibition with rescue), replicated across two labs (Prigge and Müller groups)","pmids":["17244193"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2007,"finding":"Scavenged lipoate is not attached to the apicoplast PDH E2 subunit, indicating that LipL1-mediated lipoate scavenging drives mitochondrial lipoylation while apicoplast lipoylation relies on biosynthesis; these two pathways are not redundant.","method":"Immunoblot with anti-PDH E2 antibodies; radiolabelled lipoate incorporation","journal":"Molecular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal methods (antibody cross-reactivity and radiolabelled uptake), single lab","pmids":["17244193"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2007,"finding":"LipL1 (LplA1) encodes a protein ligase confined to the mitochondrion that exclusively lipoylates substrates using salvaged lipoic acid; it cannot be compensated by LplA2 during blood-stage development, indicating a non-redundant essential function.","method":"Subcellular fractionation/localization studies; gene disruption attempts (unsuccessful in P. falciparum); functional complementation","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — localization and unsuccessful gene disruption in P. falciparum combined with LipB knockout showing LplA2 cannot substitute for LplA1, single lab","pmids":["18069893"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"finding":"LipL1 (LplA1) is essential for asexual blood-stage parasite survival: gene disruption in P. falciparum was consistently unsuccessful, and in P. berghei, LplA1-knockout parasites could not be cloned, indicating LplA1 is critical for erythrocytic-stage growth in vitro and in vivo.","method":"Genetic knockout/knock-in in P. berghei; repeated failed gene disruption attempts in P. falciparum","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic essentiality shown by inability to clone knockouts in P. berghei and failed disruption in P. falciparum, single lab, no clean conditional system","pmids":["19434237"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""},{"species":"Plasmodium berghei","strain":""}]},{"year":2014,"finding":"LipL1 catalyses lipoylation of the H-protein in the P. falciparum mitochondrion, but LipL1 alone cannot lipoylate the E2 subunits of BCDH or KDH. Instead, LipL1 and LipL2 together are required for BCDH and KDH lipoylation via a novel mechanism that is redox-sensitive: BCDH and KDH are exclusively lipoylated under strong reducing conditions, while H-protein lipoylation is favoured under less reducing conditions.","method":"In vitro lipoylation assays under varying redox conditions; subcellular localization of substrates by GFP fusion; reconstitution with purified LipL1 and LipL2","journal":"Molecular microbiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with purified proteins, multiple substrates tested, redox manipulation, orthogonal localization data, single lab but rigorous multi-method study","pmids":["25116855"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"finding":"LipL1 functions as a redox switch: depending on the redox state of lipoate, it acts either as a canonical ATP-dependent lipoate ligase (lipoylating H-protein) or as a lipoate-activating enzyme that works in conjunction with LipL2 (a lipoyltransferase) to lipoylate BCDH and KDH substrates.","method":"In vitro lipoylation assays; activity assays with reduced vs. oxidised lipoate; biochemical characterisation of LipL1 and LipL2 as distinct enzyme activities","journal":"Molecular microbiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution distinguishing two distinct enzymatic modes of LipL1, multiple orthogonal assays, validated against LipL2 activity, single lab with rigorous controls","pmids":["28836704"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"finding":"Crystal structure of a deletion construct of LipL1 (PfLipL1Δ243-279) bound to lipoate was solved, revealing it belongs to the biotin/lipoate A/B protein ligase family (PFAM PF03099). The deletion construct retains lipoylation activity confirmed by both in vitro lipoylation assay and a cell-based lipoylation assay.","method":"X-ray crystallography; in vitro lipoylation assay; cell-based lipoylation assay","journal":"Proteins","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with bound substrate plus orthogonal functional validation (in vitro and cell-based assays), single lab","pmids":["28543853"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"finding":"Conditional knockdown of