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Verma AK, Sharma A, Subramaniyam N, Gandhi CR. Augmenter of liver regeneration: Mitochondrial function and steatohepatitis. J Hepatol 2022; 77:1410-1421. [PMID: 35777586 DOI: 10.1016/j.jhep.2022.06.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/24/2022] [Accepted: 06/09/2022] [Indexed: 12/15/2022]
Abstract
Augmenter of liver regeneration (ALR), a ubiquitous fundamental life protein, is expressed more abundantly in the liver than other organs. Expression of ALR is highest in hepatocytes, which also constitutively secrete it. ALR gene transcription is regulated by NRF2, FOXA2, SP1, HNF4α, EGR-1 and AP1/AP4. ALR's FAD-linked sulfhydryl oxidase activity is essential for protein folding in the mitochondrial intermembrane space. ALR's functions also include cytochrome c reductase and protein Fe/S maturation activities. ALR depletion from hepatocytes leads to increased oxidative stress, impaired ATP synthesis and apoptosis/necrosis. Loss of ALR's functions due to homozygous mutation causes severe mitochondrial defects and congenital progressive multiorgan failure, suggesting that individuals with one functional ALR allele might be susceptible to disorders involving compromised mitochondrial function. Genetic ablation of ALR from hepatocytes induces structural and functional mitochondrial abnormalities, dysregulation of lipid homeostasis and development of steatohepatitis. High-fat diet-fed ALR-deficient mice develop non-alcoholic steatohepatitis (NASH) and fibrosis, while hepatic and serum levels of ALR are lower than normal in human NASH and NASH-cirrhosis. Thus, ALR deficiency may be a critical predisposing factor in the pathogenesis and progression of NASH.
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Affiliation(s)
- Alok Kumar Verma
- Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA; Cincinnati VA Medical Center, Cincinnati, Ohio, USA
| | - Akanksha Sharma
- Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA; Cincinnati VA Medical Center, Cincinnati, Ohio, USA
| | - Nithyananthan Subramaniyam
- Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Chandrashekhar R Gandhi
- Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA; Cincinnati VA Medical Center, Cincinnati, Ohio, USA; Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA.
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2
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West JD. Experimental Approaches for Investigating Disulfide-Based Redox Relays in Cells. Chem Res Toxicol 2022; 35:1676-1689. [PMID: 35771680 DOI: 10.1021/acs.chemrestox.2c00123] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Reversible oxidation of cysteine residues within proteins occurs naturally during normal cellular homeostasis and can increase during oxidative stress. Cysteine oxidation often leads to the formation of disulfide bonds, which can impact protein folding, stability, and function. Work in both prokaryotic and eukaryotic models over the past five decades has revealed several multiprotein systems that use thiol-dependent oxidoreductases to mediate disulfide bond reduction, formation, and/or rearrangement. Here, I provide an overview of how these systems operate to carry out disulfide exchange reactions in different cellular compartments, with a focus on their roles in maintaining redox homeostasis, transducing redox signals, and facilitating protein folding. Additionally, I review thiol-independent and thiol-dependent approaches for interrogating what proteins partner together in such disulfide-based redox relays. While the thiol-independent approaches rely either on predictive measures or standard procedures for monitoring protein-protein interactions, the thiol-dependent approaches include direct disulfide trapping methods as well as thiol-dependent chemical cross-linking. These strategies may prove useful in the systematic characterization of known and newly discovered disulfide relay mechanisms and redox switches involved in oxidant defense, protein folding, and cell signaling.
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Affiliation(s)
- James D West
- Biochemistry & Molecular Biology Program, Departments of Biology and Chemistry, The College of Wooster, Wooster, Ohio 44691, United States
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3
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Abstract
Import and oxidative folding of proteins in the mitochondrial intermembrane space differ among eukaryotic lineages. While opisthokonts such as yeast rely on the receptor and oxidoreductase Mia40 in combination with the Mia40:cytochrome c oxidoreductase Erv, kinetoplastid parasites and other Excavata/Discoba lack Mia40 but have a functional Erv homologue. Whether excavate Erv homologues rely on a Mia40 replacement or directly interact with imported protein substrates remains controversial. Here, we used the CRISPR-Cas9 system to generate a set of tagged and untagged homozygous mutants of LTERV from the kinetoplastid model parasite Leishmania tarentolae. Modifications of the shuttle cysteine motif of LtErv were lethal, whereas replacement of clamp residue Cys17 or removal of the kinetoplastida-specific second (KISS) domain had no impact on parasite viability under standard growth conditions. However, removal of the KISS domain rendered parasites sensitive to heat stress and led to the accumulation of homodimeric and mixed LtErv disulfides. We therefore determined and compared the redox interactomes of tagged wild-type LtErv and LtErvΔKISS using stable isotope labeling by amino acids in cell culture (SILAC) and quantitative mass spectrometry. While the Mia40-replacement candidate Mic20 and all but one typical substrate with twin Cx3/9C-motifs were absent in both redox interactomes, we identified a small set of alternative potential interaction partners with putative redox-active cysteine residues. In summary, our study reveals parasite-specific intracellular structure-function relationships and redox interactomes of LtErv with implications for current hypotheses on mitochondrial protein import in nonopisthokonts. IMPORTANCE The discovery of the redox proteins Mia40/CHCHD4 and Erv1/ALR, as well as the elucidation of their relevance for oxidative protein folding in the mitochondrial intermembrane space of yeast and mammals, founded a new research topic in redox biology and mitochondrial protein import. The lack of Mia40/CHCHD4 in protist lineages raises fundamental and controversial questions regarding the conservation and evolution of this essential pathway. Do protist Erv homologues act alone, or do they use the candidate Mic20 or another protein as a Mia40 replacement? Furthermore, we previously showed that Erv homologues in L. tarentolae and the human pathogen L. infantum are not only essential but also differ structurally and mechanistically from yeast and human Erv1/ALR. Here, we analyzed the relevance of such structural differences in vivo and determined the first redox interactomes of a nonopisthokont Erv homologue. Our data challenge recent hypotheses on mitochondrial protein import in nonopisthokonts.
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Zhao F, Zou MH. Role of the Mitochondrial Protein Import Machinery and Protein Processing in Heart Disease. Front Cardiovasc Med 2021; 8:749756. [PMID: 34651031 PMCID: PMC8505727 DOI: 10.3389/fcvm.2021.749756] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 08/26/2021] [Indexed: 12/12/2022] Open
Abstract
Mitochondria are essential organelles for cellular energy production, metabolic homeostasis, calcium homeostasis, cell proliferation, and apoptosis. About 99% of mammalian mitochondrial proteins are encoded by the nuclear genome, synthesized as precursors in the cytosol, and imported into mitochondria by mitochondrial protein import machinery. Mitochondrial protein import systems function not only as independent units for protein translocation, but also are deeply integrated into a functional network of mitochondrial bioenergetics, protein quality control, mitochondrial dynamics and morphology, and interaction with other organelles. Mitochondrial protein import deficiency is linked to various diseases, including cardiovascular disease. In this review, we describe an emerging class of protein or genetic variations of components of the mitochondrial import machinery involved in heart disease. The major protein import pathways, including the presequence pathway (TIM23 pathway), the carrier pathway (TIM22 pathway), and the mitochondrial intermembrane space import and assembly machinery, related translocases, proteinases, and chaperones, are discussed here. This review highlights the importance of mitochondrial import machinery in heart disease, which deserves considerable attention, and further studies are urgently needed. Ultimately, this knowledge may be critical for the development of therapeutic strategies in heart disease.
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Affiliation(s)
- Fujie Zhao
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA, United States
| | - Ming-Hui Zou
- Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA, United States
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5
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Dimogkioka AR, Lees J, Lacko E, Tokatlidis K. Protein import in mitochondria biogenesis: guided by targeting signals and sustained by dedicated chaperones. RSC Adv 2021; 11:32476-32493. [PMID: 35495482 PMCID: PMC9041937 DOI: 10.1039/d1ra04497d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 09/25/2021] [Indexed: 12/31/2022] Open
Abstract
Mitochondria have a central role in cellular metabolism; they are responsible for the biosynthesis of amino acids, lipids, iron-sulphur clusters and regulate apoptosis. About 99% of mitochondrial proteins are encoded by nuclear genes, so the biogenesis of mitochondria heavily depends on protein import pathways into the organelle. An intricate system of well-studied import machinery facilitates the import of mitochondrial proteins. In addition, folding of the newly synthesized proteins takes place in a busy environment. A system of folding helper proteins, molecular chaperones and co-chaperones, are present to maintain proper conformation and thus avoid protein aggregation and premature damage. The components of the import machinery are well characterised, but the targeting signals and how they are recognised and decoded remains in some cases unclear. Here we provide some detail on the types of targeting signals involved in the protein import process. Furthermore, we discuss the very elaborate chaperone systems of the intermembrane space that are needed to overcome the particular challenges for the folding process in this compartment. The mechanisms that sustain productive folding in the face of aggregation and damage in mitochondria are critical components of the stress response and play an important role in cell homeostasis.
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Affiliation(s)
- Anna-Roza Dimogkioka
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow University Avenue Glasgow G12 8QQ Scotland UK
| | - Jamie Lees
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow University Avenue Glasgow G12 8QQ Scotland UK
| | - Erik Lacko
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow University Avenue Glasgow G12 8QQ Scotland UK
| | - Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow University Avenue Glasgow G12 8QQ Scotland UK
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Finger Y, Riemer J. Protein import by the mitochondrial disulfide relay in higher eukaryotes. Biol Chem 2021; 401:749-763. [PMID: 32142475 DOI: 10.1515/hsz-2020-0108] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/24/2020] [Indexed: 12/19/2022]
Abstract
The proteome of the mitochondrial intermembrane space (IMS) contains more than 100 proteins, all of which are synthesized on cytosolic ribosomes and consequently need to be imported by dedicated machineries. The mitochondrial disulfide relay is the major import machinery for soluble proteins in the IMS. Its major component, the oxidoreductase MIA40, interacts with incoming substrates, retains them in the IMS, and oxidatively folds them. After this reaction, MIA40 is reoxidized by the sulfhydryl oxidase augmenter of liver regeneration, which couples disulfide formation by this machinery to the activity of the respiratory chain. In this review, we will discuss the import of IMS proteins with a focus on recent findings showing the diversity of disulfide relay substrates, describing the cytosolic control of this import system and highlighting the physiological relevance of the disulfide relay machinery in higher eukaryotes.
