Affinage

FECH

Ferrochelatase, mitochondrial · UniProt P22830

Round 2 corrected
Length
423 aa
Mass
47.9 kDa
Annotated
2026-04-28
53 papers in source corpus 9 papers cited in narrative 9 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

FECH encodes ferrochelatase, the homodimeric mitochondrial membrane-associated enzyme that catalyzes the terminal step of heme biosynthesis by inserting ferrous iron into protoporphyrin IX (PPIX) to form heme, with ferrous iron delivered directly by frataxin (PMID:1184741, PMID:15123683). The 2.0 Å crystal structure reveals two [2Fe-2S] clusters and a hydrophobic lip that mediates inner mitochondrial membrane association and forms the entrance to the catalytic pocket (PMID:11175906). FECH expression is transcriptionally regulated by c-Myc binding to promoter E-boxes and post-transcriptionally by nonsense-mediated decay of a misspliced transcript generated by a common intronic hypomorphic SNP (IVS3-48T/C), which modulates penetrance of dominant erythropoietic protoporphyria (EPP) (PMID:11753383, PMID:21903580). Loss of FECH activity—whether by genetic mutation, gene knockout, or chemical inhibition—causes PPIX accumulation, triggers apoptosis and innate immune activation, and can induce iron overload and ferroptosis (PMID:1184741, PMID:39409147, PMID:35697292).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 1975 High

    Establishing ferrochelatase as the primary enzymatic defect in erythropoietic protoporphyria resolved the molecular basis of PPIX accumulation and photosensitivity in EPP patients.

    Evidence Radiochemical enzyme assay (59Fe incorporation into porphyrin) in liver biopsies and cultured fibroblasts from EPP patients versus controls

    PMID:1184741

    Open questions at the time
    • Gene not yet cloned; molecular identity of enzyme unknown
    • Mechanism of catalysis unresolved
    • Inheritance pattern and genetic modifiers not defined
  2. 1991 High

    Mapping the FECH gene to chromosome 18q22 provided the chromosomal foundation for genetic analysis of EPP and mutation screening.

    Evidence cDNA hybridization to sorted chromosomes and FISH with a genomic clone

    PMID:1783383

    Open questions at the time
    • No mutations in EPP families yet identified at this locus
    • Three-dimensional structure of the enzyme unknown
  3. 2001 High

    The high-resolution crystal structure of human ferrochelatase revealed the homodimeric architecture, two [2Fe-2S] clusters, and a membrane-proximal hydrophobic lip forming the active-site entrance, providing a structural framework for catalysis.

    Evidence X-ray crystallography at 2.0 Å with iron anomalous scattering

    PMID:11175906

    Open questions at the time
    • Iron donor delivering Fe²⁺ to the active site not identified
    • Role of [2Fe-2S] clusters in catalysis versus structural integrity unclear
    • No substrate-bound structure available
  4. 2001 High

    Discovery that a common intronic SNP (IVS3-48T/C) generates an aberrant splice site whose transcript is degraded by NMD explained how a hypomorphic trans allele modulates EPP penetrance, answering why heterozygous loss-of-function mutations show variable clinical expression.

    Evidence Haplotype segregation in EPP families, aberrant splice-site characterization, NMD demonstration

    PMID:11753383

    Open questions at the time
    • Quantitative relationship between residual FECH activity threshold and clinical phenotype not precisely defined
    • Whether other cis-regulatory variants similarly modulate expression not explored
  5. 2004 High

    Identification of frataxin as the direct ferrous iron donor to ferrochelatase linked the heme biosynthesis pathway to Friedreich ataxia biology and explained how mitochondrial iron is channeled to the active site.

    Evidence In vitro reconstitution of iron delivery from holofrataxin to ferrochelatase, pulldown and affinity measurements

    PMID:15123683

    Open questions at the time
    • Structural basis of the frataxin–ferrochelatase interaction not resolved
    • Whether alternative iron donors exist in vivo not excluded
  6. 2011 Medium

    Demonstrating that c-Myc binds E-boxes in the FECH promoter and that CpG demethylation at these sites promotes c-Myc/Max-driven transcription revealed how FECH expression is coupled to erythroid differentiation signals.

    Evidence ChIP, promoter methylation analysis, nuclear fractionation, siRNA knockdown in erythroid cell models

    PMID:21903580

    Open questions at the time
    • Contribution of c-Myc regulation relative to other transcription factors (e.g., GATA-1) not compared
    • In vivo validation in primary erythroid progenitors lacking
  7. 2020 Medium

    Placing FECH activity downstream of a Ras/MEK–HIF-1α signaling axis established that oncogenic signaling can co-opt heme biosynthesis to manage PPIX levels in cancer cells.

