{"gene":"GLRX5","run_date":"2026-06-10T01:55:21","timeline":{"discoveries":[{"year":1999,"finding":"Yeast Grx5 (ortholog of human GLRX5) is a monothiol glutaredoxin required to protect against constitutive oxidative protein damage; grx5 null mutants show increased total protein carbonyl content and specific oxidation of proteins such as transketolase, and are highly sensitive to menadione and hydrogen peroxide.","method":"Genetic deletion (grx5 null mutant), protein carbonyl assay, growth sensitivity assays, synthetic lethality with grx2 and grx3/grx4 double mutants","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (genetic, biochemical, phenotypic), independently established in yeast model with clear functional readouts","pmids":["10567543"],"is_preprint":false},{"year":2002,"finding":"Yeast Grx5 localizes to the mitochondrial matrix (mature form lacks the first 29 amino acids of the translation product) and is required for iron-sulfur (Fe/S) cluster assembly; absence of Grx5 causes iron accumulation and inactivation of Fe/S-dependent enzymes. Overexpression of SSQ1 and ISA2 (Fe/S assembly genes) suppresses grx5 phenotypes, placing Grx5 in the mitochondrial Fe/S assembly machinery.","method":"Subcellular fractionation/localization, genetic epistasis (suppressor overexpression), enzyme activity assays, iron measurement in null mutants","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (localization, epistasis, enzymatic assays), replicated across labs","pmids":["11950925"],"is_preprint":false},{"year":2002,"finding":"Structure-function analysis of yeast Grx5 identifies Cys60 and Gly61 as essential for function (Fe/S cluster assembly and oxidant resistance), while Cys117 is not essential; Gly115/Gly116 are important for glutathione cleft formation; Phe50 is required for proper thioredoxin-fold beta-sheet structure.","method":"Site-directed mutagenesis of conserved residues, 3D modeling, phenotypic assays (oxidant sensitivity, respiratory growth, amino acid auxotrophy, iron accumulation)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — mutagenesis with multiple phenotypic readouts and structural modeling, single lab but comprehensive","pmids":["12138088"],"is_preprint":false},{"year":2003,"finding":"Yeast Grx5 has a redox potential of -175 mV; the conserved Cys60 (pKa 5.0) forms a transient mixed disulfide with glutathione (GSSG), which then promotes a decrease in Cys117 pKa (8.2 → lower) triggering an intramolecular disulfide bond between Cys60 and Cys117; the disulfide is reduced by GSH ~20× more slowly than E. coli Grx1; Grx5 efficiently reduces glutathiolated substrate proteins, consistent with a thiol reductase function in mitochondria.","method":"Purification of wild-type and C60S/C117S mutant proteins, redox potential measurement, iodoacetamide titration at different pH, in vitro glutathionylation/reduction assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro biochemical reconstitution with mutagenesis, multiple quantitative assays, single lab","pmids":["12730244"],"is_preprint":false},{"year":2006,"finding":"Human GLRX5 (hGRX5) contains a mitochondrial targeting sequence and, when expressed in the mitochondrial matrix of yeast grx5 null mutants, fully rescues the Fe/S cluster assembly defects, demonstrating functional conservation of human GLRX5 in mitochondrial Fe/S biogenesis.","method":"Heterologous complementation in yeast grx5 null mutant, mitochondrial targeting/localization, phenotypic rescue assays","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic complementation with localization evidence, single lab, cross-species approach","pmids":["16566929"],"is_preprint":false},{"year":2010,"finding":"Fission yeast Grx5 interacts in vivo with Fe/S scaffold proteins Isa1 and Isa2 in mitochondria (demonstrated by bimolecular fluorescence complementation); multi-copy overexpression of isa1+ or isa2+ (but not isu1+ or ssc1+) suppresses grx5 null growth defects and partially restores Fe/S enzyme activities; Grx5 also supports mitochondrial DNA integrity.","method":"Bimolecular fluorescence complementation (BiFC) for in vivo protein interaction, multi-copy suppressor screen, Fe/S enzyme activity assays, mtDNA quantification","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — BiFC interaction plus genetic epistasis with biochemical readouts, single lab","pmids":["20085751"],"is_preprint":false},{"year":2011,"finding":"Crystal structure of human GLRX5 bound to two [2Fe-2S] clusters and four GSH molecules reveals: (1) tetrameric organization with clusters buried in the interior; (2) each [2Fe-2S] cluster coordinated by the N-terminal active-site Cys67 thiols from two protomers and two cysteine thiols from two GSH molecules; (3) the apoprotein is monomeric while the holo form is tetrameric; (4) glutathionylation of Cys67 occurs in the absence of cluster, potentially protecting it; (5) apo-GLRX5 reduces glutathione mixed disulfides ~100× more slowly than GLRX2 but is active as a glutathione-dependent electron donor for ribonucleotide reductase.","method":"X-ray crystallography, gel-filtration chromatography, analytical ultracentrifugation, mass spectrometry, in vitro enzymatic assay","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with functional validation by multiple orthogonal biophysical and biochemical methods","pmids":["21029046"],"is_preprint":false},{"year":2013,"finding":"Mitochondrial Hsp70 chaperone Ssq1 interacts with Grx5 at a binding site distinct from that of scaffold protein Isu1; Grx5 binding is most pronounced for the ADP-bound form of Ssq1; Grx5 binding does not stimulate Ssq1 ATPase activity; the proximity of Isu1 and Grx5 on Ssq1 facilitates rapid Fe/S cluster transfer from Isu1 to Grx5; Grx5 and its bound Fe/S cluster are required for maturation of all cellular Fe/S proteins regardless of cluster type or subcellular localization.","method":"In vivo and in vitro interaction assays, ATPase activity measurement, Fe/S cluster transfer assays, genetic depletion studies","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro reconstitution of cluster transfer combined with in vivo epistasis and multiple biochemical assays","pmids":["23615440"],"is_preprint":false},{"year":2013,"finding":"Human GLRX5 mutations cause variant nonketotic hyperglycinemia with deficient lipoylation of mitochondrial proteins and reduced pyruvate dehydrogenase activity; transfection with wild-type GLRX5 corrects the biochemical deficiency in patient cells, establishing GLRX5 as required for lipoylation (and thus indirectly for glycine cleavage enzyme function).","method":"Patient cell biochemistry, transfection rescue experiments, enzyme activity assays (lipoylation, PDH, glycine cleavage), genetic sequencing","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional rescue by transfection with wild-type gene in human patient cells, multiple biochemical endpoints","pmids":["24334290"],"is_preprint":false},{"year":2016,"finding":"Using GLRX5 knockout K562 cells, the K101Q mutation (preventing Fe/S binding to GLRX5) and the L148S mutation (interfering with Fe/S transfer from GLRX5 to downstream targets IRP1, mitochondrial aconitase, and ferrochelatase) define distinct functional domains; GLRX5 is required for lipoylation of pyruvate dehydrogenase