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Affiliation(s)
- Yannik Finger
- Institute for Biochemistry, Redox Biochemistry, University of Cologne, Zülpicher Str. 47a/R. 3.49, D-50674 Cologne, Germany
| | - Jan Riemer
- Department of Chemistry, Institute for Biochemistry, Redox Biochemistry, University of Cologne, and Cologne Excellence Cluster on Cellular Stress Response in Aging-Associated Diseases, Zülpicher Str. 47a/R. 3.49, D-50674 Cologne, Germany
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7
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The Mia40/CHCHD4 Oxidative Folding System: Redox Regulation and Signaling in the Mitochondrial Intermembrane Space. Antioxidants (Basel) 2021; 10:antiox10040592. [PMID: 33921425 PMCID: PMC8069373 DOI: 10.3390/antiox10040592] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/06/2021] [Accepted: 04/09/2021] [Indexed: 12/20/2022] Open
Abstract
Mitochondria are critical for several cellular functions as they control metabolism, cell physiology, and cell death. The mitochondrial proteome consists of around 1500 proteins, the vast majority of which (about 99% of them) are encoded by nuclear genes, with only 13 polypeptides in human cells encoded by mitochondrial DNA. Therefore, it is critical for all the mitochondrial proteins that are nuclear-encoded to be targeted precisely and sorted specifically to their site of action inside mitochondria. These processes of targeting and sorting are catalysed by protein translocases that operate in each one of the mitochondrial sub-compartments. The main protein import pathway for the intermembrane space (IMS) recognises proteins that are cysteine-rich, and it is the only import pathway that chemically modifies the imported precursors by introducing disulphide bonds to them. In this manner, the precursors are trapped in the IMS in a folded state. The key component of this pathway is Mia40 (called CHCHD4 in human cells), which itself contains cysteine motifs and is subject to redox regulation. In this review, we detail the basic components of the MIA pathway and the disulphide relay mechanism that underpins the electron transfer reaction along the oxidative folding mechanism. Then, we discuss the key protein modulators of this pathway and how they are interlinked to the small redox-active molecules that critically affect the redox state in the IMS. We present also evidence that the mitochondrial redox processes that are linked to iron–sulfur clusters biogenesis and calcium homeostasis coalesce in the IMS at the MIA machinery. The fact that the MIA machinery and several of its interactors and substrates are linked to a variety of common human diseases connected to mitochondrial dysfunction highlight the potential of redox processes in the IMS as a promising new target for developing new treatments for some of the most complex and devastating human diseases.
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8
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CHCHD4 (MIA40) and the mitochondrial disulfide relay system. Biochem Soc Trans 2021; 49:17-27. [PMID: 33599699 PMCID: PMC7925007 DOI: 10.1042/bst20190232] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 12/19/2020] [Accepted: 01/06/2021] [Indexed: 12/13/2022]
Abstract
Mitochondria are pivotal for normal cellular physiology, as they perform a crucial role in diverse cellular functions and processes, including respiration and the regulation of bioenergetic and biosynthetic pathways, as well as regulating cellular signalling and transcriptional networks. In this way, mitochondria are central to the cell's homeostatic machinery, and as such mitochondrial dysfunction underlies the pathology of a diverse range of diseases including mitochondrial disease and cancer. Mitochondrial import pathways and targeting mechanisms provide the means to transport into mitochondria the hundreds of nuclear-encoded mitochondrial proteins that are critical for the organelle's many functions. One such import pathway is the highly evolutionarily conserved disulfide relay system (DRS) within the mitochondrial intermembrane space (IMS), whereby proteins undergo a form of oxidation-dependent protein import. A central component of the DRS is the oxidoreductase coiled-coil-helix-coiled-coil-helix (CHCH) domain-containing protein 4 (CHCHD4, also known as MIA40), the human homologue of yeast Mia40. Here, we summarise the recent advances made to our understanding of the role of CHCHD4 and the DRS in physiology and disease, with a specific focus on the emerging importance of CHCHD4 in regulating the cellular response to low oxygen (hypoxia) and metabolism in cancer.
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9
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Bhopatkar AA, Uversky VN, Rangachari V. Disorder and cysteines in proteins: A design for orchestration of conformational see-saw and modulatory functions. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 174:331-373. [PMID: 32828470 DOI: 10.1016/bs.pmbts.2020.06.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Being responsible for more than 90% of cellular functions, protein molecules are workhorses in all the life forms. In order to cater for such a high demand, proteins have evolved to adopt diverse structures that allow them to perform myriad of functions. Beginning with the genetically directed amino acid sequence, the classical understanding of protein function involves adoption of hierarchically complex yet ordered structures. However, advances made over the last two decades have revealed that inasmuch as 50% of eukaryotic proteome exists as partially or fully disordered structures. Significance of such intrinsically disordered proteins (IDPs) is further realized from their ability to exhibit multifunctionality, a feature attributable to their conformational plasticity. Among the coded amino acids, cysteines are considered to be "order-promoting" due to their ability to form inter- or intramolecular disulfide bonds, which confer robust thermal stability to the protein structure in oxidizing conditions. The co-existence of order-promoting cysteines with disorder-promoting sequences seems counter-intuitive yet many proteins have evolved to contain such sequences. In this chapter, we review some of the known cysteine-containing protein domains categorized based on the number of cysteines they possess. We show that many protein domains contain disordered sequences interspersed with cysteines. We show that a positive correlation exists between the degree of cysteines and disorder within the sequences that flank them. Furthermore, based on the computational platform, IUPred2A, we show that cysteine-rich sequences display significant disorder in the reduced but not the oxidized form, increasing the potential for such sequences to function in a redox-sensitive manner. Overall, this chapter provides insights into an exquisite evolutionary design wherein disordered sequences with interspersed cysteines enable potential modulatory protein functions under stress and environmental conditions, which thus far remained largely inconspicuous.
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Affiliation(s)
- Anukool A Bhopatkar
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, MS, United States
| | - Vladimir N Uversky
- Department of Molecular Medicine and Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, United States; Laboratory of New Methods in Biology, Institute for Biological Instrumentation of the Russian Academy of Sciences, Federal Research Center "Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences", Pushchino, Moscow Region, Russia
| | - Vijayaraghavan Rangachari
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg, MS, United States; Center of Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg, MS, United States.
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10
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Habich M, Salscheider SL, Murschall LM, Hoehne MN, Fischer M, Schorn F, Petrungaro C, Ali M, Erdogan AJ, Abou-Eid S, Kashkar H, Dengjel J, Riemer J. Vectorial Import via a Metastable Disulfide-Linked Complex Allows for a Quality Control Step and Import by the Mitochondrial Disulfide Relay. Cell Rep 2020; 26:759-774.e5. [PMID: 30650365 DOI: 10.1016/j.celrep.2018.12.092] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 11/15/2018] [Accepted: 12/20/2018] [Indexed: 01/31/2023] Open
Abstract
Disulfide formation in the mitochondrial intermembrane space (IMS) is an essential process. It is catalyzed by the disulfide relay machinery, which couples substrate import and oxidation. The machinery relies on the oxidoreductase and chaperone CHCHD4-Mia40. Here, we report on the driving force for IMS import and on a redox quality control mechanism. We demonstrate that unfolded reduced proteins, upon translocation into the IMS, initiate formation of a metastable disulfide-linked complex with CHCHD4. If this interaction does not result in productive oxidation, then substrates are released to the cytosol and degraded by the proteasome. Based on these data, we propose a redox quality control step at the level of the disulfide-linked intermediate that relies on the vectorial nature of IMS import. Our findings also provide the mechanistic framework to explain failures in import of numerous human disease mutants in CHCHD4 substrates.
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Affiliation(s)
- Markus Habich
- Institute for Biochemistry, Department of Chemistry, University of Cologne, Zuelpicher Str. 47a/R. 3.49, 50674 Cologne, Germany
| | - Silja Lucia Salscheider
- Institute for Biochemistry, Department of Chemistry, University of Cologne, Zuelpicher Str. 47a/R. 3.49, 50674 Cologne, Germany
| | - Lena Maria Murschall
- Institute for Biochemistry, Department of Chemistry, University of Cologne, Zuelpicher Str. 47a/R. 3.49, 50674 Cologne, Germany
| | - Michaela Nicole Hoehne
- Institute for Biochemistry, Department of Chemistry, University of Cologne, Zuelpicher Str. 47a/R. 3.49, 50674 Cologne, Germany
| | - Manuel Fischer
- Institute for Biochemistry, Department of Chemistry, University of Cologne, Zuelpicher Str. 47a/R. 3.49, 50674 Cologne, Germany
| | - Fabian Schorn
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC) and Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, CECAD Research Center, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Carmelina Petrungaro
- Institute for Biochemistry, Department of Chemistry, University of Cologne, Zuelpicher Str. 47a/R. 3.49, 50674 Cologne, Germany
| | - Muna Ali
- Institute for Biochemistry, Department of Chemistry, University of Cologne, Zuelpicher Str. 47a/R. 3.49, 50674 Cologne, Germany
| | - Alican J Erdogan
- Institute for Biochemistry, Department of Chemistry, University of Cologne, Zuelpicher Str. 47a/R. 3.49, 50674 Cologne, Germany
| | - Shadi Abou-Eid
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Hamid Kashkar
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC) and Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, CECAD Research Center, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany
| | - Joern Dengjel
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Jan Riemer
- Institute for Biochemistry, Department of Chemistry, University of Cologne, Zuelpicher Str. 47a/R. 3.49, 50674 Cologne, Germany.