LipL1 (LplA1) in P. berghei using an ATc-inducible system causes severely impaired growth in vivo during the first 8 days and retarded blood-stage development in vitro; late-stage parasites recover viability coinciding with significant upregulation of lplA2 mRNA, indicating lplA2 can serve as an alternative lipoylation pathway to compensate for LipL1 loss.","method":"Conditional knockout using ATc-inducible system in P. berghei; in vivo parasitemia measurement; in vitro growth assay; RT-PCR for lplA1 and lplA2 expression","journal":"Parasites & vectors","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional genetic system with phenotypic and expression analysis, single lab, no protein-level confirmation of LipL2 compensatory activity","pmids":["28655332"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]}],"current_model":"PF3D7_1314600 (LipL1) is an ATP-dependent lipoate ligase localized to the P. falciparum mitochondrion that functions as a redox switch: under less reducing conditions it acts as a canonical lipoate ligase to lipoylate the H-protein of the glycine cleavage system, whereas under strongly reducing conditions it acts as a lipoate-activating enzyme working together with LipL2 to lipoylate the E2 subunits of BCDH and KDH; LipL1 is essential for intraerythrocytic parasite survival and its crystal structure bound to lipoate has been determined."},"narrative":{"mechanistic_narrative":"PF3D7_1314600 (LipL1) is a mitochondrial ATP-dependent lipoate-protein ligase of P. falciparum that drives lipoylation of mitochondrial 2-oxoacid dehydrogenase machinery using lipoate acquired by scavenging rather than de novo synthesis [PMID:15225307, PMID:17244193]. It localizes to the parasite mitochondrion and functions as a genuine lipoate ligase, restoring lipoate scavenging in lipoylation-deficient bacteria; chemical inhibition of LipL1 by 8-bromo-octanoate arrests intraerythrocytic growth and blocks lipoate incorporation into parasite proteins, an effect reversed by exogenous lipoate [PMID:15225307, PMID:17244193]. LipL1-mediated scavenging feeds mitochondrial, but not apicoplast, lipoylation, establishing these as non-redundant pathways [PMID:17244193]. Mechanistically LipL1 operates as a redox switch: under less reducing conditions it acts as a canonical ligase that lipoylates the glycine cleavage system H-protein, whereas under strongly reducing conditions it acts as a lipoate-activating enzyme that cooperates with the lipoyltransferase LipL2 to lipoylate the E2 subunits of branched-chain 2-oxoacid dehydrogenase (BCDH) and 2-oxoglutarate dehydrogenase (KDH) [PMID:25116855, PMID:28836704]. A crystal structure of a LipL1 deletion construct bound to lipoate places it in the biotin/lipoate A/B protein ligase family [PMID:28543853]. LipL1 is essential for asexual blood-stage survival: gene disruption repeatedly failed in P. falciparum and knockouts could not be cloned in P. berghei, though conditional knockdown in P. berghei can be partially compensated by upregulation of lplA2 [PMID:18069893, PMID:19434237, PMID:28655332].","teleology":[{"year":2004,"claim":"Establishing where LipL1 acts and whether it is a bona fide lipoate ligase was the first step in placing lipoate metabolism in the parasite; the finding localized it to the mitochondrion and confirmed catalytic function.","evidence":"GFP fusion of N-terminal targeting sequence in intraerythrocytic parasites plus complementation of lipA/lipB-deficient bacteria","pmids":["15225307"],"confidence":"Medium","gaps":["Full-length localization not shown, only N-terminal sequence","Endogenous substrates not identified","Enzymatic mechanism not characterized"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2007,"claim":"Whether LipL1 activity is required for parasite growth and which lipoate source it uses was unknown; chemical inhibition with rescue and radiolabelled tracing showed LipL1 scavenges lipoate to lipoylate mitochondrial proteins and that this is growth-critical, distinct from apicoplast lipoylation.","evidence":"Bacterial complementation, radiolabelled lipoate incorporation, 8-bromo-octanoate inhibition with lipoate rescue, anti-PDH E2 immunoblot","pmids":["17244193","18069893"],"confidence":"Medium","gaps":["Specific mitochondrial substrates not yet resolved","Inhibitor selectivity for LipL1 versus other enzymes not fully excluded","Non-redundancy with LplA2 inferred, not directly demonstrated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2009,"claim":"Genetic essentiality