complex and α-ketoglutarate dehydrogenase complex components.","method":"CRISPR/genetic knockout of GLRX5 in K562 cells, mutant transfection, Fe/S enzyme activity assays (IRP1, m-aconitase, ferrochelatase, succinate dehydrogenase), lipoylation western blot","journal":"Journal of cellular biochemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO cell line with multiple orthogonal enzyme activity readouts and structure-function mutagenesis","pmids":["26100117"],"is_preprint":false},{"year":2017,"finding":"Human mitochondrial BOLA1 and BOLA3 each form [2Fe-2S] cluster-bridged dimeric heterocomplexes with GRX5; BOLA1-GRX5 coordinates a reduced Rieske-type [2Fe-2S]1+ cluster while BOLA3-GRX5 coordinates an oxidized ferredoxin-like [2Fe-2S]2+ cluster; BOLA1-GRX5 is preferentially formed over BOLA3-GRX5 due to higher cluster binding affinity.","method":"UV/vis spectroscopy, CD spectroscopy, EPR spectroscopy, NMR spectroscopy, computational protein-protein docking (experimentally-driven structural models)","journal":"Biochimica et biophysica acta. General subjects","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal spectroscopic methods with structural modeling, single lab but rigorous characterization","pmids":["28483642"],"is_preprint":false},{"year":2017,"finding":"Glutathione residues in the GRX5 binding pocket provide ionic and hydrogen-bonding contacts critical for cluster chirality; Cys67 of GRX5 coordinates the [2Fe-2S] cluster through glutathione; substitution of glutathione analogs or other thiols (DTT, L-cysteine) allows cluster reconstitution and transfer to apo ferredoxin 1 at comparable rates, but alters CD spectra reflecting perturbations in local cluster chirality.","method":"In vitro chemical reconstitution with natural and non-natural amino acid substitutions, CD spectroscopy, cluster transfer kinetics to apo ferredoxin","journal":"Journal of biological inorganic chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro reconstitution with mutagenesis but single lab and limited functional validation beyond spectroscopy","pmids":["29264659"],"is_preprint":false},{"year":2019,"finding":"GLRX5 mutations (Cys67Tyr and Met128Lys) in a sideroblastic anemia patient impair both ferrochelatase activity (without porphyrin accumulation) and ALAS2 activity (possibly via defective succinyl-CoA biogenesis); structural analysis confirms Cys67 coordinates the [2Fe-2S] cluster and Met128 is implicated in partner protein interactions; GLRX5 loss also causes oxidative stress (reduced glutathione, decreased aconitase activity), mtDNA damage, and decreased respiratory chain complex I and IV activities.","method":"Patient-derived lymphoblastoid and CD34+ cell biochemistry, 3D structure analysis, enzyme activity assays (ferrochelatase, ALAS2, aconitase, complexes I/IV), oxidative stress markers, mtDNA quantification","journal":"Molecular genetics and metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal biochemical assays in patient-derived cells, single lab, structural modeling to support mechanistic claims","pmids":["30660387"],"is_preprint":false},{"year":2020,"finding":"[2Fe-2S]-bridged BOLA1-GLRX5 heterodimeric complex can accept cluster from ISCU or [2Fe-2S](GS)4 but not from ISCA1 or ISCA2; the holo BOLA1-GLRX5 complex is incapable of donating cluster to apo protein acceptors, providing experimental evidence for a non-trafficking (likely redox) role distinct from the cluster-donating BOLA3-GLRX5 complex.","method":"CD spectroscopy-based cluster transfer kinetics, in vitro reconstitution with defined donor/acceptor proteins","journal":"The FEBS journal","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro reconstitution with defined biochemical readouts, single lab, limited to kinetic/spectroscopic characterization","pmids":["32542995"],"is_preprint":false},{"year":2025,"finding":"Purified Grx5 precursor protein, imported into isolated Grx5-depleted yeast mitochondria, rescues both intra-mitochondrial Fe/S cluster synthesis and generation of the exported Fe/S intermediate (Fe-S)int required for cytoplasmic Fe/S assembly; mitochondria lacking Isa1 or Isa2 can still synthesize [2Fe-2S] but not [4Fe-4S] clusters and can still support cytoplasmic Fe/S assembly, placing Grx5 upstream of Isa1/Isa2 as a central hub for both mitochondrial and cytoplasmic Fe/S cluster biogenesis.","method":"Isolated mitochondria and cytoplasm from S. cerevisiae, in vitro import of purified Grx5 precursor, Fe/S cluster synthesis assays in isolated organelles, genetic depletion of Grx5/Isa1/Isa2","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with purified protein import plus genetic depletion and multiple biochemical readouts, single lab but rigorous","pmids":["40074084"],"is_preprint":false}],"current_model":"Human GLRX5 is a mitochondrial matrix monothiol glutaredoxin that coordinates a [2Fe-2S] cluster via its active-site Cys67 and two glutathione molecules, functioning as a central hub in the iron-sulfur cluster (ISC) assembly pathway: it accepts pre-assembled Fe/S clusters from the scaffold protein ISCU (facilitated by the Hsp70 chaperone Ssq1/HSPA9 acting as a scaffold for both proteins), forms cluster-bridged heterodimeric complexes with BOLA1 (redox role) and BOLA3 (trafficking role), and is required for maturation of all cellular Fe/S proteins as well as for lipoylation of mitochondrial enzymes (PDH, α-KGDH) and heme biosynthesis via ferrochelatase and ALAS2 activities; loss-of-function mutations in humans cause sideroblastic anemia and variant nonketotic hyperglycinemia."},"narrative":{"mechanistic_narrative":"GLRX5 is a mitochondrial matrix monothiol glutaredoxin that serves as a central hub of the iron-sulfur (Fe/S) cluster assembly pathway, required for maturation of all cellular Fe/S proteins regardless of cluster type or subcellular location [PMID:11950925, PMID:23615440, PMID:40074084]. It coordinates a bridging [2Fe-2S] cluster through its active-site Cys67 and two glutathione molecules, transitioning from a monomeric apoprotein to a cluster-bound oligomer, with glutathione contacts dictating cluster chirality [PMID:21029046, PMID:29264659]. GLRX5 receives pre-assembled clusters from the scaffold protein ISCU/Isu1, a transfer facilitated by the mitochondrial Hsp70 chaperone Ssq1, which binds GLRX5 at a site distinct from the scaffold and positions the two proteins for rapid cluster hand-off [PMID:23615440]; reconstitution in isolated mitochondria places GLRX5 upstream of the Isa1/Isa2 machinery and shows it is needed both for intramitochondrial Fe/S synthesis and for the exported intermediate that supports cytoplasmic Fe/S assembly [PMID:40074084]. Downstream, GLRX5 forms cluster-bridged heterodimers with BOLA1 and BOLA3 that diverge functionally: BOLA1-GLRX5 binds a reduced Rieske-type cluster and cannot donate it (a non-trafficking, redox role), whereas BOLA3-GLRX5 carries an oxidized ferredoxin-type cluster competent for trafficking [PMID:28483642, PMID:32542995]. Through this activity GLRX5 enables maturation of Fe/S enzymes including IRP1, mitochondrial aconitase, ferrochelatase and succinate dehydrogenase, lipoylation of the pyruvate dehydrogenase and α-ketoglutarate dehydrogenase complexes, and heme biosynthesis via ferrochelatase and ALAS2 [PMID:26100117, PMID:30660387]. Loss-of-function GLRX5 mutations in humans cause sideroblastic anemia and variant nonketotic hyperglycinemia, with patient defects in lipoylation and PDH activity corrected by wild-type GLRX5 [PMID:24334290, PMID:30660387].","teleology":[{"year":1999,"claim":"Established the founding function of the GLRX5 ortholog as a monothiol glutaredoxin protecting cells against oxidative protein damage, before any Fe/S role was known.","evidence":"Genetic deletion of yeast grx5 with protein carbonyl assays and oxidant sensitivity screens","pmids":["10567543"],"confidence":"High","gaps":["Did not identify a molecular substrate or distinguish a direct redox role from an indirect consequence of metabolic dysfunction","No connection to Fe/S biology yet"]},{"year":2002,"claim":"Localized the protein to the mitochondrial matrix and placed it in the Fe/S assembly machinery, recasting the oxidative phenotype as a downstream consequence of failed Fe/S biogenesis.","evidence":"Subcellular fractionation, suppressor-overexpression epistasis (SSQ1, ISA2), Fe/S enzyme assays and iron measurement in yeast null mutants","pmids":["11950925"],"confidence":"High","gaps":["Did not define the biochemical step catalyzed within the pathway","Mechanism of iron accumulation not resolved"]},{"year":2002,"claim":"Mapped the residues essential for both Fe/S assembly and oxidant resistance, identifying the active-site cysteine and the glutathione cleft as functionally required.","evidence":"Site-directed mutagenesis with 3D modeling and multiple phenotypic readouts in yeast","pmids":["12138088"],"confidence":"High","gaps":["Structural model not experimentally determined at the time","Did not establish whether the active-site cysteine binds a cluster directly"]},{"year":2003,"claim":"Defined the redox chemistry of the active site, showing a GSH-dependent thiol reductase cycle and quantifying its sluggish kinetics relative to dithiol glutaredoxins.","evidence":"Purified wild-type and cysteine-mutant proteins, redox potential and pKa measurements, in vitro glutathionylation/reduction assays","pmids":["12730244"],"confidence":"High","gaps":["Did not reconcile the slow reductase activity with the essential Fe/S role","Physiological substrate of the reductase activity not identified"]},{"year":2006,"claim":"Demonstrated functional conservation by showing human GLRX5 targeted to yeast mitochondria fully rescues Fe/S defects, validating the yeast model for human biology.","evidence":"Heterologous complementation of yeast grx5 null with human GLRX5 plus localization","pmids":["16566929"],"confidence":"Medium","gaps":["Cross-species rescue does not prove identical human partner interactions","Single lab"]},{"year":2010,"claim":"Established direct in vivo interaction with the Isa scaffold proteins and linked GLRX5 to mtDNA integrity, beginning to define its protein partnerships within the pathway.","evidence":"Bimolecular fluorescence complementation, multi-copy suppressor screen and Fe/S enzyme assays in fission yeast","pmids":["20085751"],"confidence":"Medium","gaps":["BiFC indicates proximity but not direct stable complex stoichiometry","Directionality of cluster flow between Grx5 and Isa not resolved"]},{"year":2010,"claim":"Provided the structural basis for cluster coordination, showing a [2Fe-2S] cluster bridged by Cys67 from two protomers and two glutathione thiols, with an apo-monomer/holo-oligomer transition.","evidence":"X-ray crystallography of human GLRX5 with biophysical and enzymatic validation","pmids":["21029046"],"confidence":"High","gaps":["Static structure does not capture cluster transfer dynamics","Relationship between the crystallographic tetramer and physiological transfer complexes unclear"]},{"year":2013,"claim":"Defined the Hsp70 chaperone Ssq1 as the platform that juxtaposes scaffold and GLRX5 to enable rapid cluster transfer, and established GLRX5 as required for maturation of all cellular Fe/S proteins.","evidence":"In vivo and in vitro interaction, ATPase, and cluster transfer assays with genetic depletion in yeast","pmids":["23615440"],"confidence":"High","gaps":["Did not resolve how cluster is released to specific downstream acceptors","Human ortholog (HSPA9) interaction inferred by homology, not directly tested here"]},{"year":2013,"claim":"Linked GLRX5 to human disease and to lipoylation, showing patient mutations cause variant nonketotic hyperglycinemia via defective lipoylation, with rescue by wild-type GLRX5.","evidence":"Patient cell biochemistry, transfection rescue, and enzyme activity assays","pmids":["24334290"],"confidence":"High","gaps":["Connection between Fe/S defect and lipoylation loss is indirect via Fe/S-dependent lipoyl synthase","Did not quantify cluster occupancy in patient cells"]},{"year":2016,"claim":"Separated GLRX5 function into cluster-binding and cluster-transfer steps through human KO cells and structure-function mutants, mapping discrete defects to downstream Fe/S targets and lipoylation.","evidence":"CRISPR GLRX5 knockout K562 cells with K101Q/L148S mutant rescue and multiple Fe/S enzyme and lipoylation readouts","pmids":["26100117"],"confidence":"High","gaps":["Did not identify the direct acceptor proteins for each transfer step","Mechanism by which L148S impairs transfer not structurally resolved"]},{"year":2017,"claim":"Identified divergent BOLA1 and BOLA3 heterocomplexes with distinct cluster types, revealing two functionally specialized GLRX5-containing complexes.","evidence":"UV/vis, CD, EPR, NMR spectroscopy and protein-protein docking on reconstituted human complexes","pmids":["28483642"],"confidence":"High","gaps":["Functional roles assigned by cluster type were not yet tested by transfer assays","In vivo abundance of each complex not measured"]},{"year":2017,"claim":"Showed that glutathione in the binding pocket controls cluster chirality and that thiol substitutions permit transfer to apo ferredoxin, refining the chemistry of cluster handling.","evidence":"In vitro reconstitution with natural and non-natural amino acid substitutions, CD spectroscopy, transfer kinetics to apo ferredoxin","pmids":["29264659"],"confidence":"Medium","gaps":["Single lab in vitro reconstitution","Functional consequence of altered chirality in cells not established"]},{"year":2020,"claim":"Distinguished the BOLA1-GLRX5 and BOLA3-GLRX5 complexes functionally, showing BOLA1-GLRX5 accepts but cannot donate cluster (a non-trafficking/redox role) versus the donating BOLA3-GLRX5 complex.","evidence":"CD spectroscopy cluster transfer kinetics with defined donor/acceptor proteins","pmids":["32542995"],"confidence":"Medium","gaps":["In vitro inability to donate does not exclude a partner-dependent donation in cells","Physiological redox substrate of BOLA1-GLRX5 unidentified"]},{"year":2025,"claim":"Positioned GLRX5 upstream of the Isa1/Isa2 machinery as the central hub for both mitochondrial and exported cytoplasmic Fe/S assembly using organellar reconstitution.","evidence":"In vitro import of purified Grx5 precursor into isolated yeast mitochondria with Fe/S synthesis assays and genetic depletion of Grx5/Isa1/Isa2","pmids":["40074084"],"confidence":"High","gaps":["Molecular identity of the exported (Fe-S)int intermediate not defined","How GLRX5 partitions