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Holbrook LM, Sasikumar P, Stanley RG, Simmonds AD, Bicknell AB, Gibbins JM. The platelet-surface thiol isomerase enzyme ERp57 modulates platelet function. J Thromb Haemost 2012; 10:278-88. [PMID: 22168334 PMCID: PMC3444690 DOI: 10.1111/j.1538-7836.2011.04593.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 11/30/2011] [Indexed: 01/06/2023]
Abstract
BACKGROUND Thiol isomerases are a family of endoplasmic reticulum enzymes which orchestrate redox-based modifications of protein disulphide bonds. Previous studies have identified important roles for the thiol isomerases PDI and ERp5 in the regulation of normal platelet function. AIM Recently, we demonstrated the presence of a further five thiol isomerases at the platelet surface. In this report we aim to report the role of one of these enzymes - ERp57 in the regulation of platelet function. METHODS/RESULTS Using enzyme activity function blocking antibodies, we demonstrate a role for ERp57 in platelet aggregation, dense granule secretion, fibrinogen binding, calcium mobilisation and thrombus formation under arterial conditions. In addition to the effects of ERp57 on isolated platelets, we observe the presence of ERp57 in the developing thrombus in vivo. Furthermore the inhibition of ERp57 function was found to reduce laser-injury induced arterial thrombus formation in a murine model of thrombosis. CONCLUSIONS These data suggest that ERp57 is important for normal platelet function and opens up the possibility that the regulation of platelet function by a range of cell surface thiol isomerases may represent a broad paradigm for the regulation of haemostasis and thrombosis.
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Affiliation(s)
- L-M Holbrook
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Berkshire, UK.
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52
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Abstract
Analysis of the human genome reveals that approximately a third of all open reading frames code for proteins that enter the endoplasmic reticulum (ER), demonstrating the importance of this organelle for global protein maturation. The path taken by a polypeptide through the secretory pathway starts with its translocation across or into the ER membrane. It then must fold and be modified correctly in the ER before being transported via the Golgi apparatus to the cell surface or another destination. Being physically segregated from the cytosol means that the ER lumen has a distinct folding environment. It contains much of the machinery for fulfilling the task of protein production, including complex pathways for folding, assembly, modification, quality control, and recycling. Importantly, the compartmentalization means that several modifications that do not occur in the cytosol, such as glycosylation and extensive disulfide bond formation, can occur to secreted proteins to enhance their stability before their exposure to the extracellular milieu. How these various machineries interact during the normal pathway of folding and protein secretion is the subject of this review.
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Affiliation(s)
- Ineke Braakman
- Cellular Protein Chemistry, Faculty of Science, Utrecht University, Utrecht, The Netherlands.
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53
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Jung J, Coe H, Michalak M. Specialization of endoplasmic reticulum chaperones for the folding and function of myelin glycoproteins P0 and PMP22. FASEB J 2011; 25:3929-37. [DOI: 10.1096/fj.11-184911] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Joanna Jung
- Department of BiochemistryUniversity of Alberta Edmonton Alberta Canada
| | - Helen Coe
- Department of BiochemistryUniversity of Alberta Edmonton Alberta Canada
- Department of PediatricsUniversity of Alberta Edmonton Alberta Canada
| | - Marek Michalak
- Department of BiochemistryUniversity of Alberta Edmonton Alberta Canada
- Department of PediatricsUniversity of Alberta Edmonton Alberta Canada
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54
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Roberson EC, Tully JE, Guala AS, Reiss JN, Godburn KE, Pociask DA, Alcorn JF, Riches DWH, Dienz O, Janssen-Heininger YMW, Anathy V. Influenza induces endoplasmic reticulum stress, caspase-12-dependent apoptosis, and c-Jun N-terminal kinase-mediated transforming growth factor-β release in lung epithelial cells. Am J Respir Cell Mol Biol 2011; 46:573-81. [PMID: 21799120 DOI: 10.1165/rcmb.2010-0460oc] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Influenza A virus (IAV) infection is known to induce endoplasmic reticulum (ER) stress, Fas-dependent apoptosis, and TGF-β production in a variety of cells. However, the relationship between these events in murine primary tracheal epithelial cells (MTECS), which are considered one of the primary sites of IAV infection and replication, is unclear. We show that IAV infection induced ER stress marker activating transcription factor-6 and endoplasmic reticulum protein 57-kD (ERp57), but not C/EBP homologous protein (CHOP). In contrast, the ER stress inducer thapsigargin (THP) increased CHOP. IAV infection activated caspases and apoptosis, independently of Fas and caspase-8, in MTECs. Instead, apoptosis was mediated by caspase-12. A decrease in ERp57 attenuated the IAV burden and decreased caspase-12 activation and apoptosis in epithelial cells. TGF-β production was enhanced in IAV-infected MTECs, compared with THP or staurosporine. IAV infection caused the activation of c-Jun N-terminal kinase (JNK). Furthermore, IAV-induced TGF-β production required the presence of JNK1, a finding that suggests a role for JNK1 in IAV-induced epithelial injury and subsequent TGF-β production. These novel findings suggest a potential mechanistic role for a distinct ER stress response induced by IAV, and a profibrogenic/repair response in contrast to other pharmacological inducers of ER stress. These responses may also have a potential role in acute lung injury, fibroproliferative acute respiratory distress syndrome, and the recently identified H1N1 influenza-induced exacerbations of chronic obstructive pulmonary disease (Wedzicha JA. Proc Am Thorac Soc 2004;1:115-120) and idiopathic pulmonary fibrosis (Umeda Y, et al. Int Med 2010;49:2333-2336).
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Affiliation(s)
- Elle C Roberson
- Department of Pathology, University of Vermont, Burlington, VT 05405, USA
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55
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Bernasconi R, Molinari M. ERAD and ERAD tuning: disposal of cargo and of ERAD regulators from the mammalian ER. Curr Opin Cell Biol 2011; 23:176-83. [PMID: 21075612 PMCID: PMC7172097 DOI: 10.1016/j.ceb.2010.10.002] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 10/12/2010] [Accepted: 10/14/2010] [Indexed: 11/26/2022]
Abstract
The endoplasmic reticulum (ER) is the site of maturation for secretory and membrane proteins in eukaryotic cells. Unsuccessful folding attempts are eventually interrupted and most folding-defective polypeptides are dislocated across the ER membrane and degraded by cytosolic proteasomes in a complex series of events collectively defined as ER-associated degradation (ERAD). Uncontrolled ERAD activity might prematurely interrupt ongoing folding programs. At steady state, this is prevented by ERAD tuning, that is, the removal of select ERAD regulators from the ER and their degradation by proteasomes and by endo-lysosomal proteases. In Coronaviruses infected cells, the formation of LC3-I coated vesicles containing ERAD regulators cleared from the ER lumen is co-opted to anchor viral replication and transcription complexes to ER-derived membranes.
