51
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A Perspective on Transport of Proteins into Mitochondria: A Myriad of Open Questions. J Mol Biol 2015; 427:1135-58. [DOI: 10.1016/j.jmb.2015.02.001] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 01/30/2015] [Accepted: 02/02/2015] [Indexed: 11/22/2022]
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Gandhi CR, Chaillet JR, Nalesnik MA, Kumar S, Dangi A, Demetris AJ, Ferrell R, Wu T, Divanovic S, Stankeiwicz T, Shaffer B, Stolz DB, Harvey SAK, Wang J, Starzl TE. Liver-specific deletion of augmenter of liver regeneration accelerates development of steatohepatitis and hepatocellular carcinoma in mice. Gastroenterology 2015; 148:379-391.e4. [PMID: 25448926 PMCID: PMC4802363 DOI: 10.1053/j.gastro.2014.10.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 10/06/2014] [Accepted: 10/07/2014] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS Augmenter of liver regeneration (ALR, encoded by GFER) is a widely distributed pleiotropic protein originally identified as a hepatic growth factor. However, little is known about its roles in hepatic physiology and pathology. We created mice with liver-specific deletion of ALR to study its function. METHODS We developed mice with liver-specific deletion of ALR (ALR-L-KO) using the albumin-Cre/LoxP system. Liver tissues were collected from ALR-L-KO mice and ALR(floxed/floxed) mice (controls) and analyzed by histology, reverse-transcription polymerase chain reaction, immunohistochemistry, electron microscopy, and techniques to measure fibrosis and lipids. Liver tissues from patients with and without advanced liver disease were determined by immunoblot analysis. RESULTS Two weeks after birth, livers of ALR-L-KO mice contained low levels of ALR and adenosine triphosphate (ATP); they had reduced mitochondrial respiratory function and increased oxidative stress, compared with livers from control mice, and had excessive steatosis, and hepatocyte apoptosis. Levels of carbamyl-palmitoyl transferase 1a and ATP synthase subunit ATP5G1 were reduced in livers of ALR-L-KO mice, indicating defects in mitochondrial fatty acid transport and ATP synthesis. Electron microscopy showed mitochondrial swelling with abnormalities in shapes and numbers of cristae. From weeks 2-4 after birth, levels of steatosis and apoptosis decreased in ALR-L-KO mice, and numbers of ALR-expressing cells increased, along with ATP levels. However, at weeks 4-8 after birth, livers became inflamed, with hepatocellular necrosis, ductular proliferation, and fibrosis; hepatocellular carcinoma developed by 1 year after birth in nearly 60% of the mice. Hepatic levels of ALR were also low in ob/ob mice and alcohol-fed mice with liver steatosis, compared with controls. Levels of ALR were lower in liver tissues from patients with advanced alcoholic liver disease and nonalcoholic steatohepatitis than in control liver tissues. CONCLUSIONS We developed mice with liver-specific deletion of ALR, and showed that it is required for mitochondrial function and lipid homeostasis in the liver. ALR-L-KO mice provide a useful model for investigating the pathogenesis of steatohepatitis and its complications.
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Affiliation(s)
- Chandrashekhar R Gandhi
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Surgery, University of Cincinnati, Cincinnati, Ohio; Cincinnati VA Medical Center, Cincinnati, Ohio; Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh, Pennsylvania.
| | - J Richard Chaillet
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pennsylvania
| | - Michael A Nalesnik
- Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh, Pennsylvania; Department of Pathology, University of Pittsburgh, Pennsylvania
| | - Sudhir Kumar
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Anil Dangi
- Department of Surgery, University of Cincinnati, Cincinnati, Ohio; Cincinnati VA Medical Center, Cincinnati, Ohio
| | - A Jake Demetris
- Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh, Pennsylvania; Department of Pathology, University of Pittsburgh, Pennsylvania
| | - Robert Ferrell
- School of Public Health, University of Pittsburgh, Pennsylvania
| | - Tong Wu
- Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana
| | - Senad Divanovic
- Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Traci Stankeiwicz
- Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Benjamin Shaffer
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pennsylvania
| | - Donna B Stolz
- Department of Cell Biology, University of Pittsburgh, Pennsylvania
| | | | - Jiang Wang
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Thomas E Starzl
- Thomas E. Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh, Pennsylvania
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Bölter B, Soll J, Schwenkert S. Redox meets protein trafficking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:949-56. [PMID: 25626173 DOI: 10.1016/j.bbabio.2015.01.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 01/16/2015] [Accepted: 01/19/2015] [Indexed: 11/15/2022]
Abstract
After the engulfment of two prokaryotic organisms, the thus emerged eukaryotic cell needed to establish means of communication and signaling to properly integrate the acquired organelles into its metabolism. Regulatory mechanisms had to evolve to ensure that chloroplasts and mitochondria smoothly function in accordance with all other cellular processes. One essential process is the post-translational import of nuclear encoded organellar proteins, which needs to be adapted according to the requirements of the plant. The demand for protein import is constantly changing depending on varying environmental conditions, as well as external and internal stimuli or different developmental stages. Apart from long-term regulatory mechanisms such as transcriptional/translation control, possibilities for short-term acclimation are mandatory. To this end, protein import is integrated into the cellular redox network, utilizing the recognition of signals from within the organelles and modifying the efficiency of the translocon complexes. Thereby, cellular requirements can be communicated throughout the whole organism. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Affiliation(s)
- Bettina Bölter
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany
| | - Jürgen Soll
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany.
