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Abstract
SIGNIFICANCE Disturbance of glutathione (GSH) metabolism is a hallmark of numerous diseases, yet GSH functions are poorly understood. One key to this question is to consider its functional compartmentation. GSH is present in the endoplasmic reticulum (ER), where it competes with substrates for oxidation by the oxidative folding machinery, composed in eukaryotes of the thiol oxidase Ero1 and proteins from the disulfide isomerase family (protein disulfide isomerase). Yet, whether GSH is required for proper ER oxidative protein folding is a highly debated question. Recent Advances: Oxidative protein folding has been thoroughly dissected over the past decades, and its actors and their mode of action elucidated. Genetically encoded GSH probes have recently provided an access to subcellular redox metabolism, including the ER. CRITICAL ISSUES Of the few often-contradictory models of the role of GSH in the ER, the most popular suggest it serves as reducing power. Yet, as a reductant, GSH also activates Ero1, which questions how GSH can nevertheless support protein reduction. Hence, whether GSH operates in the ER as a reductant, an oxidant, or just as a "blank" compound mirroring ER/periplasm redox activity is a highly debated question, which is further stimulated by the puzzling occurrence of GSH in the Escherichia coli periplasmic "secretory" compartment, aside from the Dsb thiol-reducing and oxidase pathways. FUTURE DIRECTIONS Addressing the mechanisms controlling GSH traffic in and out of the ER/periplasm and its recycling will help address GSH function in secretion. In addition, as thioredoxin reductase was recently implicated in ER oxidative protein folding, the relative contribution of each of these two reducing pathways should now be addressed. Antioxid. Redox Signal. 27, 1178-1199.
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Affiliation(s)
- Agnès Delaunay-Moisan
- Institute for Integrative Biology of the Cell (I2BC), LSOC, SBIGEM, CEA, CNRS, Université Paris-Sud , Université Paris-Saclay, Gif-sur-Yvette, France
| | - Alise Ponsero
- Institute for Integrative Biology of the Cell (I2BC), LSOC, SBIGEM, CEA, CNRS, Université Paris-Sud , Université Paris-Saclay, Gif-sur-Yvette, France
| | - Michel B Toledano
- Institute for Integrative Biology of the Cell (I2BC), LSOC, SBIGEM, CEA, CNRS, Université Paris-Sud , Université Paris-Saclay, Gif-sur-Yvette, France
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Ponsero AJ, Igbaria A, Darch MA, Miled S, Outten CE, Winther JR, Palais G, D'Autréaux B, Delaunay-Moisan A, Toledano MB. Endoplasmic Reticulum Transport of Glutathione by Sec61 Is Regulated by Ero1 and Bip. Mol Cell 2017; 67:962-973.e5. [PMID: 28918898 DOI: 10.1016/j.molcel.2017.08.012] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 06/29/2017] [Accepted: 08/18/2017] [Indexed: 10/18/2022]
Abstract
In the endoplasmic reticulum (ER), Ero1 catalyzes disulfide bond formation and promotes glutathione (GSH) oxidation to GSSG. Since GSSG cannot be reduced in the ER, maintenance of the ER glutathione redox state and levels likely depends on ER glutathione import and GSSG export. We used quantitative GSH and GSSG biosensors to monitor glutathione import into the ER of yeast cells. We found that glutathione enters the ER by facilitated diffusion through the Sec61 protein-conducting channel, while oxidized Bip (Kar2) inhibits transport. Increased ER glutathione import triggers H2O2-dependent Bip oxidation through Ero1 reductive activation, which inhibits glutathione import in a negative regulatory loop. During ER stress, transport is activated by UPR-dependent Ero1 induction, and cytosolic glutathione levels increase. Thus, the ER redox poise is tuned by reciprocal control of glutathione import and Ero1 activation. The ER protein-conducting channel is permeable to small molecules, provided the driving force of a concentration gradient.