cluster between mitochondrial maturation and export not resolved"]},{"year":null,"claim":"The physiological redox substrate of the GLRX5 thiol reductase activity and the precise molecular nature of the exported Fe/S intermediate it generates remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No identified in vivo target of GLRX5 glutaredoxin reductase activity distinct from its Fe/S role","Chemical identity and protein carrier of the cytoplasmic (Fe-S)int intermediate unknown","Determinants directing cluster to BOLA1 vs BOLA3 complexes in cells not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[3,6]},{"term_id":"GO:0140104","term_label":"molecular carrier activity","supporting_discovery_ids":[6,7,14]},{"term_id":"GO:0016491","term_label":"oxidoreductase activity","supporting_discovery_ids":[3,6]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[1,4]}],"pathway":[{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[1,7,14]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[9,12]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[8,12]}],"complexes":["BOLA1-GLRX5 [2Fe-2S]-bridged heterodimer","BOLA3-GLRX5 [2Fe-2S]-bridged heterodimer"],"partners":["ISCU","HSPA9","BOLA1","BOLA3","ISCA1","ISCA2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q86SX6","full_name":"Glutaredoxin-related protein 5, mitochondrial","aliases":["Monothiol glutaredoxin-5"],"length_aa":157,"mass_kda":16.6,"function":"Monothiol glutaredoxin involved in mitochondrial iron-sulfur (Fe/S) cluster transfer (PubMed:20364084, PubMed:23615440). Receives 2Fe/2S clusters from scaffold protein ISCU and mediates their transfer to apoproteins, to the 4Fe/FS cluster biosynthesis machinery, or export from mitochondrion (PubMed:20364084, PubMed:23615440, PubMed:24334290). Required for normal regulation of hemoglobin synthesis by the iron-sulfur protein ACO1 (PubMed:20364084)","subcellular_location":"Mitochondrion matrix","url":"https://www.uniprot.org/uniprotkb/Q86SX6/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/GLRX5","classification":"Common Essential","n_dependent_lines":704,"n_total_lines":1208,"dependency_fraction":0.5827814569536424},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/GLRX5","total_profiled":1310},"omim":[{"mim_id":"616860","title":"ANEMIA, SIDEROBLASTIC, 3, PYRIDOXINE-REFRACTORY; SIDBA3","url":"https://www.omim.org/entry/616860"},{"mim_id":"616859","title":"SPASTICITY, CHILDHOOD-ONSET, WITH HYPERGLYCINEMIA; SPAHGC","url":"https://www.omim.org/entry/616859"},{"mim_id":"614462","title":"HYPERGLYCINEMIA, LACTIC ACIDOSIS, AND SEIZURES; HGCLAS","url":"https://www.omim.org/entry/614462"},{"mim_id":"614299","title":"MULTIPLE MITOCHONDRIAL DYSFUNCTIONS SYNDROME 2 WITH HYPERGLYCINEMIA; MMDS2","url":"https://www.omim.org/entry/614299"},{"mim_id":"613183","title":"BOLA FAMILY MEMBER 3; BOLA3","url":"https://www.omim.org/entry/613183"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Mitochondria","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/GLRX5"},"hgnc":{"alias_symbol":["PR01238","GRX5"],"prev_symbol":["C14orf87"]},"alphafold":{"accession":"Q86SX6","domains":[{"cath_id":"3.40.30.10","chopping":"39-155","consensus_level":"high","plddt":94.3517,"start":39,"end":155}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86SX6","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q86SX6-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q86SX6-F1-predicted_aligned_error_v6.png","plddt_mean":82.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=GLRX5","jax_strain_url":"https://www.jax.org/strain/search?query=GLRX5"},"sequence":{"accession":"Q86SX6","fasta_url":"https://rest.uniprot.org/uniprotkb/Q86SX6.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q86SX6/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86SX6"}},"corpus_meta":[{"pmid":"11950925","id":"PMC_11950925","title":"Grx5 is a mitochondrial glutaredoxin required for the activity of iron/sulfur enzymes.","date":"2002","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/11950925","citation_count":379,"is_preprint":false},{"pmid":"10567543","id":"PMC_10567543","title":"Grx5 glutaredoxin plays a central role in protection against protein oxidative damage in Saccharomyces cerevisiae.","date":"1999","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/10567543","citation_count":246,"is_preprint":false},{"pmid":"24334290","id":"PMC_24334290","title":"Variant non ketotic hyperglycinemia is caused by mutations in LIAS, BOLA3 and the novel gene GLRX5.","date":"2013","source":"Brain : a journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/24334290","citation_count":170,"is_preprint":false},{"pmid":"12730244","id":"PMC_12730244","title":"Biochemical characterization of yeast mitochondrial Grx5 monothiol glutaredoxin.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12730244","citation_count":109,"is_preprint":false},{"pmid":"23615440","id":"PMC_23615440","title":"The mitochondrial Hsp70 chaperone Ssq1 facilitates Fe/S cluster transfer from Isu1 to Grx5 by complex formation.","date":"2013","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/23615440","citation_count":105,"is_preprint":false},{"pmid":"21029046","id":"PMC_21029046","title":"The crystal structure of human GLRX5: iron-sulfur cluster co-ordination, tetrameric assembly and monomer activity.","date":"2011","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/21029046","citation_count":102,"is_preprint":false},{"pmid":"12138088","id":"PMC_12138088","title":"Structure-function analysis of yeast Grx5 monothiol glutaredoxin defines essential amino acids for the function of the protein.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12138088","citation_count":63,"is_preprint":false},{"pmid":"16566929","id":"PMC_16566929","title":"Prokaryotic and eukaryotic monothiol glutaredoxins are able to perform the functions of Grx5 in the biogenesis of Fe/S clusters in yeast mitochondria.","date":"2006","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/16566929","citation_count":63,"is_preprint":false},{"pmid":"20085751","id":"PMC_20085751","title":"Monothiol glutaredoxin Grx5 interacts with Fe-S scaffold proteins Isa1 and Isa2 and supports Fe-S assembly and DNA integrity in mitochondria of fission yeast.","date":"2010","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/20085751","citation_count":53,"is_preprint":false},{"pmid":"28483642","id":"PMC_28483642","title":"Structural insights into the molecular function of human [2Fe-2S] BOLA1-GRX5 and [2Fe-2S] BOLA3-GRX5 complexes.","date":"2017","source":"Biochimica et biophysica acta. General subjects","url":"https://pubmed.ncbi.nlm.nih.gov/28483642","citation_count":44,"is_preprint":false},{"pmid":"26100117","id":"PMC_26100117","title":"Functional Analysis of GLRX5 Mutants Reveals Distinct Functionalities of GLRX5 Protein.","date":"2016","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/26100117","citation_count":36,"is_preprint":false},{"pmid":"30660387","id":"PMC_30660387","title":"GLRX5 mutations impair heme biosynthetic enzymes ALA synthase 2 and ferrochelatase in Human congenital sideroblastic anemia.","date":"2019","source":"Molecular genetics and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/30660387","citation_count":25,"is_preprint":false},{"pmid":"15382238","id":"PMC_15382238","title":"Predictive