    Evidence MEK inhibitor treatment, HIF-1α knockdown, FECH activity assay in RasV12-transformed cells and transgenic mouse models

    PMID:33335181

    Open questions at the time
    • Whether HIF-1α regulates FECH transcriptionally or post-translationally not resolved
    • Generalizability beyond Ras-driven tumors untested
  8. 2022 Medium

    Identification of FECH as the direct target of the flavonoid DMC showed that chemical FECH inhibition causes iron overload and ferroptosis, linking heme pathway disruption to a regulated cell death modality.

    Evidence Thermal proteome profiling target identification, enzymatic activity assay, FECH knockdown, ferroptosis marker quantification

    PMID:35697292

    Open questions at the time
    • Binding site of DMC on FECH not structurally defined
    • Whether ferroptosis is a direct consequence of PPIX accumulation or iron dyshomeostasis not disentangled
  9. 2024 Medium

    CRISPR knockout of fech in zebrafish confirmed that complete loss of ferrochelatase triggers PPIX accumulation, intrinsic apoptosis, and innate immune cell expansion in vivo, extending the phenotypic consequences beyond erythroid lineages.

    Evidence CRISPR/Cas9 fech knockout zebrafish, fluorescence PPIX imaging, apoptosis staining, qRT-PCR, immune cell staining

    PMID:39409147

    Open questions at the time
    • Mechanism linking PPIX accumulation to macrophage/neutrophil expansion not defined
    • Whether immune activation is cell-autonomous or secondary to tissue damage unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include the precise catalytic role of the [2Fe-2S] clusters, the structural basis of frataxin–ferrochelatase iron transfer, and how PPIX accumulation drives innate immune activation.
  • No substrate-bound or frataxin-complexed structure of human ferrochelatase available
  • Functional role of [2Fe-2S] clusters (catalytic vs. structural vs. sensing) unresolved
  • Signaling pathway from PPIX accumulation to immune cell expansion not characterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0016740 transferase activity 3 GO:0016829 lyase activity 2
Localization
GO:0005739 mitochondrion 2
Pathway
R-HSA-1430728 Metabolism 3 R-HSA-1643685 Disease 2
Partners
FXN

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1975 Ferrochelatase (heme synthetase) catalyzes the terminal step of heme biosynthesis—chelation of ferrous iron with porphyrin—and its activity is markedly deficient in liver and cultured skin fibroblasts of patients with erythropoietic protoporphyria, establishing deficient ferrochelatase as the primary enzymatic defect in protoporphyria. Radiochemical enzyme assay using 59Fe and deuteroporphyrin/protoporphyrin as substrates in liver biopsies and skin fibroblast sonicates The Journal of clinical investigation High 1184741
2001 Human ferrochelatase is a homodimeric (86 kDa) mitochondrial membrane-associated enzyme whose 2.0 Å crystal structure reveals two [2Fe-2S] clusters, a 12-residue hydrophobic lip mediating membrane association that also forms the entrance to the active site pocket, and a conserved active site geometry supporting a catalytic model for ferrous iron insertion into protoporphyrin IX to form heme. X-ray crystallography at 2.0 Å resolution using single-wavelength iron anomalous scattering Nature structural biology High 11175906
2001 The penetrance of dominant erythropoietic protoporphyria is modulated by a hypomorphic FECH allele: an intronic SNP (IVS3-48T/C) activates an aberrant splice acceptor site, generating a misspliced mRNA that is degraded by nonsense-mediated decay (NMD), thereby reducing steady-state FECH mRNA and enzyme levels below the threshold required for clinical expression. Haplotype segregation analysis, identification of aberrant splice site usage, NMD mechanism characterization Nature genetics High 11753383
2004 Human frataxin (holofrataxin) is a high-affinity iron-binding partner of ferrochelatase that directly delivers ferrous iron to ferrochelatase to mediate the terminal step of mitochondrial heme biosynthesis; distinct binding affinities of holofrataxin for ferrochelatase versus the ISU scaffold protein allow discrimination between heme and iron-sulfur cluster biosynthesis pathways. Protein–protein interaction (pulldown/reconstitution), iron delivery assay in vitro, affinity measurements The Journal of biological chemistry High 15123683
2011 The transcription factor c-Myc regulates FECH gene expression by binding to E-boxes in the FECH promoter; 5-aza-2'-deoxycytidine demethylates these E-box-containing CpG sites and promotes nuclear translocation of c-Myc and its heterodimerization with Max, thereby increasing FECH transcription, heme biosynthesis, and erythroid differentiation. Promoter methylation analysis, ChIP, nuclear fractionation, siRNA knockdown in erythroid cell models The Journal of biological chemistry Medium 21903580
2020 The Ras/MEK signaling pathway suppresses FECH activity through a HIF-1α-dependent axis: MEK activation induces HIF-1α expression, which increases FECH activity and thereby converts protoporphyrin IX (PpIX) to heme, reducing PpIX accumulation in cancer cells; MEK inhibition reduces HIF-1α and diminishes FECH activity. MEK inhibitor treatment, HIF-1α knockdown, FECH activity assay, RasV12-transformed cell and transgenic mouse models Scientific reports Medium 33335181
2022 FECH is a direct molecular target of the flavonoid 4,4'-dimethoxychalcone (DMC): DMC inhibits FECH enzymatic activity (confirmed by thermal proteome profiling and enzymatic assay), which, together with Nrf2/HMOX1 pathway activation, leads to iron overload and ferroptosis in cancer cells. Thermal proteome profiling (TPP) target identification, FECH enzymatic activity assay, FECH knockdown, ferroptosis markers Free radical biology & medicine Medium 35697292
1991 The human ferrochelatase gene (FECH) maps to chromosome 18q22, establishing the chromosomal locus for the enzyme and for erythropoietic protoporphyria. Chromosomal hybridization of cDNA to sorted chromosomes; fluorescent in situ hybridization with a genomic clone Genomics High 1783383
2024 Loss of ferrochelatase (fech knockout via CRISPR/Cas9) in zebrafish larvae causes protoporphyrin IX accumulation, morphological defects, apoptosis (elevated bax/bcl2 ratio), and increased macrophage/neutrophil production, confirming that fech is required for PPIX clearance and its deficiency triggers innate immune activation and intrinsic apoptosis in vivo. CRISPR/Cas9 knockout zebrafish model, fluorescence imaging of PPIX, acridine orange apoptosis staining, qRT-PCR, neutral red/Sudan black immune cell staining International journal of molecular sciences Medium 39409147