| | - Serena Schwenkert
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany
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Gornicka A, Bragoszewski P, Chroscicki P, Wenz LS, Schulz C, Rehling P, Chacinska A. A discrete pathway for the transfer of intermembrane space proteins across the outer membrane of mitochondria. Mol Biol Cell 2014; 25:3999-4009. [PMID: 25318675 PMCID: PMC4263444 DOI: 10.1091/mbc.e14-06-1155] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The TOM translocase serves as a portal for proteins destined to the mitochondrial membranes and matrix. This study determines how proteins targeted to the MIA pathway arrive in the intermembrane space. A different mode of the transport across the outer membrane for intermembrane space proteins with the help of Tom40 is postulated. Mitochondrial proteins are synthesized on cytosolic ribosomes and imported into mitochondria with the help of protein translocases. For the majority of precursor proteins, the role of the translocase of the outer membrane (TOM) and mechanisms of their transport across the outer mitochondrial membrane are well recognized. However, little is known about the mode of membrane translocation for proteins that are targeted to the intermembrane space via the redox-driven mitochondrial intermembrane space import and assembly (MIA) pathway. On the basis of the results obtained from an in organello competition import assay, we hypothesized that MIA-dependent precursor proteins use an alternative pathway to cross the outer mitochondrial membrane. Here we demonstrate that this alternative pathway involves the protein channel formed by Tom40. We sought a translocation intermediate by expressing tagged versions of MIA-dependent proteins in vivo. We identified a transient interaction between our model substrates and Tom40. Of interest, outer membrane translocation did not directly involve other core components of the TOM complex, including Tom22. Thus MIA-dependent proteins take another route across the outer mitochondrial membrane that involves Tom40 in a form that is different from the canonical TOM complex.
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Affiliation(s)
- Agnieszka Gornicka
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Piotr Bragoszewski
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Piotr Chroscicki
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
| | - Lena-Sophie Wenz
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, D-79104 Freiburg, Germany
| | - Christian Schulz
- Department of Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany
| | - Peter Rehling
- Department of Cellular Biochemistry, University Medical Center Göttingen, D-37073 Göttingen, Germany
| | - Agnieszka Chacinska
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
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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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Mitochondrial thiol oxidase Erv1: both shuttle cysteine residues are required for its function with distinct roles. Biochem J 2014; 460:199-210. [PMID: 24625320 PMCID: PMC4019985 DOI: 10.1042/bj20131540] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Erv1 (essential for respiration and viability 1), is an essential component of the MIA (mitochondrial import and assembly) pathway, playing an important role in the oxidative folding of mitochondrial intermembrane space proteins. In the MIA pathway, Mia40, a thiol oxidoreductase with a CPC motif at its active site, oxidizes newly imported substrate proteins. Erv1 a FAD-dependent thiol oxidase, in turn reoxidizes Mia40 via its N-terminal Cys30–Cys33 shuttle disulfide. However, it is unclear how the two shuttle cysteine residues of Erv1 relay electrons from the Mia40 CPC motif to the Erv1 active-site Cys130–Cys133 disulfide. In the present study, using yeast genetic approaches we showed that both shuttle cysteine residues of Erv1 are required for cell growth. In organelle and in vitro studies confirmed that both shuttle cysteine residues were indeed required for import of MIA pathway substrates and Erv1 enzyme function to oxidize Mia40. Furthermore, our results revealed that the two shuttle cysteine residues of Erv1 are functionally distinct. Although Cys33 is essential for forming the intermediate disulfide Cys33–Cys130′ and transferring electrons to the redox active-site directly, Cys30 plays two important roles: (i) dominantly interacts and receives electrons from the Mia40 CPC motif; and (ii) resolves the Erv1 Cys33–Cys130 intermediate disulfide. Taken together, we conclude that both shuttle cysteine residues are required for Erv1 function, and play complementary, but distinct, roles to ensure rapid turnover of active Erv1. Erv1 is a sulfydryl oxidase, an essential component of mitochondrial MIA pathway. The present study shows that both shuttle cysteine residues of Erv1 are required for its function, they play complementary, but distinct, roles to ensure rapid turnover of active enzyme.