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Affiliation(s)
- Alise J Ponsero
- Institute for Integrative Biology of the Cell (I2BC), CEA-Saclay, CNRS, Université Paris-Saclay, ISVJC/SBIGEM, Laboratoire Stress Oxydant et Cancer, 91191 Gif-sur-Yvette, France
| | - Aeid Igbaria
- Institute for Integrative Biology of the Cell (I2BC), CEA-Saclay, CNRS, Université Paris-Saclay, ISVJC/SBIGEM, Laboratoire Stress Oxydant et Cancer, 91191 Gif-sur-Yvette, France
| | - Maxwell A Darch
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
| | - Samia Miled
- Institute for Integrative Biology of the Cell (I2BC), CEA-Saclay, CNRS, Université Paris-Saclay, ISVJC/SBIGEM, Laboratoire Stress Oxydant et Cancer, 91191 Gif-sur-Yvette, France
| | - Caryn E Outten
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
| | - Jakob R Winther
- Department of Biology, University of Copenhagen, 2200 Copenhagen N, Denmark
| | - Gael Palais
- Institute for Integrative Biology of the Cell (I2BC), CEA-Saclay, CNRS, Université Paris-Saclay, ISVJC/SBIGEM, Laboratoire Stress Oxydant et Cancer, 91191 Gif-sur-Yvette, France
| | - Benoit D'Autréaux
- Institute for Integrative Biology of the Cell (I2BC), CEA-Saclay, CNRS, Université Paris-Saclay, ISVJC/SBIGEM, Laboratoire Stress Oxydant et Cancer, 91191 Gif-sur-Yvette, France
| | - Agnès Delaunay-Moisan
- Institute for Integrative Biology of the Cell (I2BC), CEA-Saclay, CNRS, Université Paris-Saclay, ISVJC/SBIGEM, Laboratoire Stress Oxydant et Cancer, 91191 Gif-sur-Yvette, France
| | - Michel B Toledano
- Institute for Integrative Biology of the Cell (I2BC), CEA-Saclay, CNRS, Université Paris-Saclay, ISVJC/SBIGEM, Laboratoire Stress Oxydant et Cancer, 91191 Gif-sur-Yvette, France.
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Periyasamy P, Shinohara T. Age-related cataracts: Role of unfolded protein response, Ca 2+ mobilization, epigenetic DNA modifications, and loss of Nrf2/Keap1 dependent cytoprotection. Prog Retin Eye Res 2017; 60:1-19. [PMID: 28864287 DOI: 10.1016/j.preteyeres.2017.08.003] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 08/26/2017] [Accepted: 08/28/2017] [Indexed: 12/11/2022]
Abstract
Age-related cataracts are closely associated with lens chronological aging, oxidation, calcium imbalance, hydration and crystallin modifications. Accumulating evidence indicates that misfolded proteins are generated in the endoplasmic reticulum (ER) by most cataractogenic stresses. To eliminate misfolded proteins from cells before they can induce senescence, the cells activate a clean-up machinery called the ER stress/unfolded protein response (UPR). The UPR also activates the nuclear factor-erythroid-2-related factor 2 (Nrf2), a central transcriptional factor for cytoprotection against stress. Nrf2 activates nearly 600 cytoprotective target genes. However, if ER stress reaches critically high levels, the UPR activates destructive outputs to trigger programmed cell death. The UPR activates mobilization of ER-Ca2+ to the cytoplasm and results in activation of Ca2+-dependent proteases to cleave various enzymes and proteins which cause the loss of normal lens function. The UPR also enhances the overproduction of reactive oxygen species (ROS), which damage lens constituents and induce failure of the Nrf2 dependent cytoprotection. Kelch-like ECH-associated protein 1 (Keap1) is an oxygen sensor protein and regulates the levels of Nrf2 by the proteasomal degradation. A significant loss of DNA methylation in diabetic cataracts was found in the Keap1 promoter, which overexpresses the Keap1 protein. Overexpressed Keap1 significantly decreases the levels of Nrf2. Lower levels of Nrf2 induces loss of the redox balance toward to oxidative stress thereby leading to failure of lens cytoprotection. Here, this review summarizes the overall view of ER stress, increases in Ca2+ levels, protein cleavage, and loss of the well-established stress protection in somatic lens cells.
