Affinage

NDUFS7

NADH dehydrogenase [ubiquinone] iron-sulfur protein 7, mitochondrial · UniProt O75251

Length
213 aa
Mass
23.6 kDa
Annotated
2026-04-29
28 papers in source corpus 12 papers cited in narrative 12 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

NDUFS7 (PSST) is a core catalytic subunit of mitochondrial complex I (NADH:ubiquinone oxidoreductase) that couples electron transfer from iron-sulfur cluster N2 to ubiquinone reduction within a ~30 Å quinone-binding tunnel formed at the NDUFS7/NDUFS2(49 kDa)/ND1 interface. Conserved loop residues, including critical arginine and aspartate residues, control ubiquinone diffusion, retention, and proton translocation, while the subunit harbors the shared high-affinity binding site for structurally diverse complex I inhibitors including rotenone, piericidin A, pyridaben, and fenpyroximate (PMID:10097178, PMID:12930834, PMID:31226318, PMID:22353032). NDUFS7 is post-translationally hydroxylated at Arg-73 by the assembly factor NDUFAF5 early in complex I biogenesis, and its loss abolishes fully assembled complex I, elevates reactive oxygen species, and triggers compensatory upregulation of the SLC7A11/glutathione axis (PMID:27226634, PMID:17604671, PMID:38823363). NRF2 directly regulates NDUFS7 transcription, and biallelic NDUFS7 mutations cause isolated complex I deficiency (PMID:41869290, PMID:17604671).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 1999 High

    Identification of NDUFS7 as the subunit harboring the inhibitor/ubiquinone-binding site resolved where electron transfer from cluster N2 converges with quinone reduction and where all major complex I inhibitors act.

    Evidence Photoaffinity labeling with [³H]TDP, competitive binding with rotenone/piericidin A/bullatacin, protein sequencing in bovine heart and bacterial complex I

    PMID:10097178

    Open questions at the time
    • Atomic-resolution binding pose of inhibitors not determined
    • Relative contribution of NDUFS7 vs. adjacent subunits to binding affinity not quantified
  2. 2000 High

    Systematic mutagenesis of conserved acidic residues in the PSST homolog established which residues are essential for catalysis versus cluster N2 ligation, ruling out a conserved acidic fourth ligand for N2.

    Evidence Site-directed mutagenesis of D136, E140, E89 and others in Yarrowia lipolytica with EPR spectroscopy and activity assays

    PMID:10811805 PMID:12930834

    Open questions at the time
    • Identity of the true fourth N2 ligand remained unresolved at this stage
    • Proton translocation mechanism at D136/E140 not fully delineated
  3. 2001 High

    Demonstrating reciprocal redox-dependent labeling of NDUFS7 and ND1 established that these two subunits dynamically interact at the semiquinone-binding site, coupling electron input to quinone chemistry.

    Evidence Photoaffinity labeling with [³H]TDP modulated by NADH preincubation and competitive inhibitors MPP+/stigmatellin

    PMID:11418099

    Open questions at the time
    • Structural basis of dynamic PSST–ND1 interaction not resolved
    • Whether semiquinone is a catalytic intermediate or side product not settled
  4. 2007 Medium

    A disease-causing intronic mutation producing truncated NDUFS7 demonstrated that this subunit is indispensable for biogenesis of fully assembled complex I, linking NDUFS7 deficiency to isolated complex I deficiency.

    Evidence Patient-derived cells with c.17-1167 C>G mutation, Blue Native PAGE showing selective complex I loss, RT-PCR identifying cryptic exon

    PMID:17604671

    Open questions at the time
    • No complementation/rescue experiment performed in patient cells
    • Residual complex I activity not quantified
  5. 2012 High

    Mapping fenpyroximate binding to the PSST/49 kDa interface pinpointed the pharmacophore orientation within the quinone-binding pocket, refining the topology of the shared inhibitor-binding site.

