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Nieto-Panqueva F, Vázquez-Acevedo M, Hamel PP, González-Halphen D. Identification of factors limiting the allotopic production of the Cox2 subunit of yeast cytochrome c oxidase. Genetics 2024; 227:iyae058. [PMID: 38626319 DOI: 10.1093/genetics/iyae058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 03/29/2024] [Accepted: 04/01/2024] [Indexed: 04/18/2024] Open
Abstract
Mitochondrial genes can be artificially relocalized in the nuclear genome in a process known as allotopic expression, such is the case of the mitochondrial cox2 gene, encoding subunit II of cytochrome c oxidase (CcO). In yeast, cox2 can be allotopically expressed and is able to restore respiratory growth of a cox2-null mutant if the Cox2 subunit carries the W56R substitution within the first transmembrane stretch. However, the COX2W56R strain exhibits reduced growth rates and lower steady-state CcO levels when compared to wild-type yeast. Here, we investigated the impact of overexpressing selected candidate genes predicted to enhance internalization of the allotopic Cox2W56R precursor into mitochondria. The overproduction of Cox20, Oxa1, and Pse1 facilitated Cox2W56R precursor internalization, improving the respiratory growth of the COX2W56R strain. Overproducing TIM22 components had a limited effect on Cox2W56R import, while overproducing TIM23-related components showed a negative effect. We further explored the role of the Mgr2 subunit within the TIM23 translocator in the import process by deleting and overexpressing the MGR2 gene. Our findings indicate that Mgr2 is instrumental in modulating the TIM23 translocon to correctly sort Cox2W56R. We propose a biogenesis pathway followed by the allotopically produced Cox2 subunit based on the participation of the 2 different structural/functional forms of the TIM23 translocon, TIM23MOTOR and TIM23SORT, that must follow a concerted and sequential mode of action to insert Cox2W56R into the inner mitochondrial membrane in the correct Nout-Cout topology.
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Affiliation(s)
- Felipe Nieto-Panqueva
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-243, 04510 D.F. (Mexico), México
| | - Miriam Vázquez-Acevedo
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-243, 04510 D.F. (Mexico), México
| | - Patrice P Hamel
- Department of Molecular Genetics and Department of Biological Chemistry and Pharmacology, The Ohio State University, 582 Aronoff laboratory, 318 W. 12th Avenue, Columbus, OH 43210, USA
- School of BioScience and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, 632 014, India
| | - Diego González-Halphen
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-243, 04510 D.F. (Mexico), México
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Luo H, Wang Z. Pan-cancer analysis reveals potential immunological and prognostic roles of COA6 in human cancers and preliminary exploration of COA6 in bladder cancer. Cell Signal 2024; 117:111111. [PMID: 38395184 DOI: 10.1016/j.cellsig.2024.111111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/15/2024] [Accepted: 02/19/2024] [Indexed: 02/25/2024]
Abstract
BACKGROUND Cytochrome C oxidase assembly factor 6 (COA6) is significantly involved in the progression of cancer and is aberrantly expressed in disease. Nevertheless, the comprehensive analysis of COA6 using many omics techniques, and its impact on the prognosis and immunological microenvironment of cancer patients, remains unexplored. METHODS We gathered data from 33 cancer cases and conducted a thorough analysis of abnormalities in COA6 gene expression. This analysis included examining its relevance to disease, its diagnostic and prognostic value, pathway enrichment, the immune microenvironment, its association with immune checkpoints, and its ability to predict patient response to immunotherapy and natural small molecule drugs that target the COA6 protein. Ultimately, we examined the function of COA6 in bladder cancer by in vitro research. RESULTS Our study revealed significant variations in gene expression and identified COA6 as a potential diagnostic biomarker for cancer. COA6 was also discovered to have a crucial function in pan-cancer involving the tumor microenvironment. COA6 has a strong correlation with well-known immunological checkpoints, including TMB and MSI. Molecular docking identified natural small chemical inhibitors that specifically target the COA6 protein. Ultimately, scientific evidence has verified that suppressing the expression of the COA6 gene hinders the growth and infiltration of bladder cancer cells. CONCLUSIONS Our study emphasizes the significant potential of COA6 as a predictive and immunotherapeutic response biomarker. This finding may lead to future investigation into the mechanism of tumor infiltration and the therapeutic possibilities of COA6 in cancer.
