NDUFS1

NDUFS1 is the 75 kDa iron-sulfur subunit of mitochondrial complex I (NADH:ubiquinone oxidoreductase) that is essential for electron transfer, complex I assembly, supercomplex stability, and oxidative phosphorylation. Loss-of-function mutations destabilize the N-module, abolish electron transfer between iron-sulfur clusters, and cause complex I deficiency with mitochondrial ROS accumulation, TCA cycle feedback inhibition, and apoptotic pathway activation (PMID:11349233, PMID:31557978, PMID:36462614). NDUFS1 mitochondrial import requires AKAP1 and is antagonized by MDM2-mediated cytoplasmic sequestration; its activity is further regulated by caspase-3 cleavage at D255 (amplifying apoptotic ROS and lysosomal membrane permeabilization), glutathionylation (promoting reverse-electron-transfer ROS), SIRT3-dependent deacetylation (causing complex I dissociation), and RNF43-mediated ubiquitin-proteasomal degradation (PMID:32072193, PMID:30879903, PMID:23788428, PMID:36290766, PMID:40493314, PMID:38988031). Biallelic NDUFS1 mutations cause autosomal recessive mitochondrial complex I deficiency (PMID:11349233, PMID:20382551).

1. 2001 High

   Establishing NDUFS1 as a disease gene: before this work, the genetic basis of many complex I deficiency cases was unknown; identification of multiple point mutations and deletions in NDUFS1 in patients proved it is a nuclear-encoded subunit required for complex I function and that its loss causes Mendelian mitochondrial disease.

   Evidence dHPLC and direct sequencing of patient fibroblast cDNA identifying five point mutations and one large deletion

   PMID:11349233

   Open questions at the time

   • Precise structural consequences of individual mutations on iron-sulfur cluster coordination were not resolved
   • No systematic genotype-phenotype correlation established
2. 2006 High

   Linking NDUFS1 mutation to ROS overproduction: beyond reduced activity, the Q522K mutation demonstrated that NDUFS1 dysfunction causes mitochondrial superoxide and H₂O₂ accumulation, glutathione depletion, and membrane potential loss, establishing NDUFS1 as a critical gatekeeper of mitochondrial redox homeostasis.

   Evidence Patient fibroblast assays using MitoSOX, H2DCFDA, JC-1, glutathione quantification, and cAMP-mediated pharmacological rescue

   PMID:16478720

   Open questions at the time

   • Mechanism by which dibutyryl-cAMP restores complex I activity was not defined
   • Whether ROS is cause or consequence of membrane potential loss was not resolved
3. 2010 High

   Defining NDUFS1's role in complex I assembly: Blue Native PAGE of patient fibroblasts demonstrated that NDUFS1 mutations impair not just catalytic activity but the physical assembly of the holoenzyme, establishing it as an assembly-essential core subunit.

   Evidence BN-PAGE and complex I activity assays across multiple patient fibroblast lines

   PMID:20382551

   Open questions at the time

   • Which assembly intermediate is stalled was not identified
   • Whether chaperones are involved in NDUFS1 incorporation was unknown
4. 2013 High

   Identifying NDUFS1 as a caspase-3 substrate that amplifies apoptosis: it was unknown how mitochondrial ROS bursts are triggered downstream of MOMP; this work showed caspase-3 cleaves NDUFS1, disrupting complex I and generating ROS that triggers lysosomal membrane permeabilization, thereby coupling intrinsic apoptosis to lysosomal cell death.

   Evidence Caspase non-cleavable NDUFS1 mutant expression; caspase-3/7 and Bax/Bak KO cells; MitoQ rescue; LMP and cathepsin release assays

   PMID:23788428

   Open questions at the time

   • Exact cleavage site was mapped but full cleavage fragment characterization was incomplete
   • Whether other respiratory chain subunits are also cleaved was not addressed
5. 2019 High

   Discovering MDM2 as a cytoplasmic sequestrator of NDUFS1: this revealed a p53-independent, non-canonical role for MDM2 in which its N-terminal domain directly binds NDUFS1, prevents mitochondrial localization, and destabilizes complex I and supercomplexes, linking oncogene biology to OXPHOS regulation.

   Evidence Co-IP, GST-pulldown, BN-PAGE supercomplex analysis, oxygen consumption; Drosophila and murine transgenic models

   PMID:30879903

   Open questions at the time

   • Whether MDM2 regulation of NDUFS1 is constitutive or signal-dependent was not resolved
   • Stoichiometry of MDM2–NDUFS1 interaction in normal physiology unknown
6. 2019 High

   Mapping NDUFS1 deficiency to N-module destabilization and metabolic rewiring: proteomics and metabolomics of patient cells showed that biallelic mutations specifically destabilize the entire N-module and disrupt electron transfer between iron-sulfur clusters, with secondary metabolic consequences including TCA cycle inhibition and glutathione depletion.

   Evidence Quantitative mass spectrometry proteomics and metabolomics in patient-derived cells

   PMID:31557978

   Open questions at the time

   • Which specific iron-sulfur cluster pair is disrupted was inferred but not directly measured by EPR
   • Contribution of individual metabolic changes to pathology not dissected
7. 2020 High

   Identifying AKAP1 as required for NDUFS1 mitochondrial import: it was unclear how the nuclear-encoded NDUFS1 is delivered to mitochondria; AKAP1 was shown to physically interact with NDUFS1 and promote its translocation, with AKAP1 deficiency phenocopying NDUFS1 loss in cardiomyocytes.