    Evidence Two orthogonal ¹²⁵I-fenpyroximate photoaffinity probes with limited proteolysis and mass spectrometry fragment mapping in bovine complex I

    PMID:22353032

    Open questions at the time
    • No cryo-EM or crystal structure with bound inhibitor at this point
    • Contribution of ND1 interface residues not mapped with equivalent resolution
  6. 2016 High

    Discovery that NDUFAF5 hydroxylates NDUFS7 Arg-73 early in assembly revealed the first known post-translational modification of this subunit and placed it within the complex I assembly pathway before junction formation.

    Evidence Mass spectrometry identification of Arg-73 hydroxylation, Blue Native PAGE assembly intermediates, NDUFAF5 functional characterization

    PMID:27226634

    Open questions at the time
    • Functional consequence of Arg-73 hydroxylation on catalytic activity not directly tested
    • Whether hydroxylation is reversible or regulatory is unknown
  7. 2019 High

    Mutagenesis of conserved loop arginines facing the quinone tunnel, combined with microsecond molecular dynamics, established that NDUFS7 loop residues actively control ubiquinone diffusion and retention near N2 rather than serving a purely structural role.

    Evidence Site-directed mutagenesis with activity assays and Blue Native PAGE in Yarrowia lipolytica, multi-microsecond MD simulations

    PMID:31226318

    Open questions at the time
    • Experimental validation of MD-predicted quinone poses lacking
    • Whether loop dynamics change with proton-motive force not tested
  8. 2023 Medium

    Convergent p.V91M resistance mutations across six independent clones confirmed NDUFS7 as a direct drug target for the complex I inhibitor DX2-201, validating pharmacological targeting of NDUFS7 in cancer cells.

    Evidence Exome sequencing of six independently selected DX2-201-resistant clones, cell viability assays, syngeneic tumor model

    PMID:37588763

    Open questions at the time
    • Binding affinity and structural basis of V91M resistance not determined
    • In vivo efficacy not tested with NDUFS7-mutant tumors
  9. 2024 Medium

    NDUFS7 knockout in human cells revealed that its loss elevates ROS and triggers compensatory SLC7A11-mediated cystine import and glutathione biosynthesis, placing NDUFS7 upstream of a defined redox-homeostasis pathway.

    Evidence NDUFS7 knockout in HEK293T cells with ROS measurement, SLC7A11 knockdown/overexpression, glutathione assays

    PMID:38823363

    Open questions at the time
    • Whether SLC7A11 compensation occurs in primary or differentiated cell types unknown
    • Source of ROS (complex I flavin site vs. quinone site) not discriminated
  10. 2024 Medium

    Cross-species complementation in Drosophila validated that the canine p.Val179Met variant is functionally deleterious, establishing an in vivo system to assess NDUFS7 variant pathogenicity.

    Evidence Drosophila ND-20 knockdown with canine wildtype vs. V179M NDUFS7 overexpression rescue assay

    PMID:38316835

    Open questions at the time
    • Biochemical mechanism of Val179Met dysfunction not characterized
    • Partial rescue by wildtype suggests dosage or species-compatibility limitations
  11. 2026 Medium

    Identification of NRF2 as a direct transcriptional regulator of NDUFS7 linked oxidative stress signaling to complex I biogenesis, with NDUFS7 restoration rescuing mitochondrial defects from NRF2 loss.

