Pecina 2003 Biochim Biophys Acta
|Pecina P, Capkova M, Chowdhury SK, Drahota Z, Dubot A, Vojtiskova A, Hansikova H, Houstekova H, Zeman J, Godinot C, Houstek J (2003) Functional alteration of cytochrome c oxidase by SURF1 mutations in Leigh syndrome. Biochim Biophys Acta 1639:53-63.|
Abstract: Subacute necrotising encephalomyopathy (Leigh syndrome) due to cytochrome c oxidase (CIV; COX) deficiency is often caused by mutations in the SURF1 gene, encoding the Surf1 protein essential for CIV assembly. We have investigated five patients with different SURF1 mutations resulting in the absence of Surf1 protein. All of them presented with severe and generalised CIV defect. Immunoelectrophoretic analysis of cultured fibroblasts revealed 85% decrease of the normal-size CIV complexes and significant accumulation of incomplete COX assemblies of 90–120 kDa. Spectrophotometric assay of CIV activity showed a 70–90% decrease in lauryl maltoside (LM)-solubilised fibroblasts. In contrast, oxygen consumption analysis in whole cells revealed only a 13–31% decrease of COX activity, which was completely inhibited by detergent in patient cells but not in controls. In patient fibroblasts ADP-stimulated respiration was 50% decreased and cytofluorometry showed a significant decrease of mitochondrial membrane potential ΔΨm in State 4, as well as a 2.4-fold higher sensitivity of ΔΨm to uncoupler. We conclude that the absence of the Surf1 protein leads to the formation of incomplete CIV complexes, which in situ maintain rather high electron-transport activity, while their H+-pumping is impaired. Enzyme inactivation by the detergent in patient cells indicates instability of incomplete CIV assemblies.
• Keywords: Cytochrome c oxidase, SURF1, Leigh syndrome, Mitochondrial disorder
Labels: MiParea: Respiration, nDNA;cell genetics, mt-Medicine, Patients Pathology: Inherited
Organism: Human Tissue;cell: Endothelial;epithelial;mesothelial cell, Fibroblast Preparation: Intact cells, Permeabilized cells Enzyme: Complex IV;cytochrome c oxidase Regulation: Coupling efficiency;uncoupling, mt-Membrane potential, Uncoupler Coupling state: LEAK, OXPHOS, ET Pathway: S, CIV HRR: Oxygraph-2k