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11
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Abstract
Mitochondria are essential organelles of eukaryotic cells. They consist of hundreds of different proteins that exhibit crucial activities in respiration, catabolic metabolism and the synthesis of amino acids, lipids, heme and iron-sulfur clusters. With the exception of a handful of hydrophobic mitochondrially encoded membrane proteins, all these proteins are synthesized on cytosolic ribosomes, targeted to receptors on the mitochondrial surface, and transported across or inserted into the outer and inner mitochondrial membrane before they are folded and assembled into their final native structure. This review article provides a comprehensive overview of the mechanisms and components of the mitochondrial protein import systems with a particular focus on recent developments in the field.
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Affiliation(s)
- Katja G Hansen
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany
| | - Johannes M Herrmann
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany.
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12
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Ueda E, Tamura Y, Sakaue H, Kawano S, Kakuta C, Matsumoto S, Endo T. Myristoyl group-aided protein import into the mitochondrial intermembrane space. Sci Rep 2019; 9:1185. [PMID: 30718713 PMCID: PMC6362269 DOI: 10.1038/s41598-018-38016-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 12/12/2018] [Indexed: 12/20/2022] Open
Abstract
The MICOS complex mediates formation of the crista junctions in mitochondria. Here we analyzed the mitochondrial import pathways for the six yeast MICOS subunits as a step toward understanding of the assembly mechanisms of the MICOS complex. Mic10, Mic12, Mic26, Mic27, and Mic60 used the presequence pathway to reach the intermembrane space (IMS). In contrast, Mic19 took the TIM40/MIA pathway, through its CHCH domain, to reach the IMS. Unlike canonical TIM40/MIA substrates, presence of the N-terminal unfolded DUF domain impaired the import efficiency of Mic19, yet N-terminal myristoylation of Mic19 circumvented this effect. The myristoyl group of Mic19 binds to Tom20 of the TOM complex as well as the outer membrane, which may lead to "entropy pushing" of the DUF domain followed by the CHCH domain of Mic19 into the import channel, thereby achieving efficient import.
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Affiliation(s)
- Eri Ueda
- Department of Chemistry, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, 464-8602, Japan
- Department of Biological Science, Graduate School of Science, Osaka University, 1-1 machikaneyama-cho, Toyonaka, 560-0043, Osaka, Japan
| | - Yasushi Tamura
- Department of Material and Biological Chemistry, Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata, 990-8560, Japan
| | - Haruka Sakaue
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, 603-8555, Japan
- Research Center for Protein Dynamics, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, 603-8555, Japan
| | - Shin Kawano
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, 603-8555, Japan
- Research Center for Protein Dynamics, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, 603-8555, Japan
| | - Chika Kakuta
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, 603-8555, Japan
| | - Shunsuke Matsumoto
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, 603-8555, Japan
- Research Center for Protein Dynamics, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, 603-8555, Japan
| | - Toshiya Endo
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, 603-8555, Japan.
- Research Center for Protein Dynamics, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto, 603-8555, Japan.
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13
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Gupta P, Venugopal SK. Augmenter of liver regeneration: A key protein in liver regeneration and pathophysiology. Hepatol Res 2018; 48:587-596. [PMID: 29633440 DOI: 10.1111/hepr.13077] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 03/10/2018] [Accepted: 03/29/2018] [Indexed: 12/22/2022]
Abstract
Liver is constantly exposed to pathogens, viruses, chemicals, and toxins, and several of them cause injury, leading to the loss of liver mass and sometimes resulting in cirrhosis and cancer. Under physiological conditions, liver can regenerate if the loss of cells is less than the proliferation of hepatocytes. If the loss is more than the proliferation, the radical treatment available is liver transplantation. Due to this reason, the search for an alternative therapeutic agent has been the focus of liver research. Liver regeneration is regulated by several growth factors; one of the key factors is augmenter of liver regeneration (ALR). Involvement of ALR has been reported in crucial processes such as oxidative phosphorylation, maintenance of mitochondria and mitochondrial biogenesis, and regulation of autophagy and cell proliferation. Augmenter of liver regeneration has been observed to be involved in liver regeneration by not only overcoming cell cycle inhibition but by maintaining the stem cell pool as well. These observations have created curiosity regarding the possible role of ALR in maintenance of liver health. Thus, this review brings a concise presentation of the work done in areas exploring the role of ALR in normal liver physiology and in liver health maintenance by fighting liver diseases, such as liver failure, non-alcoholic fatty liver disease/non-alcoholic steatohepatitis, viral infections, cirrhosis, and hepatocellular carcinoma.
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Affiliation(s)
- Parul Gupta
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, India
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14
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A single-cysteine mutant and chimeras of essential Leishmania Erv can complement the loss of Erv1 but not of Mia40 in yeast. Redox Biol 2017; 15:363-374. [PMID: 29310075 PMCID: PMC5760468 DOI: 10.1016/j.redox.2017.12.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 12/17/2017] [Accepted: 12/21/2017] [Indexed: 11/21/2022] Open
Abstract
Mia40/CHCHD4 and Erv1/ALR are essential for oxidative protein folding in the mitochondrial intermembrane space of yeast and mammals. In contrast, many protists, including important apicomplexan and kinetoplastid parasites, lack Mia40. Furthermore, the Erv homolog of the model parasite Leishmania tarentolae (LtErv) was shown to be incompatible with Saccharomyces cerevisiae Mia40 (ScMia40). Here we addressed structure-function relationships of ScErv1 and LtErv as well as their compatibility with the oxidative protein folding system in yeast using chimeric, truncated, and mutant Erv constructs. Chimeras between the N-terminal arm of ScErv1 and a variety of truncated LtErv constructs were able to rescue yeast cells that lack ScErv1. Yeast cells were also viable when only a single cysteine residue was replaced in LtErvC17S. Thus, the presence and position of the C-terminal arm and the kinetoplastida-specific second (KISS) domain of LtErv did not interfere with its functionality in the yeast system, whereas a relatively conserved cysteine residue before the flavodomain rendered LtErv incompatible with ScMia40. The question whether parasite Erv homologs might also exert the function of Mia40 was addressed in another set of complementation assays. However, neither the KISS domain nor other truncated or mutant LtErv constructs were able to rescue yeast cells that lack ScMia40. The general relevance of Erv and its candidate substrate small Tim1 was analyzed for the related parasite L. infantum. Repeated unsuccessful knockout attempts suggest that both genes are essential in this human pathogen and underline the potential of mitochondrial protein import pathways for future intervention strategies.
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15
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Abstract
SIGNIFICANCE Glutathione metabolism is comparable to a jigsaw puzzle with too many pieces. It is supposed to comprise (i) the reduction of disulfides, hydroperoxides, sulfenic acids, and nitrosothiols, (ii) the detoxification of aldehydes, xenobiotics, and heavy metals, and (iii) the synthesis of eicosanoids, steroids, and iron-sulfur clusters. In addition, glutathione affects oxidative protein folding and redox signaling. Here, I try to provide an overview on the relevance of glutathione-dependent pathways with an emphasis on quantitative data. Recent Advances: Intracellular redox measurements reveal that the cytosol, the nucleus, and mitochondria contain very little glutathione disulfide and that oxidative challenges are rapidly counterbalanced. Genetic approaches suggest that iron metabolism is the centerpiece of the glutathione puzzle in yeast. Furthermore, recent biochemical studies provide novel insights on glutathione transport processes and uncoupling mechanisms. CRITICAL ISSUES Which parts of the glutathione puzzle are most relevant? Does this explain the high intracellular concentrations of reduced glutathione? How can iron-sulfur cluster biogenesis, oxidative protein folding, or redox signaling occur at high glutathione concentrations? Answers to these questions not only seem to depend on the organism, cell type, and subcellular compartment but also on different ideologies among researchers. FUTURE DIRECTIONS A rational approach to compare the relevance of glutathione-dependent pathways is to combine genetic and quantitative kinetic data. However, there are still many missing pieces and too little is known about the compartment-specific repertoire and concentration of numerous metabolites, substrates, enzymes, and transporters as well as rate constants and enzyme kinetic patterns. Gathering this information might require the development of novel tools but is crucial to address potential kinetic competitions and to decipher uncoupling mechanisms to solve the glutathione puzzle. Antioxid. Redox Signal. 27, 1130-1161.
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Affiliation(s)
- Marcel Deponte
- Department of Parasitology, Ruprecht-Karls University , Heidelberg, Germany
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16
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Peleh V, Zannini F, Backes S, Rouhier N, Herrmann JM. Erv1 of Arabidopsis thaliana can directly oxidize mitochondrial intermembrane space proteins in the absence of redox-active Mia40. BMC Biol 2017; 15:106. [PMID: 29117860 PMCID: PMC5679390 DOI: 10.1186/s12915-017-0445-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/19/2017] [Indexed: 11/20/2022] Open
Abstract
Background Many proteins of the mitochondrial intermembrane space (IMS) contain structural disulfide bonds formed by the mitochondrial disulfide relay. In fungi and animals, the sulfhydryl oxidase Erv1 ‘generates’ disulfide bonds that are passed on to the oxidoreductase Mia40, which oxidizes substrate proteins. A different structural organization of plant Erv1 proteins compared to that of animal and fungal orthologs was proposed to explain its inability to complement the corresponding yeast mutant. Results Herein, we have revisited the biochemical and functional properties of Arabidopsis thaliana Erv1 by both in vitro reconstituted activity assays and complementation of erv1 and mia40 yeast mutants. These mutants were viable, however, they showed severe defects in the biogenesis of IMS proteins. The plant Erv1 was unable to oxidize yeast Mia40 and rather even blocked its activity. Nevertheless, it was able to mediate the import and folding of mitochondrial proteins. Conclusions We observed that plant Erv1, unlike its homologs in fungi and animals, can promote protein import and oxidative protein folding in the IMS independently of the oxidoreductase Mia40. In accordance to the absence of Mia40 in many protists, our study suggests that the mitochondrial disulfide relay evolved in a stepwise reaction from an Erv1-only system to which Mia40 was added in order to improve substrate specificity. The mitochondrial disulfide relay evolved in a step-wise manner from an Erv1-only system. ![]()
Electronic supplementary material The online version of this article (doi:10.1186/s12915-017-0445-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Valentina Peleh
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany
| | - Flavien Zannini
- Unité Mixte de Recherches 1136 Interactions Arbres-Microorganismes, Université de Lorraine/INRA, Faculté des sciences et technologies, 54500 Vandoeuvre-lès-Nancy, Nancy, France
| | - Sandra Backes
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany
| | - Nicolas Rouhier
- Unité Mixte de Recherches 1136 Interactions Arbres-Microorganismes, Université de Lorraine/INRA, Faculté des sciences et technologies, 54500 Vandoeuvre-lès-Nancy, Nancy, France.
| | - Johannes M Herrmann
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany.