was untested; failed disruption in P. falciparum and inability to clone knockouts in P. berghei established LipL1 as required for erythrocytic-stage growth in vitro and in vivo.","evidence":"Knockout/knock-in attempts in P. berghei and repeated failed gene disruption in P. falciparum","pmids":["19434237"],"confidence":"Medium","gaps":["No conditional system to confirm essentiality directly","Stage-specific requirement beyond blood stage not addressed"],"attribution":[{"species":"Plasmodium falciparum","strain":""},{"species":"Plasmodium berghei","strain":""}]},{"year":2014,"claim":"The substrate range and cofactor requirements were unresolved; in vitro reconstitution showed LipL1 alone lipoylates H-protein but requires LipL2 to lipoylate BCDH and KDH E2 subunits, and that substrate selection is redox-dependent.","evidence":"In vitro lipoylation assays under varied redox conditions, GFP-fusion substrate localization, reconstitution with purified LipL1 and LipL2","pmids":["25116855"],"confidence":"High","gaps":["Physiological redox state in vivo not measured","Structural basis of the LipL1–LipL2 cooperation not defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"claim":"How one enzyme could serve two substrate classes was open; biochemical dissection defined LipL1 as a redox switch that toggles between canonical ligase and lipoate-activating enzyme modes, and a lipoate-bound crystal structure assigned it to the biotin/lipoate A/B ligase family.","evidence":"In vitro lipoylation assays with reduced versus oxidised lipoate, activity assays distinguishing LipL1 and LipL2, and X-ray crystallography of PfLipL1Δ243-279 with orthogonal functional validation","pmids":["28836704","28543853"],"confidence":"High","gaps":["In vivo trigger controlling the redox switch not identified","Structure of the LipL1–LipL2 complex or full-length LipL1 not solved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2017,"claim":"Whether LipL1 loss could be tolerated was tested by conditional knockdown, which caused severe early growth impairment in P. berghei with late recovery coinciding with lplA2 upregulation, indicating a compensatory alternative pathway.","evidence":"ATc-inducible conditional knockout in P. berghei, in vivo parasitemia and in vitro growth assays, RT-PCR for lplA1 and lplA2","pmids":["28655332"],"confidence":"Medium","gaps":["Compensation inferred from mRNA, not confirmed at protein or activity level","P. falciparum conditional confirmation lacking"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":null,"claim":"What physiological signal sets the mitochondrial redox state that selects between LipL1's ligase and activating-enzyme modes, and the structural mechanism of LipL1–LipL2 cooperation, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No in vivo measurement of the redox trigger","No structure of the LipL1–LipL2 assembly","Compensation by LplA2 not validated at the protein level"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["LIPL2 (LIPOYLTRANSFERASE COFACTOR IN REDUCING-CONDITION MODE)"],"other_free_text":["Uses scavenged/salvaged lipoate rather than de novo biosynthesis; mitochondrial lipoylation is non-redundant with apicoplast biosynthesis [#2]","Acts as a redox switch: canonical ligase toward H-protein under less reducing conditions, lipoate-activating enzyme (with LipL2) toward BCDH and KDH E2 subunits under strongly reducing conditions [#5, #6]","Essential for asexual blood-stage survival; partial compensation by lplA2 upregulation upon conditional knockdown in P. berghei [#3, #4, #8]","Belongs to the biotin/lipoate A/B protein ligase family (PFAM PF03099); lipoate-bound crystal structure of a deletion construct solved [#7]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"17244193","id":"PMC_17244193","title":"Scavenging of the cofactor lipoate is essential for the survival of the malaria parasite Plasmodium falciparum.","date":"2007","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/17244193","citation_count":66,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["LipL1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"15225307","id":"PMC_15225307","title":"The human malaria parasite Plasmodium falciparum has distinct organelle-specific lipoylation pathways.","date":"2004","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/15225307","citation_count":64,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"18069893","id":"PMC_18069893","title":"Apicoplast lipoic acid protein ligase B is not essential