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Schaefer-Ramadan S, Thorpe C, Rozovsky S. Site-specific insertion of selenium into the redox-active disulfide of the flavoprotein augmenter of liver regeneration. Arch Biochem Biophys 2014; 548:60-5. [PMID: 24582598 PMCID: PMC4009370 DOI: 10.1016/j.abb.2014.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 01/29/2014] [Accepted: 02/03/2014] [Indexed: 11/23/2022]
Abstract
Augmenter of liver regeneration (sfALR) is a small disulfide-bridged homodimeric flavoprotein with sulfhydryl oxidase activity. Here, we investigate the catalytic and spectroscopic consequences of selectively replacing C145 by a selenocysteine to complement earlier studies in which random substitution of ∼90% of the 6 cysteine residues per sfALR monomer was achieved growing Escherichia coli on selenite. A selenocysteine insertion sequence (SECIS) element was installed within the gene for human sfALR. SecALR2 showed a spectrum comparable to that of wild-type sfALR. The catalytic efficiency of SecALR2 towards dithiothreitol was 6.8-fold lower than a corresponding construct in which position 145 was returned to a cysteine residue while retaining the additional mutations introduced with the SECIS element. This all-cysteine control enzyme formed a mixed disulfide between C142 and β-mercaptoethanol releasing C145 to form a thiolate-flavin charge transfer absorbance band at ∼530nm. In contrast, SecALR2 showed a prominent long-wavelength absorbance at 585 nm consistent with the expectation that a selenolate would be a better charge-transfer donor to the isoalloxazine ring. These data show the robustness of the ALR protein fold towards the multiple mutations required to insert the SECIS element and provide the first example of a selenolate to flavin charge-transfer complex.
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Affiliation(s)
| | - Colin Thorpe
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Sharon Rozovsky
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States.
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The mitochondrial disulfide relay system: roles in oxidative protein folding and beyond. Int J Cell Biol 2013; 2013:742923. [PMID: 24348563 PMCID: PMC3848088 DOI: 10.1155/2013/742923] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 10/01/2013] [Indexed: 12/31/2022] Open
Abstract
Disulfide bond formation drives protein import of most proteins of the mitochondrial intermembrane space (IMS). The main components of this disulfide relay machinery are the oxidoreductase Mia40 and the sulfhydryl oxidase Erv1/ALR. Their precise functions have been elucidated in molecular detail for the yeast and human enzymes in vitro and in intact cells. However, we still lack knowledge on how Mia40 and Erv1/ALR impact cellular and organism physiology and whether they have functions beyond their role in disulfide bond formation. Here we summarize the principles of oxidation-dependent protein import mediated by the mitochondrial disulfide relay. We proceed by discussing recently described functions of Mia40 in the hypoxia response and of ALR in influencing mitochondrial morphology and its importance for tissue development and embryogenesis. We also include a discussion of the still mysterious function of Erv1/ALR in liver regeneration.