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Yu Q, Zhang B, Li J, Zhang B, Wang H, Li M. Endoplasmic reticulum-derived reactive oxygen species (ROS) is involved in toxicity of cell wall stress to Candida albicans. Free Radic Biol Med 2016; 99:572-583. [PMID: 27650297 DOI: 10.1016/j.freeradbiomed.2016.09.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/28/2016] [Accepted: 09/16/2016] [Indexed: 12/22/2022]
Abstract
The cell wall is an important cell structure in both fungi and bacteria, and hence becomes a common antimicrobial target. The cell wall-perturbing agents disrupt synthesis and function of cell wall components, leading to cell wall stress and consequent cell death. However, little is known about the detailed mechanisms by which cell wall stress renders fungal cell death. In this study, we found that ROS scavengers drastically attenuated the antifungal effect of cell wall-perturbing agents to the model fungal pathogen Candida albicans, and these agents caused remarkable ROS accumulation and activation of oxidative stress response (OSR) in this fungus. Interestingly, cell wall stress did not cause mitochondrial dysfunction and elevation of mitochondrial superoxide levels. Furthermore, the iron chelator 2,2'-bipyridyl (BIP) and the hydroxyl radical scavengers could not attenuate cell wall stress-caused growth inhibition and ROS accumulation. However, cell wall stress up-regulated expression of unfold protein response (UPR) genes, enhanced protein secretion and promoted protein folding-related oxidation of Ero1, an important source of ROS production. These results indicated that oxidation of Ero1 in the endoplasmic reticulum (ER), rather than mitochondrial electron transport and Fenton reaction, contributed to cell wall stress-related ROS accumulation and consequent growth inhibition. Our findings uncover a novel link between cell wall integrity (CWI), ER function and ROS production in fungal cells, and shed novel light on development of strategies promoting the antifungal efficacy of cell wall-perturbing agents against fungal infections.
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Affiliation(s)
- Qilin Yu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071, PR China
| | - Bing Zhang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071, PR China
| | - Jianrong Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071, PR China
| | - Biao Zhang
- Tianjin Traditional Chinese Medicine University, Tianjin 300193, PR China
| | - Honggang Wang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071, PR China
| | - Mingchun Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071, PR China.
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Niu Y, Zhang L, Yu J, Wang CC, Wang L. Novel Roles of the Non-catalytic Elements of Yeast Protein-disulfide Isomerase in Its Interplay with Endoplasmic Reticulum Oxidoreductin 1. J Biol Chem 2016; 291:8283-94. [PMID: 26846856 DOI: 10.1074/jbc.m115.694257] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Indexed: 11/06/2022] Open
Abstract
The formation of disulfide bonds in the endoplasmic reticulum (ER) of eukaryotic cells is catalyzed by the sulfhydryl oxidase, ER oxidoreductin 1 (Ero1), and protein-disulfide isomerase (PDI). PDI is oxidized by Ero1 to continuously introduce disulfides into substrates, and feedback regulates Ero1 activity by manipulating the regulatory disulfides of Ero1. In this study we find that yeast Ero1p is enzymatically active even with its regulatory disulfides intact, and further activation of Ero1p by reduction of the regulatory disulfides requires the reduction of non-catalytic Cys(90)-Cys(97)disulfide in Pdi1p. The principal client-binding site in the Pdi1pb' domain is necessary not only for the functional Ero1p-Pdi1p disulfide relay but also for the activation of Ero1p. We also demonstrate by complementary activation assays that the regulatory disulfides in Ero1p are much more stable than those in human Ero1α. These new findings on yeast Ero1p-Pdi1p interplay reveal significant differences from our previously identified mode of human Ero1α-PDI interplay and provide insights into the evolution of the eukaryotic oxidative protein folding pathway.