for Plasmodium falciparum.","date":"2007","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/18069893","citation_count":42,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["LplA1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"22607141","id":"PMC_22607141","title":"Lipoic acid metabolism of Plasmodium--a suitable drug target.","date":"2012","source":"Current pharmaceutical design","url":"https://pubmed.ncbi.nlm.nih.gov/22607141","citation_count":31,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["LplA1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"19434237","id":"PMC_19434237","title":"Knockout studies reveal an important role of Plasmodium lipoic acid protein ligase A1 for asexual blood stage parasite survival.","date":"2009","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/19434237","citation_count":26,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["LplA1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"25116855","id":"PMC_25116855","title":"Redox-dependent lipoylation of mitochondrial proteins in Plasmodium falciparum.","date":"2014","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/25116855","citation_count":19,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["LipL1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28836704","id":"PMC_28836704","title":"A novel lipoate attachment enzyme is shared by Plasmodium and Chlamydia species.","date":"2017","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/28836704","citation_count":13,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfLipL1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28655332","id":"PMC_28655332","title":"Conditional knock-out of lipoic acid protein ligase 1 reveals redundancy pathway for lipoic acid metabolism in Plasmodium berghei malaria parasite.","date":"2017","source":"Parasites & vectors","url":"https://pubmed.ncbi.nlm.nih.gov/28655332","citation_count":4,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["LplA1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28543853","id":"PMC_28543853","title":"Crystal structure of lipoate-bound lipoate ligase 1, LipL1, from Plasmodium falciparum.","date":"2017","source":"Proteins","url":"https://pubmed.ncbi.nlm.nih.gov/28543853","citation_count":3,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["LipL1","PfLipL1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7242,"output_tokens":2618,"usd":0.030498,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8055,"output_tokens":3350,"usd":0.062012,"stage2_stop_reason":"end_turn"},"total_usd":0.09251,"stage1_batch_id":"msgbatch_011BPjN2BL33F8cJXD1r7V7T","stage2_batch_id":"msgbatch_01Qwg6vP7qxkpL6Gsc7tajsb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2004,\n      \"finding\": \"LipL1 (lipoic acid protein ligase) localizes to the mitochondrion of P. falciparum, as established by GFP fusion of its N-terminal sequence expressed in intraerythrocytic parasites; functionality was confirmed by complementation of lipA/lipB-deficient bacteria.\",\n      \"method\": \"GFP fusion live imaging of N-terminal sequences; bacterial complementation assay\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by GFP fusion with functional validation by bacterial complementation, single lab\",\n      \"pmids\": [\"15225307\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"LipL1 restores lipoate scavenging in lipoylation-deficient bacteria, demonstrating it is a functional lipoate ligase. 8-bromo-octanoate inhibits LipL1 activity and arrests P. falciparum intraerythrocytic growth, decreasing incorporation of radiolabelled lipoate into parasite proteins; this growth inhibition is reversed by exogenous lipoate, consistent with specific interference with lipoate scavenging.\",\n      \"method\": \"Bacterial complementation assay; in vitro growth inhibition assay with radiolabelled lipoate incorporation; lipoate rescue experiment\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (complementation, radiolabelled substrate incorporation, chemical inhibition with rescue), replicated across two labs (Prigge and Müller groups)\",\n      \"pmids\": [\"17244193\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Scavenged lipoate is not attached to the apicoplast PDH E2 subunit, indicating that LipL1-mediated lipoate scavenging drives mitochondrial lipoylation while apicoplast lipoylation relies on biosynthesis; these two pathways are not redundant.