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59
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Schaefer-Ramadan S, Gannon SA, Thorpe C. Human augmenter of liver regeneration: probing the catalytic mechanism of a flavin-dependent sulfhydryl oxidase. Biochemistry 2013; 52:8323-32. [PMID: 24147449 DOI: 10.1021/bi401305w] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Augmenter of liver regeneration is a member of the ERV family of small flavin-dependent sulfhydryl oxidases that contain a redox-active CxxC disulfide bond in redox communication with the isoalloxazine ring of bound FAD. These enzymes catalyze the oxidation of thiol substrates with the reduction of molecular oxygen to hydrogen peroxide. This work studies the catalytic mechanism of the short, cytokine form of augmenter of liver regeneration (sfALR) using model thiol substrates of the enzyme. The redox potential of the proximal disulfide in sfALR was found to be approximately 57 mV more reducing than the flavin chromophore, in agreement with titration experiments. Rapid reaction studies show that dithiothreitol (DTT) generates a transient mixed disulfide intermediate with sfALR signaled by a weak charge-transfer interaction between the thiolate of C145 and the oxidized flavin. The subsequent transfer of reducing equivalents to the flavin ring is relatively slow, with a limiting apparent rate constant of 12.4 s(-1). However, reoxidation of the reduced flavin by molecular oxygen is even slower (2.3 s(-1) at air saturation) and thus largely limits turnover at 5 mM DTT. The nature of the charge-transfer complexes observed with DTT was explored using a range of simple monothiols to mimic the initial nucleophilic attack on the proximal disulfide. While β-mercaptoethanol is a very poor substrate of sfALR (∼0.3 min(-1) at 100 mM thiol), it rapidly generates a mixed disulfide intermediate allowing the thiolate of C145 to form a strong charge-transfer complex with the flavin. Unlike the other monothiols tested, glutathione is unable to form charge-transfer complexes and is an undetectable substrate of the oxidase. These data are rationalized on the basis of the stringent steric requirements for thiol-disulfide exchange reactions. The inability of the relatively bulky glutathione to attain the in-line geometry required for efficient disulfide exchange in sfALR may be physiologically important in preventing the oxidase from catalyzing the potentially harmful oxidation of intracellular glutathione.
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Affiliation(s)
- Stephanie Schaefer-Ramadan
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716-2522, United States
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60
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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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61
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Kallergi E, Kalef-Ezra E, Karagouni-Dalakoura K, Tokatlidis K. Common Players in Mitochondria Biogenesis and Neuronal Protection Against Stress-Induced Apoptosis. Neurochem Res 2013; 39:546-55. [DOI: 10.1007/s11064-013-1109-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/01/2013] [Accepted: 07/08/2013] [Indexed: 10/26/2022]
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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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63
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Human anamorsin binds [2Fe–2S] clusters with unique electronic properties. J Biol Inorg Chem 2013; 18:883-93. [DOI: 10.1007/s00775-013-1033-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 08/05/2013] [Indexed: 11/27/2022]
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64
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Varabyova A, Topf U, Kwiatkowska P, Wrobel L, Kaus-Drobek M, Chacinska A. Mia40 and MINOS act in parallel with Ccs1 in the biogenesis of mitochondrial Sod1. FEBS J 2013; 280:4943-59. [PMID: 23802566 DOI: 10.1111/febs.12409] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 05/23/2013] [Accepted: 06/24/2013] [Indexed: 11/26/2022]
Abstract
Superoxide dismutase 1 (Sod1) is a major superoxide-scavenging enzyme in the eukaryotic cell, and is localized in the cytosol and intermembrane space of mitochondria. Sod1 requires its specific chaperone Ccs1 and disulfide bond formation in order to be retained in the intermembrane space. Our study identified a pool of Sod1 that is present in the reduced state in mitochondria that lack Ccs1. We created yeast mutants with mutations in highly conserved amino acid residues corresponding to human mutations that cause amyotrophic lateral sclerosis, and found that some of the mutant proteins were present in the reduced state. These mutant variants of Sod1 were efficiently localized in mitochondria. Localization of the reduced, Ccs1-independent forms of Sod1 relied on Mia40, an essential component of the mitochondrial intermembrane space import and assembly pathway that is responsible for the biogenesis of intermembrane space proteins. Furthermore, the mitochondrial inner membrane organizing system (MINOS), which is responsible for mitochondrial membrane architecture, differentially modulated the presence of reduced Sod1 in mitochondria. Thus, we identified novel mitochondrial players that are possibly involved in pathological conditions caused by changes in the biogenesis of Sod1.