reconstruction of the mitochondrial iron-sulfur cluster assembly metabolism. II. Role of glutaredoxin Grx5.","date":"2004","source":"Proteins","url":"https://pubmed.ncbi.nlm.nih.gov/15382238","citation_count":25,"is_preprint":false},{"pmid":"32449295","id":"PMC_32449295","title":"A novel lncRNA BADLNCR1 inhibits bovine adipogenesis by repressing GLRX5 expression.","date":"2020","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32449295","citation_count":19,"is_preprint":false},{"pmid":"38677272","id":"PMC_38677272","title":"Salvia miltiorrhiza Bge. processed with porcine cardiac blood inhibited GLRX5-mediated ferroptosis alleviating cerebral ischemia-reperfusion injury.","date":"2024","source":"Phytomedicine : international journal of phytotherapy and phytopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/38677272","citation_count":12,"is_preprint":false},{"pmid":"38100056","id":"PMC_38100056","title":"Exosomes from hypoxic pretreated ADSCs attenuate ultraviolet light-induced skin injury via GLRX5 delivery and ferroptosis inhibition.","date":"2023","source":"Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology","url":"https://pubmed.ncbi.nlm.nih.gov/38100056","citation_count":11,"is_preprint":false},{"pmid":"33813722","id":"PMC_33813722","title":"HACE1, GLRX5, and ELP2 gene variant cause spastic paraplegies.","date":"2021","source":"Acta neurologica Belgica","url":"https://pubmed.ncbi.nlm.nih.gov/33813722","citation_count":9,"is_preprint":false},{"pmid":"40074084","id":"PMC_40074084","title":"Mitochondrial glutaredoxin Grx5 functions as a central hub for cellular iron-sulfur cluster assembly.","date":"2025","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/40074084","citation_count":8,"is_preprint":false},{"pmid":"34054912","id":"PMC_34054912","title":"Case Report: A Variant Non-ketotic Hyperglycinemia With GLRX5 Mutations: Manifestation of Deficiency of Activities of the Respiratory Chain Enzymes.","date":"2021","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/34054912","citation_count":8,"is_preprint":false},{"pmid":"34732213","id":"PMC_34732213","title":"GLRX5-associated [Fe-S] cluster biogenesis disorder: further characterisation of the neurological phenotype and long-term outcome.","date":"2021","source":"Orphanet journal of rare diseases","url":"https://pubmed.ncbi.nlm.nih.gov/34732213","citation_count":7,"is_preprint":false},{"pmid":"29264659","id":"PMC_29264659","title":"Investigation of glutathione-derived electrostatic and hydrogen-bonding interactions and their role in defining Grx5 [2Fe-2S] cluster optical spectra and transfer chemistry.","date":"2017","source":"Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/29264659","citation_count":7,"is_preprint":false},{"pmid":"32542995","id":"PMC_32542995","title":"Cluster exchange reactivity of [2Fe-2S]-bridged heterodimeric BOLA1-GLRX5.","date":"2020","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/32542995","citation_count":6,"is_preprint":false},{"pmid":"39323869","id":"PMC_39323869","title":"Case report: Unveiling genetic and phenotypic variability in Nonketotic hyperglycinemia: an atypical early onset case associated with a novel GLRX5 variant.","date":"2024","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/39323869","citation_count":1,"is_preprint":false},{"pmid":"19478456","id":"PMC_19478456","title":"Cloning, overproduction, purification, crystallization and preliminary X-ray diffraction analysis of yeast glutaredoxin Grx5.","date":"2009","source":"Acta crystallographica. Section F, Structural biology and crystallization communications","url":"https://pubmed.ncbi.nlm.nih.gov/19478456","citation_count":1,"is_preprint":false},{"pmid":"40415601","id":"PMC_40415601","title":"Infant With a Severe Form of GLRX5-Related Atypical Hyperglycinemia Exhibiting Novel Cardiac and Neurologic Disease Manifestations at Autopsy.","date":"2025","source":"Pediatric and developmental pathology : the official journal of the Society for Pediatric Pathology and the Paediatric Pathology Society","url":"https://pubmed.ncbi.nlm.nih.gov/40415601","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.06.24.600531","title":"Effect of Over-expression of GRXs on Thermo and Acetic Acid Stress Tolerance of  <i>Saccharomyces cerevisiae</i>","date":"2024-06-25","source":"bioRxiv","url":"https://doi.org/10.1101/2024.06.24.600531","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15202,"output_tokens":4372,"usd":0.055593,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12417,"output_tokens":4616,"usd":0.088743,"stage2_stop_reason":"end_turn"},"total_usd":0.144336,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1999,\n      \"finding\": \"Yeast Grx5 (ortholog of human GLRX5) is a monothiol glutaredoxin required to protect against constitutive oxidative protein damage; grx5 null mutants show increased total protein carbonyl content and specific oxidation of proteins such as transketolase, and are highly sensitive to menadione and hydrogen peroxide.\",\n      \"method\": \"Genetic deletion (grx5 null mutant), protein carbonyl assay, growth sensitivity assays, synthetic lethality with grx2 and grx3/grx4 double mutants\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (genetic, biochemical, phenotypic), independently established in yeast model with clear functional readouts\",\n      \"pmids\": [\"10567543\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Yeast Grx5 localizes to the mitochondrial matrix (mature form lacks the first 29 amino acids of the translation product) and is required for iron-sulfur (Fe/S) cluster assembly; absence of Grx5 causes iron accumulation and inactivation of Fe/S-dependent enzymes. Overexpression of SSQ1 and ISA2 (Fe/S assembly genes) suppresses grx5 phenotypes, placing Grx5 in the mitochondrial Fe/S assembly machinery.\",\n      \"method\": \"Subcellular fractionation/localization, genetic epistasis (suppressor overexpression), enzyme activity assays, iron measurement in null mutants\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (localization, epistasis, enzymatic assays), replicated across labs\",\n      \"pmids\": [\"11950925\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Structure-function analysis of yeast Grx5 identifies Cys60 and Gly61 as essential for function (Fe/S cluster assembly and oxidant resistance), while Cys117 is not essential; Gly115/Gly116 are important for glutathione cleft formation; Phe50 is required for proper thioredoxin-fold beta-sheet structure.\",\n      \"method\": \"Site-directed mutagenesis of conserved residues, 3D modeling, phenotypic assays (oxidant sensitivity, respiratory growth, amino acid auxotrophy, iron accumulation)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — mutagenesis with multiple phenotypic readouts and structural modeling, single lab but comprehensive\",\n      \"pmids\": [\"12138088\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Yeast Grx5 has a redox potential of -175 mV; the conserved Cys60 (pKa 5.0) forms a transient mixed disulfide with glutathione (GSSG), which then promotes a decrease in Cys117 pKa (8.2 → lower) triggering an intramolecular disulfide bond between Cys60 and Cys117; the disulfide is reduced by GSH ~20× more slowly than E. coli Grx1; Grx5 efficiently reduces glutathiolated substrate proteins, consistent with a thiol reductase function in mitochondria.