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17
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Kang Y, Fielden LF, Stojanovski D. Mitochondrial protein transport in health and disease. Semin Cell Dev Biol 2017; 76:142-153. [PMID: 28765093 DOI: 10.1016/j.semcdb.2017.07.028] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 07/18/2017] [Accepted: 07/19/2017] [Indexed: 01/17/2023]
Abstract
Mitochondria are fundamental structures that fulfil important and diverse functions within cells, including cellular respiration and iron-sulfur cluster biogenesis. Mitochondrial function is reliant on the organelles proteome, which is maintained and adjusted depending on cellular requirements. The majority of mitochondrial proteins are encoded by nuclear genes and must be trafficked to, and imported into the organelle following synthesis in the cytosol. These nuclear-encoded mitochondrial precursors utilise dynamic and multimeric translocation machines to traverse the organelles membranes and be partitioned to the appropriate mitochondrial subcompartment. Yeast model systems have been instrumental in establishing the molecular basis of mitochondrial protein import machines and mechanisms, however unique players and mechanisms are apparent in higher eukaryotes. Here, we review our current knowledge on mitochondrial protein import in human cells and how dysfunction in these pathways can lead to disease.
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Affiliation(s)
- Yilin Kang
- Department of Biochemistry and Molecular Biology and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Laura F Fielden
- Department of Biochemistry and Molecular Biology and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Diana Stojanovski
- Department of Biochemistry and Molecular Biology and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia.
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18
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Go YM, Jones DP. Redox theory of aging: implications for health and disease. Clin Sci (Lond) 2017; 131:1669-1688. [PMID: 28667066 PMCID: PMC5773128 DOI: 10.1042/cs20160897] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/15/2017] [Accepted: 05/18/2017] [Indexed: 02/07/2023]
Abstract
Genetics ultimately defines an individual, yet the phenotype of an adult is extensively determined by the sequence of lifelong exposures, termed the exposome. The redox theory of aging recognizes that animals evolved within an oxygen-rich environment, which created a critical redox interface between an organism and its environment. Advances in redox biology show that redox elements are present throughout metabolic and structural systems and operate as functional networks to support the genome in adaptation to environmental resources and challenges during lifespan. These principles emphasize that physical and functional phenotypes of an adult are determined by gene-environment interactions from early life onward. The principles highlight the critical nature of cumulative exposure memories in defining changes in resilience progressively during life. Both plasma glutathione and cysteine systems become oxidized with aging, and the recent finding that cystine to glutathione ratio in human plasma predicts death in coronary artery disease (CAD) patients suggests this could provide a way to measure resilience of redox networks in aging and disease. The emerging concepts of cumulative gene-environment interactions warrant focused efforts to elucidate central mechanisms by which exposure memory governs health and etiology, onset and progression of disease.
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Affiliation(s)
- Young-Mi Go
- Division of Pulmonary Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, U.S.A
| | - Dean P Jones
- Division of Pulmonary Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, U.S.A.
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19
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Habich M, Riemer J. Detection of Cysteine Redox States in Mitochondrial Proteins in Intact Mammalian Cells. Methods Mol Biol 2017; 1567:105-138. [PMID: 28276016 DOI: 10.1007/978-1-4939-6824-4_8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Import, folding, and activity regulation of mitochondrial proteins are important for mitochondrial function. Cysteine residues play crucial roles in these processes as their thiol groups can undergo (reversible) oxidation reactions. For example, during import of many intermembrane space (IMS) proteins, cysteine oxidation drives protein folding and translocation over the outer membrane. Mature mitochondrial proteins can undergo changes in the redox state of specific cysteine residues, for example, as part of their enzymatic reaction cycle or as adaptations to changes of the local redox environment which might influence their activity. Here we describe methods to study changes in cysteine residue redox states in intact cells. These approaches allow to monitor oxidation-driven protein import as well as changes of cysteine redox states in mature proteins during oxidative stress or during the reaction cycle of thiol-dependent enzymes like oxidoreductases.
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Affiliation(s)
- Markus Habich
- Institute for Biochemistry, University of Cologne, Zuelpicher Str 47a, 50674, Cologne, Germany
| | - Jan Riemer
- Institute for Biochemistry, University of Cologne, Zuelpicher Str 47a, 50674, Cologne, Germany.
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20
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Manganas P, MacPherson L, Tokatlidis K. Oxidative protein biogenesis and redox regulation in the mitochondrial intermembrane space. Cell Tissue Res 2016; 367:43-57. [PMID: 27632163 PMCID: PMC5203823 DOI: 10.1007/s00441-016-2488-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/05/2016] [Indexed: 12/22/2022]
Abstract
Mitochondria are organelles that play a central role in cellular metabolism, as they are responsible for processes such as iron/sulfur cluster biogenesis, respiration and apoptosis. Here, we describe briefly the various protein import pathways for sorting of mitochondrial proteins into the different subcompartments, with an emphasis on the targeting to the intermembrane space. The discovery of a dedicated redox-controlled pathway in the intermembrane space that links protein import to oxidative protein folding raises important questions on the redox regulation of this process. We discuss the salient features of redox regulation in the intermembrane space and how such mechanisms may be linked to the more general redox homeostasis balance that is crucial not only for normal cell physiology but also for cellular dysfunction.
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Affiliation(s)
- Phanee Manganas
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Lisa MacPherson
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Kostas Tokatlidis
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
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21
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Peleh V, Cordat E, Herrmann JM. Mia40 is a trans-site receptor that drives protein import into the mitochondrial intermembrane space by hydrophobic substrate binding. eLife 2016; 5. [PMID: 27343349 PMCID: PMC4951193 DOI: 10.7554/elife.16177] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 06/24/2016] [Indexed: 11/13/2022] Open
Abstract
Many proteins of the mitochondrial IMS contain conserved cysteines that are oxidized to disulfide bonds during their import. The conserved IMS protein Mia40 is essential for the oxidation and import of these proteins. Mia40 consists of two functional elements: an N-terminal cysteine-proline-cysteine motif conferring substrate oxidation, and a C-terminal hydrophobic pocket for substrate binding. In this study, we generated yeast mutants to dissect both Mia40 activities genetically and biochemically. Thereby we show that the substrate-binding domain of Mia40 is both necessary and sufficient to promote protein import, indicating that trapping by Mia40 drives protein translocation. An oxidase-deficient Mia40 mutant is inviable, but can be partially rescued by the addition of the chemical oxidant diamide. Our results indicate that Mia40 predominantly serves as a trans-site receptor of mitochondria that binds incoming proteins via hydrophobic interactions thereby mediating protein translocation across the outer membrane by a ‘holding trap’ rather than a ‘folding trap’ mechanism. DOI:http://dx.doi.org/10.7554/eLife.16177.001 Human, yeast and other eukaryotic cells contain compartments called mitochondria that perform several vital tasks, including supplying the cell with energy. Each mitochondrion is surrounded by an inner and an outer membrane, which are separated by an intermembrane space that contains a host of molecules, including proteins. Intermembrane space proteins are made in the cytosol before being transported into the intermembrane space through pores in the mitochondrion’s outer membrane. Many of these proteins have the ability to form disulfide bonds within their structures, which help the proteins to fold and assemble correctly, but they only acquire these bonds once they have entered the intermembrane space. An enzyme called Mia40 sits inside the intermembrane space and helps other proteins to fold correctly. This Mia40-induced folding had been suggested to help proteins to move into the intermembrane space. Mia40 contains two important regions: one region acts as an enzyme and adds disulfide bonds to other proteins, and the other region binds to the intermembrane space proteins. Peleh et al. have now generated versions of Mia40 that lack one or the other of these regions in yeast cells, and then tested to see if these mutants could drive proteins across the outer membrane of mitochondria. The results show that it is the ability of Mia40 to bind proteins – and not its enzyme activity – that is essential for importing proteins into the intermembrane space. As disulfide bond formation is not critical for importing proteins into the intermembrane space, future studies could test whether Mia40 also helps to transport proteins that cannot form disulfide bonds. Presumably, Mia40 has a much broader relevance for importing mitochondrial proteins than was previously thought. DOI:http://dx.doi.org/10.7554/eLife.16177.002
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Affiliation(s)
- Valentina Peleh
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
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22
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Petrungaro C, Zimmermann KM, Küttner V, Fischer M, Dengjel J, Bogeski I, Riemer J. The Ca(2+)-Dependent Release of the Mia40-Induced MICU1-MICU2 Dimer from MCU Regulates Mitochondrial Ca(2+) Uptake. Cell Metab 2015; 22:721-33. [PMID: 26387864 DOI: 10.1016/j.cmet.2015.08.019] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 05/24/2015] [Accepted: 08/14/2015] [Indexed: 12/13/2022]
Abstract
The essential oxidoreductase Mia40/CHCHD4 mediates disulfide bond formation and protein folding in the mitochondrial intermembrane space. Here, we investigated the interactome of Mia40 thereby revealing links between thiol-oxidation and apoptosis, energy metabolism, and Ca(2+) signaling. Among the interaction partners of Mia40 is MICU1-the regulator of the mitochondrial Ca(2+) uniporter (MCU), which transfers Ca(2+) across the inner membrane. We examined the biogenesis of MICU1 and find that Mia40 introduces an intermolecular disulfide bond that links MICU1 and its inhibitory paralog MICU2 in a heterodimer. Absence of this disulfide bond results in increased receptor-induced mitochondrial Ca(2+) uptake. In the presence of the disulfide bond, MICU1-MICU2 heterodimer binding to MCU is controlled by Ca(2+) levels: the dimer associates with MCU at low levels of Ca(2+) and dissociates upon high Ca(2+) concentrations. Our findings support a model in which mitochondrial Ca(2+) uptake is regulated by a Ca(2+)-dependent remodeling of the uniporter complex.
