COA6 is a mitochondrial complex IV assembly factor critical for biogenesis of mtDNA-encoded COX2

Hum Mol Genet. 2015 Oct 1;24(19):5404-15. doi: 10.1093/hmg/ddv265.

David A Stroud ¹, Megan J Maher ², Caroline Lindau ², F-Nora Vögtle ³, Ann E Frazier ⁴, Elliot Surgenor ¹, Hayley Mountford ⁴, Abeer P Singh ², Matteo Bonas ², Silke Oeljeklaus ⁵, Bettina Warscheid ⁵, Chris Meisinger ⁶, David R Thorburn ³, Michael T Ryan ⁷

Affiliations

1 Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Melbourne, Australia.
2 Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, 3086 Melbourne, Australia.
3 Institut für Biochemie und Molekularbiologie, ZBMZ, University of Freiburg, 79104 Freiburg, Germany.
4 Murdoch Childrens Research Institute and Victorian Clinical Genetics Services, Royal Children's Hospital, University of Melbourne and Department of Pediatrics, University of Melbourne, 3052 Melbourne, Australia and.
5 Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology and BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
6 Institut für Biochemie und Molekularbiologie, ZBMZ, University of Freiburg, 79104 Freiburg, Germany, Department of Biochemistry and Functional Proteomics, Institute of Biology II, Faculty of Biology and BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany.
7 Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Melbourne, Australia, michael.ryan@monash.edu.

PMID: 26160915 DOI: 10.1093/hmg/ddv265

Abstract

Biogenesis of complex IV of the mitochondrial respiratory chain requires assembly factors for subunit maturation, co-factor attachment and stabilization of intermediate assemblies. A pathogenic mutation in COA6, leading to substitution of a conserved tryptophan for a cysteine residue, results in a loss of complex IV activity and cardiomyopathy. Here, we demonstrate that the complex IV defect correlates with a severe loss in complex IV assembly in patient heart but not fibroblasts. Complete loss of COA6 activity using gene editing in HEK293T cells resulted in a profound growth defect due to complex IV deficiency, caused by impaired biogenesis of the copper-bound mitochondrial DNA-encoded subunit COX2 and subsequent accumulation of complex IV assembly intermediates. We show that the pathogenic mutation in COA6 does not affect its import into mitochondria but impairs its maturation and stability. Furthermore, we show that COA6 has the capacity to bind copper and can associate with newly translated COX2 and the mitochondrial copper chaperone SCO1. Our data reveal that COA6 is intricately involved in the copper-dependent biogenesis of COX2.

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