\",\n      \"method\": \"Purification of wild-type and C60S/C117S mutant proteins, redox potential measurement, iodoacetamide titration at different pH, in vitro glutathionylation/reduction assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro biochemical reconstitution with mutagenesis, multiple quantitative assays, single lab\",\n      \"pmids\": [\"12730244\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Human GLRX5 (hGRX5) contains a mitochondrial targeting sequence and, when expressed in the mitochondrial matrix of yeast grx5 null mutants, fully rescues the Fe/S cluster assembly defects, demonstrating functional conservation of human GLRX5 in mitochondrial Fe/S biogenesis.\",\n      \"method\": \"Heterologous complementation in yeast grx5 null mutant, mitochondrial targeting/localization, phenotypic rescue assays\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic complementation with localization evidence, single lab, cross-species approach\",\n      \"pmids\": [\"16566929\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Fission yeast Grx5 interacts in vivo with Fe/S scaffold proteins Isa1 and Isa2 in mitochondria (demonstrated by bimolecular fluorescence complementation); multi-copy overexpression of isa1+ or isa2+ (but not isu1+ or ssc1+) suppresses grx5 null growth defects and partially restores Fe/S enzyme activities; Grx5 also supports mitochondrial DNA integrity.\",\n      \"method\": \"Bimolecular fluorescence complementation (BiFC) for in vivo protein interaction, multi-copy suppressor screen, Fe/S enzyme activity assays, mtDNA quantification\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — BiFC interaction plus genetic epistasis with biochemical readouts, single lab\",\n      \"pmids\": [\"20085751\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Crystal structure of human GLRX5 bound to two [2Fe-2S] clusters and four GSH molecules reveals: (1) tetrameric organization with clusters buried in the interior; (2) each [2Fe-2S] cluster coordinated by the N-terminal active-site Cys67 thiols from two protomers and two cysteine thiols from two GSH molecules; (3) the apoprotein is monomeric while the holo form is tetrameric; (4) glutathionylation of Cys67 occurs in the absence of cluster, potentially protecting it; (5) apo-GLRX5 reduces glutathione mixed disulfides ~100× more slowly than GLRX2 but is active as a glutathione-dependent electron donor for ribonucleotide reductase.\",\n      \"method\": \"X-ray crystallography, gel-filtration chromatography, analytical ultracentrifugation, mass spectrometry, in vitro enzymatic assay\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with functional validation by multiple orthogonal biophysical and biochemical methods\",\n      \"pmids\": [\"21029046\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Mitochondrial Hsp70 chaperone Ssq1 interacts with Grx5 at a binding site distinct from that of scaffold protein Isu1; Grx5 binding is most pronounced for the ADP-bound form of Ssq1; Grx5 binding does not stimulate Ssq1 ATPase activity; the proximity of Isu1 and Grx5 on Ssq1 facilitates rapid Fe/S cluster transfer from Isu1 to Grx5; Grx5 and its bound Fe/S cluster are required for maturation of all cellular Fe/S proteins regardless of cluster type or subcellular localization.\",\n      \"method\": \"In vivo and in vitro interaction assays, ATPase activity measurement, Fe/S cluster transfer assays, genetic depletion studies\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro reconstitution of cluster transfer combined with in vivo epistasis and multiple biochemical assays\",\n      \"pmids\": [\"23615440\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Human GLRX5 mutations cause variant nonketotic hyperglycinemia with deficient lipoylation of mitochondrial proteins and reduced pyruvate dehydrogenase activity; transfection with wild-type GLRX5 corrects the biochemical deficiency in patient cells, establishing GLRX5 as required for lipoylation (and thus indirectly for glycine cleavage enzyme function).\",\n      \"method\": \"Patient cell biochemistry, transfection rescue experiments, enzyme activity assays (lipoylation, PDH, glycine cleavage), genetic sequencing\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional rescue by transfection with wild-type gene in human patient cells, multiple biochemical endpoints\",\n      \"pmids\": [\"24334290\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Using GLRX5 knockout K562 cells, the K101Q mutation (preventing Fe/S binding to GLRX5) and the L148S mutation (interfering with Fe/S transfer from GLRX5 to downstream targets IRP1, mitochondrial aconitase, and ferrochelatase) define distinct functional domains; GLRX5 is required for lipoylation of pyruvate dehydrogenase complex and α-ketoglutarate dehydrogenase complex components.\",\n      \"method\": \"CRISPR/genetic knockout of GLRX5 in K562 cells, mutant transfection, Fe/S enzyme activity assays (IRP1, m-aconitase, ferrochelatase, succinate dehydrogenase), lipoylation western blot\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO cell line with multiple orthogonal enzyme activity readouts and structure-function mutagenesis\",\n      \"pmids\": [\"26100117\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Human mitochondrial BOLA1 and BOLA3 each form [2Fe-2S] cluster-bridged dimeric heterocomplexes with GRX5; BOLA1-GRX5 coordinates a reduced Rieske-type [2Fe-2S]1+ cluster while BOLA3-GRX5 coordinates an oxidized ferredoxin-like [2Fe-2S]2+ cluster; BOLA1-GRX5 is preferentially formed over BOLA3-GRX5 due to higher cluster binding affinity.\",\n      \"method\": \"UV/vis spectroscopy, CD spectroscopy, EPR spectroscopy, NMR spectroscopy, computational protein-protein docking (experimentally-driven structural models)\",\n      \"journal\": \"Biochimica et biophysica acta. General subjects\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal spectroscopic methods with structural modeling, single lab but rigorous characterization\",\n      \"pmids\": [\"28483642\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Glutathione residues in the GRX5 binding pocket provide ionic and hydrogen-bonding contacts critical for cluster chirality; Cys67 of GRX5 coordinates the [2Fe-2S] cluster through glutathione; substitution of glutathione analogs or other thiols (DTT, L-cysteine) allows cluster reconstitution and transfer to apo ferredoxin 1 at comparable rates, but alters CD spectra reflecting perturbations in local cluster chirality.\",\n      \"method\": \"In vitro chemical reconstitution with natural and non-natural amino acid substitutions, CD spectroscopy, cluster transfer kinetics to apo ferredoxin\",\n      \"journal\": \"Journal of biological inorganic chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro reconstitution with mutagenesis but single lab and limited functional validation beyond spectroscopy\",\n      \"pmids\": [\"29264659\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"GLRX5 mutations (Cys67Tyr and Met128Lys) in a sideroblastic anemia patient impair both ferrochelatase activity (without porphyrin accumulation) and ALAS2 activity (possibly via defective succinyl-CoA biogenesis); structural analysis confirms Cys67 coordinates the [2Fe-2S] cluster and Met128 is implicated in partner protein interactions; GLRX5 loss also causes oxidative stress (reduced glutathione, decreased aconitase activity), mtDNA damage, and decreased respiratory chain complex I and IV activities.