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56
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Galli C, Bernasconi R, Soldà T, Calanca V, Molinari M. Malectin participates in a backup glycoprotein quality control pathway in the mammalian ER. PLoS One 2011; 6:e16304. [PMID: 21298103 PMCID: PMC3027649 DOI: 10.1371/journal.pone.0016304] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 12/09/2010] [Indexed: 01/10/2023] Open
Abstract
Malectin is a conserved, endoplasmic reticulum (ER)-resident lectin that recognizes high mannose oligosaccharides displaying terminal glucose residues. Here we show that Malectin is an ER stress-induced protein that selectively associates with glycopolypeptides without affecting their entry and their retention in the Calnexin chaperone system. Analysis of the obligate Calnexin client influenza virus hemagglutinin (HA) revealed that Calnexin and Malectin associated with different timing to different HA conformers and that Malectin associated with misfolded HA. Analysis of the facultative Calnexin clients NHK and α1-antitrypsin (α1AT) revealed that induction of Malectin expression to simulate conditions of ER stress resulted in persistent association between the ER lectin and the model cargo glycoproteins, interfered with processing of cargo-linked oligosaccharides and reduced cargo secretion. We propose that Malectin intervention is activated upon ER stress to inhibit secretion of defective gene products that might be generated under conditions of aberrant functioning of the ER quality control machinery.
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Affiliation(s)
- Carmela Galli
- Institute for Research in Biomedicine, Bellinzona, Switzerland
| | | | - Tatiana Soldà
- Institute for Research in Biomedicine, Bellinzona, Switzerland
| | - Verena Calanca
- Institute for Research in Biomedicine, Bellinzona, Switzerland
| | - Maurizio Molinari
- Institute for Research in Biomedicine, Bellinzona, Switzerland
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- * E-mail:
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57
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Participation of lectin chaperones and thiol oxidoreductases in protein folding within the endoplasmic reticulum. Curr Opin Cell Biol 2010; 23:157-66. [PMID: 21094034 DOI: 10.1016/j.ceb.2010.10.011] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 10/05/2010] [Accepted: 10/21/2010] [Indexed: 01/21/2023]
Abstract
Protein folding within the endoplasmic reticulum occurs in conjunction with a complex array of molecular chaperones and folding catalysts that assist the folding process as well as function in quality control processes to monitor the outcome. In this review, we summarize recent advances in the calnexin/calreticulin chaperone system that is directed primarily toward Asn-linked glycoproteins, as well as the protein disulfide isomerase family of enzymes that catalyze disulfide formation, reduction, and isomerization. We highlight issues related to function and substrate specificity as well as the functional interplay between the two systems.
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58
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Pedone E, Limauro D, D’Ambrosio K, De Simone G, Bartolucci S. Multiple catalytically active thioredoxin folds: a winning strategy for many functions. Cell Mol Life Sci 2010; 67:3797-814. [PMID: 20625793 PMCID: PMC11115506 DOI: 10.1007/s00018-010-0449-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 06/23/2010] [Accepted: 06/28/2010] [Indexed: 10/19/2022]
Abstract
The Thioredoxin (Trx) fold is a versatile protein scaffold consisting of a four-stranded β-sheet surrounded by three α-helices. Various insertions are possible on this structural theme originating different proteins, which show a variety of functions and specificities. During evolution, the assembly of different Trx fold domains has been used many times to build new multi-domain proteins able to perform a large number of catalytic functions. To clarify the interaction mode of the different Trx domains within a multi-domain structure and how their combination can affect catalytic performances, in this review, we report on a structural and functional analysis of the most representative proteins containing more than one catalytically active Trx domain: the eukaryotic protein disulfide isomerases (PDIs), the thermophilic protein disulfide oxidoreductases (PDOs) and the hybrid peroxiredoxins (Prxs).
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Affiliation(s)
- Emilia Pedone
- Istituto di Biostrutture e Bioimmagini-CNR, via Mezzocannone 16, 80134 Naples, Italy
| | - Danila Limauro
- Dipartimento di Biologia Strutturale e Funzionale, Università degli Studi di Napoli “Federico II”, Complesso Universitario Monte S. Angelo, Via Cinthia, 80126 Naples, Italy
| | - Katia D’Ambrosio
- Istituto di Biostrutture e Bioimmagini-CNR, via Mezzocannone 16, 80134 Naples, Italy
| | - Giuseppina De Simone
- Istituto di Biostrutture e Bioimmagini-CNR, via Mezzocannone 16, 80134 Naples, Italy
| | - Simonetta Bartolucci
- Dipartimento di Biologia Strutturale e Funzionale, Università degli Studi di Napoli “Federico II”, Complesso Universitario Monte S. Angelo, Via Cinthia, 80126 Naples, Italy
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59
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Reggiori F, Monastyrska I, Verheije MH, Calì T, Ulasli M, Bianchi S, Bernasconi R, de Haan CAM, Molinari M. Coronaviruses Hijack the LC3-I-positive EDEMosomes, ER-derived vesicles exporting short-lived ERAD regulators, for replication. Cell Host Microbe 2010; 7:500-8. [PMID: 20542253 PMCID: PMC7103375 DOI: 10.1016/j.chom.2010.05.013] [Citation(s) in RCA: 310] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 04/09/2010] [Accepted: 05/11/2010] [Indexed: 12/21/2022]
Abstract
Coronaviruses (CoV), including SARS and mouse hepatitis virus (MHV), are enveloped RNA viruses that induce formation of double-membrane vesicles (DMVs) and target their replication and transcription complexes (RTCs) on the DMV-limiting membranes. The DMV biogenesis has been connected with the early secretory pathway. CoV-induced DMVs, however, lack conventional endoplasmic reticulum (ER) or Golgi protein markers, leaving their membrane origins in question. We show that MHV co-opts the host cell machinery for COPII-independent vesicular ER export of a short-living regulator of ER-associated degradation (ERAD), EDEM1, to derive cellular membranes for replication. MHV infection causes accumulation of EDEM1 and OS-9, another short-living ER chaperone, in the DMVs. DMVs are coated with the nonlipidated LC3/Atg8 autophagy marker. Downregulation of LC3, but not inactivation of host cell autophagy, protects cells from CoV infection. Our study identifies the host cellular pathway hijacked for supplying CoV replication membranes and describes an autophagy-independent role for nonlipidated LC3-I.
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Affiliation(s)
- Fulvio Reggiori
- Department of Cell Biology, University Medical Centre Utrecht, 3584 CX Utrecht, The Netherlands.
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60
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Kozlov G, Määttänen P, Thomas DY, Gehring K. A structural overview of the PDI family of proteins. FEBS J 2010; 277:3924-36. [DOI: 10.1111/j.1742-4658.2010.07793.x] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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61
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Rutkevich LA, Cohen-Doyle MF, Brockmeier U, Williams DB. Functional relationship between protein disulfide isomerase family members during the oxidative folding of human secretory proteins. Mol Biol Cell 2010; 21:3093-105. [PMID: 20660153 PMCID: PMC2938376 DOI: 10.1091/mbc.e10-04-0356] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
To examine the relationship between protein disulfide isomerase family members within the mammalian endoplasmic reticulum, PDI, ERp57, ERp72, and P5 were depleted with high efficiency in human hepatoma cells, either singly or in combination. The impact was assessed on the oxidative folding of several well-characterized secretory proteins. We show that PDI plays a predominant role in oxidative folding because its depletion delayed disulfide formation in all secretory proteins tested. However, the phenotype was surprisingly modest suggesting that other family members are able to compensate for PDI depletion, albeit with reduced efficacy. ERp57 also exhibited broad specificity, overlapping with that of PDI, but with preference for glycosylated substrates. Depletion of both PDI and ERp57 revealed that some substrates require both enzymes for optimal folding and, furthermore, led to generalized protein misfolding, impaired export from the ER, and degradation. In contrast, depletion of ERp72 or P5, either alone or in combination with PDI or ERp57 had minimal impact, revealing a narrow substrate specificity for ERp72 and no detectable role for P5 in oxidative protein folding.