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Affiliation(s)
- Hong Luo
- Department of Oncology, Yancheng Branch of Nanjing Drum Tower Hospital, Yancheng 224001, Jiangsu Province, China
| | - Zhiyong Wang
- Gastrointestinal Surgery, Wuhan Union Hospital, Wuhan 430022, Hubei, China.
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Povea-Cabello S, Brischigliaro M, Fernández-Vizarra E. Emerging mechanisms in the redox regulation of mitochondrial cytochrome c oxidase assembly and function. Biochem Soc Trans 2024; 52:873-885. [PMID: 38526156 DOI: 10.1042/bst20231183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/12/2024] [Accepted: 03/14/2024] [Indexed: 03/26/2024]
Abstract
In eukaryotic cells, mitochondria perform cellular respiration through a series of redox reactions ultimately reducing molecular oxygen to water. The system responsible for this process is the respiratory chain or electron transport system (ETS) composed of complexes I-IV. Due to its function, the ETS is the main source of reactive oxygen species (ROS), generating them on both sides of the mitochondrial inner membrane, i.e. the intermembrane space (IMS) and the matrix. A correct balance between ROS generation and scavenging is important for keeping the cellular redox homeostasis and other important aspects of cellular physiology. However, ROS generated in the mitochondria are important signaling molecules regulating mitochondrial biogenesis and function. The IMS contains a large number of redox sensing proteins, containing specific Cys-rich domains, that are involved in ETS complex biogenesis. The large majority of these proteins function as cytochrome c oxidase (COX) assembly factors, mainly for the handling of copper ions necessary for the formation of the redox reactive catalytic centers. A particular case of ROS-regulated COX assembly factor is COA8, whose intramitochondrial levels are increased by oxidative stress, promoting COX assembly and/or protecting the enzyme from oxidative damage. In this review, we will discuss the current knowledge concerning the role played by ROS in regulating mitochondrial activity and biogenesis, focusing on the COX enzyme and with a special emphasis on the functional role exerted by the redox sensitive Cys residues contained in the COX assembly factors.
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Affiliation(s)
- Suleva Povea-Cabello
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
- Veneto Institute of Molecular Medicine, 35129 Padova, Italy
| | - Michele Brischigliaro
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
- Veneto Institute of Molecular Medicine, 35129 Padova, Italy
| | - Erika Fernández-Vizarra
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy
- Veneto Institute of Molecular Medicine, 35129 Padova, Italy
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Horten P, Song K, Garlich J, Hardt R, Colina-Tenorio L, Horvath SE, Schulte U, Fakler B, van der Laan M, Becker T, Stuart RA, Pfanner N, Rampelt H. Identification of MIMAS, a multifunctional mega-assembly integrating metabolic and respiratory biogenesis factors of mitochondria. Cell Rep 2024; 43:113772. [PMID: 38393949 PMCID: PMC11010658 DOI: 10.1016/j.celrep.2024.113772] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 01/03/2024] [Accepted: 01/24/2024] [Indexed: 02/25/2024] Open
Abstract
The mitochondrial inner membrane plays central roles in bioenergetics and metabolism and contains several established membrane protein complexes. Here, we report the identification of a mega-complex of the inner membrane, termed mitochondrial multifunctional assembly (MIMAS). Its large size of 3 MDa explains why MIMAS has escaped detection in the analysis of mitochondria so far. MIMAS combines proteins of diverse functions from respiratory chain assembly to metabolite transport, dehydrogenases, and lipid biosynthesis but not the large established supercomplexes of the respiratory chain, ATP synthase, or prohibitin scaffold. MIMAS integrity depends on the non-bilayer phospholipid phosphatidylethanolamine, in contrast to respiratory supercomplexes whose stability depends on cardiolipin. Our findings suggest that MIMAS forms a protein-lipid mega-assembly in the mitochondrial inner membrane that integrates respiratory biogenesis and metabolic processes in a multifunctional platform.