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Affiliation(s)
- Aksana Varabyova
- International Institute of Molecular and Cell Biology, Warsaw, Poland
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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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66
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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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Fischer M, Horn S, Belkacemi A, Kojer K, Petrungaro C, Habich M, Ali M, Küttner V, Bien M, Kauff F, Dengjel J, Herrmann JM, Riemer J. Protein import and oxidative folding in the mitochondrial intermembrane space of intact mammalian cells. Mol Biol Cell 2013; 24:2160-70. [PMID: 23676665 PMCID: PMC3708723 DOI: 10.1091/mbc.e12-12-0862] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Oxidative folding facilitates protein import into the mitochondrial intermembrane space. An analysis of the process in intact mammalian cells reveals the contributions of Mia40, ALR, glutathione, and the membrane potential. Proteins that rely on oxidative folding remain stable and reduced in the cytosol for several minutes. Oxidation of cysteine residues to disulfides drives import of many proteins into the intermembrane space of mitochondria. Recent studies in yeast unraveled the basic principles of mitochondrial protein oxidation, but the kinetics under physiological conditions is unknown. We developed assays to follow protein oxidation in living mammalian cells, which reveal that import and oxidative folding of proteins are kinetically and functionally coupled and depend on the oxidoreductase Mia40, the sulfhydryl oxidase augmenter of liver regeneration (ALR), and the intracellular glutathione pool. Kinetics of substrate oxidation depends on the amount of Mia40 and requires tightly balanced amounts of ALR. Mia40-dependent import of Cox19 in human cells depends on the inner membrane potential. Our observations reveal considerable differences in the velocities of mitochondrial import pathways: whereas preproteins with bipartite targeting sequences are imported within seconds, substrates of Mia40 remain in the cytosol for several minutes and apparently escape premature degradation and oxidation.
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Affiliation(s)
- Manuel Fischer
- Cellular Biochemistry, University of Kaiserslautern, 67663 Kaiserslautern, Germany
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68
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The ubiquitin-proteasome system regulates mitochondrial intermembrane space proteins. Mol Cell Biol 2013; 33:2136-48. [PMID: 23508107 DOI: 10.1128/mcb.01579-12] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Mitochondrial precursor proteins are synthesized in the cytosol and subsequently imported into mitochondria. The import of mitochondrial intermembrane space proteins is coupled with their oxidative folding and governed by the mitochondrial intermembrane space import and assembly (MIA) pathway. The cytosolic steps that precede mitochondrial import are not well understood. We identified a role for the ubiquitin-proteasome system in the biogenesis of intermembrane space proteins. Interestingly, the function of the ubiquitin-proteasome system is not restricted to conditions of mitochondrial protein import failure. The ubiquitin-proteasome system persistently removes a fraction of intermembrane space proteins under physiological conditions, acting as a negative regulator in the biogenesis of this class of proteins. Thus, the ubiquitin-proteasome system plays an important role in determining the levels of proteins targeted to the intermembrane space of mitochondria.
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69
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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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70
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Wrobel L, Trojanowska A, Sztolsztener ME, Chacinska A. Mitochondrial protein import: Mia40 facilitates Tim22 translocation into the inner membrane of mitochondria. Mol Biol Cell 2013; 24:543-54. [PMID: 23283984 PMCID: PMC3583659 DOI: 10.1091/mbc.e12-09-0649] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The MIA pathway governs the localization and oxidative folding of intermembrane space proteins. This study reports that the MIA pathway is involved in the transport of mitochondrial inner membrane protein Tim22, thereby broadening the known functions of MIA to the biogenesis of inner membrane proteins. The mitochondrial intermembrane space assembly (MIA) pathway is generally considered to be dedicated to the redox-dependent import and biogenesis of proteins localized to the intermembrane space of mitochondria. The oxidoreductase Mia40 is a central component of the pathway responsible for the transfer of disulfide bonds to intermembrane space precursor proteins, causing their oxidative folding. Here we present the first evidence that the function of Mia40 is not restricted to the transport and oxidative folding of intermembrane space proteins. We identify Tim22, a multispanning membrane protein and core component of the TIM22 translocase of inner membrane, as a protein with cysteine residues undergoing oxidation during Tim22 biogenesis. We show that Mia40 is involved in the biogenesis and complex assembly of Tim22. Tim22 forms a disulfide-bonded intermediate with Mia40 upon import into mitochondria. Of interest, Mia40 binds the Tim22 precursor also via noncovalent interactions. We propose that Mia40 not only is responsible for disulfide bond formation, but also assists the Tim22 protein in its integration into the inner membrane of mitochondria.