\",\n      \"method\": \"Patient-derived lymphoblastoid and CD34+ cell biochemistry, 3D structure analysis, enzyme activity assays (ferrochelatase, ALAS2, aconitase, complexes I/IV), oxidative stress markers, mtDNA quantification\",\n      \"journal\": \"Molecular genetics and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal biochemical assays in patient-derived cells, single lab, structural modeling to support mechanistic claims\",\n      \"pmids\": [\"30660387\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"[2Fe-2S]-bridged BOLA1-GLRX5 heterodimeric complex can accept cluster from ISCU or [2Fe-2S](GS)4 but not from ISCA1 or ISCA2; the holo BOLA1-GLRX5 complex is incapable of donating cluster to apo protein acceptors, providing experimental evidence for a non-trafficking (likely redox) role distinct from the cluster-donating BOLA3-GLRX5 complex.\",\n      \"method\": \"CD spectroscopy-based cluster transfer kinetics, in vitro reconstitution with defined donor/acceptor proteins\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro reconstitution with defined biochemical readouts, single lab, limited to kinetic/spectroscopic characterization\",\n      \"pmids\": [\"32542995\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Purified Grx5 precursor protein, imported into isolated Grx5-depleted yeast mitochondria, rescues both intra-mitochondrial Fe/S cluster synthesis and generation of the exported Fe/S intermediate (Fe-S)int required for cytoplasmic Fe/S assembly; mitochondria lacking Isa1 or Isa2 can still synthesize [2Fe-2S] but not [4Fe-4S] clusters and can still support cytoplasmic Fe/S assembly, placing Grx5 upstream of Isa1/Isa2 as a central hub for both mitochondrial and cytoplasmic Fe/S cluster biogenesis.\",\n      \"method\": \"Isolated mitochondria and cytoplasm from S. cerevisiae, in vitro import of purified Grx5 precursor, Fe/S cluster synthesis assays in isolated organelles, genetic depletion of Grx5/Isa1/Isa2\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with purified protein import plus genetic depletion and multiple biochemical readouts, single lab but rigorous\",\n      \"pmids\": [\"40074084\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"Human GLRX5 is a mitochondrial matrix monothiol glutaredoxin that coordinates a [2Fe-2S] cluster via its active-site Cys67 and two glutathione molecules, functioning as a central hub in the iron-sulfur cluster (ISC) assembly pathway: it accepts pre-assembled Fe/S clusters from the scaffold protein ISCU (facilitated by the Hsp70 chaperone Ssq1/HSPA9 acting as a scaffold for both proteins), forms cluster-bridged heterodimeric complexes with BOLA1 (redox role) and BOLA3 (trafficking role), and is required for maturation of all cellular Fe/S proteins as well as for lipoylation of mitochondrial enzymes (PDH, α-KGDH) and heme biosynthesis via ferrochelatase and ALAS2 activities; loss-of-function mutations in humans cause sideroblastic anemia and variant nonketotic hyperglycinemia.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"GLRX5 is a mitochondrial matrix monothiol glutaredoxin that serves as a central hub of the iron-sulfur (Fe/S) cluster assembly pathway, required for maturation of all cellular Fe/S proteins regardless of cluster type or subcellular location [#1, #7, #14]. It coordinates a bridging [2Fe-2S] cluster through its active-site Cys67 and two glutathione molecules, transitioning from a monomeric apoprotein to a cluster-bound oligomer, with glutathione contacts dictating cluster chirality [#6, #11]. GLRX5 receives pre-assembled clusters from the scaffold protein ISCU/Isu1, a transfer facilitated by the mitochondrial Hsp70 chaperone Ssq1, which binds GLRX5 at a site distinct from the scaffold and positions the two proteins for rapid cluster hand-off [#7]; reconstitution in isolated mitochondria places GLRX5 upstream of the Isa1/Isa2 machinery and shows it is needed both for intramitochondrial Fe/S synthesis and for the exported intermediate that supports cytoplasmic Fe/S assembly [#14]. Downstream, GLRX5 forms cluster-bridged heterodimers with BOLA1 and BOLA3 that diverge functionally: BOLA1-GLRX5 binds a reduced Rieske-type cluster and cannot donate it (a non-trafficking, redox role), whereas BOLA3-GLRX5 carries an oxidized ferredoxin-type cluster competent for trafficking [#10, #13]. Through this activity GLRX5 enables maturation of Fe/S enzymes including IRP1, mitochondrial aconitase, ferrochelatase and succinate dehydrogenase, lipoylation of the pyruvate dehydrogenase and \\u03b1-ketoglutarate dehydrogenase complexes, and heme biosynthesis via ferrochelatase and ALAS2 [#9, #12]. Loss-of-function GLRX5 mutations in humans cause sideroblastic anemia and variant nonketotic hyperglycinemia, with patient defects in lipoylation and PDH activity corrected by wild-type GLRX5 [#8, #12].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established the founding function of the GLRX5 ortholog as a monothiol glutaredoxin protecting cells against oxidative protein damage, before any Fe/S role was known.\",\n      \"evidence\": \"Genetic deletion of yeast grx5 with protein carbonyl assays and oxidant sensitivity screens\",\n      \"pmids\": [\"10567543\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify a molecular substrate or distinguish a direct redox role from an indirect consequence of metabolic dysfunction\", \"No connection to Fe/S biology yet\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Localized the protein to the mitochondrial matrix and placed it in the Fe/S assembly machinery, recasting the oxidative phenotype as a downstream consequence of failed Fe/S biogenesis.\",\n      \"evidence\": \"Subcellular fractionation, suppressor-overexpression epistasis (SSQ1, ISA2), Fe/S enzyme assays and iron measurement in yeast null mutants\",\n      \"pmids\": [\"11950925\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the biochemical step catalyzed within the pathway\", \"Mechanism of iron accumulation not resolved\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Mapped the residues essential for both Fe/S assembly and oxidant resistance, identifying the active-site cysteine and the glutathione cleft as functionally required.\",\n      \"evidence\": \"Site-directed mutagenesis with 3D modeling and multiple phenotypic readouts in yeast\",\n      \"pmids\": [\"12138088\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural model not experimentally determined at the time\", \"Did not establish whether the active-site cysteine binds a cluster directly\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Defined the redox chemistry of the active site, showing a GSH-dependent thiol reductase cycle and quantifying its sluggish kinetics relative to dithiol glutaredoxins.