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Affiliation(s)
- Patrick Horten
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Kuo Song
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Joshua Garlich
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Robert Hardt
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany
| | - Lilia Colina-Tenorio
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Susanne E Horvath
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Uwe Schulte
- Institute of Physiology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany
| | - Martin van der Laan
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling, PZMS, Faculty of Medicine, Saarland University, 66421 Homburg, Germany
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany
| | - Rosemary A Stuart
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
| | - Heike Rampelt
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
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Jäkel T, Raisch L, Richter S, Wirth M, Birenbaum D, Ginting S, Khoprasert Y, Mackenstedt U, Wassermann M. Morphological and molecular phylogenetic characterization of Sarcocystis kani sp. nov. and other novel, closely related Sarcocystis spp. infecting small mammals and colubrid snakes in Asia. Int J Parasitol Parasites Wildl 2023; 22:184-198. [PMID: 37915771 PMCID: PMC10615900 DOI: 10.1016/j.ijppaw.2023.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/24/2023] [Accepted: 10/09/2023] [Indexed: 11/03/2023]
Abstract
We investigated the morphology and phylogenetic relationships of novel and previously recognized Sarcocystis spp. infecting small mammals and colubrid snakes in Asia. The nuclear 18S rRNA and mitochondrial cox1 of Sarcocystis sp.1 from mangrove snakes (Boiga dendrophila) in Thailand and Sarcocystis sp.2 from a ricefield rat (Rattus argentiventer) in Sumatra were partially sequenced. Sporocysts of Sarcocystis sp.1 induced development of sarcocysts in experimentally infected rats, which showed a unique ultrastructure that was observed previously by S.P. Kan in rats from Malaysia; therefore, we describe this species as Sarcocystis kani sp. nov. Its integration into the 18S rRNA phylogeny of Sarcocystis spp. cycling between small mammals and colubrid snakes helped clarify relationships among the so-called S. zuoi-complex of molecularly cryptic species: Sarcocystis kani sp. nov., S. sp.2, S. attenuati, S. scandentiborneensis, and S. zuoi were all included in this clade. Tree topology was resolved into dichotomies congruent with the morphological disparities between the taxa. However, cox1 gene sequencing (including newly sequenced S. singaporensis and S. zamani) revealed that Sarcocystis kani, S. attenuati, and S. scandentiborneensis were identical suggesting a recent, common ancestry. To identify other distinctive features, lineage-specific molecular patterns within both genes were examined revealing that all 18S rRNA sequences of the S. zuoi - complex possess a unique, 7-nt long motif in helix 38 of domain V7 that was different in S. clethrionomyelaphis which branched off basally from the complex. Three-dimensional homology modelling of COX1 protein structure identified amino acid substitutions within the barcode area specific for the S. zuoi-complex and substantial divergence in structurally important amino acids between Sarcocystis species of snakes as definitive hosts and other lineages of the Sarcocystidae. We discuss the utility of selected genes for species delimitation of the Sarcocystis spp. under investigation, which probably evolved during recent radiations of their intermediate and definitive hosts.
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Affiliation(s)
- Thomas Jäkel
- University of Hohenheim, Institute of Biology, Department of Parasitology, Stuttgart, Germany
- Department of Agriculture, Plant Protection Research and Development Office, Bangkok, Thailand
| | - Lisa Raisch
- University of Hohenheim, Institute of Biology, Department of Parasitology, Stuttgart, Germany
| | - Sarah Richter
- University of Hohenheim, Institute of Biology, Department of Parasitology, Stuttgart, Germany
| | - Mareike Wirth
- University of Hohenheim, Institute of Biology, Department of Parasitology, Stuttgart, Germany
| | - Damaris Birenbaum
- University of Hohenheim, Institute of Biology, Department of Parasitology, Stuttgart, Germany
| | | | - Yuvaluk Khoprasert
- Department of Agriculture, Plant Protection Research and Development Office, Bangkok, Thailand
| | - Ute Mackenstedt
- University of Hohenheim, Institute of Biology, Department of Parasitology, Stuttgart, Germany
| | - Marion Wassermann
- University of Hohenheim, Institute of Biology, Department of Parasitology, Stuttgart, Germany
- University of Hohenheim, Center of Biodiversity and Integrative Taxonomy, Stuttgart, Germany