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Affiliation(s)
- Lidia Wrobel
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland
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71
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72
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Divergence of Erv1-associated mitochondrial import and export pathways in trypanosomes and anaerobic protists. EUKARYOTIC CELL 2012; 12:343-55. [PMID: 23264646 DOI: 10.1128/ec.00304-12] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In yeast (Saccharomyces cerevisiae) and animals, the sulfhydryl oxidase Erv1 functions with Mia40 in the import and oxidative folding of numerous cysteine-rich proteins in the mitochondrial intermembrane space (IMS). Erv1 is also required for Fe-S cluster assembly in the cytosol, which uses at least one mitochondrially derived precursor. Here, we characterize an essential Erv1 orthologue from the protist Trypanosoma brucei (TbERV1), which naturally lacks a Mia40 homolog. We report kinetic parameters for physiologically relevant oxidants cytochrome c and O(2), unexpectedly find O(2) and cytochrome c are reduced simultaneously, and demonstrate that efficient reduction of O(2) by TbERV1 is not dependent upon a simple O(2) channel defined by conserved histidine and tyrosine residues. Massive mitochondrial swelling following TbERV1 RNA interference (RNAi) provides evidence that trypanosome Erv1 functions in IMS protein import despite the natural absence of the key player in the yeast and animal import pathways, Mia40. This suggests significant evolutionary divergence from a recently established paradigm in mitochondrial cell biology. Phylogenomic profiling of genes also points to a conserved role for TbERV1 in cytosolic Fe-S cluster assembly. Conversely, loss of genes implicated in precursor delivery for cytosolic Fe-S assembly in Entamoeba, Trichomonas, and Giardia suggests fundamental differences in intracellular trafficking pathways for activated iron or sulfur species in anaerobic versus aerobic eukaryotes.
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73
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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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74
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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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75
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Schaefer SA, Dong M, Rubenstein RP, Wilkie WA, Bahnson BJ, Thorpe C, Rozovsky S. (77)Se enrichment of proteins expands the biological NMR toolbox. J Mol Biol 2012; 425:222-31. [PMID: 23159557 DOI: 10.1016/j.jmb.2012.11.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 11/06/2012] [Accepted: 11/07/2012] [Indexed: 10/27/2022]
Abstract
Sulfur, a key contributor to biological reactivity, is not amendable to investigations by biological NMR spectroscopy. To utilize selenium as a surrogate, we have developed a generally applicable (77)Se isotopic enrichment method for heterologous proteins expressed in Escherichia coli. We demonstrate (77)Se NMR spectroscopy of multiple selenocysteine and selenomethionine residues in the sulfhydryl oxidase augmenter of liver regeneration (ALR). The resonances of the active-site residues were assigned by comparing the NMR spectra of ALR bound to oxidized and reduced flavin adenine dinucleotide. An additional resonance appears only in the presence of the reducing agent and disappears readily upon exposure to air and subsequent reoxidation of the flavin. Hence, (77)Se NMR spectroscopy can be used to report the local electronic environment of reactive and structural sulfur sites, as well as changes taking place in those locations during catalysis.
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Affiliation(s)
- Stephanie A Schaefer
- 136 Brown Laboratory, Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
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76
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Abstract
A protein's function is intimately linked to its correct subcellular location, yet the machinery required for protein synthesis is predominately cytosolic. How proteins are trafficked through the confines of the cell and integrated into the appropriate cellular compartments has puzzled and intrigued researchers for decades. Indeed, studies exploring this premise revealed elaborate cellular protein translocation and sorting systems, which ensure that all proteins are shuttled to the appropriate cellular destination, where they fulfill their specific functions. This holds true for mitochondria, where sophisticated molecular machines serve to recognize incoming precursor proteins and integrate them into the functional framework of the organelle. We summarize the recent progress in our understanding of mitochondrial protein sorting and the machineries and mechanisms that mediate and regulate this highly dynamic cellular process essential for survival of virtually all eukaryotic cells.
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77
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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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78
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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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79
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Guo PC, Ma JD, Jiang YL, Wang SJ, Bao ZZ, Yu XJ, Chen Y, Zhou CZ. Structure of yeast sulfhydryl oxidase erv1 reveals electron transfer of the disulfide relay system in the mitochondrial intermembrane space. J Biol Chem 2012; 287:34961-34969. [PMID: 22910915 DOI: 10.1074/jbc.m112.394759] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The disulfide relay system in the mitochondrial intermembrane space drives the import of proteins with twin CX(9)C or twin CX(3)C motifs by an oxidative folding mechanism. This process requires disulfide bond transfer from oxidized Mia40 to a substrate protein. Reduced Mia40 is reoxidized/regenerated by the FAD-linked sulfhydryl oxidase Erv1 (EC 1.8.3.2). Full-length Erv1 consists of a flexible N-terminal shuttle domain (NTD) and a conserved C-terminal core domain (CTD). Here, we present crystal structures at 2.0 Å resolution of the CTD and at 3.0 Å resolution of a C30S/C133S double mutant of full-length Erv1 (Erv1FL). Similar to previous homologous structures, the CTD exists as a homodimer, with each subunit consisting of a conserved four-helix bundle that accommodates the isoalloxazine ring of FAD and an additional single-turn helix. The structure of Erv1FL enabled us to identify, for the first time, the three-dimensional structure of the Erv1NTD, which is an amphipathic helix flanked by two flexible loops. This structure also represents an intermediate state of electron transfer from the NTD to the CTD of another subunit. Comparative structural analysis revealed that the four-helix bundle of the CTD forms a wide platform for the electron donor NTD. Moreover, computational simulation combined with multiple-sequence alignment suggested that the amphipathic helix close to the shuttle redox enter is critical for the recognition of Mia40, the upstream electron donor. These findings provide structural insights into electron transfer from Mia40 via the shuttle domain of one subunit of Erv1 to the CTD of another Erv1 subunit.
