| 2014 |
COA6 (C1orf31) is required for respiratory complex IV (cytochrome c oxidase) biogenesis. Loss of COA6 in yeast, zebrafish, and human cells causes complex IV assembly defects. Conserved cysteine residues in the Cx9CxnCx10C motif are essential for COA6 function. Exogenous copper supplementation completely rescues respiratory and complex IV assembly defects in yeast coa6Δ cells, establishing a role in mitochondrial copper metabolism. |
Yeast genetic deletion (coa6Δ), site-directed mutagenesis of conserved motif residues, zebrafish morpholino knockdown, copper supplementation rescue assay, evolutionary and localization analysis |
Human molecular genetics |
High |
24549041
|
| 2015 |
COA6 is specifically required for biogenesis of the copper-bound mtDNA-encoded subunit COX2. Loss of COA6 (by CRISPR gene editing in HEK293T cells) impairs COX2 maturation and causes accumulation of complex IV assembly intermediates. COA6 can bind copper and physically associates with newly translated COX2 and the mitochondrial copper chaperone SCO1. A pathogenic W59C mutation does not prevent mitochondrial import of COA6 but impairs its maturation and stability. |
CRISPR/Cas9 gene editing in HEK293T cells, growth assays, pulldown/co-immunoprecipitation with COX2 and SCO1, copper-binding assay, pulse-chase analysis, import assay |
Human molecular genetics |
High |
26160915
|
| 2015 |
COA6 interacts transiently with the copper-containing catalytic domain of newly synthesized COX2 and with the copper metallochaperone SCO2. COA6 and SCO2 interact physically, and pathogenic mutations in each protein disrupt this complex formation. COA6 deficiency causes rapid turnover of newly synthesized COX2, defining COA6 as a constituent of the mitochondrial copper relay system for COX2 metallation. |
Co-immunoprecipitation, pulse-chase analysis of COX2 synthesis/turnover, analysis of pathogenic mutation effects on COA6-SCO2 complex formation |
Cell metabolism |
High |
25959673
|
| 2014 |
In patient fibroblasts with undetectable COA6 protein, steady-state levels of complex IV and several of its subunits are reduced, monomeric COX1 assembly intermediate accumulates, and there is increased turnover of mitochondrially encoded complex IV subunits. CI/CIII2/CIVn supercomplexes remain unaffected. Copper supplementation partially rescues complex IV deficiency in patient fibroblasts. |
Patient fibroblast characterization, western blot for complex IV subunits and assembly intermediates, BN-PAGE for supercomplexes, pulse-chase for subunit turnover, copper supplementation rescue |
Human mutation |
Medium |
25339201
|
| 2015 |
Genetic epistasis in yeast shows that simultaneous deletion of Coa6 and Sco2, or Coa6 and Cox12 (COX6B), completely abrogates Cox2 biogenesis. Copper supplementation fails to rescue Cox2 in these double mutants. Overexpression of Cox12 or Sco proteins partially rescues coa6Δ, indicating overlapping but non-redundant roles in copper delivery to Cox2. Patient mutations in Coa6 disrupt Coa6-Cox2 physical interaction, providing biochemical basis for disease pathogenesis. Physical interactions between Coa6, Cox2, Cox12, and Sco proteins were demonstrated biochemically. |
Yeast double-deletion genetic epistasis, copper supplementation rescue, overexpression suppression, co-immunoprecipitation/pulldown between Coa6, Cox2, Cox12, Sco proteins |
Human molecular genetics |
High |
26669719
|
| 2019 |
Solution NMR structure of COA6 reveals a coiled-coil-helix-coiled-coil-helix (CHCH) domain typical of redox-active IMS proteins. COA6 can reduce copper-coordinating disulfides of its client proteins SCO1 and COX2, enabling copper binding. Interaction surfaces and reduction potentials of COA6 and its client proteins were determined, supporting a mechanism where COA6 acts as a disulfide reductase to facilitate copper delivery to cytochrome c oxidase. |
Solution NMR structure determination, thiol-disulfide oxidoreductase activity assay, reduction potential measurements, interaction surface mapping |
Cell reports |
High |
31851937
|
| 2019 |
Crystal structures of human COA6 and the pathogenic W59C mutant protein were solved. COA6 adopts a 3-helical bundle structure with the first two helices tethered by disulfide bonds; one disulfide likely provides the copper-binding site. The W59C pathogenic mutant undergoes disulfide-mediated oligomerization, providing a structural explanation for its loss-of-function. |
X-ray crystallography of wild-type and W59C COA6 |
Life science alliance |
High |
31515291
|
| 2020 |
COA6 acts as a thiol-reductase to reduce disulfide bridges on critical cysteine residues in SCO1 and SCO2, which is required for CuA center formation in COX2. Cysteines within the CX3CXNH domain of SCO2 mediate its interaction with COA6 but are dispensable for SCO2-SCO1 interaction. Loss of COA6 causes combined complex I and complex IV deficiency and impairs membrane potential-driven protein transport across the inner mitochondrial membrane. |
Biochemical thiol-reductase activity assays, domain mutagenesis (SCO2 CX3CXNH cysteines), co-immunoprecipitation, assessment of mitochondrial membrane potential and protein import |
Journal of molecular biology |
High |
32061935
|
| 2025 |
COA6 physically interacts with NDUFA4L2 in hepatocellular carcinoma cells (by Co-IP). COA6 deficiency promotes ROS accumulation and activates cuproptosis in HCC cells and blocks the JAK-STAT signaling pathway. |
Co-immunoprecipitation (COA6 with NDUFA4L2), siRNA knockdown, ROS assay, western blot for JAK-STAT pathway components, in vivo xenograft |
Biochimica et biophysica acta. Molecular cell research |
Low |
41015250
|
| 2026 |
CoQ10 directly binds to COA6 (Coa6) as identified by drug-target engagement approaches. Viral vector-mediated overexpression of Coa6 in Purkinje cells partially recapitulates CoQ10-associated improvements in respiratory chain complex levels and working memory in PC-Drp1-/- mice; Coa6 knockdown attenuates these CoQ10 benefits, placing Coa6 as a direct molecular target through which CoQ10 enhances mitochondrial respiratory chain function. |
Drug-target engagement assay (CoQ10-COA6 binding), viral vector-mediated Coa6 overexpression and knockdown in Purkinje cells, respiratory chain complex activity assays, behavioral testing (eight-arm radial maze) |
Translational neurodegeneration |
Medium |
42036720
|