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Han S, Ye T, Mao Y, Hu B, Wang C. Cuproptosis-Related Genes CDK1 and COA6 Involved in the Prognosis Prediction of Liver Hepatocellular Carcinoma. DISEASE MARKERS 2023; 2023:5552798. [PMID: 37215201 PMCID: PMC10195163 DOI: 10.1155/2023/5552798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 01/07/2023] [Accepted: 03/29/2023] [Indexed: 05/24/2023]
Abstract
Background Liver hepatocellular carcinoma (LIHC) is the most frequently seen type of primary liver cancer. Cuproptosis is a novel form of cell death highly associated with mitochondrial metabolism. However, the clinical impact and pertinent mechanism of cuproptosis genes in LIHC remain largely unknown. Methods From public databases, we systematically assessed common genes from LIHC differentially expressed genes (DEGs) and cuproptosis-related genes using bioinformatics analysis. These common genes were then analyzed by enrichment analysis, mutation analysis, risk score model, and others to find candidate hub genes related to LIHC and cuproptosis. Next, hub genes were determined by expression, clinical factors, immunoassay, and prognostic nomogram. Results Based on 129 cuproptosis-related genes and 3492 LIHC DEGs, we totally identified 21 downregulated and 18 upregulated common genes, and they were enriched in pathways, such as zinc ion homeostasis and oxidative phosphorylation. In the mutation analysis, missense mutation was the most common type in LIHC patients, and the common gene F5 had the highest mutation frequency. After LASSO-Cox regression analysis and prognostic analysis, CDK1, ABCB6, LCAT, and COA6 were identified as prognostic signature genes. Among them, ABCB6 and LCAT were lowly expressed in tumors, and CDK1 and COA6 were highly expressed in tumors. In addition, ABCB6 and LCAT were negatively correlated with 6 kinds of immune cells, while CDK1 and COA6 were positively correlated with them. CDK1 and COA6 were identified as hub genes related to LIHC by Cox regression analysis and prognostic nomogram. Conclusion CDK1 and COA6 are two oncogenes in LIHC, which are involved in the molecular mechanism of cuproptosis and LIHC. Besides, CDK1 and COA6 can positively regulate the expressions of immune cells in LIHC. In clinical practice, they can be used as immunotherapeutic targets and prognostic predictors in LIHC, which sheds new light on the scientific fields of cuproptosis and LIHC.
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Affiliation(s)
- Sanfeng Han
- Central Laboratory, Institute of Fudan-Minhang Academic Health System, Minhang Hospital, Fudan University, China
| | - Tao Ye
- Department of Oncology, Minhang Hospital, Fudan University, China
- Key Laboratory of Whole-Period Monitoring and Precise Intervention of Digestive Cancer (SMHC), Minhang Hospital & AHS, Fudan University, China
| | - Yuqin Mao
- Center for Traditional Chinese Medicine and Gut Microbiota, Minhang Hospital, Fudan University, 201199 Shanghai, China
| | - Bo Hu
- Department of Oncology, Minhang Hospital, Fudan University, China
- Key Laboratory of Whole-Period Monitoring and Precise Intervention of Digestive Cancer (SMHC), Minhang Hospital & AHS, Fudan University, China
| | - Chen Wang
- Department of Oncology, Minhang Hospital, Fudan University, China
- Key Laboratory of Whole-Period Monitoring and Precise Intervention of Digestive Cancer (SMHC), Minhang Hospital & AHS, Fudan University, China
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Zhu Z, Hou Q, Wang B, Li C, Liu L, Gong W, Chai J, Guo H, Jia Y. FKBP4 regulates 5-fluorouracil sensitivity in colon cancer by controlling mitochondrial respiration. Life Sci Alliance 2022; 5:5/11/e202201413. [PMID: 35981890 PMCID: PMC9389594 DOI: 10.26508/lsa.202201413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 08/05/2022] [Accepted: 08/09/2022] [Indexed: 11/24/2022] Open
Abstract
FKBP4 controls mitochondrial respiration via modulating COA6-mediated biogenesis and activity of mitochondrial complex IV, thereby regulating 5-fluorouracil sensitivity in colon cancer. Mitochondrial respiration and metabolism play a key role in the pathogenesis and progression of colon adenocarcinoma (COAD). Here, we report a functional pool of FKBP4, a co-chaperone protein, in the mitochondrial intermembrane space (IMS) of colon cancer cells. We found that IMS-localized FKBP4 is essential for the maintenance of mitochondrial respiration, thus contributing to the sensitivity of COAD cells to 5-fluorouracil (5-FU). Mechanistically, FKBP4 interacts with COA6 and controls the assembly of the mitochondrial COA6/SCO1/SCO2 complex, thereby governing COA6-regulated biogenesis and activity of mitochondrial cytochrome c oxidase (complex IV). Thus, our data reveal IMS-localized FKBP4 as a novel regulator of 5-FU sensitivity in COAD, linking mitochondrial respiration to 5-FU sensitivity in COAD.