Source papers

Stage 0 corpus · 53 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2002 Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. Proceedings of the National Academy of Sciences of the United States of America 1479 12477932
2009 Defining the human deubiquitinating enzyme interaction landscape. Cell 1282 19615732
2015 The BioPlex Network: A Systematic Exploration of the Human Interactome. Cell 1118 26186194
2017 Architecture of the human interactome defines protein communities and disease networks. Nature 1085 28514442
2015 A human interactome in three quantitative dimensions organized by stoichiometries and abundances. Cell 1015 26496610
2003 Complete sequencing and characterization of 21,243 full-length human cDNAs. Nature genetics 754 14702039
2021 Dual proteome-scale networks reveal cell-specific remodeling of the human interactome. Cell 705 33961781
2011 Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium. Briefings in bioinformatics 656 21873635
2011 Global landscape of HIV-human protein complexes. Nature 593 22190034
1994 Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides. Gene 492 8125298
2004 The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). Genome research 438 15489334
2022 OpenCell: Endogenous tagging for the cartography of human cellular organization. Science (New York, N.Y.) 432 35271311
2010 Systematic analysis of human protein complexes identifies chromosome segregation proteins. Science (New York, N.Y.) 421 20360068
2005 Diversification of transcriptional modulation: large-scale identification and characterization of putative alternative promoters of human genes. Genome research 409 16344560
1996 Normalization and subtraction: two approaches to facilitate gene discovery. Genome research 401 8889548
2021 A proximity-dependent biotinylation map of a human cell. Nature 339 34079125
2010 Dynamics of cullin-RING ubiquitin ligase network revealed by systematic quantitative proteomics. Cell 318 21145461
2019 Mitochondrial ClpP-Mediated Proteolysis Induces Selective Cancer Cell Lethality. Cancer cell 298 31056398
2015 Inhibition of the Mitochondrial Protease ClpP as a Therapeutic Strategy for Human Acute Myeloid Leukemia. Cancer cell 293 26058080
2017 Genome-wide CRISPR screen identifies HNRNPL as a prostate cancer dependency regulating RNA splicing. Proceedings of the National Academy of Sciences of the United States of America 282 28611215
2021 Quantitative high-confidence human mitochondrial proteome and its dynamics in cellular context. Cell metabolism 239 34800366
1975 Heme synthetase deficiency in human protoporphyria. Demonstration of the defect in liver and cultured skin fibroblasts. The Journal of clinical investigation 232 1184741
2004 Frataxin-mediated iron delivery to ferrochelatase in the final step of heme biosynthesis. The Journal of biological chemistry 226 15123683
2016 Mitochondrial Protein Interaction Mapping Identifies Regulators of Respiratory Chain Function. Molecular cell 220 27499296
2016 An organelle-specific protein landscape identifies novel diseases and molecular mechanisms. Nature communications 211 27173435
2018 An AP-MS- and BioID-compatible MAC-tag enables comprehensive mapping of protein interactions and subcellular localizations. Nature communications 201 29568061
2001 The penetrance of dominant erythropoietic protoporphyria is modulated by expression of wildtype FECH. Nature genetics 196 11753383
2001 The 2.0 A structure of human ferrochelatase, the terminal enzyme of heme biosynthesis. Nature structural biology 181 11175906
2014 Global mapping of herpesvirus-host protein complexes reveals a transcription strategy for late genes. Molecular cell 173 25544563
2011 MINOS1 is a conserved component of mitofilin complexes and required for mitochondrial function and cristae organization. Molecular biology of the cell 150 22114354
2020 A High-Density Human Mitochondrial Proximity Interaction Network. Cell metabolism 148 32877691