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Affiliation(s)
- Peng-Chao Guo
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei Anhui 230027, China
| | - Jin-Di Ma
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei Anhui 230027, China
| | - Yong-Liang Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei Anhui 230027, China
| | - Shu-Jie Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei Anhui 230027, China
| | - Zhang-Zhi Bao
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei Anhui 230027, China
| | - Xiao-Jie Yu
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei Anhui 230027, China
| | - Yuxing Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei Anhui 230027, China
| | - Cong-Zhao Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei Anhui 230027, China.
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80
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Florence Q, Wu CK, Habel J, Swindell JT, Wang BC, Rose JP. The structure of augmenter of liver regeneration crystallized in the presence of 50 mM CdCl2 reveals a novel Cd2Cl4O6 cluster that aids in crystal packing. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:1128-33. [PMID: 22948913 DOI: 10.1107/s0907444912022561] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 05/17/2012] [Indexed: 11/11/2022]
Abstract
The crystal structure of the protein augmenter of liver regeneration containing a 14-residue hexahistidine purification tag (hsALR) has been determined to 2.4 Å resolution by Cd-SAD using a highly redundant data set collected on a rotating-anode home X-ray source and processed in 1998. The hsALR crystal structure is a tetramer composed of two homodimers bridged by a novel Cd(2)Cl(4)O(6) cluster via binding to the side-chain carboxylate groups of two solvent-exposed aspartic acid residues. A comparison with the native sALR tetramer shows that the cluster dramatically changes the hsALR dimer-dimer interface, which can now better accommodate the extra 14 N-terminal residues associated with the purification tag. The refined 2.4 Å resolution structure is in good agreement with both the X-ray data (R(cryst) of 0.165, R(free) of 0.211) and the expected stereochemistry (r.m.s. deviations from ideality for bond lengths and bond angles of 0.007 Å and 1.15°, respectively).
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Affiliation(s)
- Quentin Florence
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
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81
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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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82
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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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83
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Kallergi E, Andreadaki M, Kritsiligkou P, Katrakili N, Pozidis C, Tokatlidis K, Banci L, Bertini I, Cefaro C, Ciofi-Baffoni S, Gajda K, Peruzzini R. Targeting and maturation of Erv1/ALR in the mitochondrial intermembrane space. ACS Chem Biol 2012; 7:707-14. [PMID: 22296668 DOI: 10.1021/cb200485b] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interaction of Mia40 with Erv1/ALR is central to the oxidative protein folding in the intermembrane space of mitochondria (IMS) as Erv1/ALR oxidizes reduced Mia40 to restore its functional state. Here we address the role of Mia40 in the import and maturation of Erv1/ALR. The C-terminal FAD-binding domain of Erv1/ALR has an essential role in the import process by creating a transient intermolecular disulfide bond with Mia40. The action of Mia40 is selective for the formation of both intra and intersubunit structural disulfide bonds of Erv1/ALR, but the complete maturation process requires additional binding of FAD. Both of these events must follow a specific sequential order to allow Erv1/ALR to reach the fully functional state, illustrating a new paradigm for protein maturation in the IMS.