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Affiliation(s)
- Yingbo Niu
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 and the University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lihui Zhang
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 and the University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiaojiao Yu
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 and the University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chih-Chen Wang
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 and
| | - Lei Wang
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 and
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Ramming T, Okumura M, Kanemura S, Baday S, Birk J, Moes S, Spiess M, Jenö P, Bernèche S, Inaba K, Appenzeller-Herzog C. A PDI-catalyzed thiol-disulfide switch regulates the production of hydrogen peroxide by human Ero1. Free Radic Biol Med 2015; 83:361-72. [PMID: 25697776 DOI: 10.1016/j.freeradbiomed.2015.02.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Revised: 02/02/2015] [Accepted: 02/06/2015] [Indexed: 12/16/2022]
Abstract
Oxidative folding in the endoplasmic reticulum (ER) involves ER oxidoreductin 1 (Ero1)-mediated disulfide formation in protein disulfide isomerase (PDI). In this process, Ero1 consumes oxygen (O2) and releases hydrogen peroxide (H2O2), but none of the published Ero1 crystal structures reveal any potential pathway for entry and exit of these reactants. We report that additional mutation of the Cys(208)-Cys(241) disulfide in hyperactive Ero1α (Ero1α-C104A/C131A) potentiates H2O2 production, ER oxidation, and cell toxicity. This disulfide clamps two helices that seal the flavin cofactor where O2 is reduced to H2O2. Through its carboxyterminal active site, PDI unlocks this seal by forming a Cys(208)/Cys(241)-dependent mixed-disulfide complex with Ero1α. The H2O2-detoxifying glutathione peroxidase 8 also binds to the Cys(208)/Cys(241) loop region. Supported by O2 diffusion simulations, these data describe the first enzymatically controlled O2 access into a flavoprotein active site, provide molecular-level understanding of Ero1α regulation and H2O2 production/detoxification, and establish the deleterious consequences of constitutive Ero1 activity.
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Affiliation(s)
- Thomas Ramming
- Division of Molecular & Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, 4056 Basel, Switzerland
| | - Masaki Okumura
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Shingo Kanemura
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Sefer Baday
- Swiss Institutes of Bioinformatics, University of Basel, 4056 Basel, Switzerland; Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Julia Birk
- Division of Molecular & Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, 4056 Basel, Switzerland
| | - Suzette Moes
- Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Martin Spiess
- Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Paul Jenö
- Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Simon Bernèche
- Swiss Institutes of Bioinformatics, University of Basel, 4056 Basel, Switzerland; Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
| | - Christian Appenzeller-Herzog
- Division of Molecular & Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, 4056 Basel, Switzerland.
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Delaunay-Moisan A, Appenzeller-Herzog C. The antioxidant machinery of the endoplasmic reticulum: Protection and signaling. Free Radic Biol Med 2015; 83:341-51. [PMID: 25744411 DOI: 10.1016/j.freeradbiomed.2015.02.019] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 02/20/2015] [Accepted: 02/22/2015] [Indexed: 12/16/2022]
Abstract
Cellular metabolism is inherently linked to the production of oxidizing by-products, including reactive oxygen species (ROS) hydrogen peroxide (H2O2). When present in excess, H2O2 can damage cellular biomolecules, but when produced in coordinated fashion, it typically serves as a mobile signaling messenger. It is therefore not surprising that cell health critically relies on both low-molecular-weight and enzymatic antioxidant components, which protect from ROS-mediated damage and shape the propagation and duration of ROS signals. This review focuses on H2O2-antioxidant cross talk in the endoplasmic reticulum (ER), which is intimately linked to the process of oxidative protein folding. ER-resident or ER-regulated sources of H2O2 and other ROS, which are subgrouped into constitutive and stimulated sources, are discussed and set into context with the diverse antioxidant mechanisms in the organelle. These include two types of peroxide-reducing enzymes, a high concentration of glutathione derived from the cytosol, and feedback-regulated thiol-disulfide switches, which negatively control the major ER oxidase ER oxidoreductin-1. Finally, new evidence highlighting emerging principles of H2O2-based cues at the ER will likely set a basis for establishing ER redox processes as a major line of future signaling research. A fundamental problem that remains to be solved is the specific, quantitative, time resolved, and targeted detection of H2O2 in the ER and in specialized ER subdomains.
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Affiliation(s)
- Agnès Delaunay-Moisan
- Laboratoire Stress Oxydants et Cancer, CEA-Saclay, Service de Biologie Intégrative et de Génétique Moléculaire, Institut de Biologie et de Technologie de Saclay, Commissariat à l׳Energie Atomique et aux Energies Alternatives, F-91191 Gif Sur Yvette, France/Institute for Integrative Biology of the Cell (I2BC), Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France.
