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Duan Z, Chen K, Yang T, You R, Chen B, Li J, Liu L. Mechanisms of Endoplasmic Reticulum Protein Homeostasis in Plants. Int J Mol Sci 2023; 24:17599. [PMID: 38139432 PMCID: PMC10743519 DOI: 10.3390/ijms242417599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 12/24/2023] Open
Abstract
Maintenance of proteome integrity is essential for cell function and survival in changing cellular and environmental conditions. The endoplasmic reticulum (ER) is the major site for the synthesis of secretory and membrane proteins. However, the accumulation of unfolded or misfolded proteins can perturb ER protein homeostasis, leading to ER stress and compromising cellular function. Eukaryotic organisms have evolved sophisticated and conserved protein quality control systems to ensure protein folding fidelity via the unfolded protein response (UPR) and to eliminate potentially harmful proteins via ER-associated degradation (ERAD) and ER-phagy. In this review, we summarize recent advances in our understanding of the mechanisms of ER protein homeostasis in plants and discuss the crosstalk between different quality control systems. Finally, we will address unanswered questions in this field.
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Affiliation(s)
- Zhihao Duan
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China
| | - Kai Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China
| | - Tao Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China
| | - Ronghui You
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China
| | - Binzhao Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China
| | - Jianming Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China
- Department of Biology, Hong Kong Baptist University, Kowloon, Hong Kong
| | - Linchuan Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China
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Wu X, Siggel M, Ovchinnikov S, Mi W, Svetlov V, Nudler E, Liao M, Hummer G, Rapoport TA. Structural basis of ER-associated protein degradation mediated by the Hrd1 ubiquitin ligase complex. Science 2020; 368:368/6489/eaaz2449. [PMID: 32327568 DOI: 10.1126/science.aaz2449] [Citation(s) in RCA: 130] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 01/18/2020] [Accepted: 03/11/2020] [Indexed: 12/13/2022]
Abstract
Misfolded luminal endoplasmic reticulum (ER) proteins undergo ER-associated degradation (ERAD-L): They are retrotranslocated into the cytosol, polyubiquitinated, and degraded by the proteasome. ERAD-L is mediated by the Hrd1 complex (composed of Hrd1, Hrd3, Der1, Usa1, and Yos9), but the mechanism of retrotranslocation remains mysterious. Here, we report a structure of the active Hrd1 complex, as determined by cryo-electron microscopy analysis of two subcomplexes. Hrd3 and Yos9 jointly create a luminal binding site that recognizes glycosylated substrates. Hrd1 and the rhomboid-like Der1 protein form two "half-channels" with cytosolic and luminal cavities, respectively, and lateral gates facing one another in a thinned membrane region. These structures, along with crosslinking and molecular dynamics simulation results, suggest how a polypeptide loop of an ERAD-L substrate moves through the ER membrane.
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Affiliation(s)
- Xudong Wu
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Marc Siggel
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Sergey Ovchinnikov
- Faculty of Arts and Sciences, Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA
| | - Wei Mi
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.,Present address: Department of Pharmacology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Vladimir Svetlov
- Howard Hughes Medical Institute and Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Evgeny Nudler
- Howard Hughes Medical Institute and Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany.,Institute of Biophysics, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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Kniss A, Kazemi S, Löhr F, Berger M, Rogov VV, Güntert P, Sommer T, Jarosch E, Dötsch V. Structural investigation of glycan recognition by the ERAD quality control lectin Yos9. JOURNAL OF BIOMOLECULAR NMR 2018; 72:1-10. [PMID: 30066206 DOI: 10.1007/s10858-018-0201-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 07/30/2018] [Indexed: 06/08/2023]
Abstract
Yos9 is an essential component of the endoplasmic reticulum associated protein degradation (ERAD) system that is responsible for removing terminally misfolded proteins from the ER lumen and mediating proteasomal degradation in the cytosol. Glycoproteins that fail to attain their native conformation in the ER expose a distinct oligosaccharide structure, a terminal α1,6-linked mannose residue, that is specifically recognized by the mannose 6-phoshate receptor homology (MRH) domain of Yos9. We have determined the structure of the MRH domain of Yos9 in its free form and complexed with 3α, 6α-mannopentaose. We show that binding is achieved by loops between β-strands performing an inward movement and that this movement also affects the entire β-barrel leading to a twist. These rearrangements may facilitate the processing of client proteins by downstream acting factors. In contrast, other oligosaccharides such as 2α-mannobiose bind weakly with only locally occurring chemical shift changes underscoring the specificity of this substrate selection process within ERAD.
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Affiliation(s)
- Andreas Kniss
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Sina Kazemi
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Frank Löhr
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Maren Berger
- Max-Delbrück Center for Molecular Medicine, Robert-Rössle-Str. 10, 13125, Berlin-Buch, Germany
| | - Vladimir V Rogov
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Peter Güntert
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
- Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093, Zurich, Switzerland
- Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo, 192-0397, Japan
| | - Thomas Sommer
- Max-Delbrück Center for Molecular Medicine, Robert-Rössle-Str. 10, 13125, Berlin-Buch, Germany
- Institute for Biology, Humboldt Universität zu Berlin, Invalidenstrasse 43, 10115, Berlin, Germany
| | - Ernst Jarosch
- Max-Delbrück Center for Molecular Medicine, Robert-Rössle-Str. 10, 13125, Berlin-Buch, Germany
| | - Volker Dötsch
- Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany.