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Affiliation(s)
- Carmelina Petrungaro
- Cellular Biochemistry, University of Kaiserslautern, Erwin-Schroedinger-Str. 13, 67663 Kaiserslautern, Germany; Institute of Biochemistry, University of Cologne, Zuelpicher Str. 47, 50674 Cologne, Germany
| | - Katharina M Zimmermann
- Department of Biophysics, CIPMM, School of Medicine, University of Saarland, 66421, Homburg, Germany
| | - Victoria Küttner
- Department of Dermatology, Medical Center, Freiburg Institute for Advanced Studies, BIOSS Centre for Biological Signaling Studies, ZBSA Center for Biological Systems Analysis, University of Freiburg, Habsburgerstr. 49, 79104 Freiburg, Germany
| | - Manuel Fischer
- Cellular Biochemistry, University of Kaiserslautern, Erwin-Schroedinger-Str. 13, 67663 Kaiserslautern, Germany
| | - Jörn Dengjel
- Department of Dermatology, Medical Center, Freiburg Institute for Advanced Studies, BIOSS Centre for Biological Signaling Studies, ZBSA Center for Biological Systems Analysis, University of Freiburg, Habsburgerstr. 49, 79104 Freiburg, Germany
| | - Ivan Bogeski
- Department of Biophysics, CIPMM, School of Medicine, University of Saarland, 66421, Homburg, Germany
| | - Jan Riemer
- Cellular Biochemistry, University of Kaiserslautern, Erwin-Schroedinger-Str. 13, 67663 Kaiserslautern, Germany; Institute of Biochemistry, University of Cologne, Zuelpicher Str. 47, 50674 Cologne, Germany.
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23
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Abstract
![]()
Mitochondria are fundamental intracellular organelles with key
roles in important cellular processes like energy production, Fe/S
cluster biogenesis, and homeostasis of lipids and inorganic ions.
Mitochondrial dysfunction is consequently linked to many human pathologies
(cancer, diabetes, neurodegeneration, stroke) and apoptosis. Mitochondrial
biogenesis relies on protein import as most mitochondrial proteins
(about 10–15% of the human proteome) are imported after their
synthesis in the cytosol. Over the last several years many mitochondrial
translocation pathways have been discovered. Among them, the import
pathway that targets proteins to the intermembrane space (IMS) stands
out as it is the only one that couples import to folding and oxidation
and results in the covalent modification of the incoming precursor
that adopt internal disulfide bonds in the process (the MIA pathway).
The discovery of this pathway represented a significant paradigm shift
as it challenged the prevailing dogma that the endoplasmic reticulum
is the only compartment of eukaryotic cells where oxidative folding
can occur. The concept of the oxidative folding pathway was
first proposed
on the basis of folding and import data for the small Tim proteins
that have conserved cysteine motifs and must adopt intramolecular
disulfides after import so that they are retained in the organelle.
The introduction of disulfides in the IMS is catalyzed by Mia40 that
functions as a chaperone inducing their folding. The sulfhydryl oxidase
Erv1 generates the disulfide pairs de novo using either molecular
oxygen or, cytochrome c and other proteins as terminal
electron acceptors that eventually link this folding process to respiration.
The solution NMR structure of Mia40 (and supporting biochemical experiments)
showed that Mia40 is a novel type of disulfide donor whose recognition
capacity for its substrates relies on a hydrophobic binding cleft
found adjacent to a thiol active CPC motif. Targeting of the substrates
to this pathway is guided by a novel type of IMS targeting signal
called ITS or MISS. This consists of only 9 amino acids, found upstream
or downstream of a unique Cys that is primed for docking to Mia40
when the substrate is accommodated in the Mia40 binding cleft. Different
routes exist to complete the folding of the substrates and their final
maturation in the IMS. Identification of new Mia40 substrates (some
even without the requirement of their cysteines) reveals an expanded
chaperone-like activity of this protein in the IMS. New evidence on
the targeting of redox active proteins like thioredoxin, glutaredoxin,
and peroxiredoxin into the IMS suggests the presence of redox-dependent
regulatory mechanisms of the protein folding and import process in
mitochondria. Maintenance of redox balance in mitochondria is crucial
for normal cell physiology and depends on the cross-talk between the
various redox signaling processes and the mitochondrial oxidative
folding pathway.
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Affiliation(s)
- Amelia Mordas
- Institute
of Molecular Cell and Systems Biology, College of Medical Veterinary
and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Kostas Tokatlidis
- Institute
of Molecular Cell and Systems Biology, College of Medical Veterinary
and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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24
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Human mitochondrial MIA40 (CHCHD4) is a component of the Fe-S cluster export machinery. Biochem J 2015; 471:231-41. [PMID: 26275620 DOI: 10.1042/bj20150012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 08/14/2015] [Indexed: 02/07/2023]
Abstract
Mitochondria play an essential role in synthesis and export of iron-sulfur (Fe-S) clusters to other sections of a cell. Although the mechanism of Fe-S cluster synthesis is well elucidated, information on the identity of the proteins involved in the export pathway is limited. The present study identifies hMIA40 (human mitochondrial intermembrane space import and assembly protein 40), also known as CHCHD4 (coiled-coil-helix-coiled-coil-helix domain-containing 4), as a component of the mitochondrial Fe-S cluster export machinery. hMIA40 is an iron-binding protein with the ability to bind iron in vivo and in vitro. hMIA40 harbours CPC (Cys-Pro-Cys) motif-dependent Fe-S clusters that are sensitive to oxidation. Depletion of hMIA40 results in accumulation of iron in mitochondria concomitant with decreases in the activity and stability of Fe-S-containing cytosolic enzymes. Intriguingly, overexpression of either the mitochondrial export component or cytosolic the Fe-S cluster assembly component does not have any effect on the phenotype of hMIA40-depleted cells. Taken together, our results demonstrate an indispensable role for hMIA40 for the export of Fe-S clusters from mitochondria.
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25
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Neal SE, Dabir DV, Tienson HL, Horn DM, Glaeser K, Ogozalek Loo RR, Barrientos A, Koehler CM. Mia40 Protein Serves as an Electron Sink in the Mia40-Erv1 Import Pathway. J Biol Chem 2015; 290:20804-20814. [PMID: 26085103 DOI: 10.1074/jbc.m115.669440] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Indexed: 11/06/2022] Open
Abstract
A redox-regulated import pathway consisting of Mia40 and Erv1 mediates the import of cysteine-rich proteins into the mitochondrial intermembrane space. Mia40 is the oxidoreductase that inserts two disulfide bonds into the substrate simultaneously. However, Mia40 has one redox-active cysteine pair, resulting in ambiguity about how Mia40 accepts numerous electrons during substrate oxidation. In this study, we have addressed the oxidation of Tim13 in vitro and in organello. Reductants such as glutathione and ascorbate inhibited both the oxidation of the substrate Tim13 in vitro and the import of Tim13 and Cmc1 into isolated mitochondria. In addition, a ternary complex consisting of Erv1, Mia40, and substrate, linked by disulfide bonds, was not detected in vitro. Instead, Mia40 accepted six electrons from substrates, and this fully reduced Mia40 was sensitive to protease, indicative of conformational changes in the structure. Mia40 in mitochondria from the erv1-101 mutant was also trapped in a completely reduced state, demonstrating that Mia40 can accept up to six electrons as substrates are imported. Therefore, these studies support that Mia40 functions as an electron sink to facilitate the insertion of two disulfide bonds into substrates.
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Affiliation(s)
- Sonya E Neal
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095
| | - Deepa V Dabir
- Department of Biology, Loyola Marymount University, Los Angeles, California 90045
| | - Heather L Tienson
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095
| | - Darryl M Horn
- Department of Neurology and Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida 33136
| | - Kathrin Glaeser
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095
| | - Rachel R Ogozalek Loo
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095
| | - Antoni Barrientos
- Department of Neurology and Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida 33136
| | - Carla M Koehler
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, UCLA, Los Angeles, California 90095.
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26
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Koch JR, Schmid FX. Mia40 is optimized for function in mitochondrial oxidative protein folding and import. ACS Chem Biol 2014; 9:2049-57. [PMID: 24983157 DOI: 10.1021/cb500408n] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mia40 catalyzes oxidative protein folding in mitochondria. It contains a unique catalytic CPC dithiol flanked by a hydrophobic groove, and unlike other oxidoreductases, it forms long-lived mixed disulfides with substrates. We show that this distinctive property originates neither from particular properties of mitochondrial substrates nor from the CPC motif of Mia40. The catalytic cysteines of Mia40 display unusually low chemical reactivity, as expressed in conventional pK values and reduction potentials. The stability of the mixed disulfide intermediate is coupled energetically with hydrophobic interactions between Mia40 and the substrate. Based on these properties, we suggest a mechanism for Mia40, where the hydrophobic binding site is employed to select a substrate thiol for forming the initial mixed disulfide. Its long lifetime is used to retain partially folded proteins in the mitochondria and to direct folding toward forming the native disulfide bonds.
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Affiliation(s)
- Johanna R. Koch
- Laboratorium
für Biochemie
und Bayreuther Zentrum für Molekulare Biologie, Universität Bayreuth, 95440 Bayreuth, Germany
| | - Franz X. Schmid
- Laboratorium
für Biochemie
und Bayreuther Zentrum für Molekulare Biologie, Universität Bayreuth, 95440 Bayreuth, Germany
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27
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Herrmann JM, Riemer J. Three approaches to one problem: protein folding in the periplasm, the endoplasmic reticulum, and the intermembrane space. Antioxid Redox Signal 2014; 21:438-56. [PMID: 24483706 DOI: 10.1089/ars.2014.5841] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
SIGNIFICANCE The bacterial periplasm, the endoplasmic reticulum (ER), and the intermembrane space (IMS) of mitochondria contain dedicated machineries for the incorporation of disulfide bonds into polypeptides, which cooperate with chaperones, proteases, and assembly factors during protein biogenesis. RECENT ADVANCES The mitochondrial disulfide relay was identified only very recently. The current knowledge of the protein folding machinery of the IMS will be described in detail in this review and compared with the "more established" systems of the periplasm and the ER. CRITICAL ISSUES While the disulfide relays of all three compartments adhere to the same principle, the specific designs and functions of these systems differ considerably. In particular, the cooperation with other folding systems makes the situation in each compartment unique. FUTURE DIRECTIONS The biochemical properties of the oxidation machineries are relatively well understood. However, it still remains largely unclear as to how the quality control systems of "oxidizing" compartments orchestrate the activities of oxidoreductases, chaperones, proteases, and signaling molecules to ensure protein homeostasis.