2022 Flavonoid 4,4'-dimethoxychalcone induced ferroptosis in cancer cells by synergistically activating Keap1/Nrf2/HMOX1 pathway and inhibiting FECH. Free radical biology & medicine 67 35697292
1991 Assignment of the human ferrochelatase gene (FECH) and a locus for protoporphyria to chromosome 18q22. Genomics 62 1783383
2007 Gene dosage analysis identifies large deletions of the FECH gene in 10% of families with erythropoietic protoporphyria. The Journal of investigative dermatology 30 17597821
2020 MEK reduces cancer-specific PpIX accumulation through the RSK-ABCB1 and HIF-1α-FECH axes. Scientific reports 21 33335181
2011 5-aza-2'-deoxycytidine activates iron uptake and heme biosynthesis by increasing c-Myc nuclear localization and binding to the E-boxes of transferrin receptor 1 (TfR1) and ferrochelatase (Fech) genes. The Journal of biological chemistry 21 21903580
1994 Molecular analysis of functional and nonfunctional genes for human ferrochelatase: isolation and characterization of a FECH pseudogene and its sublocalization on chromosome 3. Genomics 13 8034322
2019 Targeted resequencing of FECH locus reveals that a novel deep intronic pathogenic variant and eQTLs may cause erythropoietic protoporphyria (EPP) through a methylation-dependent mechanism. Genetics in medicine : official journal of the American College of Medical Genetics 12 31273344
2021 Nkx3-1 and Fech genes might be switch genes involved in pituitary non-functioning adenoma invasiveness. Scientific reports 7 34686726
2010 A homoallelic FECH mutation in a patient with both erythropoietic protoporphyria and palmar keratoderma. Journal of the European Academy of Dermatology and Venereology : JEADV 7 20337824
2022 The role of the genetic variant FECH rs11660001 in the occurrence of anti-tuberculosis drug-induced liver injury. Journal of clinical pharmacy and therapeutics 6 35470464
2007 A 10376 bp deletion of FECH gene responsible for erythropoietic protoporphyria. Blood cells, molecules & diseases 6 17888693
2021 Down-regulation of IGHG1 enhances Protoporphyrin IX accumulation and inhibits hemin biosynthesis in colorectal cancer by suppressing the MEK-FECH axis. Open life sciences 5 34553073
2018 Digital PCR (dPCR) analysis reveals that the homozygous c.315-48T>C variant in the FECH gene might cause erythropoietic protoporphyria (EPP). Molecular genetics and metabolism 5 29941360
2014 Comparative uptake of ¹⁸F-FEN-DPAZn2, ¹⁸F-FECH, ¹⁸F-fluoride, and ¹⁸F-FDG in fibrosarcoma and aseptic inflammation. Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine 5 24751349
2009 A novel large deletion and three polymorphisms in the FECH gene associated with erythropoietic protoporphyria. Clinical chemistry and laboratory medicine 5 19055472
2009 A novel splicing mutation and haplotype analysis of the FECH gene in a Chinese family with erythropoietic protoporphyria. Journal of the European Academy of Dermatology and Venereology : JEADV 5 19888946
2024 CRISPR/Cas9-Mediated fech Knockout Zebrafish: Unraveling the Pathogenesis of Erythropoietic Protoporphyria and Facilitating Drug Screening. International journal of molecular sciences 4 39409147
2015 A Novel Mutation in the FECH Gene in a Czech Family with Erythropoietic Protoporphyria and a Population Study of IVS3-48C Variant Contributing to the Disease. Folia biologica 3 26789144
2019 Characterization of a novel pathogenic variant in the FECH gene associated with erythropoietic protoporphyria. Molecular genetics and metabolism reports 2 31304091
2016 Identification of FECH gene multiple variations in two Chinese patients with erythropoietic protoporphyria and a review. Journal of Zhejiang University. Science. B 2 27704751
2011 Erythropoietic protoporphyria: a family study and report of a novel mutation in the FECH gene. European journal of dermatology : EJD 2 21659066
2025 Effects of FECH Gene Polymorphisms and Serum Ferrochelatase Levels on Antituberculosis Drug-Induced Liver Injury in China. Fundamental & clinical pharmacology 0 40582371