Loop recognition and copper-mediated disulfide reduction underpin metal site assembly of Cu
            <sub>A</sub>
            in human cytochrome oxidase

Morgada, Marcos N.; Abriata, Luciano A.; Cefaro, Chiara; Gajda, Karolina; Banci, Lucia; Vila, Alejandro J.

doi:10.1073/pnas.1505056112

Cited by 62 publications

(91 citation statements)

References 47 publications

(60 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to Leary et al (26), based on studies in cultured human cells, SCO2 and then SCO1 successively transfer a copper ion to COX2, and subsequently SCO2 acts as a thiol-disulfide oxidoreductase for SCO1. However, a recent in vitro biochemical study (31) reported that SCO1 is a metallochaperone that selectively transfers Cu(I) ions based on loop recognition, whereas SCO2 is a copper-dependent thiol reductase of the Cu A cysteine ligands in COX2. Hence, in this scenario, the reduction of the apo-Cu A disulfide by SCO2 Cu(I) is carried out by the metal and not by the thiols.…”

Section: Discussionmentioning

confidence: 99%

Human mitochondrial cytochrome c oxidase assembly factor COX18 acts transiently as a membrane insertase within the subunit 2 maturation module

Bourens¹,

Barrientos

2017

Journal of Biological Chemistry

View full text Add to dashboard Cite

Edited by John M. Denu Defects in mitochondrial cytochrome c oxidase or respiratory chain complex IV (CIV) assembly are a frequent cause of human mitochondrial disorders. Specifically, mutations in four conserved assembly factors impinging the biogenesis of the mitochondrion-encoded catalytic core subunit 2 (COX2) result in myopathies. These factors afford stability of newly synthesized COX2 (the dystonia-ataxia syndrome protein COX20), a protein with two transmembrane domains, and maturation of its copper center, Cu A (cardiomyopathy proteins SCO1, SCO2, and COA6). COX18 is an additional COX2 assembly factor that belongs to the Oxa1 family of membrane protein insertases. Here, we used a gene-editing approach to generate a human COX18 knock-out HEK293T cell line that displays isolated complete CIV deficiency. We demonstrate that COX20 stabilizes COX2 during insertion of its N-proximal transmembrane domain, and subsequently, COX18 transiently interacts with COX2 to promote translocation across the inner membrane of the COX2 C-tail that contains the apo-Cu A site. The release of COX18 from this complex coincides with the binding of the SCO1-SCO2-COA6 copper metallation module to COX2-COX20 to finalize COX2 biogenesis. Therefore, COX18 is a new candidate when screening for mitochondrial disorders associated with isolated CIV deficiency.In nucleated human cells, mitochondria are central organelles that harbor the enzymes required for cellular respiration and aerobic energy production through oxidative phosphorylation (OXPHOS).2 These multimeric complexes are formed by subunits encoded in the nuclear and mitochondrial genomes that are assembled into functional units with the assistance of a myriad of nucleus-encoded ancillary proteins, generally called assembly factors. Mutations in OXPHOS subunits or assembly factors result in failure to fulfill the energy demands of most tissues with a major incidence in those with high energy

show abstract

Section: Discussionmentioning

confidence: 99%

Human mitochondrial cytochrome c oxidase assembly factor COX18 acts transiently as a membrane insertase within the subunit 2 maturation module

Bourens¹,

Barrientos

2017

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Cu A site formation requires that copper is transferred from COX17 to SCO1, which subsequently catalyzes its insertion into COX2 (9). SCO2 appears to be essential for this latter copper transfer step because it acts as an oxidoreductase on the cysteinyl thiolates of COX2 (15,16).…”

mentioning

confidence: 99%

The mammalian phosphate carrier SLC25A3 is a mitochondrial copper transporter required for cytochrome c oxidase biogenesis

Boulet

Vest

Maynard

et al. 2018

Journal of Biological Chemistry

108

View full text Add to dashboard Cite

Edited by Ruma BanerjeeCopper is required for the activity of cytochrome c oxidase (COX), the terminal electron-accepting complex of the mitochondrial respiratory chain. The likely source of copper used for COX biogenesis is a labile pool found in the mitochondrial matrix. In mammals, the proteins that transport copper across the inner mitochondrial membrane remain unknown. We previously reported that the mitochondrial carrier family protein Pic2 in budding yeast is a copper importer. The closest Pic2 ortholog in mammalian cells is the mitochondrial phosphate carrier SLC25A3. Here, to investigate whether SLC25A3 also transports copper, we manipulated its expression in several murine and human cell lines. SLC25A3 knockdown or deletion consistently resulted in an isolated COX deficiency in these cells, and copper addition to the culture medium suppressed these biochemical defects. Consistent with a conserved role for SLC25A3 in copper transport, its heterologous expression in yeast complemented copper-specific defects observed upon deletion of PIC2. Additionally, assays in Lactococcus lactis and in reconstituted liposomes directly demonstrated that SLC25A3 functions as a copper transporter. Taken together, these data indicate that SLC25A3 can transport copper both in vitro and in vivo.Mitochondrial dysfunction contributes to the pathogenesis of heart failure, neurodegenerative disorders, myopathies, and diabetes (1). Mitochondria are dynamic, double membranebound organelles with a semi-permeable outer membrane that allows exchange of metabolites between the cytosol and the intermembrane space (IMS).5 In contrast, the inner membrane (IM) that separates the IMS and the matrix is tightly sealed. Thus, numerous transporters are required to provide the matrix with a diverse range of substrates that are necessary to support metabolism, the biogenesis of iron-sulfur clusters, and the assembly of the electron transport chain (ETC) required for oxidative phosphorylation (2).Cytochrome c oxidase (COX) is the terminal electron-accepting complex of the ETC. Mammalian COX contains 14 major subunits, two of which bind three redox centers required for electron transfer (3). The catalytic core consists of the mitochondrially-encoded subunits COX1, COX2, and COX3. COX2 binds the binuclear Cu A site required for accepting electrons from cytochrome c. These electrons are then transferred to the cofactors of COX1, first to heme a and then to the heme a 3 -Cu B site where oxygen is bound. COX biogenesis requires Ͼ25 accessory proteins known as COX assembly factors (1). The overwhelming majority of ETC defects that underlie mitochondrial dysfunction and human disease is caused by pathogenic mutations in accessory factors (1). At least nine of these factors facilitate the insertion of the copper cofactors that are essential for the catalytic competence of the COX holoenzyme (4). In yeast, it has been demonstrated that the copper used for COX assembly comes from the matrix, and this matrix copper pool is conserved in mammals (5, 6). Howe...

