2. Academic Validation
  3. COX16 is required for assembly of cytochrome c oxidase in human cells and is involved in copper delivery to COX2

COX16 is required for assembly of cytochrome c oxidase in human cells and is involved in copper delivery to COX2

  • Biochim Biophys Acta Bioenerg. 2018 Apr;1859(4):244-252. doi: 10.1016/j.bbabio.2018.01.004.
Cristina Cerqua 1,  Valeria Morbidoni 1,  Maria Andrea Desbats 1,  Mara Doimo 2,  Chiara Frasson 3,  Sabrina Sacconi 4,  Maria Cristina Baldoin 1,  Geppo Sartori 5,  Giuseppe Basso 3,  Leonardo Salviati 6,  Eva Trevisson 7
Affiliations

Affiliations

  • 1 Clinical Genetics Unit, Department of Women and Children's Health, University of Padova, Via Giustiniani 3 and IRP Città della Speranza, Corso Stati Uniti 4, Padova, Italy.
  • 2 Clinical Genetics Unit, Department of Women and Children's Health, University of Padova, Via Giustiniani 3 and IRP Città della Speranza, Corso Stati Uniti 4, Padova, Italy; Department of Medical Biochemistry and Biophysics, Umeå University, SE-901 87, Umeå, Sweden.
  • 3 Hematology-Oncology Laboratory, Department of Women and Children's Health, University of Padova, Via Giustiniani 3, Padova, Italy.
  • 4 CNRS UMR7277, INSERM U1091, IBV - Institute of Biology Valrose, UNS Université Nice Sophia-Antipolis, Faculté de Médecine, Parc Valrose, Nice, CEDEX, France; Centre de référence des Maladies Neuromusculaires, Hôpital Archet 1, 151, Route Saint-Antoine de Ginestière, Nice, France.
  • 5 Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58B, Padova, Italy.
  • 6 Clinical Genetics Unit, Department of Women and Children's Health, University of Padova, Via Giustiniani 3 and IRP Città della Speranza, Corso Stati Uniti 4, Padova, Italy. Electronic address: leonardo.salviati@unipd.it.
  • 7 Clinical Genetics Unit, Department of Women and Children's Health, University of Padova, Via Giustiniani 3 and IRP Città della Speranza, Corso Stati Uniti 4, Padova, Italy. Electronic address: eva.trevisson@unipd.it.
PMID: 29355485 DOI: 10.1016/j.bbabio.2018.01.004
Abstract

Cytochrome c oxidase (COX), complex IV of the mitochondrial respiratory chain, is comprised of 14 structural subunits, several prosthetic groups and metal cofactors, among which copper. Its biosynthesis involves a number of ancillary proteins, encoded by the COX-assembly genes that are required for the stabilization and membrane insertion of the nascent polypeptides, the synthesis of the prosthetic groups, and the delivery of the metal cofactors, in particular of copper. Recently, a modular model for COX assembly has been proposed, based on the sequential incorporation of different assembly modules formed by specific subunits. We have cloned and characterized the human homologue of yeast COX16. We show that human COX16 encodes a small mitochondrial transmembrane protein that faces the intermembrane space and is highly expressed in skeletal and cardiac muscle. Its knockdown in C. elegans produces COX deficiency, and its ablation in HEK293 cells impairs COX assembly. Interestingly, COX16 knockout cells retain significant COX activity, suggesting that the function of COX16 is partially redundant. Analysis of steady-state levels of COX subunits and of assembly intermediates by Blue-Native gels shows a pattern similar to that reported in cells lacking COX18, suggesting that COX16 is required for the formation of the COX2 subassembly module. Moreover, COX16 co-immunoprecipitates with COX2. Finally, we found that copper supplementation increases COX activity and restores normal steady state levels of COX subunits in COX16 knockout cells, indicating that, even in the absence of a canonical copper binding motif, COX16 could be involved in copper delivery to COX2.

Keywords

Copper; Cytochrome c oxidase; Cytochrome c oxidase assembly; Mitochondrial respiratory chain.

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