    Evidence ChIP-seq for NRF2 binding at NDUFS7 locus, NRF2 knockout mice, NDUFS7 rescue in NRF2-deficient trabecular meshwork cells

    PMID:41869290

    Open questions at the time
    • Whether NRF2 regulation of NDUFS7 operates in all tissues or is cell-type restricted
    • Mechanism by which NDUFS7 alone rescues complex I in NRF2-deficient background not explained

Open questions

Synthesis pass · forward-looking unresolved questions
  • The structural basis for how NDUFS7 Arg-73 hydroxylation influences complex I assembly competence, the precise atomic mechanism by which loop dynamics couple electron transfer to proton translocation, and whether pharmacological targeting of the NDUFS7 quinone site can be therapeutically exploited remain unresolved.
  • No high-resolution structure of NDUFS7 with bound inhibitor in a catalytically defined state
  • Functional role of Arg-73 hydroxylation untested by non-hydroxylatable mutant in mammalian system
  • Therapeutic window for NDUFS7-targeted complex I inhibitors in cancer not established

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0016491 oxidoreductase activity 5 GO:0098772 molecular function regulator activity 3
Localization
GO:0005739 mitochondrion 4
Pathway
R-HSA-1430728 Metabolism 6 R-HSA-8953897 Cellular responses to stimuli 2
Complex memberships
Mitochondrial complex I (NADH:ubiquinone oxidoreductase)

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1999 PSST (NDUFS7) subunit of complex I is the primary site of photoaffinity labeling by the potent inhibitor [3H]TDP (trifluoromethyldiazirinyl-pyridaben), establishing that PSST functionally couples electron transfer from iron-sulfur cluster N2 to ubiquinone; all structurally diverse potent complex I inhibitors (rotenone, piericidin A, bullatacin, pyridaben) compete for this same binding site on PSST, and the equivalent bacterial subunit NQO6 shares this conserved function. Photoaffinity labeling with [3H]TDP, protein sequencing, immunoprecipitation, competitive binding assays, enzyme inhibition assays Proceedings of the National Academy of Sciences of the United States of America High 10097178
2001 PSST (NDUFS7) and ND1 subunits of complex I are functionally coupled at the quinone-binding region: NADH increases PSST labeling while decreasing ND1 labeling; MPP+ and stigmatellin show opposite effects (increased ND1, decreased PSST labeling), indicating dynamic interaction between these two subunits at a semiquinone binding site. Photoaffinity labeling with [3H]TDP, competitive binding, preincubation with NADH/inhibitors Biochimica et biophysica acta High 11418099
2000 Conserved acidic residues D136 and E140 in the PSST homologue (Yarrowia lipolytica) play a central role in proton translocation and ubiquinone interaction; E89 (proposed fourth ligand of iron-sulfur center N2) is not a ligand of N2 as EPR spectra show unchanged N2 amount but shifted spectrum upon mutation to glutamine, alanine, or cysteine. Site-directed mutagenesis, EPR spectroscopy, enzymatic activity assays in Yarrowia lipolytica The Journal of biological chemistry High 10811805
2003 Two aspartic acid residues D99 and D115 in the PSST homologue (NUKM, Yarrowia lipolytica) are essential for complex I catalytic activity; their mutation to Asn, Glu, or Gly reduces activity to 5–8% of wild-type and reduces the EPR N2 signal by ~50%, while complex I remains stably assembled. No conserved acidic residue in PSST serves as the fourth ligand of iron-sulfur cluster N2. Site-directed mutagenesis of all 8 conserved acidic residues, EPR spectroscopy, enzyme activity assays, Blue Native PAGE The Journal of biological chemistry High 12930834