\",\n      \"method\": \"Immunoblot with anti-PDH E2 antibodies; radiolabelled lipoate incorporation\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal methods (antibody cross-reactivity and radiolabelled uptake), single lab\",\n      \"pmids\": [\"17244193\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"LipL1 (LplA1) encodes a protein ligase confined to the mitochondrion that exclusively lipoylates substrates using salvaged lipoic acid; it cannot be compensated by LplA2 during blood-stage development, indicating a non-redundant essential function.\",\n      \"method\": \"Subcellular fractionation/localization studies; gene disruption attempts (unsuccessful in P. falciparum); functional complementation\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — localization and unsuccessful gene disruption in P. falciparum combined with LipB knockout showing LplA2 cannot substitute for LplA1, single lab\",\n      \"pmids\": [\"18069893\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"LipL1 (LplA1) is essential for asexual blood-stage parasite survival: gene disruption in P. falciparum was consistently unsuccessful, and in P. berghei, LplA1-knockout parasites could not be cloned, indicating LplA1 is critical for erythrocytic-stage growth in vitro and in vivo.\",\n      \"method\": \"Genetic knockout/knock-in in P. berghei; repeated failed gene disruption attempts in P. falciparum\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic essentiality shown by inability to clone knockouts in P. berghei and failed disruption in P. falciparum, single lab, no clean conditional system\",\n      \"pmids\": [\"19434237\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"},\n        {\"species\": \"Plasmodium berghei\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"LipL1 catalyses lipoylation of the H-protein in the P. falciparum mitochondrion, but LipL1 alone cannot lipoylate the E2 subunits of BCDH or KDH. Instead, LipL1 and LipL2 together are required for BCDH and KDH lipoylation via a novel mechanism that is redox-sensitive: BCDH and KDH are exclusively lipoylated under strong reducing conditions, while H-protein lipoylation is favoured under less reducing conditions.\",\n      \"method\": \"In vitro lipoylation assays under varying redox conditions; subcellular localization of substrates by GFP fusion; reconstitution with purified LipL1 and LipL2\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with purified proteins, multiple substrates tested, redox manipulation, orthogonal localization data, single lab but rigorous multi-method study\",\n      \"pmids\": [\"25116855\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"LipL1 functions as a redox switch: depending on the redox state of lipoate, it acts either as a canonical ATP-dependent lipoate ligase (lipoylating H-protein) or as a lipoate-activating enzyme that works in conjunction with LipL2 (a lipoyltransferase) to lipoylate BCDH and KDH substrates.\",\n      \"method\": \"In vitro lipoylation assays; activity assays with reduced vs. oxidised lipoate; biochemical characterisation of LipL1 and LipL2 as distinct enzyme activities\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution distinguishing two distinct enzymatic modes of LipL1, multiple orthogonal assays, validated against LipL2 activity, single lab with rigorous controls\",\n      \"pmids\": [\"28836704\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Crystal structure of a deletion construct of LipL1 (PfLipL1Δ243-279) bound to lipoate was solved, revealing it belongs to the biotin/lipoate A/B protein ligase family (PFAM PF03099). The deletion construct retains lipoylation activity confirmed by both in vitro lipoylation assay and a cell-based lipoylation assay.\",\n      \"method\": \"X-ray crystallography; in vitro lipoylation assay; cell-based lipoylation assay\",\n      \"journal\": \"Proteins\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with bound substrate plus orthogonal functional validation (in vitro and cell-based assays), single lab\",\n      \"pmids\": [\"28543853\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Conditional knockdown of LipL1 (LplA1) in P. berghei using an ATc-inducible system causes severely impaired growth in vivo during the first 8 days and retarded blood-stage development in vitro; late-stage parasites recover viability coinciding with significant upregulation of lplA2 mRNA, indicating lplA2 can serve as an alternative lipoylation pathway to compensate for LipL1 loss.