\",\n      \"evidence\": \"Purified wild-type and cysteine-mutant proteins, redox potential and pKa measurements, in vitro glutathionylation/reduction assays\",\n      \"pmids\": [\"12730244\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not reconcile the slow reductase activity with the essential Fe/S role\", \"Physiological substrate of the reductase activity not identified\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Demonstrated functional conservation by showing human GLRX5 targeted to yeast mitochondria fully rescues Fe/S defects, validating the yeast model for human biology.\",\n      \"evidence\": \"Heterologous complementation of yeast grx5 null with human GLRX5 plus localization\",\n      \"pmids\": [\"16566929\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cross-species rescue does not prove identical human partner interactions\", \"Single lab\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Established direct in vivo interaction with the Isa scaffold proteins and linked GLRX5 to mtDNA integrity, beginning to define its protein partnerships within the pathway.\",\n      \"evidence\": \"Bimolecular fluorescence complementation, multi-copy suppressor screen and Fe/S enzyme assays in fission yeast\",\n      \"pmids\": [\"20085751\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"BiFC indicates proximity but not direct stable complex stoichiometry\", \"Directionality of cluster flow between Grx5 and Isa not resolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Provided the structural basis for cluster coordination, showing a [2Fe-2S] cluster bridged by Cys67 from two protomers and two glutathione thiols, with an apo-monomer/holo-oligomer transition.\",\n      \"evidence\": \"X-ray crystallography of human GLRX5 with biophysical and enzymatic validation\",\n      \"pmids\": [\"21029046\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Static structure does not capture cluster transfer dynamics\", \"Relationship between the crystallographic tetramer and physiological transfer complexes unclear\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined the Hsp70 chaperone Ssq1 as the platform that juxtaposes scaffold and GLRX5 to enable rapid cluster transfer, and established GLRX5 as required for maturation of all cellular Fe/S proteins.\",\n      \"evidence\": \"In vivo and in vitro interaction, ATPase, and cluster transfer assays with genetic depletion in yeast\",\n      \"pmids\": [\"23615440\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve how cluster is released to specific downstream acceptors\", \"Human ortholog (HSPA9) interaction inferred by homology, not directly tested here\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Linked GLRX5 to human disease and to lipoylation, showing patient mutations cause variant nonketotic hyperglycinemia via defective lipoylation, with rescue by wild-type GLRX5.\",\n      \"evidence\": \"Patient cell biochemistry, transfection rescue, and enzyme activity assays\",\n      \"pmids\": [\"24334290\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Connection between Fe/S defect and lipoylation loss is indirect via Fe/S-dependent lipoyl synthase\", \"Did not quantify cluster occupancy in patient cells\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Separated GLRX5 function into cluster-binding and cluster-transfer steps through human KO cells and structure-function mutants, mapping discrete defects to downstream Fe/S targets and lipoylation.\",\n      \"evidence\": \"CRISPR GLRX5 knockout K562 cells with K101Q/L148S mutant rescue and multiple Fe/S enzyme and lipoylation readouts\",\n      \"pmids\": [\"26100117\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the direct acceptor proteins for each transfer step\", \"Mechanism by which L148S impairs transfer not structurally resolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified divergent BOLA1 and BOLA3 heterocomplexes with distinct cluster types, revealing two functionally specialized GLRX5-containing complexes.\",\n      \"evidence\": \"UV/vis, CD, EPR, NMR spectroscopy and protein-protein docking on reconstituted human complexes\",\n      \"pmids\": [\"28483642\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional roles assigned by cluster type were not yet tested by transfer assays\", \"In vivo abundance of each complex not measured\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed that glutathione in the binding pocket controls cluster chirality and that thiol substitutions permit transfer to apo ferredoxin, refining the chemistry of cluster handling.\",\n      \"evidence\": \"In vitro reconstitution with natural and non-natural amino acid substitutions, CD spectroscopy, transfer kinetics to apo ferredoxin\",\n      \"pmids\": [\"29264659\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab in vitro reconstitution\", \"Functional consequence of altered chirality in cells not established\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Distinguished the BOLA1-GLRX5 and BOLA3-GLRX5 complexes functionally, showing BOLA1-GLRX5 accepts but cannot donate cluster (a non-trafficking/redox role) versus the donating BOLA3-GLRX5 complex.\",\n      \"evidence\": \"CD spectroscopy cluster transfer kinetics with defined donor/acceptor proteins\",\n      \"pmids\": [\"32542995\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vitro inability to donate does not exclude a partner-dependent donation in cells\", \"Physiological redox substrate of BOLA1-GLRX5 unidentified\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Positioned GLRX5 upstream of the Isa1/Isa2 machinery as the central hub for both mitochondrial and exported cytoplasmic Fe/S assembly using organellar reconstitution.\",\n      \"evidence\": \"In vitro import of purified Grx5 precursor into isolated yeast mitochondria with Fe/S synthesis assays and genetic depletion of Grx5/Isa1/Isa2\",\n      \"pmids\": [\"40074084\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular identity of the exported (Fe-S)int intermediate not defined\", \"How GLRX5 partitions cluster between mitochondrial maturation and export not resolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The physiological redox substrate of the GLRX5 thiol reductase activity and the precise molecular nature of the exported Fe/S intermediate it generates remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No identified in vivo target of GLRX5 glutaredoxin reductase activity distinct from its Fe/S role\", \"Chemical identity and protein carrier of the cytoplasmic (Fe-S)int intermediate unknown\", \"Determinants directing cluster to BOLA1 vs BOLA3 complexes in cells not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [3, 6]},\n      {\"term_id\": \"GO:0140104\", \"supporting_discovery_ids\": [6, 7, 14]},\n      {\"term_id\": \"GO:0016491\", \"supporting_discovery_ids\": [3, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [1, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [1, 7, 14]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [9, 12]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [8, 12]}\n    ],\n    \"complexes\": [\n      \"BOLA1-GLRX5 [2Fe-2S]-bridged heterodimer\",\n      \"BOLA3-GLRX5 [2Fe-2S]-bridged heterodimer\"\n    ],\n    \"partners\": [\n      \"ISCU\",\n      \"HSPA9\",\n      \"BOLA1\",\n      \"BOLA3\",\n      \"ISCA1\",\n      \"ISCA2\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}