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Affiliation(s)
- Lori A Rutkevich
- Department of Biochemistry, University of Toronto, Toronto, Canada
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62
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Tamura T, Sunryd JC, Hebert DN. Sorting things out through endoplasmic reticulum quality control. Mol Membr Biol 2010; 27:412-27. [PMID: 20553226 DOI: 10.3109/09687688.2010.495354] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The endoplasmic reticulum (ER) is a highly organized and specialized organelle optimized for the production of proteins. It is comprised of a highly interconnected network of tubules that contain a large set of resident proteins dedicated to the maturation and processing of proteins that traverse the eukaryotic secretory pathway. As protein maturation is an imperfect process, frequently resulting in misfolding and/or the formation of aggregates, proteins are subjected to a series of evaluation processes within the ER. Proteins deemed native are sorted for anterograde trafficking, while immature or non-native proteins are initially retained in the ER in an attempt to rescue the aberrant products. Terminally misfolded substrates are eventually targeted for turnover through the ER-associated degradation or ERAD pathway to protect the cell from the release of a defective product. A clearer picture of the identity of the machinery involved in these quality control evaluation processes and their mechanisms of actions has emerged over the past decade.
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Affiliation(s)
- Taku Tamura
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
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63
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Pearse BR, Tamura T, Sunryd JC, Grabowski GA, Kaufman RJ, Hebert DN. The role of UDP-Glc:glycoprotein glucosyltransferase 1 in the maturation of an obligate substrate prosaposin. J Cell Biol 2010; 189:829-41. [PMID: 20498017 PMCID: PMC2878942 DOI: 10.1083/jcb.200912105] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 04/28/2010] [Indexed: 01/02/2023] Open
Abstract
An endoplasmic reticulum (ER) quality control system assists in efficient folding and disposal of misfolded proteins. N-linked glycans are critical in these events because their composition dictates interactions with molecular chaperones. UDP-glucose:glycoprotein glucosyltransferase 1 (UGT1) is a key quality control factor of the ER. It adds glucoses to N-linked glycans of nonglucosylated substrates that fail a quality control test, supporting additional rounds of chaperone binding and ER retention. How UGT1 functions in its native environment is poorly understood. The role of UGT1 in the maturation of glycoproteins at basal expression levels was analyzed. Prosaposin was identified as a prominent endogenous UGT1 substrate. A dramatic decrease in the secretion of prosaposin was observed in ugt1(-/-) cells with prosaposin localized to large juxtanuclear aggresome-like inclusions, which is indicative of its misfolding and the essential role that UGT1 plays in its proper maturation. A model is proposed that explains how UGT1 may aid in the folding of sequential domain-containing proteins such as prosaposin.
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Affiliation(s)
- Bradley R. Pearse
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
| | - Taku Tamura
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
| | - Johan C. Sunryd
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
| | - Gregory A. Grabowski
- Division of Human Genetics, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229
| | - Randal J. Kaufman
- Howard Hughes Medical Institute, Department of Biological Chemistry, and Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI 48109
| | - Daniel N. Hebert
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
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64
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Kawabe S, Yokoyama Y. Molecular cloning of calnexin and calreticulin in the Pacific oyster Crassostrea gigas and its expression in response to air exposure. Mar Genomics 2010; 3:19-27. [PMID: 21798193 DOI: 10.1016/j.margen.2010.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 12/18/2009] [Accepted: 01/11/2010] [Indexed: 10/19/2022]
Abstract
Calnexin (CNX) and calreticulin (CRT) are endoplasmic reticulum (ER) chaperones. CNX is a type I transmembrane protein and CRT is a soluble CNX homologue. In the ER, CNX and CRT are important for Ca(2+) homeostasis and protein maturation. Here, we describe the full-length cDNA of the first mollusk CNX (cgCNX) and a second mollusk CRT (cgCRT) from the oyster Crassostrea gigas. CgCNX, containing 3255bp, was composed of a 1764bp open reading frame (ORF) that encodes a 588-amino acid protein. CgCRT, containing 1727bp, was composed of a 1242bp ORF that encodes a 414-amino acid protein. CgCNX and cgCRT contains an N-terminal 21- and 16-amino acid sequence, respectively, which is characteristic of a signal sequence. At the C-terminus, cgCRT also contains the KDEL (-Lys-Asp-Glu-Leu) peptide motif suggesting that cgCRT localizes in the ER. Northern blot analysis showed that both cgCNX and cgCRT mRNAs are induced by air exposure. The expression patterns of cgCNX mRNA differed from those of cgCRT during air exposure. This suggests that these two molecular chaperones have different roles in the response to air exposure.
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Affiliation(s)
- Shinya Kawabe
- Department of Marine Bioscience, Fukui Prefectural University, Obama, Japan
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65
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De Giorgio MR, Yoshioka M, St-Amand J. Feeding regulates the expression of pancreatic genes in gastric mucosa. J Obes 2010; 2010:371950. [PMID: 21234387 PMCID: PMC3017904 DOI: 10.1155/2010/371950] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2010] [Revised: 11/19/2010] [Accepted: 11/23/2010] [Indexed: 01/09/2023] Open
Abstract
The ineffective short-term control of feeding behavior compromises energy homeostasis and can lead to obesity. The gastrointestinal tract secretes several regulatory peptides. However, little is known about the stomach peptide contribution to the acute regulation of intake. In an attempt to identify new gastric signals, the serial analysis of gene expression (SAGE) method was used for the transcription profiling of stomach mucosa in 7 groups of mice: fasting and sacrificed 30 minutes, 1 hour, 3 hours after a low-fat (LF) or high-fat (HF) ad libitum meal. In total, 35 genes were differentially modulated by LF and HF meals compared to fasting, including 15 mRNAs coding for digestive enzymes/secretory proteins, and 10 novel transcripts. Although the basic expression profile did not undergo substantial variations, both LF and HF meals influenced the transcription. This study represents the first global analysis of stomach transcriptome as induced by different nutritional stimuli. Further studies including the characterization of novel genes may help to identify new targets for the therapy and prevention of obesity.