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Hudson DA, Gannon SA, Thorpe C. Oxidative protein folding: from thiol-disulfide exchange reactions to the redox poise of the endoplasmic reticulum. Free Radic Biol Med 2015; 80:171-82. [PMID: 25091901 PMCID: PMC4312752 DOI: 10.1016/j.freeradbiomed.2014.07.037] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2014] [Accepted: 07/23/2014] [Indexed: 12/21/2022]
Abstract
This review examines oxidative protein folding within the mammalian endoplasmic reticulum (ER) from an enzymological perspective. In protein disulfide isomerase-first (PDI-first) pathways of oxidative protein folding, PDI is the immediate oxidant of reduced client proteins and then addresses disulfide mispairings in a second isomerization phase. In PDI-second pathways the initial oxidation is PDI-independent. Evidence for the rapid reduction of PDI by reduced glutathione is presented in the context of PDI-first pathways. Strategies and challenges are discussed for determination of the concentrations of reduced and oxidized glutathione and of the ratios of PDI(red):PDI(ox). The preponderance of evidence suggests that the mammalian ER is more reducing than first envisaged. The average redox state of major PDI-family members is largely to almost totally reduced. These observations are consistent with model studies showing that oxidative protein folding proceeds most efficiently at a reducing redox poise consistent with a stoichiometric insertion of disulfides into client proteins. After a discussion of the use of natively encoded fluorescent probes to report the glutathione redox poise of the ER, this review concludes with an elaboration of a complementary strategy to discontinuously survey the redox state of as many redox-active disulfides as can be identified by ratiometric LC-MS-MS methods. Consortia of oxidoreductases that are in redox equilibrium can then be identified and compared to the glutathione redox poise of the ER to gain a more detailed understanding of the factors that influence oxidative protein folding within the secretory compartment.
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Affiliation(s)
- Devin A Hudson
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Shawn A Gannon
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Colin Thorpe
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
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Wang J, Pareja KA, Kaiser CA, Sevier CS. Redox signaling via the molecular chaperone BiP protects cells against endoplasmic reticulum-derived oxidative stress. eLife 2014; 3:e03496. [PMID: 25053742 PMCID: PMC4132286 DOI: 10.7554/elife.03496] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Oxidative protein folding in the endoplasmic reticulum (ER) has emerged as a potentially significant source of cellular reactive oxygen species (ROS). Recent studies suggest that levels of ROS generated as a byproduct of oxidative folding rival those produced by mitochondrial respiration. Mechanisms that protect cells against oxidant accumulation within the ER have begun to be elucidated yet many questions still remain regarding how cells prevent oxidant-induced damage from ER folding events. Here we report a new role for a central well-characterized player in ER homeostasis as a direct sensor of ER redox imbalance. Specifically we show that a conserved cysteine in the lumenal chaperone BiP is susceptible to oxidation by peroxide, and we demonstrate that oxidation of this conserved cysteine disrupts BiP's ATPase cycle. We propose that alteration of BiP activity upon oxidation helps cells cope with disruption to oxidative folding within the ER during oxidative stress. DOI:http://dx.doi.org/10.7554/eLife.03496.001 The endoplasmic reticulum is the cellular compartment where approximately one third of the cell's proteins are made. Inside, chaperone molecules bind to newly made protein chains and help them to fold into the three-dimensional structure required for the protein to work correctly. A chaperone called Ero1 helps to facilitate this folding process by catalyzing a reaction that forms strong chemical bonds, which help stabilize the final protein structures. However, this help from Ero1 comes at a cost: forming a stabilizing bond this way also produces a peroxide molecule as a byproduct. Peroxide is a ‘reactive oxygen species’: a chemical that can oxidize and damage proteins and DNA, which can potentially kill the cell. Three other enzymes in the endoplasmic reticulum can convert peroxide into water, to protect the cells from reactive oxygen species build-up. However, not all cells that use Ero1 have these other enzymes, suggesting that other pathways must exist to manage reactive oxygen species. Wang et al. took advantage of