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Affiliation(s)
- Johannes M Herrmann
- 1 Department of Cell Biology, University of Kaiserslautern , Kaiserslautern, Germany
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28
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Identification and characterization of mitochondrial Mia40 as an iron–sulfur protein. Biochem J 2013; 455:27-35. [DOI: 10.1042/bj20130442] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mia40 is a highly conserved mitochondrial protein playing an essential role during biogenesis of mitochondrial proteins. Here we show that Mia40 is a novel iron–sulfur protein that binds a [2Fe–2S] cluster in a dimer form with its CPC motifs.
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29
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Chatzi A, Sideris DP, Katrakili N, Pozidis C, Tokatlidis K. Biogenesis of yeast Mia40 - uncoupling folding from import and atypical recognition features. FEBS J 2013; 280:4960-9. [PMID: 23937629 DOI: 10.1111/febs.12482] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 08/06/2013] [Accepted: 08/07/2013] [Indexed: 11/28/2022]
Abstract
The discovery of the mitochondrial intermembrane space assembly (MIA) pathway was followed by studies that focused mainly on the typical small substrates of this disulfide relay system and the interactions between its two central partners: the oxidoreductase Mia40 and the FAD-protein Erv1. Recent studies have revealed that more complex proteins utilize this pathway, including Mia40 itself. In the present study, we dissect the Mia40 biogenesis in distinct stages, supporting a kinetically coordinated sequence of events, starting with (a) import and insertion through the Tim23 translocon, followed by (b) folding of the core of imported Mia40 assisted by the endogenous Mia40 and (c) final interaction with Erv1. The interaction with endogenous Mia40 and the subsequent interaction with Erv1 represent kinetically distinguishable steps that rely on completely different determinants. Interaction with Mia40 proceeds very early (within 30 s) and is characterized by no Cys-specificity, an increased tolerance to mutations of the hydrophobic substrate-binding cleft and no apparent dependence on glutathione as a proofreading mechanism. All of these features illustrate a very atypical behaviour for the Mia40 precursor compared to other substrates of the MIA pathway. By contrast, interaction with Erv1 occurs after 5 min of import and relies on a more stringent specificity.
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Affiliation(s)
- Afroditi Chatzi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas (IMBB-FORTH), Heraklion, Greece; Department of Biology, University of Crete, Heraklion, Greece
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30
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Chatzi A, Tokatlidis K. The mitochondrial intermembrane space: a hub for oxidative folding linked to protein biogenesis. Antioxid Redox Signal 2013; 19:54-62. [PMID: 22901034 DOI: 10.1089/ars.2012.4855] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
SIGNIFICANCE The introduction of disulfide bonds in proteins of the mitochondrial intermembrane space (IMS) is fundamental for their folding and assembly. This oxidative folding process depends on the disulfide donor/import receptor Mia40 and the flavin adenine dinucleotide oxidase Erv1 and concerns proteins involved in mitochondrial biogenesis, respiratory complex assembly, and metal transfer. RECENT ADVANCES The recently determined structural basis of the interaction between Mia40 and some substrates provides a framework for the electron transfer process. A possible proofreading role for the cellular reductant glutathione has been proposed, while other studies suggest the association of Mia40 and Erv1 in dynamic multiprotein complexes in the IMS. CRITICAL ISSUES The association of Mia40 with Erv1 and substrates in large multiprotein complexes is critical. Completion of substrate folding by additional disulfide bonds after initial binding to Mia40 remains unclear. Furthermore, a more general role for Mia40 in recognizing substrates targeted to other compartments, or even without specific cysteine motifs, remains an intriguing possibility. FUTURE DIRECTIONS Dissecting a regulatory role of intramitochondrial protein complex organization and small redox-active molecules will be crucial for understanding oxidative folding in the IMS. This should have an impact on the physiology of human cells, as disease-linked mutations of key components of this process have been manifested, and their expression in stem cells appears crucial for development.
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Affiliation(s)
- Afroditi Chatzi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas IMBB-FORTH, Heraklion, Greece
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31
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A small molecule inhibitor of redox-regulated protein translocation into mitochondria. Dev Cell 2013; 25:81-92. [PMID: 23597483 DOI: 10.1016/j.devcel.2013.03.006] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 01/29/2013] [Accepted: 03/06/2013] [Indexed: 01/08/2023]
Abstract
The mitochondrial disulfide relay system of Mia40 and Erv1/ALR facilitates import of the small translocase of the inner membrane (Tim) proteins and cysteine-rich proteins. A chemical screen identified small molecules that inhibit Erv1 oxidase activity, thereby facilitating dissection of the disulfide relay system in yeast and vertebrate mitochondria. One molecule, mitochondrial protein import blockers from the Carla Koehler laboratory (MitoBloCK-6), attenuated the import of Erv1 substrates into yeast mitochondria and inhibited oxidation of Tim13 and Cmc1 in in vitro reconstitution assays. In addition, MitoBloCK-6 revealed an unexpected role for Erv1 in the carrier import pathway, namely transferring substrates from the translocase of the outer membrane complex onto the small Tim complexes. Cardiac development was impaired in MitoBloCK-6-exposed zebrafish embryos. Finally, MitoBloCK-6 induced apoptosis via cytochrome c release in human embryonic stem cells (hESCs) but not in differentiated cells, suggesting an important role for ALR in hESC homeostasis.
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32
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Banci L, Bertini I, Cefaro C, Ciofi-Baffoni S, Gajda K, Felli IC, Gallo A, Pavelkova A, Kallergi E, Andreadaki M, Katrakili N, Pozidis C, Tokatlidis K. An intrinsically disordered domain has a dual function coupled to compartment-dependent redox control. J Mol Biol 2013; 425:594-608. [PMID: 23207295 DOI: 10.1016/j.jmb.2012.11.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Revised: 11/03/2012] [Accepted: 11/25/2012] [Indexed: 11/20/2022]
Abstract
The functional role of unstructured protein domains is an emerging field in the frame of intrinsically disordered proteins. The involvement of intrinsically disordered domains (IDDs) in protein targeting and biogenesis processes in mitochondria is so far not known. Here, we have characterized the structural/dynamic and functional properties of an IDD of the sulfhydryl oxidase ALR (augmenter of liver regeneration) located in the intermembrane space of mitochondria. At variance to the unfolded-to-folded structural transition of several intrinsically disordered proteins, neither substrate recognition events nor redox switch of its shuttle cysteine pair is linked to any such structural change. However, this unstructured domain performs a dual function in two cellular compartments: it acts (i) as a mitochondrial targeting signal in the cytosol and (ii) as a crucial recognition site in the disulfide relay system of intermembrane space. This domain provides an exciting new paradigm for IDDs ensuring two distinct functions that are linked to intracellular organelle targeting.
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Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy.
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33
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Sztolsztener ME, Brewinska A, Guiard B, Chacinska A. Disulfide bond formation: sulfhydryl oxidase ALR controls mitochondrial biogenesis of human MIA40. Traffic 2012. [PMID: 23186364 DOI: 10.1111/tra.12030] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The conserved MIA pathway is responsible for the import and oxidative folding of proteins destined for the intermembrane space of mitochondria. In contrast to a wealth of information obtained from studies with yeast, the function of the MIA pathway in higher eukaryotes has remained enigmatic. Here, we took advantage of the molecular understanding of the MIA pathway in yeast and designed a model of the human MIA pathway. The yeast model for MIA consists of two critical components, the disulfide bond carrier Mia40 and sulfhydryl oxidase Erv1/ALR. Human MIA40 and ALR substituted for their yeast counterparts in the essential function for the oxidative biogenesis of mitochondrial intermembrane space proteins. In addition, the sulfhydryl oxidases ALR/Erv1 were found to be involved in the mitochondrial localization of human MIA40. Furthermore, the defective accumulation of human MIA40 in mitochondria underlies a recently identified disease that is caused by amino acid exchange in ALR. Thus, human ALR is an important factor that controls not only the ability of MIA40 to bind and oxidize protein clients but also the localization of human MIA40 in mitochondria.
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Affiliation(s)
- Malgorzata E Sztolsztener
- International Institute of Molecular and Cell Biology, Laboratory of Mitochondrial Biogenesis Warsaw, 02-109, Poland
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34
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Site-Specific PEGylation of Therapeutic Proteins via Optimization of Both Accessible Reactive Amino Acid Residues and PEG Derivatives. BioDrugs 2012; 26:209-15. [DOI: 10.1007/bf03261880] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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35
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Eckers E, Petrungaro C, Gross D, Riemer J, Hell K, Deponte M. Divergent molecular evolution of the mitochondrial sulfhydryl:cytochrome C oxidoreductase Erv in opisthokonts and parasitic protists. J Biol Chem 2012; 288:2676-88. [PMID: 23233680 DOI: 10.1074/jbc.m112.420745] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mia40 and the sulfhydryl:cytochrome c oxidoreductase Erv1/ALR are essential for oxidative protein import into the mitochondrial intermembrane space in yeast and mammals. Although mitochondrial protein import is functionally conserved in the course of evolution, many organisms seem to lack Mia40. Moreover, except for in organello import studies and in silico analyses, nothing is known about the function and properties of protist Erv homologues. Here we compared Erv homologues from yeast, the kinetoplastid parasite Leishmania tarentolae, and the non-related malaria parasite Plasmodium falciparum. Both parasite proteins have altered cysteine motifs, formed intermolecular disulfide bonds in vitro and in vivo, and could not replace Erv1 from yeast despite successful mitochondrial protein import in vivo. To analyze its enzymatic activity, we established the expression and purification of recombinant full-length L. tarentolae Erv and compared the mechanism with related and non-related flavoproteins. Enzyme assays indeed confirmed an electron transferase activity with equine and yeast cytochrome c, suggesting a conservation of the enzymatic activity in different eukaryotic lineages. However, although Erv and non-related flavoproteins are intriguing examples of convergent molecular evolution resulting in similar enzyme properties, the mechanisms of Erv homologues from parasitic protists and opisthokonts differ significantly. In summary, the Erv-mediated reduction of cytochrome c might be highly conserved throughout evolution despite the apparent absence of Mia40 in many eukaryotes. Nevertheless, the knowledge on mitochondrial protein import in yeast and mammals cannot be generally transferred to all other eukaryotes, and the corresponding pathways, components, and mechanisms remain to be analyzed.