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Affiliation(s)
- Maria Rita De Giorgio
- Functional Genomics Laboratory, CREMOGH, CRCHUQ, and Department of Molecular Medicine, Laval University, 2705 Boulevard Laurier, Quebec city, QC, Canada G1V 4G2
| | - Mayumi Yoshioka
- Functional Genomics Laboratory, CREMOGH, CRCHUQ, and Department of Molecular Medicine, Laval University, 2705 Boulevard Laurier, Quebec city, QC, Canada G1V 4G2
| | - Jonny St-Amand
- Functional Genomics Laboratory, CREMOGH, CRCHUQ, and Department of Molecular Medicine, Laval University, 2705 Boulevard Laurier, Quebec city, QC, Canada G1V 4G2
- *Jonny St-Amand:
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66
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Abstract
Global folding of polypeptides entering the endoplasmic reticulum (ER) starts as soon as they emerge from the narrow Sec61 translocon. Attainment of the native structure can take from several minutes to hours, depending on the gene product. Until then, non-native folding intermediates must be protected from molecular chaperones that recognize misfolded determinants and could prematurely interrupt folding programs by re-directing them to disposal pathways. On the other hand, futile folding attempts must actively be stopped to prevent intraluminal accumulation of defective cargo. This review describes recent advances in understanding how terminally misfolded polypeptides are extracted from the folding environment and directed to specific dislocons within the ER membrane for transfer to the cytoplasm for proteasome-mediated degradation.
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67
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Pearse BR, Hebert DN. Lectin chaperones help direct the maturation of glycoproteins in the endoplasmic reticulum. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1803:684-93. [PMID: 19891995 DOI: 10.1016/j.bbamcr.2009.10.008] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 10/09/2009] [Accepted: 10/20/2009] [Indexed: 02/06/2023]
Abstract
Eukaryotic secretory pathway cargo fold to their native structures within the confines of the endoplasmic reticulum (ER). To ensure a high degree of folding fidelity, a multitude of covalent and noncovalent constraints are imparted upon nascent proteins. These constraints come in the form of topological restrictions or membrane tethers, covalent modifications, and interactions with a series of molecular chaperones. N-linked glycosylation provides inherent benefits to proper folding and creates a platform for interactions with specific chaperones and Cys modifying enzymes. Recent insights into this timeline of protein maturation have revealed mechanisms for protein glycosylation and iterative targeting of incomplete folding intermediates, which provides nurturing interactions with molecular chaperones that assist in the efficient maturation of proteins in the eukaryotic secretory pathway.
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Affiliation(s)
- Bradley R Pearse
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
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68
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Jessop CE, Watkins RH, Simmons JJ, Tasab M, Bulleid NJ. Protein disulphide isomerase family members show distinct substrate specificity: P5 is targeted to BiP client proteins. J Cell Sci 2009; 122:4287-95. [PMID: 19887585 DOI: 10.1242/jcs.059154] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
At least 17 members of the protein disulphide isomerase (PDI) family of oxidoreductases are present in the endoplasmic reticulum (ER) of mammalian cells. They are thought to catalyse disulphide formation to aid folding or to regulate protein function; however, little is known about their individual functions. Here, we show that some proteins that enter the ER are clients for single oxidoreductases, whereas others are clients for several PDI-like enzymes. We previously identified potential substrates for ERp57, and here identify substrates for ERp18 and ERp46. In addition, we analysed the specificity of substrates towards PDI, ERp72, ERp57, ERp46, ERp18 and P5. Strikingly, ERp18 shows specificity towards a component of the complement cascade, pentraxin-related protein PTX3, whereas ERp46 has specificity towards peroxiredoxin-4, a thioredoxin peroxidase. By contrast, most PDI family members react with Ero1alpha. Moreover, P5 forms a non-covalent complex with immunoglobulin heavy chain binding protein (BiP) and shows specificity towards BiP client proteins. These findings highlight cooperation between BiP and P5, and demonstrate that individual PDI family members recognise specific substrate proteins.
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Affiliation(s)
- Catherine E Jessop
- Faculty of Life Sciences, Michael Smith Building, University of Manchester, Manchester, M13 9PT, UK
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69
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Hatahet F, Ruddock LW. Protein disulfide isomerase: a critical evaluation of its function in disulfide bond formation. Antioxid Redox Signal 2009; 11:2807-50. [PMID: 19476414 DOI: 10.1089/ars.2009.2466] [Citation(s) in RCA: 498] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Disulfide bond formation is probably involved in the biogenesis of approximately one third of human proteins. A central player in this essential process is protein disulfide isomerase or PDI. PDI was the first protein-folding catalyst reported. However, despite more than four decades of study, we still do not understand much about its physiological mechanisms of action. This review examines the published literature with a critical eye. This review aims to (a) provide background on the chemistry of disulfide bond formation and rearrangement, including the concept of reduction potential, before examining the structure of PDI; (b) detail the thiol-disulfide exchange reactions that are catalyzed by PDI in vitro, including a critical examination of the assays used to determine them; (c) examine oxidation and reduction of PDI in vivo, including not only the role of ERo1 but also an extensive assessment of the role of glutathione, as well as other systems, such as peroxide, dehydroascorbate, and a discussion of vitamin K-based systems; (d) consider the in vivo reactions of PDI and the determination and implications of the redox state of PDI in vivo; and (e) discuss other human and yeast PDI-family members.
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Affiliation(s)
- Feras Hatahet
- Department of Biochemistry, University of Oulu , Oulu, Finland
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70
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Kozlov G, Määttänen P, Schrag JD, Hura GL, Gabrielli L, Cygler M, Thomas DY, Gehring K. Structure of the noncatalytic domains and global fold of the protein disulfide isomerase ERp72. Structure 2009; 17:651-9. [PMID: 19446521 DOI: 10.1016/j.str.2009.02.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Revised: 02/17/2009] [Accepted: 02/19/2009] [Indexed: 02/03/2023]
Abstract
Protein disulfide isomerases are a family of proteins that catalyze the oxidation and isomerization of disulfide bonds in newly synthesized proteins in the endoplasmic reticulum. The family includes general enzymes such as PDI that recognize unfolded proteins, and others that are selective for specific classes of proteins. Here, we report the X-ray crystal structure of central non-catalytic domains of a specific isomerase, ERp72 (also called CaBP2 and protein disulfide-isomerase A4) from Rattus norvegicus. The structure reveals strong similarity to ERp57, a PDI-family member that interacts with the lectin-like chaperones calnexin and calreticulin but, unexpectedly, ERp72 does not interact with calnexin as shown by isothermal titration calorimetry and nuclear magnetic resonance (NMR) spectroscopy. Small-angle X-ray scattering (SAXS) of ERp72 was used to develop models of the full-length protein using both rigid body refinement and ab initio simulated annealing of dummy atoms. The two methods show excellent agreement and define the relative positions of the five thioredoxin-like domains of ERp72 and potential substrate or chaperone binding sites.
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Affiliation(s)
- Guennadi Kozlov
- Department of Biochemistry, McGill University, 3655 Promenade Sir William Osler, Montréal, Québec, Canada
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71
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Kim Y, Kang K, Kim I, Lee YJ, Oh C, Ryoo J, Jeong E, Ahn K. Molecular mechanisms of MHC class I-antigen processing: redox considerations. Antioxid Redox Signal 2009; 11:907-36. [PMID: 19178136 DOI: 10.1089/ars.2008.2316] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Major histocompatibility complex (MHC) class I molecules present antigenic peptides to the cell surface for screening by CD8(+) T cells. A number of ER-resident chaperones assist the assembly of peptides onto MHC class I molecules, a process that can be divided into several steps. Early folding of the MHC class I heavy chain is followed by its association with beta(2)-microglobulin (beta(2)m). The MHC class I heavy chain-beta(2)m heterodimer is incorporated into the peptide-loading complex, leading to peptide loading, release of the peptide-filled MHC class I molecules from the peptide-loading complex, and exit of the complete MHC class I complex from the ER. Because proper antigen presentation is vital for normal immune responses, the assembly of MHC class I molecules requires tight regulation. Emerging evidence indicates that thiol-based redox regulation plays critical roles in MHC class I-restricted antigen processing and presentation, establishing an unexpected link between redox biology and antigen processing. We review the influences of redox regulation on antigen processing and presentation. Because redox signaling pathways are a rich source of validated drug targets, newly discovered redox biology-mediated mechanisms of antigen processing may facilitate the development of more selective and therapeutic drugs or vaccines against immune diseases.