yeast cells containing a hyperactive mutant version of the Ero1 enzyme to look for alternative detoxifying mechanisms that occur when the cell is stressed by an excess of reactive oxygen species. In these cells, Wang et al. observed that the high levels of reactive oxygen species caused part of a chaperone molecule called BiP to oxidize. This modification of BiP acts like a switch that the reactive oxygen species flip on. When activated by the reactive oxygen species, BiP enhances its activity as a folding molecular chaperone, keeping proteins apart. This is thought to allow BiP to minimize the protein misfolding that may otherwise occur in the wake of the damage caused by the building levels of peroxide. Wang et al. created a mutant BiP chaperone that mimics the oxidized form, and found that it also protects cells from the damage inflicted by the excess of reactive oxygen species. Wang et al. propose that the BiP chaperone may be an important sensor of reactive oxygen species that changes its activity when these harmful chemicals are present and helps to protect the cell from damage. The success in mimicking the protective effects of oxidized BiP with a mutant BiP suggest that in the future one may be able to design small molecule drugs that bind to BiP to produce the activity of the modified form. DOI:http://dx.doi.org/10.7554/eLife.03496.002
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Affiliation(s)
- Jie Wang
- Department of Molecular Medicine, Cornell University, Ithaca, United States
| | - Kristeen A Pareja
- Department of Molecular Medicine, Cornell University, Ithaca, United States
| | - Chris A Kaiser
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Carolyn S Sevier
- Department of Molecular Medicine, Cornell University, Ithaca, United States
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Kakihana T, Araki K, Vavassori S, Iemura SI, Cortini M, Fagioli C, Natsume T, Sitia R, Nagata K. Dynamic regulation of Ero1α and peroxiredoxin 4 localization in the secretory pathway. J Biol Chem 2013; 288:29586-94. [PMID: 23979138 PMCID: PMC3795256 DOI: 10.1074/jbc.m113.467845] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In the early secretory compartment (ESC), a network of chaperones and enzymes assists oxidative folding of nascent proteins. Ero1 flavoproteins oxidize protein disulfide isomerase (PDI), generating H2O2 as a byproduct. Peroxiredoxin 4 (Prx4) can utilize luminal H2O2 to oxidize PDI, thus favoring oxidative folding while limiting oxidative stress. Interestingly, neither ER oxidase contains known ER retention signal(s), raising the question of how cells prevent their secretion. Here we show that the two proteins share similar intracellular localization mechanisms. Their secretion is prevented by sequential interactions with PDI and ERp44, two resident proteins of the ESC-bearing KDEL-like motifs. PDI binds preferentially Ero1α, whereas ERp44 equally retains Ero1α and Prx4. The different binding properties of Ero1α and Prx4 increase the robustness of ER redox homeostasis.
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Affiliation(s)
- Taichi Kakihana
- From the Department of Molecular and Cellular Biology, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8397, Japan
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Margittai É, Csala M, Mandl J, Bánhegyi G. Participation of low molecular weight electron carriers in oxidative protein folding. Int J Mol Sci 2009; 10:1346-1359. [PMID: 19399252 PMCID: PMC2672033 DOI: 10.3390/ijms10031346] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 03/08/2009] [Accepted: 03/17/2009] [Indexed: 11/30/2022] Open
Abstract
Oxidative protein folding is mediated by a proteinaceous electron relay system, in which the concerted action of protein disulfide isomerase and Ero1 delivers the electrons from thiol groups to the final acceptor. Oxygen appears to be the final oxidant in aerobic living organisms, although the existence of alternative electron acceptors, e.g. fumarate or nitrate, cannot be excluded. Whilst the protein components of the system are well-known, less attention has been turned to the role of low molecular weight electron carriers in the process. The function of ascorbate, tocopherol and vitamin K has been raised recently. In vitro and in vivo evidence suggests that these redox-active compounds can contribute to the functioning of oxidative folding. This review focuses on the participation of small molecular weight redox compounds in oxidative protein folding.
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Affiliation(s)
| | | | | | - Gábor Bánhegyi
- Author to whom correspondence should be addressed; E-Mail:
; Tel. +36-1-4591500; Fax: +36-1-2662615
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