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Affiliation(s)
- Elisabeth Eckers
- Department of Parasitology, Ruprecht-Karls University, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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36
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Bourens M, Dabir DV, Tienson HL, Sorokina I, Koehler CM, Barrientos A. Role of twin Cys-Xaa9-Cys motif cysteines in mitochondrial import of the cytochrome C oxidase biogenesis factor Cmc1. J Biol Chem 2012; 287:31258-69. [PMID: 22767599 PMCID: PMC3438957 DOI: 10.1074/jbc.m112.383562] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 07/02/2012] [Indexed: 11/06/2022] Open
Abstract
The Mia40 import pathway facilitates the import and oxidative folding of cysteine-rich protein substrates into the mitochondrial intermembrane space. Here we describe the in vitro and in organello oxidative folding of Cmc1, a twin CX(9)C-containing substrate, which contains an unpaired cysteine. In vitro, Cmc1 can be oxidized by the import receptor Mia40 alone when in excess or at a lower rate by only the sulfhydryl oxidase Erv1. However, physiological and efficient Cmc1 oxidation requires Erv1 and Mia40. Cmc1 forms a stable intermediate with Mia40 and is released from this interaction in the presence of Erv1. The three proteins are shown to form a ternary complex in mitochondria. Our results suggest that this mechanism facilitates efficient formation of multiple disulfides and prevents the formation of non-native disulfide bonds.
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Affiliation(s)
- Myriam Bourens
- Neurology, University of Miami Miller School of Medicine, Miami, Florida 33136
| | - Deepa V. Dabir
- the Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, and
| | - Heather L. Tienson
- the Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, and
| | | | - Carla M. Koehler
- the Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, and
| | - Antoni Barrientos
- From the Departments of Biochemistry & Molecular Biology and
- Neurology, University of Miami Miller School of Medicine, Miami, Florida 33136
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37
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Böttinger L, Gornicka A, Czerwik T, Bragoszewski P, Loniewska-Lwowska A, Schulze-Specking A, Truscott KN, Guiard B, Milenkovic D, Chacinska A. In vivo evidence for cooperation of Mia40 and Erv1 in the oxidation of mitochondrial proteins. Mol Biol Cell 2012; 23:3957-69. [PMID: 22918950 PMCID: PMC3469512 DOI: 10.1091/mbc.e12-05-0358] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The intermembrane space of mitochondria accommodates the essential mitochondrial intermembrane space assembly (MIA) machinery that catalyzes oxidative folding of proteins. The disulfide bond formation pathway is based on a relay of reactions involving disulfide transfer from the sulfhydryl oxidase Erv1 to Mia40 and from Mia40 to substrate proteins. However, the substrates of the MIA typically contain two disulfide bonds. It was unclear what the mechanisms are that ensure that proteins are released from Mia40 in a fully oxidized form. In this work, we dissect the stage of the oxidative folding relay, in which Mia40 binds to its substrate. We identify dynamics of the Mia40-substrate intermediate complex. Our experiments performed in a native environment, both in organello and in vivo, show that Erv1 directly participates in Mia40-substrate complex dynamics by forming a ternary complex. Thus Mia40 in cooperation with Erv1 promotes the formation of two disulfide bonds in the substrate protein, ensuring the efficiency of oxidative folding in the intermembrane space of mitochondria.
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Affiliation(s)
- Lena Böttinger
- Institut für Biochemie und Molekularbiologie, Zentrum für Biochemie und Molekulare Zellforschung, 79104 Freiburg, Germany
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38
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Cytosolic thioredoxin system facilitates the import of mitochondrial small Tim proteins. EMBO Rep 2012; 13:916-22. [PMID: 22878414 DOI: 10.1038/embor.2012.116] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Revised: 07/05/2012] [Accepted: 07/13/2012] [Indexed: 11/08/2022] Open
Abstract
Thiol-disulphide redox regulation has a key role during the biogenesis of mitochondrial intermembrane space (IMS) proteins. Only the Cys-reduced form of precursor proteins can be imported into mitochondria, which is followed by disulphide bond formation in the mitochondrial IMS. In contrast to the wealth of knowledge on the oxidation process inside mitochondria, little is known about how precursors are maintained in an import-competent form in the cytosol. Here we provide the first evidence that the cytosolic thioredoxin system is required to maintain the IMS small Tim proteins in reduced forms and facilitate their mitochondrial import during respiratory growth.
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39
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Zhang C, Yang XL, Yuan YH, Pu J, Liao F. Site-specific PEGylation of therapeutic proteins via optimization of both accessible reactive amino acid residues and PEG derivatives. BioDrugs 2012. [PMID: 22721556 DOI: 10.2165/11633350-000000000-00000] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Modification of accessible amino acid residues with poly(ethylene glycol) [PEG] is a widely used technique for formulating therapeutic proteins. In practice, site-specific PEGylation of all selected/engineered accessible nonessential reactive residues of therapeutic proteins with common activated PEG derivatives is a promising strategy to concomitantly improve pharmacokinetics, allow retention of activity, alleviate immunogenicity, and avoid modification isomers. Specifically, through molecular engineering of a therapeutic protein, accessible essential residues reactive to an activated PEG derivative are substituted with unreactive residues provided that protein activity is retained, and a limited number of accessible nonessential reactive residues with optimized distributions are selected/introduced. Subsequently, all accessible nonessential reactive residues are completely PEGylated with the activated PEG derivative in great excess. Branched PEG derivatives containing new PEG chains with negligible metabolic toxicity are more desirable for site-specific PEGylation. Accordingly, for the successful formulation of therapeutic proteins, optimization of the number and distributions of accessible nonessential reactive residues via molecular engineering can be integrated with the design of large-sized PEG derivatives to achieve site-specific PEGylation of all selected/engineered accessible reactive residues.
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Affiliation(s)
- Chun Zhang
- Unit for Analytical Probes and Protein Biotechnology, Key Laboratory of Medical Laboratory Diagnostics of the Education Ministry, College of Laboratory Medicine, Chongqing Medical University, China
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40
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Banci L, Bertini I, Ciofi-Baffoni S, Jaiswal D, Neri S, Peruzzini R, Winkelmann J. Structural characterization of CHCHD5 and CHCHD7: two atypical human twin CX9C proteins. J Struct Biol 2012; 180:190-200. [PMID: 22842048 DOI: 10.1016/j.jsb.2012.07.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 07/05/2012] [Accepted: 07/16/2012] [Indexed: 11/18/2022]
Abstract
Twin CX(9)C proteins constitute a large protein family among all eukaryotes; are putative substrates of the mitochondrial Mia40-dependent import machinery; contain a coiled coil-helix-coiled coil-helix (CHCH) fold stabilized by two disulfide bonds as exemplified by three structures available for this family. However, they considerably differ at the primary sequence level and this prevents an accurate prediction of their structural models. With the aim of expanding structural information on CHCH proteins, here we structurally characterized human CHCHD5 and CHCHD7. While CHCHD5 has two weakly interacting CHCH domains which sample a range of limited conformations as a consequence of hydrophobic interactions, CHCHD7 has a third helix hydrophobically interacting with an extension of helix α2, which is part of the CHCH domain. Upon reduction of the disulfide bonds both proteins become unstructured exposing hydrophobic patches, with the result of protein aggregation/precipitation. These results suggest a model where the molecular interactions guiding the protein recognition between Mia40 and the disulfide-reduced CHCHD5 and CHCHD7 substrates occurs in vivo when the latter proteins are partially embedded in the protein import pore of the outer membrane of mitochondria.
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Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy.
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41
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Dudek J, Rehling P, van der Laan M. Mitochondrial protein import: common principles and physiological networks. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:274-85. [PMID: 22683763 DOI: 10.1016/j.bbamcr.2012.05.028] [Citation(s) in RCA: 186] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 05/24/2012] [Accepted: 05/28/2012] [Indexed: 11/28/2022]
Abstract
Most mitochondrial proteins are encoded in the nucleus. They are synthesized as precursor forms in the cytosol and must be imported into mitochondria with the help of different protein translocases. Distinct import signals within precursors direct each protein to the mitochondrial surface and subsequently onto specific transport routes to its final destination within these organelles. In this review we highlight common principles of mitochondrial protein import and address different mechanisms of protein integration into mitochondrial membranes. Over the last years it has become clear that mitochondrial protein translocases are not independently operating units, but in fact closely cooperate with each other. We discuss recent studies that indicate how the pathways for mitochondrial protein biogenesis are embedded into a functional network of various other physiological processes, such as energy metabolism, signal transduction, and maintenance of mitochondrial morphology. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.
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Affiliation(s)
- Jan Dudek
- Abteilung Biochemie II, Universität Göttingen, 37073 Göttingen, Germany
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42
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Stojanovski D, Bragoszewski P, Chacinska A. The MIA pathway: a tight bond between protein transport and oxidative folding in mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1142-50. [PMID: 22579494 DOI: 10.1016/j.bbamcr.2012.04.014] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 04/25/2012] [Accepted: 04/26/2012] [Indexed: 11/29/2022]
Abstract
Many newly synthesized proteins obtain disulfide bonds in the bacterial periplasm, the endoplasmic reticulum (ER) and the mitochondrial intermembrane space. The acquisition of disulfide bonds is critical for the folding, assembly and activity of these proteins. Spontaneous oxidation of thiol groups is inefficient in vivo, therefore cells have developed machineries that catalyse the oxidation of substrate proteins. The identification of the machinery that mediates this process in the intermembrane space of mitochondria, known as MIA (mitochondrial intermembrane space assembly), provided a unique mechanism of protein transport. The MIA machinery introduces disulfide bonds into incoming intermembrane space precursors and thus tightly couples the process of precursor translocation to precursor oxidation. We discuss our current understanding of the MIA pathway and the mechanisms that oversee thiol-exchange reactions in mitochondria.