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Affiliation(s)
- Youngkyun Kim
- National Creative Research Center for Antigen Presentation, Department of Biological Sciences, Seoul National University, Seoul, South Korea
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72
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Michalak M, Groenendyk J, Szabo E, Gold L, Opas M. Calreticulin, a multi-process calcium-buffering chaperone of the endoplasmic reticulum. Biochem J 2009; 417:651-666. [DOI: 10.1042/bj20081847] [Citation(s) in RCA: 533] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
Calreticulin is an ER (endoplasmic reticulum) luminal Ca2+-buffering chaperone. The protein is involved in regulation of intracellular Ca2+ homoeostasis and ER Ca2+ capacity. The protein impacts on store-operated Ca2+ influx and influences Ca2+-dependent transcriptional pathways during embryonic development. Calreticulin is also involved in the folding of newly synthesized proteins and glycoproteins and, together with calnexin (an integral ER membrane chaperone similar to calreticulin) and ERp57 [ER protein of 57 kDa; a PDI (protein disulfide-isomerase)-like ER-resident protein], constitutes the ‘calreticulin/calnexin cycle’ that is responsible for folding and quality control of newly synthesized glycoproteins. In recent years, calreticulin has been implicated to play a role in many biological systems, including functions inside and outside the ER, indicating that the protein is a multi-process molecule. Regulation of Ca2+ homoeostasis and ER Ca2+ buffering by calreticulin might be the key to explain its multi-process property.
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Affiliation(s)
- Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Jody Groenendyk
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Eva Szabo
- Laboratory of Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8
| | - Leslie I. Gold
- Departments of Medicine and Pathology, New York University School of Medicine, New York, NY 10016, U.S.A
| | - Michal Opas
- Laboratory of Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8
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73
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Abstract
Peptide binding to MHC class I molecules is a component of a folding and assembly process that occurs in the endoplasmic reticulum (ER) and uses both cellular chaperones and dedicated factors. The involvement of glycoprotein quality-control chaperones and cellular oxidoreductases in peptide binding has led to models that are gradually being refined. Some aspects of the peptide loading process (e.g., the biosynthesis and degradation of MHC class I complexes) conform to models of glycoprotein quality control, but other aspects (e.g., the formation of a stable disulfide-linked dimer between tapasin and ERp57) deviate from models of chaperone and oxidoreductase function. Here we review what is known about the intersection of glycoprotein folding, oxidative reactions, and MHC class I peptide loading, emphasizing events that occur in the ER and within the MHC class I peptide loading complex.
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Affiliation(s)
- David R Peaper
- Howard Hughes Medical Institute, Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
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74
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Jessop CE, Tavender TJ, Watkins RH, Chambers JE, Bulleid NJ. Substrate specificity of the oxidoreductase ERp57 is determined primarily by its interaction with calnexin and calreticulin. J Biol Chem 2008; 284:2194-202. [PMID: 19054761 PMCID: PMC2629083 DOI: 10.1074/jbc.m808054200] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The formation of disulfides within proteins entering the secretory pathway
is catalyzed by the protein disulfide isomerase family of endoplasmic
reticulum localized oxidoreductases. One such enzyme, ERp57, is thought to
catalyze the isomerization of non-native disulfide bonds formed in
glycoproteins with unstructured disulfide-rich domains. Here we investigated
the mechanism underlying ERp57 specificity toward glycoprotein substrates and
the interdependence of ERp57 and the calnexin cycle for their correct folding.
Our results clearly show that ERp57 must be physically associated with the
calnexin cycle to catalyze isomerization reactions with most of its
substrates. In addition, some glycoproteins only require ERp57 for correct
disulfide formation if they enter the calnexin cycle. Hence, the specificity
of ER oxidoreductases is not only determined by the physical association of
enzyme and substrate but also by accessory factors, such as calnexin and
calreticulin in the case of ERp57. These conclusions suggest that the calnexin
cycle has evolved with a specialized oxidoreductase to facilitate native
disulfide formation in complex glycoproteins.
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Affiliation(s)
- Catherine E Jessop
- Faculty of Life Sciences, The Michael Smith Building, University of Manchester, Manchester, M13 9PT, United Kingdom
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75
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Calì T, Vanoni O, Molinari M. The endoplasmic reticulum crossroads for newly synthesized polypeptide chains. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2008; 83:135-79. [PMID: 19186254 DOI: 10.1016/s0079-6603(08)00604-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Tito Calì
- Institute for Research in Biomedicine, Bellizona, Switzerland
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76
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Appenzeller-Herzog C, Ellgaard L. The human PDI family: versatility packed into a single fold. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1783:535-48. [PMID: 18093543 DOI: 10.1016/j.bbamcr.2007.11.010] [Citation(s) in RCA: 300] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 11/16/2007] [Accepted: 11/20/2007] [Indexed: 12/12/2022]
Abstract
The enzymes of the protein disulfide isomerase (PDI) family are thiol-disulfide oxidoreductases of the endoplasmic reticulum (ER). They contain a CXXC active-site sequence where the two cysteines catalyze the exchange of a disulfide bond with or within substrates. The primary function of the PDIs in promoting oxidative protein folding in the ER has been extended in recent years to include roles in other processes such as ER-associated degradation (ERAD), trafficking, calcium homeostasis, antigen presentation and virus entry. Some of these functions are performed by non-catalytic members of the family that lack the active-site cysteines. Regardless of their function, all human PDIs contain at least one domain of approximately 100 amino acid residues with structural homology to thioredoxin. As we learn more about the individual proteins of the family, a complex picture is emerging that emphasizes as much their differences as their similarities, and underlines the versatility of the thioredoxin fold. Here, we primarily explore the diversity of cellular functions described for the human PDIs.
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Affiliation(s)
- Christian Appenzeller-Herzog
- Department of Molecular Biology, Universitetsparken 13, University of Copenhagen, DK - 2100 Copenhagen Ø., Denmark
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77
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Hebert DN, Molinari M. In and out of the ER: protein folding, quality control, degradation, and related human diseases. Physiol Rev 2007; 87:1377-408. [PMID: 17928587 DOI: 10.1152/physrev.00050.2006] [Citation(s) in RCA: 486] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A substantial fraction of eukaryotic gene products are synthesized by ribosomes attached at the cytosolic face of the endoplasmic reticulum (ER) membrane. These polypeptides enter cotranslationally in the ER lumen, which contains resident molecular chaperones and folding factors that assist their maturation. Native proteins are released from the ER lumen and are transported through the secretory pathway to their final intra- or extracellular destination. Folding-defective polypeptides are exported across the ER membrane into the cytosol and destroyed. Cellular and organismal homeostasis relies on a balanced activity of the ER folding, quality control, and degradation machineries as shown by the dozens of human diseases related to defective maturation or disposal of individual polypeptides generated in the ER.