   Evidence Reciprocal Co-IP/MS; Akap1-KO mouse; AAV9-Akap1 cardiac rescue restoring NDUFS1 mitochondrial localization and complex I activity

   PMID:32072193

   Open questions at the time

   • Whether AKAP1 acts as a chaperone, scaffold, or import receptor was not distinguished
   • Whether AKAP1 facilitates import of other complex I subunits is unknown
8. 2022 High

   Demonstrating glutathionylation as a reversible regulatory switch on NDUFS1: this established that NDUFS1 glutathionylation specifically inhibits complex I and increases ROS production during reverse electron transfer, providing a redox-sensitive post-translational control mechanism distinct from caspase cleavage.

   Evidence Immunocaptured complex I; disulfiram-induced glutathionylation; rotenone and S1QEL controls; Amplex Red ROS measurement; reducing agent reversal in liver mitochondria

   PMID:36290766

   Open questions at the time

   • Specific cysteine residue(s) modified were not identified
   • Physiological stimuli triggering NDUFS1 glutathionylation in vivo not established
9. 2022 High

   Systematic mapping of disease-relevant residues at subunit interfaces: modeling 17 patient mutations in the bacterial homolog nuoG revealed that many critical residues lie at subunit interfaces and disrupt assembly rather than catalysis per se, refining the structural basis of NDUFS1-linked complex I deficiency.

   Evidence E. coli nuoG systematic alanine mutagenesis; membrane vesicle NADH oxidase activity; co-IP assembly analysis; time-delayed expression

   PMID:36462614

   Open questions at the time

   • Bacterial system lacks eukaryotic supernumerary subunits, so interface effects may differ in human complex I
   • No human structural validation of interface disruption
10. 2024 Medium

    Identifying RNF43 as a ubiquitin ligase targeting NDUFS1 for proteasomal degradation: this added ubiquitination to the regulatory repertoire controlling NDUFS1 protein levels and thereby OXPHOS capacity, linking Wnt pathway components to mitochondrial metabolism.

    Evidence Co-IP; ubiquitination assay; RNF43/NDUFS1 KD/OE; OXPHOS measurement; endometriosis rat model

    PMID:38988031

    Open questions at the time

    • Specific ubiquitinated lysine residues on NDUFS1 not mapped
    • Whether RNF43 regulation is tissue-specific is unknown
    • Not independently replicated
11. 2025 High

    Defining the caspase-3 cleavage site at D255 and confirming its apoptosis-amplifying role across toxic insults: site-directed D255A mutagenesis proved that this single cleavage event is the primary mechanism by which caspase-3 disrupts complex I electron transport and amplifies mitochondrial ROS during apoptosis.

    Evidence D255A non-cleavable mutant; caspase-3 inhibition/KD; ROS and mitochondrial damage assays in trichothecene-exposed models in vivo and in vitro

    PMID:41422996

    Open questions at the time

    • Whether D255 cleavage also occurs in non-apoptotic caspase activation contexts is unknown
    • Fate of cleavage fragments not fully characterized
12. 2025 High

    Revealing SIRT3-dependent deacetylation of NDUFS1 as a mechanism for regulated complex I disassembly: berberine-activated SIRT3 deacetylates NDUFS1, causing complex I dissociation and reduced OXPHOS, demonstrating that reversible acetylation controls complex I integrity and metabolic flux.

    Evidence SIRT3 activity assays; NDUFS1 acetylation analysis; berberine–SIRT3 binding (SPR, docking); complex I dissociation; hepatocyte metabolic profiling; in vivo administration

    PMID:40493314

    Open questions at the time

    • Specific acetylated lysine residues on NDUFS1 targeted by SIRT3 not identified
    • Whether deacetylation-induced disassembly is reversible upon SIRT3 inhibition not tested
13. 2025 High

    Establishing GL-V9 as a molecular glue enhancing MDM2–NDUFS1 interaction: this pharmacological study confirmed the MDM2-NDUFS1 axis as druggable and showed that enforced cytoplasmic sequestration of NDUFS1 activates the OMA1–DELE1 integrated stress response, mapping a complete pathway from NDUFS1 depletion to apoptosis.

    Evidence SPR, CETSA, GST-pulldown, MDM2 mutagenesis, immunofluorescence, mitochondrial functional assays, OMA1-DELE1 pathway readouts

    PMID:41951044

    Open questions at the time

    • Whether OMA1–DELE1 activation is specific to NDUFS1 loss or general complex I dysfunction not distinguished
    • In vivo therapeutic efficacy and toxicity not fully assessed

• Key unresolved questions include: the precise acetylation and glutathionylation sites on NDUFS1, how NDUFS1 import is coordinated with other N-module subunit assembly, whether the caspase-3 cleavage at D255 participates in non-apoptotic signaling, and the structural basis by which NDUFS1 post-translational modifications alter iron-sulfur cluster function.
• No cryo-EM or crystal structure of modified NDUFS1 in context of human complex I
• Acetylation and glutathionylation sites not mapped at single-residue resolution
• Relative contributions of transcriptional versus post-translational regulation in different tissues unknown