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Affiliation(s)
- Emmanouela Kallergi
- Institute of Molecular Biology
and Biotechnology, Foundation for Research and Technology Hellas (IMBB-FORTH), Heraklion 71110, Crete, Greece
- Department of Biology, University of Crete, Heraklion 71409, Crete, Greece
| | - Maria Andreadaki
- Institute of Molecular Biology
and Biotechnology, Foundation for Research and Technology Hellas (IMBB-FORTH), Heraklion 71110, Crete, Greece
- Department of Biology, University of Crete, Heraklion 71409, Crete, Greece
| | - Paraskevi Kritsiligkou
- Institute of Molecular Biology
and Biotechnology, Foundation for Research and Technology Hellas (IMBB-FORTH), Heraklion 71110, Crete, Greece
- Department of Biology, University of Crete, Heraklion 71409, Crete, Greece
| | - Nitsa Katrakili
- Institute of Molecular Biology
and Biotechnology, Foundation for Research and Technology Hellas (IMBB-FORTH), Heraklion 71110, Crete, Greece
| | - Charalambos Pozidis
- Institute of Molecular Biology
and Biotechnology, Foundation for Research and Technology Hellas (IMBB-FORTH), Heraklion 71110, Crete, Greece
| | - Kostas Tokatlidis
- Institute of Molecular Biology
and Biotechnology, Foundation for Research and Technology Hellas (IMBB-FORTH), Heraklion 71110, Crete, Greece
- Department of Materials Science
and Technology, University of Crete, Heraklion
71003, Crete, Greece
| | - Lucia Banci
- Magnetic
Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019
Sesto Fiorentino, Florence, Italy
- Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019
Sesto Fiorentino, Florence, Italy
| | - Ivano Bertini
- Magnetic
Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019
Sesto Fiorentino, Florence, Italy
- Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019
Sesto Fiorentino, Florence, Italy
| | - Chiara Cefaro
- Magnetic
Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019
Sesto Fiorentino, Florence, Italy
- Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019
Sesto Fiorentino, Florence, Italy
| | - Simone Ciofi-Baffoni
- Magnetic
Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019
Sesto Fiorentino, Florence, Italy
- Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019
Sesto Fiorentino, Florence, Italy
| | - Karolina Gajda
- Magnetic
Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019
Sesto Fiorentino, Florence, Italy
| | - Riccardo Peruzzini
- Magnetic
Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019
Sesto Fiorentino, Florence, Italy
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84
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Becker T, Böttinger L, Pfanner N. Mitochondrial protein import: from transport pathways to an integrated network. Trends Biochem Sci 2012; 37:85-91. [PMID: 22178138 DOI: 10.1016/j.tibs.2011.11.004] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 11/07/2011] [Accepted: 11/08/2011] [Indexed: 01/24/2023]
Abstract
Mitochondria, the powerhouses of the cell, import most of their proteins from the cytosol. It was originally assumed that mitochondria imported precursor proteins via a general pathway but recent studies have revealed a remarkable variety of import pathways and mechanisms. Currently, five different protein import pathways can be distinguished. However, the import machineries cooperate with each other and are connected to other systems that function in the respiratory chain, mitochondrial membrane organization, protein quality control and endoplasmic reticulum-mitochondria junctions. In this Opinion, we propose that mitochondrial protein import should not be seen as an independent task of the organelle and that a network of cooperating machineries is responsible for major mitochondrial functions.
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Affiliation(s)
- Thomas Becker
- Institut für Biochemie und Molekularbiologie, ZBMZ, Universität Freiburg, 79104 Freiburg, Germany
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85
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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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86
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Herrmann JM, Riemer J. Mitochondrial disulfide relay: redox-regulated protein import into the intermembrane space. J Biol Chem 2011; 287:4426-33. [PMID: 22157015 DOI: 10.1074/jbc.r111.270678] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
99% of all mitochondrial proteins are synthesized in the cytosol, from where they are imported into mitochondria. In contrast to matrix proteins, many proteins of the intermembrane space (IMS) lack presequences and are imported in an oxidation-driven reaction by the mitochondrial disulfide relay. Incoming polypeptides are recognized and oxidized by the IMS-located receptor Mia40. Reoxidation of Mia40 is facilitated by the sulfhydryl oxidase Erv1 and the respiratory chain. Although structurally unrelated, the mitochondrial disulfide relay functionally resembles the Dsb (disufide bond) system of the bacterial periplasm, the compartment from which the IMS was derived 2 billion years ago.
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Affiliation(s)
- Johannes M Herrmann
- Department of Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663 Kaiserslautern, Germany.
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87
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Faccio G, Nivala O, Kruus K, Buchert J, Saloheimo M. Sulfhydryl oxidases: sources, properties, production and applications. Appl Microbiol Biotechnol 2011; 91:957-66. [DOI: 10.1007/s00253-011-3440-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 06/10/2011] [Accepted: 06/11/2011] [Indexed: 01/24/2023]
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