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Affiliation(s)
- Daniel N Hebert
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, Massachusetts 01003, USA.
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78
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Abstract
Protein folding in the endoplasmic reticulum is often associated with the formation of native disulfide bonds. Their primary function is to stabilize the folded structure of the protein, although disulfide bond formation can also play a regulatory role. Native disulfide bond formation is not trivial, so it is often the rate-limiting step of protein folding both in vivo and in vitro. Complex coordinated systems of molecular chaperones and protein folding catalysts have evolved to help proteins attain their correct folded conformation. This includes a family of enzymes involved in catalyzing thiol-disulfide exchange in the endoplasmic reticulum, the protein disulfide isomerase (PDI) family. There are now 17 reported PDI family members in the endoplasmic reticulum of human cells, but the functional differentiation of these is far from complete. Despite PDI being the first catalyst of protein folding reported, there is much that is still not known about its mechanisms of action. This review will focus on the interactions of the human PDI family members with substrates, including recent research on identifying and characterizing their substrate-binding sites and on determining their natural substrates in vivo.
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Affiliation(s)
- Feras Hatahet
- Biocenter Oulu and Department of Biochemistry, University of Oulu, Finland
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79
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Soldà T, Galli C, Kaufman RJ, Molinari M. Substrate-specific requirements for UGT1-dependent release from calnexin. Mol Cell 2007; 27:238-249. [PMID: 17643373 DOI: 10.1016/j.molcel.2007.05.032] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 04/19/2007] [Accepted: 05/31/2007] [Indexed: 11/16/2022]
Abstract
Newly synthesized glycoproteins displaying monoglucosylated N-glycans bind to the endoplasmic reticulum (ER) chaperone calnexin, and their maturation is catalyzed by the calnexin-associated oxidoreductase ERp57. Folding substrates are eventually released from calnexin, and terminal glucoses are removed from N-glycans. The UDP-glucose:glycoprotein glucosyltransferase (UGT1, UGGT, GT) monitors the folding state of polypeptides released from calnexin and adds back a glucose residue on N-glycans of nonnative polypeptides, thereby prolonging retention in the calnexin chaperone system for additional folding attempts. Here we show that for certain newly synthesized glycoproteins UGT1 deletion has no effect on binding to calnexin. These proteins must normally complete their folding program in one binding event. Other proteins normally undergo multiple binding events, and UGT1 deletion results in their premature release from calnexin. For other proteins, UGT1 deletion substantially delays release from calnexin, unexpectedly showing that UGT1 activity might be required for a structural maturation needed for substrate dissociation from calnexin and export from the ER.
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Affiliation(s)
- Tatiana Soldà
- Institute for Research in Biomedicine, CH-6500 Bellinzona, Switzerland
| | - Carmela Galli
- Institute for Research in Biomedicine, CH-6500 Bellinzona, Switzerland
| | - Randal J Kaufman
- Howard Hughes Medical Institute, University of Michigan Medical Center, Ann Arbor, MI 48109, USA; Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
| | - Maurizio Molinari
- Institute for Research in Biomedicine, CH-6500 Bellinzona, Switzerland.
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80
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Stepensky D, Bangia N, Cresswell P. Aggregate Formation by ERp57-Deficient MHC Class I Peptide-Loading Complexes. Traffic 2007; 8:1530-42. [PMID: 17822402 DOI: 10.1111/j.1600-0854.2007.00639.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The endoplasmic reticulum (ER)-resident proteins TAP, tapasin and ERp57 are the core components of the major histocompatibility complex (MHC) class I peptide-loading complex and play an important role in peptide loading by MHC class I-beta(2)microglobulin dimers. ERp57 and tapasin form a stable disulfide-linked heterodimer within the peptide-loading complex. We demonstrate that ERp57-deficient loading complexes, obtained by expression in a tapasin-negative cell line of a tapasin mutant (C95A) that is not able to form a disulfide bond with ERp57, are prone to aggregation. We studied the assembly, stability and aggregation of the core loading complex using cell lines stably expressing fluorescently tagged tapasin (wild type or C95A mutant) and TAP1. Part of the loading complexes containing the tagged C95A tapasin and TAP1 were sequestered in the ER, without change of their ER transmembrane topology, and were surrounded by a mesh of filaments at the cytosolic side, resulting in formation of protein aggregates with characteristic morphology. Protein aggregates were associated with changes in ER protein turnover but did not affect the cell viability and did not induce the unfolded protein response. Fluorescence resonance energy transfer analysis of the aggregate-free ER fraction revealed that lack of ERp57 did not affect the stoichiometry or stability of tapasin-TAP1 interactions in the assembled 'soluble' core loading complexes. We conclude that the presence of ERp57 is important for the stability of core loading complexes, and that in its absence, the core loading complexes may form stable aggregates within the ER.
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Affiliation(s)
- David Stepensky
- Department of Immunobiology, Howard Hughes Medical Institute, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06520, USA
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81
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Kienast A, Preuss M, Winkler M, Dick TP. Redox regulation of peptide receptivity of major histocompatibility complex class I molecules by ERp57 and tapasin. Nat Immunol 2007; 8:864-72. [PMID: 17603488 DOI: 10.1038/ni1483] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Accepted: 05/30/2007] [Indexed: 11/08/2022]
Abstract
The function of the oxidoreductase ERp57 in the major histocompatibility complex (MHC) class I peptide-loading complex has remained elusive. Here we show that in the absence of tapasin, the alpha2 disulfide bond in the MHC class I peptide-binding groove was rapidly reduced. Covalent sequestration of ERp57 by tapasin was needed to protect the alpha2 disulfide bond against reduction and thus to maintain the binding groove in a peptide-receptive state. Allelic variations in MHC class I tapasin dependency reflected their susceptibility to reduction of the alpha2 disulfide bond. In the absence of sequestration, ERp57 acted directly on the alpha2 disulfide bond. Our work provides insight into how the immune system customizes 'quality control' in the endoplasmic reticulum to fit the needs of antigen presentation.
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Affiliation(s)
- Alexandra Kienast
- Redox Regulation Research Group, German Cancer Research Center, D-69120 Heidelberg, Germany
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82
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Winter AD, McCormack G, Page AP. Protein disulfide isomerase activity is essential for viability and extracellular matrix formation in the nematode Caenorhabditis elegans. Dev Biol 2007; 308:449-61. [PMID: 17586485 DOI: 10.1016/j.ydbio.2007.05.041] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 05/21/2007] [Accepted: 05/31/2007] [Indexed: 10/23/2022]
Abstract
Protein disulfide isomerase (PDI) is a multifunctional protein required for many aspects of protein folding and transit through the endoplasmic reticulum. A conserved family of three PDIs has been functionally analysed using genetic mutants of the model organism Caenorhabditis elegans. PDI-1 and PDI-3 are individually non-essential, whereas PDI-2 is required for normal post-embryonic development. In combination, all three genes are synergistically essential for embryonic development in this nematode. Mutations in pdi-2 result in severe body morphology defects, uncoordinated movement, adult sterility, abnormal molting and aberrant collagen deposition. Many of these phenotypes are consistent with a role in collagen biogenesis and extracellular matrix formation. PDI-2 is required for the normal function of prolyl 4-hydroxylase, a key collagen-modifying enzyme. Site-directed mutagenesis indicates that the independent catalytic activity of PDI-2 may also perform an essential developmental function. PDI-2 therefore performs two critical roles during morphogenesis. The role of PDI-2 in collagen biogenesis can be restored following complementation of the mutant with human PDI.