2012 Fenpyroximate binds at the interface between the PSST and 49 kDa subunits of complex I, not at the distal membrane domain (ND5); the pharmacophoric pyrazole ring orients toward PSST (labeled in region Ser43–Arg66) while the side chain orients toward the 49 kDa subunit, within the quinone-binding pocket formed at the PSST/49 kDa/ND1 interface. Photoaffinity labeling with two 125I-labeled fenpyroximate derivatives, limited proteolysis, doubled SDS-PAGE, mass spectrometry Biochemistry High 22353032
2016 NDUFAF5, an S-adenosylmethionine-dependent assembly factor, hydroxylates Arg-73 of NDUFS7 early in the complex I assembly pathway, before formation of the junction between the peripheral and membrane arms. Mass spectrometry identification of hydroxylation, functional assembly analysis by Blue Native PAGE, biochemical characterization of NDUFAF5 activity The Journal of biological chemistry High 27226634
2019 Conserved residues in the loop of PSST (NDUFS7) facing the ~30 Å quinone-binding tunnel are critical for ubiquinone reductase activity; mutation of conserved arginine residues drastically reduces Q reductase activity despite full complex I assembly, and molecular dynamics simulations show these residues dynamically control ubiquinone diffusion and retention near the terminal electron donor N2. Site-directed mutagenesis, enzymatic activity assays, Blue Native PAGE assembly analysis, molecular dynamics simulations (microsecond scale) Biochimica et biophysica acta. Bioenergetics High 31226318
2007 NDUFS7 is essential for biogenesis of fully assembled complex I; an intronic mutation (c.17-1167 C>G) creates a cryptic exon producing a truncated 41-amino-acid protein, resulting in marked decrease in fully assembled complex I on Blue Native PAGE while other respiratory chain complexes are unaffected. Blue Native PAGE assembly analysis, patient-derived cell studies, RT-PCR demonstration of cryptic exon Molecular genetics and metabolism Medium 17604671
2023 NDUFS7 contains a direct drug-binding site: exome sequencing of six independently selected DX2-201-resistant clones all revealed a p.V91M mutation in NDUFS7, demonstrating that this residue is within the compound's binding site and that NDUFS7 inhibition suppresses oxidative phosphorylation. Exome sequencing of resistant clones, cell viability assays, in vivo syngeneic tumor model ACS pharmacology & translational science Medium 37588763
2024 NDUFS7 deficiency in HEK293T cells causes reduced cell proliferation, elevated cell death, and increased ROS; upregulation of SLC7A11 compensates by increasing cystine import and glutathione biosynthesis to mitigate apoptosis. NDUFS7 knockout in HEK293T cells, ROS measurement, SLC7A11 knockdown/overexpression, glutathione assays Biochemical and biophysical research communications Medium 38823363
2024 The canine NDUFS7 p.Val179Met missense variant fails to rescue lethality upon knockdown of the Drosophila ortholog ND-20 (whereas wildtype NDUFS7 partially rescues), establishing this residue as functionally critical for NDUFS7 activity in vivo. Drosophila in vivo complementation assay with ubiquitous knockdown of ND-20 and overexpression of wildtype vs. mutant canine NDUFS7 Scientific reports Medium 38316835
2026 NRF2 directly regulates NDUFS7 transcription (ChIP-seq confirmed binding), and NDUFS7 is required for mitochondrial complex I integrity in trabecular meshwork cells; restoration of NDUFS7 in NRF2-deficient cells or mice rescues mitochondrial impairment. ChIP-seq, NRF2 knockout mice, NRF2 knockdown/overexpression, NDUFS7 rescue experiments, mitochondrial function assays Research (Washington, D.C.) Medium 41869290