\",\n      \"method\": \"Conditional knockout using ATc-inducible system in P. berghei; in vivo parasitemia measurement; in vitro growth assay; RT-PCR for lplA1 and lplA2 expression\",\n      \"journal\": \"Parasites & vectors\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional genetic system with phenotypic and expression analysis, single lab, no protein-level confirmation of LipL2 compensatory activity\",\n      \"pmids\": [\"28655332\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PF3D7_1314600 (LipL1) is an ATP-dependent lipoate ligase localized to the P. falciparum mitochondrion that functions as a redox switch: under less reducing conditions it acts as a canonical lipoate ligase to lipoylate the H-protein of the glycine cleavage system, whereas under strongly reducing conditions it acts as a lipoate-activating enzyme working together with LipL2 to lipoylate the E2 subunits of BCDH and KDH; LipL1 is essential for intraerythrocytic parasite survival and its crystal structure bound to lipoate has been determined.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"PF3D7_1314600 (LipL1) is a mitochondrial ATP-dependent lipoate-protein ligase of P. falciparum that drives lipoylation of mitochondrial 2-oxoacid dehydrogenase machinery using lipoate acquired by scavenging rather than de novo synthesis [#0, #1, #2]. It localizes to the parasite mitochondrion and functions as a genuine lipoate ligase, restoring lipoate scavenging in lipoylation-deficient bacteria; chemical inhibition of LipL1 by 8-bromo-octanoate arrests intraerythrocytic growth and blocks lipoate incorporation into parasite proteins, an effect reversed by exogenous lipoate [#0, #1]. LipL1-mediated scavenging feeds mitochondrial, but not apicoplast, lipoylation, establishing these as non-redundant pathways [#2]. Mechanistically LipL1 operates as a redox switch: under less reducing conditions it acts as a canonical ligase that lipoylates the glycine cleavage system H-protein, whereas under strongly reducing conditions it acts as a lipoate-activating enzyme that cooperates with the lipoyltransferase LipL2 to lipoylate the E2 subunits of branched-chain 2-oxoacid dehydrogenase (BCDH) and 2-oxoglutarate dehydrogenase (KDH) [#5, #6]. A crystal structure of a LipL1 deletion construct bound to lipoate places it in the biotin/lipoate A/B protein ligase family [#7]. LipL1 is essential for asexual blood-stage survival: gene disruption repeatedly failed in P. falciparum and knockouts could not be cloned in P. berghei, though conditional knockdown in P. berghei can be partially compensated by upregulation of lplA2 [#3, #4, #8].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Establishing where LipL1 acts and whether it is a bona fide lipoate ligase was the first step in placing lipoate metabolism in the parasite; the finding localized it to the mitochondrion and confirmed catalytic function.\",\n      \"evidence\": \"GFP fusion of N-terminal targeting sequence in intraerythrocytic parasites plus complementation of lipA/lipB-deficient bacteria\",\n      \"pmids\": [\"15225307\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Full-length localization not shown, only N-terminal sequence\",\n        \"Endogenous substrates not identified\",\n        \"Enzymatic mechanism not characterized\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Whether LipL1 activity is required for parasite growth and which lipoate source it uses was unknown; chemical inhibition with rescue and radiolabelled tracing showed LipL1 scavenges lipoate to lipoylate mitochondrial proteins and that this is growth-critical, distinct from apicoplast lipoylation.\",\n      \"evidence\": \"Bacterial complementation, radiolabelled lipoate incorporation, 8-bromo-octanoate inhibition with lipoate rescue, anti-PDH E2 immunoblot\",\n      \"pmids\": [\"17244193\", \"18069893\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Specific mitochondrial substrates not yet resolved\",\n        \"Inhibitor selectivity for LipL1 versus other enzymes not fully excluded\",\n        \"Non-redundancy with LplA2 inferred, not directly demonstrated\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Genetic essentiality was untested; failed disruption in P. falciparum and inability to clone knockouts in P. berghei established LipL1 as required for erythrocytic-stage growth in vitro and in vivo.