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Affiliation(s)
- Alan D Winter
- Institute of Comparative Medicine, Veterinary Faculty, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, Scotland, UK
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83
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Abstract
The endoplasmic reticulum (ER) is the site of folding for proteins that are resident in the ER or that are destined for the Golgi, endosomes, lysosomes, the plasma membrane, or secretion. Cotranslational addition of preassembled glucose(3)-mannose(9)-N-acetylglucosamine(2) core oligosaccharides (N-glycosylation) is a common event for polypeptides synthesized in this compartment. Protein-bound oligosaccharides are exposed to several ER glycanases that sequentially remove terminal glucose or mannose residues. Their activity must be tightly regulated because the N-glycan composition determines whether the associated protein is subjected to folding attempts in the ER lumen or whether it is retrotranslocated into the cytosol and degraded.
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Affiliation(s)
- Maurizio Molinari
- Institute for Research in Biomedicine, Via V. Vela 6, CH-6500 Bellinzona, Switzerland.
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84
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Olivari S, Molinari M. Glycoprotein folding and the role of EDEM1, EDEM2 and EDEM3 in degradation of folding-defective glycoproteins. FEBS Lett 2007; 581:3658-64. [PMID: 17499246 DOI: 10.1016/j.febslet.2007.04.070] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Accepted: 04/19/2007] [Indexed: 11/20/2022]
Abstract
Proteins synthesized in the endoplasmic reticulum (ER) lumen are exposed to several dedicated chaperones and folding factors that ensure efficient maturation. Nevertheless, protein folding remains error-prone and mutations in the polypeptide sequence may significantly reduce folding-efficiency. Folding-incompetent proteins carrying N-glycans are extracted from futile folding cycles in the calnexin chaperone system upon intervention of EDEM1, EDEM2 and EDEM3, three ER-stress-induced members of the glycosyl hydrolase 47 family. This review describes current knowledge about mechanisms regulating folding and disposal of glycoproteins.
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Affiliation(s)
- Silvia Olivari
- Institute for Research in Biomedicine, CH-6500 Bellinzona, Switzerland.
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85
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Ni M, Lee AS. ER chaperones in mammalian development and human diseases. FEBS Lett 2007; 581:3641-51. [PMID: 17481612 PMCID: PMC2040386 DOI: 10.1016/j.febslet.2007.04.045] [Citation(s) in RCA: 586] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Revised: 04/13/2007] [Accepted: 04/18/2007] [Indexed: 12/16/2022]
Abstract
The field of endoplasmic reticulum (ER) stress in mammalian cells has expanded rapidly during the past decade, contributing to understanding of the molecular pathways that allow cells to adapt to perturbations in ER homeostasis. One major mechanism is mediated by molecular ER chaperones which are critical not only for quality control of proteins processed in the ER, but also for regulation of ER signaling in response to ER stress. Here, we summarized the properties and functions of GRP78/BiP, GRP94/gp96, GRP170/ORP150, GRP58/ERp57, PDI, ERp72, calnexin, calreticulin, EDEM, Herp and co-chaperones SIL1 and P58(IPK) and their role in development and diseases. Many of the new insights are derived from recently constructed mouse models where the genes encoding the chaperones are genetically altered, providing invaluable tools for examining the physiological involvement of the ER chaperones in vivo.
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Affiliation(s)
| | - Amy S. Lee
- *Department of Biochemistry and Molecular Biology and the USC/Norris Comprehensive Cancer Center, Keck School of Medicine of the University of Southern California, 1441 Eastlake Ave., Los Angeles, CA 90089-9176. Tel.: 323-865-0507; Fax: 323-865-0094; E-mail:
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86
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Abstract
Glycosylation of asparagine residues in Asn-x-Ser/Thr motifs is a common covalent modification of proteins in the lumen of the endoplasmic reticulum (ER). By substantially contributing to the overall hydrophilicity of the polypeptide, pre-assembled core glycans inhibit possible aggregation caused by the inevitable exposure of hydrophobic patches on the as yet unstructured chains. Thereafter, N-glycans are modified by ER-resident enzymes glucosidase I (GI), glucosidase II (GII), UDP-glucose:glycoprotein glucosyltransferase (UGT) and mannosidase(s) and become functional appendices that determine the fate of the associated polypeptide. Recent work has improved our understanding of how the removal of terminal glucose residues from N-glycans allows newly synthesized proteins to access the calnexin chaperone system; how substrate retention in this specialized chaperone system is regulated by de-/re-glucosylation cycles catalyzed by GII and UGT1; and how acceleration of N-glycan dismantling upon induction of EDEM variants promotes ER-associated degradation (ERAD) under conditions of ER stress. In particular, characterization of cells lacking certain ER chaperones has revealed important new information on the mechanisms regulating protein folding and quality control. Tight regulation of N-glycan modifications is crucial to maintain protein quality control, to ensure the synthesis of functional polypeptides and to avoid constipation of the ER with folding-defective polypeptides.
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Affiliation(s)
- Lloyd W Ruddock
- Biocenter Oulu and Department of Biochemistry, University of Oulu, FIN-90014 Oulu, Finland
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87
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Jessop CE, Chakravarthi S, Garbi N, Hämmerling GJ, Lovell S, Bulleid NJ. ERp57 is essential for efficient folding of glycoproteins sharing common structural domains. EMBO J 2006; 26:28-40. [PMID: 17170699 PMCID: PMC1782378 DOI: 10.1038/sj.emboj.7601505] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 11/22/2006] [Indexed: 01/02/2023] Open
Abstract
ERp57 is a member of the protein disulphide isomerase family of oxidoreductases, which are involved in native disulphide bond formation in the endoplasmic reticulum of mammalian cells. This enzyme has been shown to be associated with both calnexin and calreticulin and, therefore, has been proposed to be a glycoprotein-specific oxidoreductase. Here, we identify endogenous substrates for ERp57 by trapping mixed disulphide intermediates between enzyme and substrate. Our results demonstrate that the substrates for this enzyme are mostly heavily glycosylated, disulphide bonded proteins. In addition, we show that the substrate proteins share common structural domains, indicating that substrate specificity may involve specific structural features as well as the presence of an oligosaccharide side chain. We also show that the folding of two of the endogenous substrates for ERp57 is impaired in ERp57 knockout cells and that prevention of an interaction with calnexin or calreticulin perturbs the folding of some, but not all, substrates with multiple disulphide bonds. These results suggest a specific role for ERp57 in the isomerisation of non-native disulphide bonds in specific glycoprotein substrates.