show abstract

“…49, 50 SCO1 was originally linked to copper delivery to COX through a high copy suppressor screen of a COX17 null yeast strain. 28 Its copper is coordinated via a Cx 3 C motif and a conserved histidine residue, 51–53 and is transferred directly to the Cu A site of COX2 54 in a reaction that also requires the COX assembly factors SCO2 and COA6 (Figure 1). 55–58 Interestingly, a multitude of other IMS-localized proteins containing canonical twin Cx 9 C motifs have been implicated in COX assembly in yeast, 59 many of which have evolutionarily conserved mammalian homologues with undefined functions.…”

Section: Copper In Mitochondriamentioning

confidence: 99%

“…45 This led us to propose a model whereby SCO2 acts upon SCO1 to modulate the generation of a mitochondrial signal that regulates the rate of copper efflux from the cell. 23, 45 Subsequent studies demonstrated that SCO2 possesses a thiol-disulphide oxidoreductase activity 54, 56 that may in fact allow it to regulate the generation of a redox signal by targeting the cysteines of the Cx 3 C motif of SCO1. The transduction of this signal at least in part requires COX19, a soluble COX assembly factor which partitions between mitochondria and the cytosol in a copper-dependent manner.…”

Section: Mitochondrial Copper Chaperones Play a Key Role In The Regulmentioning

confidence: 99%

The mitochondrion: a central architect of copper homeostasis

2017

View full text Add to dashboard Cite

All known eukaryotes require copper for their development and survival. The essentiality of copper reflects its widespread use as a co-factor in conserved enzymes that catalyze biochemical reactions critical to energy production, free radical detoxification, collagen deposition, neurotransmitter biosynthesis and iron homeostasis. However, the prioritized use of copper poses an organism with a considerable challenge because, in its unbound form, copper can potentiate free radical production and displace iron-sulphur clusters to disrupt protein function. Protective mechanisms therefore evolved to mitigate this challenge and tightly regulate the acquisition, trafficking and storage of copper such that the metal ion is rarely found in its free form in the cell. Findings by a number of groups over the last ten years emphasize that this regulatory framework forms the foundation of a system that is capable of monitoring copper status and reprioritizing copper usage at both the cellular and systemic levels of organization. While the identification of relevant molecular mechanisms and signaling pathways has proven to be difficult and remains a barrier to our full understanding of the regulation of copper homeostasis, mounting evidence points to the mitochondrion as a pivotal hub in this regard in both healthy and diseased states. Here, we review our current understanding of copper handling pathways contained within the organelle and consider plausible mechanisms that may serve to functionally couple their activity to that of other cellular copper handling machinery to maintain copper homeostasis.

show abstract

Loop recognition and copper-mediated disulfide reduction underpin metal site assembly of Cu _A in human cytochrome oxidase

Cited by 62 publications

References 47 publications

Human mitochondrial cytochrome c oxidase assembly factor COX18 acts transiently as a membrane insertase within the subunit 2 maturation module

Human mitochondrial cytochrome c oxidase assembly factor COX18 acts transiently as a membrane insertase within the subunit 2 maturation module

The mammalian phosphate carrier SLC25A3 is a mitochondrial copper transporter required for cytochrome c oxidase biogenesis

The mitochondrion: a central architect of copper homeostasis

Contact Info

Product

Resources

About

Loop recognition and copper-mediated disulfide reduction underpin metal site assembly of Cu A in human cytochrome oxidase

Cited by 62 publications

References 47 publications

Human mitochondrial cytochrome c oxidase assembly factor COX18 acts transiently as a membrane insertase within the subunit 2 maturation module

Human mitochondrial cytochrome c oxidase assembly factor COX18 acts transiently as a membrane insertase within the subunit 2 maturation module

The mammalian phosphate carrier SLC25A3 is a mitochondrial copper transporter required for cytochrome c oxidase biogenesis

The mitochondrion: a central architect of copper homeostasis

Contact Info

Product

Resources

About

Loop recognition and copper-mediated disulfide reduction underpin metal site assembly of Cu _A in human cytochrome oxidase