Supercomplex-associated Cox26 protein binds to cytochrome c oxidase

• Published in: Biochimica et biophysica acta 2016-07, Vol.1863 (7), p.1643-1652
• Main Authors: Strecker, Valentina, Kadeer, Zibirnisa, Heidler, Juliana, Cruciat, Cristina-Maria, Angerer, Heike, Giese, Heiko, Pfeiffer, Kathy, Stuart, Rosemary A., Wittig, Ilka
• Format: Article
• Language: English
• Subjects: Blue native electrophoresis; Catalysis; Cytochrome c oxidase; Disulfides - metabolism; Electron Transport Complex IV - genetics; Electron Transport Complex IV - isolation & purification; Electron Transport Complex IV - metabolism; Electrophoresis; Enzyme Stability; Hydrophobic and Hydrophilic Interactions; III–IV supercomplexes; Mitochondria - enzymology; Mitochondrial Membranes - enzymology; Models, Molecular; Molecular Weight; Oxygen Consumption; Protein Binding; Protein composition; Protein Denaturation; Protein Subunits; Respiratory supercomplexes; Saccharomyces cerevisiae; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - isolation & purification; Saccharomyces cerevisiae Proteins - metabolism; Temperature
• ISSN: 0167-4889; 0006-3002; 1879-2596; 1878-2434
• DOI: 10.1016/j.bbamcr.2016.04.012

Here we identified a hydrophobic 6.4kDa protein, Cox26, as a novel component of yeast mitochondrial supercomplex comprising respiratory complexes III and IV. Multi-dimensional native and denaturing electrophoretic techniques were used to identify proteins interacting with Cox26. The majority of the Cox26 protein was found non-covalently bound to the complex IV moiety of the III–IV supercomplexes. A population of Cox26 was observed to exist in a disulfide bond partnership with the Cox2 subunit of complex IV. No pronounced growth phenotype for Cox26 deficiency was observed, indicating that Cox26 may not play a critical role in the COX enzymology, and we speculate that Cox26 may serve to regulate or support the Cox2 protein. Respiratory supercomplexes are assembled in the absence of the Cox26 protein, however their pattern slightly differs to the wild type III–IV supercomplex appearance. The catalytic activities of complexes III and IV were observed to be normal and respiration was comparable to wild type as long as cells were cultivated under normal growth conditions. Stress conditions, such as elevated temperatures resulted in mild decrease of respiration in non-fermentative media when the Cox26 protein was absent. •The hydrophobic 6.4kDa protein, Cox26, is a component of yeast mitochondrial III–IV supercomplexes.•A population of the Cox26 protein forms a disulphide bond with subunit Cox2.•We propose that Cox26 contributes to the stability of supercomplexes.