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Affiliation(s)
- Zhenyu Zhu
- Gastrointestinal Surgery Ward II, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Qingsheng Hou
- Gastrointestinal Surgery Ward II, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Bishi Wang
- Gastrointestinal Surgery Ward II, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Changhao Li
- Gastrointestinal Surgery Ward II, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Luguang Liu
- Gastrointestinal Surgery Ward II, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Weipeng Gong
- Gastrointestinal Surgery Ward II, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Jie Chai
- Gastrointestinal Surgery Ward I, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Hongliang Guo
- Gastrointestinal Surgery Ward II, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China
| | - Yanhan Jia
- Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
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Coordination of metal center biogenesis in human cytochrome c oxidase. Nat Commun 2022; 13:3615. [PMID: 35750769 PMCID: PMC9232578 DOI: 10.1038/s41467-022-31413-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 06/16/2022] [Indexed: 01/12/2023] Open
Abstract
Mitochondrial cytochrome c oxidase (CcO) or respiratory chain complex IV is a heme aa3-copper oxygen reductase containing metal centers essential for holo-complex biogenesis and enzymatic function that are assembled by subunit-specific metallochaperones. The enzyme has two copper sites located in the catalytic core subunits. The COX1 subunit harbors the CuB site that tightly associates with heme a3 while the COX2 subunit contains the binuclear CuA site. Here, we report that in human cells the CcO copper chaperones form macromolecular assemblies and cooperate with several twin CX9C proteins to control heme a biosynthesis and coordinate copper transfer sequentially to the CuA and CuB sites. These data on CcO illustrate a mechanism that regulates the biogenesis of macromolecular enzymatic assemblies with several catalytic metal redox centers and prevents the accumulation of cytotoxic reactive assembly intermediates.
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Mitochondrial COA7 is a heme-binding protein with disulfide reductase activity, which acts in the early stages of complex IV assembly. Proc Natl Acad Sci U S A 2022; 119:2110357119. [PMID: 35210360 PMCID: PMC8892353 DOI: 10.1073/pnas.2110357119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/11/2022] [Indexed: 12/12/2022] Open
Abstract
Assembly factors play key roles in the biogenesis of mitochondrial protein complexes, regulating their stabilities, activities, and incorporation of essential cofactors. Cytochrome c oxidase assembly factor 7 (COA7) is a metazoan-specific assembly factor, the absence or mutation of which in humans accompanies complex IV assembly defects and neurological conditions. Here, we report the crystal structure of COA7 to 2.4 Å resolution, revealing a banana-shaped molecule composed of five helix-turn-helix (α/α) repeats. COA7 binds heme with micromolar affinity, even though the protein structure does not resemble previously characterized heme-binding proteins. The heme-bound COA7 can redox cycle between oxidation states Fe(II) and Fe(III) and shows disulfide reductase activity toward copper binding assembly factors. We propose that COA7 functions to facilitate the biogenesis of the binuclear copper site (CuA) of complex IV. Cytochrome c oxidase (COX) assembly factor 7 (COA7) is a metazoan-specific assembly factor, critical for the biogenesis of mitochondrial complex IV (cytochrome c oxidase). Although mutations in COA7 have been linked to complex IV assembly defects and neurological conditions such as peripheral neuropathy, ataxia, and leukoencephalopathy, the precise role COA7 plays in the biogenesis of complex IV is not known. Here, we show that loss of COA7 blocks complex IV assembly after the initial step where the COX1 module is built, progression from which requires the incorporation of copper and addition of the COX2 and COX3 modules. The crystal structure of COA7, determined to 2.4 Å resolution, reveals a banana-shaped molecule composed of five helix-turn-helix (α/α) repeats, tethered by disulfide bonds. COA7 interacts transiently with the copper metallochaperones SCO1 and SCO2 and catalyzes the reduction of disulfide bonds within these proteins, which are crucial for copper relay to COX2. COA7 binds heme with micromolar affinity, through axial ligation to the central iron atom by histidine and methionine residues. We therefore propose that COA7 is a heme-binding disulfide reductase for regenerating the copper relay system that underpins complex IV assembly.
