Search results for: COX6B1 Antibody
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Mutations in the Yeast Cox12 Subunit Severely Compromise the Activity of the Mitochondrial Complex IV.
Cytochrome c oxidase 6B1 (COX6B1) is one of the less characterized subunits of the mitochondrial electron transport chain complex IV (CIV). Here, we studied the pathobiochemical and respiratory functions of Cox12 (yeast ortholog of COX6B1) using Saccharomyces cerevisiae BY4741 (cox12Δ) cells deficient by the Cox12 protein. The cells exhibited severe growth deficiency in the respiratory glycerol-ethanol medium, which could be reverted by complementation with the yeast COX12 or human COX6B1 genes. Cox12 with arginine 17 residue substituted by histidine (R17H) or cysteine (R17C) (mutations analogous to those observed in human patients) failed to complement the loss of Cox12 function. When cox12Δ cells were grown in rich respiratory/fermentative galactose medium, no changes in the expression of individual respiratory chain subunits were observed. Blue native PAGE/Western blotting analysis using antibodies against Rip1 and Cox1, which are specific components of complexes III (CIII) and IV (CIV), respectively, revealed no noticeable decrease in the native CIIICIV and CIIICIV supercomplexes (SCs). However, the association of the respiratory SC factor 2 (Rcf2) and Cox2 subunit within the SCs of cox12Δ cells was reduced, while the specific activity of CIV was downregulated by 90%. Both basal respiration and succinate-ADP stimulated state 3 respiration, as well as the mitochondrial membrane potential, were decreased in cox12Δ cells. Furthermore, cox12Δ cells and cells synthesizing Cox12 mutants R17H and R17C showed higher sensitivity to the H2O2-induced oxidative stress compared to the wild-type (WT) cells. In silico structural modeling of the WT yeast SCs revealed that Cox12 forms a network of interactions with Rcf2 and Cox2. Together, our results establish that Cox12 is essential for the CIV activity.Shubhojit Das, Soumyajit Mukherjee, Minakshi Bedi, Alok Ghosh
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#29396562 2018/02/02
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Cytochrome c oxidase deficiency, oxidative stress, possible antioxidant therapy and link to nuclear DNA damage.
In response to Ravera et al. "Fanconi anemia: from DNA repair to metabolism" commenting on our recent publication by Abu-Libdeh, Douiev et al., describing a pathogenic variant in the COX 4I1 gene simulating Fanconi anemia, we wish to add supplementary, pertinent information linking cytochrome c oxidase (COX, mitochondrial respiratory chain complex IV) dysfunction to oxidative stress and nuclear DNA damage. Elevated production of reactive oxygen species (ROS) in COX 4I1 deficient fibroblasts was detected in cells grown in glucose free medium and normalized by ascorbate or N-acetylcysteine supplementation. A pilot study shows positive nuclear staining with antibodies against Phospho-Histone H2A.X (Ser 139) indicating double-stranded DNA breaks (DBSs) both in COX 4I1 and in COX6B1 deficient fibroblasts. Additional investigation is required, and ongoing, to elucidate the precise mechanism of DNA damage in mitochondrial respiratory chain dysfunction and how it could be prevented.Liza Douiev, Bassam Abu-Libdeh, Ann Saada