\",\n      \"evidence\": \"Knockout/knock-in attempts in P. berghei and repeated failed gene disruption in P. falciparum\",\n      \"pmids\": [\"19434237\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No conditional system to confirm essentiality directly\",\n        \"Stage-specific requirement beyond blood stage not addressed\"\n      ],\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"},\n        {\"species\": \"Plasmodium berghei\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"The substrate range and cofactor requirements were unresolved; in vitro reconstitution showed LipL1 alone lipoylates H-protein but requires LipL2 to lipoylate BCDH and KDH E2 subunits, and that substrate selection is redox-dependent.\",\n      \"evidence\": \"In vitro lipoylation assays under varied redox conditions, GFP-fusion substrate localization, reconstitution with purified LipL1 and LipL2\",\n      \"pmids\": [\"25116855\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Physiological redox state in vivo not measured\",\n        \"Structural basis of the LipL1–LipL2 cooperation not defined\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"How one enzyme could serve two substrate classes was open; biochemical dissection defined LipL1 as a redox switch that toggles between canonical ligase and lipoate-activating enzyme modes, and a lipoate-bound crystal structure assigned it to the biotin/lipoate A/B ligase family.\",\n      \"evidence\": \"In vitro lipoylation assays with reduced versus oxidised lipoate, activity assays distinguishing LipL1 and LipL2, and X-ray crystallography of PfLipL1Δ243-279 with orthogonal functional validation\",\n      \"pmids\": [\"28836704\", \"28543853\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"In vivo trigger controlling the redox switch not identified\",\n        \"Structure of the LipL1–LipL2 complex or full-length LipL1 not solved\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Whether LipL1 loss could be tolerated was tested by conditional knockdown, which caused severe early growth impairment in P. berghei with late recovery coinciding with lplA2 upregulation, indicating a compensatory alternative pathway.\",\n      \"evidence\": \"ATc-inducible conditional knockout in P. berghei, in vivo parasitemia and in vitro growth assays, RT-PCR for lplA1 and lplA2\",\n      \"pmids\": [\"28655332\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Compensation inferred from mRNA, not confirmed at protein or activity level\",\n        \"P. falciparum conditional confirmation lacking\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"What physiological signal sets the mitochondrial redox state that selects between LipL1's ligase and activating-enzyme modes, and the structural mechanism of LipL1–LipL2 cooperation, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No in vivo measurement of the redox trigger\",\n        \"No structure of the LipL1–LipL2 assembly\",\n        \"Compensation by LplA2 not validated at the protein level\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0017118\", \"supporting_discovery_ids\": [1, 5, 6, 7]},\n      {\"term_id\": \"GO:0005524\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [1, 6, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 2, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0009107\", \"supporting_discovery_ids\": [1, 2, 5]},\n      {\"term_id\": \"GO:0036211\", \"supporting_discovery_ids\": [5, 6]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"LipL2 (lipoyltransferase cofactor in reducing-condition mode)\"],\n    \"other_free_text\": [\n      \"Uses scavenged/salvaged lipoate rather than de novo biosynthesis; mitochondrial lipoylation is non-redundant with apicoplast biosynthesis [#2]\",\n      \"Acts as a redox switch: canonical ligase toward H-protein under less reducing conditions, lipoate-activating enzyme (with LipL2) toward BCDH and KDH E2 subunits under strongly reducing conditions [#5, #6]\",\n      \"Essential for asexual blood-stage survival; partial compensation by lplA2 upregulation upon conditional knockdown in P. berghei [#3, #4, #8]\",\n      \"Belongs to the biotin/lipoate A/B protein ligase family (PFAM PF03099); lipoate-bound crystal structure of a deletion construct solved [#7]\"\n    ]\n  }\n}\n```","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1314600","name":null,"product":"lipoate-protein ligase 1","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1413100","name":null,"product":"lipoate-protein ligase 1","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1415200","name":null,"product":"lipoate-protein ligase 1, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"LipL1","evaluation":null}