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The Role of COA6 in the Mitochondrial Copper Delivery Pathway to Cytochrome c Oxidase. Biomolecules 2022; 12:biom12010125. [PMID: 35053273 PMCID: PMC8773535 DOI: 10.3390/biom12010125] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/09/2022] [Accepted: 01/10/2022] [Indexed: 01/27/2023] Open
Abstract
Copper is essential for the stability and activity of cytochrome c oxidase (CcO), the terminal enzyme of the mitochondrial respiratory chain. Copper is bound to COX1 and COX2, two core subunits of CcO, forming the CuB and CuA sites, respectively. Biogenesis of these two copper sites of CcO occurs separately and requires a number of evolutionarily conserved proteins that form the mitochondrial copper delivery pathway. Pathogenic mutations in some of the proteins of the copper delivery pathway, such as SCO1, SCO2, and COA6, have been shown to cause fatal infantile human disorders, highlighting the biomedical significance of understanding copper delivery mechanisms to CcO. While two decades of studies have provided a clearer picture regarding the biochemical roles of SCO1 and SCO2 proteins, some discrepancy exists regarding the function of COA6, the new member of this pathway. Initial genetic and biochemical studies have linked COA6 with copper delivery to COX2 and follow-up structural and functional studies have shown that it is specifically required for the biogenesis of the CuA site by acting as a disulfide reductase of SCO and COX2 proteins. Its role as a copper metallochaperone has also been proposed. Here, we critically review the recent literature regarding the molecular function of COA6 in CuA biogenesis.
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Geldon S, Fernández-Vizarra E, Tokatlidis K. Redox-Mediated Regulation of Mitochondrial Biogenesis, Dynamics, and Respiratory Chain Assembly in Yeast and Human Cells. Front Cell Dev Biol 2021; 9:720656. [PMID: 34557489 PMCID: PMC8452992 DOI: 10.3389/fcell.2021.720656] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/04/2021] [Indexed: 12/24/2022] Open
Abstract
Mitochondria are double-membrane organelles that contain their own genome, the mitochondrial DNA (mtDNA), and reminiscent of its endosymbiotic origin. Mitochondria are responsible for cellular respiration via the function of the electron oxidative phosphorylation system (OXPHOS), located in the mitochondrial inner membrane and composed of the four electron transport chain (ETC) enzymes (complexes I-IV), and the ATP synthase (complex V). Even though the mtDNA encodes essential OXPHOS components, the large majority of the structural subunits and additional biogenetical factors (more than seventy proteins) are encoded in the nucleus and translated in the cytoplasm. To incorporate these proteins and the rest of the mitochondrial proteome, mitochondria have evolved varied, and sophisticated import machineries that specifically target proteins to the different compartments defined by the two membranes. The intermembrane space (IMS) contains a high number of cysteine-rich proteins, which are mostly imported via the MIA40 oxidative folding system, dependent on the reduction, and oxidation of key Cys residues. Several of these proteins are structural components or assembly factors necessary for the correct maturation and function of the ETC complexes. Interestingly, many of these proteins are involved in the metalation of the active redox centers of complex IV, the terminal oxidase of the mitochondrial ETC. Due to their function in oxygen reduction, mitochondria are the main generators of reactive oxygen species (ROS), on both sides of the inner membrane, i.e., in the matrix and the IMS. ROS generation is important due to their role as signaling molecules, but an excessive production is detrimental due to unwanted oxidation reactions that impact on the function of different types of biomolecules contained in mitochondria. Therefore, the maintenance of the redox balance in the IMS is essential for mitochondrial function. In this review, we will discuss the role that redox regulation plays in the maintenance of IMS homeostasis as well as how mitochondrial ROS generation may be a key regulatory factor for ETC biogenesis, especially for complex IV.
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Affiliation(s)
| | - Erika Fernández-Vizarra
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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Ferramosca A. Mitochondrial Protein Network: From Biogenesis to Bioenergetics in Health and Disease. Int J Mol Sci 2020; 22:E1. [PMID: 33374898 PMCID: PMC7792581 DOI: 10.3390/ijms22010001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 12/18/2020] [Indexed: 12/25/2022] Open
Abstract
Mitochondria are double membrane-bound organelles which are essential for the viability of eukaryotic cells, because they play a crucial role in bioenergetics, metabolism and signaling [...].
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Affiliation(s)
- Alessandra Ferramosca
- Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy
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