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Affiliation(s)
| | | | - Natalio Garbi
- German Cancer Research Center, DKFZ, Heidelberg, Germany
| | | | - Simon Lovell
- Faculty of Life Sciences, University of Manchester, Manchester, UK
| | - Neil J Bulleid
- Faculty of Life Sciences, University of Manchester, Manchester, UK
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK. Tel.: +44 161 275 5103; Fax: +44 161 275 5082; E-mail:
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Garbi N, Hämmerling G, Tanaka S. Interaction of ERp57 and tapasin in the generation of MHC class I-peptide complexes. Curr Opin Immunol 2006; 19:99-105. [PMID: 17150345 DOI: 10.1016/j.coi.2006.11.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Accepted: 11/23/2006] [Indexed: 11/22/2022]
Abstract
Antigen presentation by MHC class I molecules is necessary for CD8 T-cell activation. Optimal peptide loading onto MHC class I molecules occurs mainly in the peptide-loading complex in the endoplasmic reticulum. The identification of a covalent association between the thiol oxidoreductase ERp57 and tapasin, and its impact on the loading complex, are important recent developments in this field of research. In the absence of ERp57, the recruitment of MHC class I molecules into this complex by tapasin is greatly impaired both in the number of molecules and in their interaction time, suggesting a key structural role for the ERp57-tapasin association in the peptide-loading complex. The role of ERp57 as a thiol oxidoreductase in the peptide-loading complex remains, however, controversial and further research regarding this subject is required.
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Affiliation(s)
- Natalio Garbi
- Division of Molecular Immunology, German Cancer Research Center DKFZ, Heidelberg, Germany.
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89
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Maattanen P, Kozlov G, Gehring K, Thomas DY. ERp57 and PDI: multifunctional protein disulfide isomerases with similar domain architectures but differing substrate–partner associationsThis paper is one of a selection of papers published in this Special Issue, entitled CSBMCB — Membrane Proteins in Health and Disease. Biochem Cell Biol 2006; 84:881-9. [PMID: 17215875 DOI: 10.1139/o06-186] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Secretory proteins become folded and acquire stabilizing disulfide bonds in the endoplasmic reticulum (ER). Correct disulfide bond formation is a key step in ER quality control (ERQC). Proteins with incorrect disulfide bonds are recognized by the quality control machinery and are retrotranslocated into the cytosol where they are degraded by the proteasome. The mammalian ER contains 17 disulfide isomerases and at least one of them, ERp57, works in conjunction with the ER lectin-like chaperones calnexin and calreticulin. The targeting of ERp57 to calnexin–calreticulin is mediated by its noncatalytic b′ domain, and analogous domains in other disulfide isomerases likely determine their substrate and partner preferences. This review discusses some explanations for the multiplicity of disulfide isomerases and highlights structural differences in the b′ domains of PDI and ERp57 as an example of how noncatalytic domains define specialized roles in oxidative folding.
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Affiliation(s)
- P Maattanen
- Biochemistry Department, McGill University, 3655 Promenade Sir William Osler, Montréal, QC H3G 1Y6, Canada.
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90
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Moremen KW, Molinari M. N-linked glycan recognition and processing: the molecular basis of endoplasmic reticulum quality control. Curr Opin Struct Biol 2006; 16:592-9. [PMID: 16938451 PMCID: PMC3976202 DOI: 10.1016/j.sbi.2006.08.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 07/04/2006] [Accepted: 08/16/2006] [Indexed: 12/30/2022]
Abstract
Nascent polypeptides emerging into the lumen of the endoplasmic reticulum (ER) are N-glycosylated on asparagines in Asn-Xxx-Ser/Thr motifs. Processing of the core oligosaccharide eventually determines the fate of the associated polypeptide by regulating entry into and retention by the calnexin chaperone system, or extraction from the ER folding environment for disposal. Recent advances have shown that at least two N-glycans are necessary for protein access to the calnexin chaperone system and that polypeptide cycling in the system is a rather rare event, which, for folding-defective polypeptides, is activated only upon persistent misfolding. Additionally, dismantling of the polypeptide-bound N-glycan interrupts futile folding attempts, and elicits preparation of the misfolded chain for dislocation into the cytosol and degradation.
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Affiliation(s)
- Kelley W Moremen
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602-4712, USA
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91
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Kozlov G, Maattanen P, Schrag JD, Pollock S, Cygler M, Nagar B, Thomas DY, Gehring K. Crystal Structure of the bb′ Domains of the Protein Disulfide Isomerase ERp57. Structure 2006; 14:1331-9. [PMID: 16905107 DOI: 10.1016/j.str.2006.06.019] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Revised: 06/10/2006] [Accepted: 06/13/2006] [Indexed: 11/23/2022]
Abstract
The synthesis of proteins in the endoplasmic reticulum (ER) is limited by the rate of correct disulfide bond formation. This process is carried out by protein disulfide isomerases, a family of ER proteins which includes general enzymes such as PDI that recognize unfolded proteins and others that are selective for specific proteins or classes. Using small-angle X-ray scattering and X-ray crystallography, we report the structure of a selective isomerase, ERp57, and its interactions with the lectin chaperone calnexin. Using isothermal titration calorimetry and NMR spectroscopy, we show that the b' domain of ERp57 binds calnexin with micromolar affinity through a conserved patch of basic residues. Disruption of this binding site by mutagenesis abrogates folding of RNase B in an in vitro assay. The relative positions of the ERp57 catalytic sites and calnexin binding site suggest that activation by calnexin is due to substrate recruitment rather than a direct stimulation of ERp57 oxidoreductase activity.
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Affiliation(s)
- Guennadi Kozlov
- Biochemistry Department, McGill University, 3655 Promenade Sir William Osler, Montréal, Québec H3G 1Y6, Canada
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92
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93
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Zhang Y, Baig E, Williams DB. Functions of ERp57 in the Folding and Assembly of Major Histocompatibility Complex Class I Molecules. J Biol Chem 2006; 281:14622-31. [PMID: 16567808 DOI: 10.1074/jbc.m512073200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ERp57 is a thiol oxidoreductase of the endoplasmic reticulum that appears to be recruited to substrates indirectly through its association with the molecular chaperones calnexin and calreticulin. However, its functions in living cells have been difficult to demonstrate. During the biogenesis of class I histocompatibility molecules, ERp57 has been detected in association with free class I heavy chains and, at a later stage, with a large complex termed the peptide loading complex. This implicates ERp57 in heavy chain disulfide formation, isomerization, or reduction as well as in the loading of peptides onto class I molecules. In this study, we show that ERp57 does indeed participate in oxidative folding of the heavy chain. Depletion of ERp57 by RNA interference delayed heavy chain disulfide bond formation, slowed folding of the heavy chain alpha(3) domain, and caused slight delays in the transport of class I molecules from the endoplasmic reticulum to the Golgi apparatus. In contrast, heavy chain-beta(2)-microglobulin association kinetics were normal, suggesting that the interaction between heavy chain and beta(2) -microglobulin does not depend on an oxidized alpha(3) domain. Likewise, the peptide loading complex assembled properly, and peptide loading appeared normal upon depletion of ERp57. These studies demonstrate that ERp57 is involved in disulfide formation in vivo but do not support a role for ERp57 in peptide loading of class I molecules. Interestingly, depletion of another thiol oxidoreductase, ERp72, had no detectable effect on class I biogenesis, consistent with a specialized role for ERp57 in this process.
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Affiliation(s)
- Yinan Zhang
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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