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Affiliation(s)
- Diana Stojanovski
- La Trobe Institute for Molecular Sciences, 3086 Melbourne, Australia
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43
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Banci L, Bertini I, Calderone V, Cefaro C, Ciofi-Baffoni S, Gallo A, Tokatlidis K. An Electron-Transfer Path through an Extended Disulfide Relay System: The Case of the Redox Protein ALR. J Am Chem Soc 2012; 134:1442-5. [DOI: 10.1021/ja209881f] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center, University of Florence, via L. Sacconi 6, Sesto Fiorentino,
Italy
- Department of Chemistry, University of Florence, via della Lastruccia 3, Sesto
Fiorentino, Italy
| | - Ivano Bertini
- Magnetic Resonance Center, University of Florence, via L. Sacconi 6, Sesto Fiorentino,
Italy
- Department of Chemistry, University of Florence, via della Lastruccia 3, Sesto
Fiorentino, Italy
| | - Vito Calderone
- Magnetic Resonance Center, University of Florence, via L. Sacconi 6, Sesto Fiorentino,
Italy
- Department of Chemistry, University of Florence, via della Lastruccia 3, Sesto
Fiorentino, Italy
| | - Chiara Cefaro
- Magnetic Resonance Center, University of Florence, via L. Sacconi 6, Sesto Fiorentino,
Italy
- Department of Chemistry, University of Florence, via della Lastruccia 3, Sesto
Fiorentino, Italy
| | - Simone Ciofi-Baffoni
- Magnetic Resonance Center, University of Florence, via L. Sacconi 6, Sesto Fiorentino,
Italy
- Department of Chemistry, University of Florence, via della Lastruccia 3, Sesto
Fiorentino, Italy
| | - Angelo Gallo
- Magnetic Resonance Center, University of Florence, via L. Sacconi 6, Sesto Fiorentino,
Italy
- Department of Chemistry, University of Florence, via della Lastruccia 3, Sesto
Fiorentino, Italy
| | - Kostas Tokatlidis
- Institute
of Molecular Biology
and Biotechnology, Foundation for Research and Technology Hellas, Heraklion 70013, Crete, Greece
- Department of Materials Science
and Technology, University of Crete, Heraklion
71003, Crete, Greece
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44
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Abstract
Depending on the organism, mitochondria consist approximately of 500-1,400 different proteins. By far most of these proteins are encoded by nuclear genes and synthesized on cytosolic ribosomes. Targeting signals direct these proteins into mitochondria and there to their respective subcompartment: the outer membrane, the intermembrane space (IMS), the inner membrane, and the matrix. Membrane-embedded translocation complexes allow the translocation of proteins across and, in the case of membrane proteins, the insertion into mitochondrial membranes. A small number of proteins are encoded by the mitochondrial genome: Most mitochondrial translation products represent hydrophobic proteins of the inner membrane which-together with many nuclear-encoded proteins-form the respiratory chain complexes. This chapter gives an overview on the mitochondrial protein translocases and the mechanisms by which they drive the transport and assembly of mitochondrial proteins.
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45
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Gross DP, Burgard CA, Reddehase S, Leitch JM, Culotta VC, Hell K. Mitochondrial Ccs1 contains a structural disulfide bond crucial for the import of this unconventional substrate by the disulfide relay system. Mol Biol Cell 2011; 22:3758-67. [PMID: 21865601 PMCID: PMC3192856 DOI: 10.1091/mbc.e11-04-0296] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The Mia40/Erv1 disulfide relay system forms a structural disulfide bond in Ccs1, an unconventional substrate of this system. Thereby it promotes import of Ccs1 into mitochondria and controls its cellular distribution. Thus this system is unexpectedly able to form single disulfide bonds in complex multidomain proteins. The copper chaperone for superoxide dismutase 1 (Ccs1) provides an important cellular function against oxidative stress. Ccs1 is present in the cytosol and in the intermembrane space (IMS) of mitochondria. Its import into the IMS depends on the Mia40/Erv1 disulfide relay system, although Ccs1 is, in contrast to typical substrates, a multidomain protein and lacks twin CxnC motifs. We report on the molecular mechanism of the mitochondrial import of Saccharomyces cerevisiae Ccs1 as the first member of a novel class of unconventional substrates of the disulfide relay system. We show that the mitochondrial form of Ccs1 contains a stable disulfide bond between cysteine residues C27 and C64. In the absence of these cysteines, the levels of Ccs1 and Sod1 in mitochondria are strongly reduced. Furthermore, C64 of Ccs1 is required for formation of a Ccs1 disulfide intermediate with Mia40. We conclude that the Mia40/Erv1 disulfide relay system introduces a structural disulfide bond in Ccs1 between the cysteine residues C27 and C64, thereby promoting mitochondrial import of this unconventional substrate. Thus the disulfide relay system is able to form, in addition to double disulfide bonds in twin CxnC motifs, single structural disulfide bonds in complex protein domains.
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Affiliation(s)
- Dominik P Gross
- Adolf-Butenandt-Institut, Lehrstuhl für Physiologische Chemie, Ludwig-Maximilians-Universität München, 81377 München, Germany
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46
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Banci L, Bertini I, Cefaro C, Ciofi-Baffoni S, Gallo A. Functional role of two interhelical disulfide bonds in human Cox17 protein from a structural perspective. J Biol Chem 2011; 286:34382-90. [PMID: 21816817 DOI: 10.1074/jbc.m111.246223] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human Cox17 is the mitochondrial copper chaperone responsible for supplying copper ions, through the assistance of Sco1, Sco2, and Cox11, to cytochrome c oxidase, the terminal enzyme of the mitochondrial energy-transducing respiratory chain. It consists of a coiled coil-helix-coiled coil-helix domain stabilized by two disulfide bonds and binds one copper(I) ion through a Cys-Cys motif. Here, the structures and the backbone mobilities of two Cox17 mutated forms with only one interhelical disulfide bond have been analyzed. It appears that the inner disulfide bond (formed by Cys-36 and Cys-45) stabilizes interhelical hydrophobic interactions, providing a structure with essentially the same structural dynamic properties of the mature Cox17 state. On the contrary, the external disulfide bond (formed by Cys-26 and Cys-55) generates a conformationally flexible α-helical protein, indicating that it is not able to stabilize interhelical packing contacts, but is important for structurally organizing the copper-binding site region.
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Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center Centro Risonanze Magnetiche and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy
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Martínez-Fábregas J, Rubio S, Díaz-Quintana A, Díaz-Moreno I, De la Rosa MÁ. Proteomic tools for the analysis of transient interactions between metalloproteins. FEBS J 2011; 278:1401-10. [PMID: 21352492 DOI: 10.1111/j.1742-4658.2011.08061.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Metalloproteins play major roles in cell metabolism and signalling pathways. In many cases, they show moonlighting behaviour, acting in different processes, depending on the physiological state of the cell. To understand these multitasking proteins, we need to discover the partners with which they carry out such novel functions. Although many technological and methodological tools have recently been reported for the detection of protein interactions, specific approaches to studying the interactions involving metalloproteins are not yet well developed. The task is even more challenging for metalloproteins, because they often form short-lived complexes that are difficult to detect. In this review, we gather the different proteomic techniques and biointeractomic tools reported in the literature. All of them have shown their applicability to the study of transient and weak protein-protein interactions, and are therefore suitable for metalloprotein interactions.
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Affiliation(s)
- Jonathan Martínez-Fábregas
- Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla-CSIC, Centro de Investigaciones Científicas Isla de la Cartuja, Sevilla, Spain
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48
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Oxidation-driven protein import into mitochondria: Insights and blind spots. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:981-9. [DOI: 10.1016/j.bbamem.2010.06.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 05/31/2010] [Accepted: 06/02/2010] [Indexed: 11/21/2022]
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49
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Zhang N, Bilsland E. Contributions of Saccharomyces cerevisiae to understanding mammalian gene function and therapy. Methods Mol Biol 2011; 759:501-523. [PMID: 21863505 DOI: 10.1007/978-1-61779-173-4_28] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Due to its genetic tractability and ease of manipulation, the yeast Saccharomyces cerevisiae has been extensively used as a model organism to understand how eukaryotic cells grow, divide, and respond to environmental changes. In this chapter, we reasoned that functional annotation of novel genes revealed by sequencing should adopt an integrative approach including both bioinformatics and experimental analysis to reveal functional conservation and divergence of complexes and pathways. The techniques and resources generated for systems biology studies in yeast have found a wide range of applications. Here we focused on using these technologies in revealing functions of genes from mammals, in identifying targets of novel and known drugs and in screening drugs targeting specific proteins and/or protein-protein interactions.
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Affiliation(s)
- Nianshu Zhang
- Department of Biochemistry, Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK.
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50
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Molecular chaperone function of Mia40 triggers consecutive induced folding steps of the substrate in mitochondrial protein import. Proc Natl Acad Sci U S A 2010; 107:20190-5. [PMID: 21059946 DOI: 10.1073/pnas.1010095107] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Several proteins of the mitochondrial intermembrane space are targeted by internal targeting signals. A class of such proteins with α-helical hairpin structure bridged by two intramolecular disulfides is trapped by a Mia40-dependent oxidative process. Here, we describe the oxidative folding mechanism underpinning this process by an exhaustive structural characterization of the protein in all stages and as a complex with Mia40. Two consecutive induced folding steps are at the basis of the protein-trapping process. In the first one, Mia40 functions as a molecular chaperone assisting α-helical folding of the internal targeting signal of the substrate. Subsequently, in a Mia40-independent manner, folding of the second substrate helix is induced by the folded targeting signal functioning as a folding scaffold. The Mia40-induced folding pathway provides a proof of principle for the general concept that internal targeting signals may operate as a folding nucleus upon compartment-specific activation.
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