Source papers

Stage 0 corpus · 28 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1999 Leigh syndrome associated with a mutation in the NDUFS7 (PSST) nuclear encoded subunit of complex I. Annals of neurology 157 10360771
1999 NADH-quinone oxidoreductase: PSST subunit couples electron transfer from iron-sulfur cluster N2 to quinone. Proceedings of the National Academy of Sciences of the United States of America 146 10097178
2001 Functional coupling of PSST and ND1 subunits in NADH:ubiquinone oxidoreductase established by photoaffinity labeling. Biochimica et biophysica acta 88 11418099
2016 A mutation in the PSST homologue of complex I (NADH:ubiquinone oxidoreductase) from Tetranychus urticae is associated with resistance to METI acaricides. Insect biochemistry and molecular biology 66 27919778
2000 Function of conserved acidic residues in the PSST homologue of complex I (NADH:ubiquinone oxidoreductase) from Yarrowia lipolytica. The Journal of biological chemistry 64 10811805
2001 The insecticide target in the PSST subunit of complex I. Pest management science 52 11695186
2012 Fenpyroximate binds to the interface between PSST and 49 kDa subunits in mitochondrial NADH-ubiquinone oxidoreductase. Biochemistry 47 22353032
2016 NDUFAF5 Hydroxylates NDUFS7 at an Early Stage in the Assembly of Human Complex I. The Journal of biological chemistry 43 27226634
2003 Two aspartic acid residues in the PSST-homologous NUKM subunit of complex I from Yarrowia lipolytica are essential for catalytic activity. The Journal of biological chemistry 40 12930834
2007 A novel mutation in the human complex I NDUFS7 subunit associated with Leigh syndrome. Molecular genetics and metabolism 38 17275378
2007 A novel mutation of the NDUFS7 gene leads to activation of a cryptic exon and impaired assembly of mitochondrial complex I in a patient with Leigh syndrome. Molecular genetics and metabolism 38 17604671
2019 Mutations in a conserved loop in the PSST subunit of respiratory complex I affect ubiquinone binding and dynamics. Biochimica et biophysica acta. Bioenergetics 35 31226318
2003 Membrane topology of PssT, the transmembrane protein component of the type I exopolysaccharide transport system in Rhizobium leguminosarum bv. trifolii strain TA1. Journal of bacteriology 31 12670974
1996 The plant mitochondrial 22 kDa (PSST) subunit of respiratory chain complex I is encoded by a nuclear gene with enhanced transcript levels in flowers. Plant molecular biology 28 8914535
1996 Assignment of the PSST subunit gene of human mitochondrial complex I to chromosome 19p13. Genomics 19 8938450
2022 The H92R substitution in PSST is a reliable diagnostic biomarker for predicting resistance to mitochondrial electron transport inhibitors of complex I in European populations of Tetranychus urticae. Pest management science 15 35613098
2023 FTSH PROTEASE 3 facilitates Complex I degradation through a direct interaction with the Complex I subunit PSST. The Plant cell 9 37177987
2023 First-in-Class NADH/Ubiquinone Oxidoreductase Core Subunit S7 (NDUFS7) Antagonist for the Treatment of Pancreatic Cancer. ACS pharmacology & translational science 9 37588763
2024 NDUFS7 variant in dogs with Leigh syndrome and its functional validation in a Drosophila melanogaster model. Scientific reports 6 38316835
2024 SLC7A11-mediated cystine import protects against NDUFS7 deficiency-induced cell death in HEK293T cells. Biochemical and biophysical research communications 5 38823363
2013 No association between genetic polymorphisms of the NDUFS7 gene and schizophrenia in Han Chinese. Psychiatric genetics 5 22935918
2025 Identification of NDUFV2, NDUFS7, OPA1, and NDUFA1 as biomarkers for Alzheimer's disease: Insights from oxidative stress and mitochondrial dysfunction in the hippocampus. Journal of Alzheimer's disease : JAD 3 40329774
2025 Mutations of the complex I PSST target gene confers acaricide resistance and a fitness cost in Panonychus citri. BMC biology 2 40597320
2005 PSST-2.0: Protein Data Bank Sequence Search Tool. Applied bioinformatics 2 16128616
2025 Novel intronic variant in NDUFS7 gene results in mitochondrial complex I assembly defect with early basal ganglia and midbrain involvement with progressive neuroimaging findings. Mitochondrion 1 39894241
2026 miR-423-5p/NDUFS7-mediated mitochondrial function modulation contributes to quercetin-induced attenuation of pulmonary fibrosis via extracellular matrix remodeling regulation. Non-coding RNA research 0 41631271
2026 NRF2 Deficiency Disrupts Mitochondrial Homeostasis via NDUFS7 in Trabecular Meshwork. Research (Washington, D.C.) 0 41869290
2002 The gene encoding the PSST subunit of respiratory chain complex I is present in more than one copy in yellow lupine. Biochimica et biophysica acta 0 12151107