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Jeong H, Sim HJ, Song EK, Lee H, Ha SC, Jun Y, Park TJ, Lee C. Crystal structure of SEL1L: Insight into the roles of SLR motifs in ERAD pathway. Sci Rep 2016; 6:20261. [PMID: 27064360 PMCID: PMC4746701 DOI: 10.1038/srep20261] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 12/31/2015] [Indexed: 11/09/2022] Open
Abstract
Terminally misfolded proteins are selectively recognized and cleared by the endoplasmic reticulum-associated degradation (ERAD) pathway. SEL1L, a component of the ERAD machinery, plays an important role in selecting and transporting ERAD substrates for degradation. We have determined the crystal structure of the mouse SEL1L central domain comprising five Sel1-Like Repeats (SLR motifs 5 to 9; hereafter called SEL1Lcent). Strikingly, SEL1Lcent forms a homodimer with two-fold symmetry in a head-to-tail manner. Particularly, the SLR motif 9 plays an important role in dimer formation by adopting a domain-swapped structure and providing an extensive dimeric interface. We identified that the full-length SEL1L forms a self-oligomer through the SEL1Lcent domain in mammalian cells. Furthermore, we discovered that the SLR-C, comprising SLR motifs 10 and 11, of SEL1L directly interacts with the N-terminus luminal loops of HRD1. Therefore, we propose that certain SLR motifs of SEL1L play a unique role in membrane bound ERAD machinery.
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Affiliation(s)
- Hanbin Jeong
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Hyo Jung Sim
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Eun Kyung Song
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Hakbong Lee
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Sung Chul Ha
- Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, Kyungbuk 37673, Korea
| | - Youngsoo Jun
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - Tae Joo Park
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
| | - Changwook Lee
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Ulsan 44919, Republic of Korea
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D'Alessio C, Dahms NM. Glucosidase II and MRH-domain containing proteins in the secretory pathway. Curr Protein Pept Sci 2015; 16:31-48. [PMID: 25692846 DOI: 10.2174/1389203716666150213160438] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 08/25/2014] [Accepted: 11/13/2014] [Indexed: 12/24/2022]
Abstract
N-glycosylation in the endoplasmic reticulum (ER) consists of the transfer of a preassembled glycan conserved among species (Glc3Man9GlcNAc2) from a lipid donor to a consensus sequence within a nascent protein that is entering the ER. The protein-linked glycans are then processed by glycosidases and glycosyltransferases in the ER producing specific structures that serve as signalling molecules for the fate of the folding glycoprotein: to stay in the ER during the folding process, to be retrotranslocated to the cytosol for proteasomal degradation if irreversibly misfolded, or to pursue transit through the secretory pathway as a mature glycoprotein. In the ER, each glycan signalling structure is recognized by a specific lectin. A domain similar to that of the mannose 6-phosphate receptors (MPRs) has been identified in several proteins of the secretory pathway. These include the beta subunit of glucosidase II (GII), a key enzyme in the early processing of the transferred glycan that removes middle and innermost glucoses and is involved in quality control of glycoprotein folding in the ER (QC), the lectins OS-9 and XTP3-B, proteins involved in the delivery of ER misfolded proteins to degradation (ERAD), the gamma subunit of the Golgi GlcNAc-1-phosphotransferase, an enzyme involved in generating the mannose 6-phosphate (M6P) signal for sorting acidic hydrolases to lysosomes, and finally the MPRs that deliver those hydrolytic enzymes to the lysosome. Each of the MRH-containing proteins recognizes a different signalling N-glycan structure. Three-dimensional structures of some of the MRH domains have been solved, providing the basis to understand recognition mechanisms.
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Affiliation(s)
| | - Nancy M Dahms
- Laboratory of Glycobiology, Fundación Instituto Leloir - Instituto de Investigaciones Bioquimicas de Buenos Aires-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina, and School of Sciences, University of Buenos Aires, C1428EHA, Buenos Aires, Argentina.
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Emerging structural insights into glycoprotein quality control coupled with N-glycan processing in the endoplasmic reticulum. Molecules 2015; 20:2475-91. [PMID: 25647580 PMCID: PMC6272264 DOI: 10.3390/molecules20022475] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 01/04/2015] [Accepted: 01/22/2015] [Indexed: 01/22/2023] Open
Abstract
In the endoplasmic reticulum (ER), the sugar chain is initially introduced onto newly synthesized proteins as a triantennary tetradecasaccharide (Glc3Man9GlcNAc2). The attached oligosaccharide chain is subjected to stepwise trimming by the actions of specific glucosidases and mannosidases. In these processes, the transiently expressed N-glycans, as processing intermediates, function as signals for the determination of glycoprotein fates, i.e., folding, transport, or degradation through interactions of a series of intracellular lectins. The monoglucosylated glycoforms are hallmarks of incompletely folded states of glycoproteins in this system, whereas the outer mannose trimming leads to ER-associated glycoprotein degradation. This review outlines the recently emerging evidence regarding the molecular and structural basis of this glycoprotein quality control system, which is regulated through dynamic interplay among intracellular lectins, glycosidases, and glycosyltransferase. Structural snapshots of carbohydrate-lectin interactions have been provided at the atomic level using X-ray crystallographic analyses. Conformational ensembles of uncomplexed triantennary high-mannose-type oligosaccharides have been characterized in a quantitative manner using molecular dynamics simulation in conjunction with nuclear magnetic resonance spectroscopy. These complementary views provide new insights into glycoprotein recognition in quality control coupled with N-glycan processing.
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Seidler PM, Shinsky SA, Hong F, Li Z, Cosgrove MS, Gewirth DT. Characterization of the Grp94/OS-9 chaperone-lectin complex. J Mol Biol 2014; 426:3590-605. [PMID: 25193139 DOI: 10.1016/j.jmb.2014.08.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 08/26/2014] [Indexed: 01/15/2023]
Abstract
Grp94 is a macromolecular chaperone belonging to the hsp90 family and is the most abundant glycoprotein in the endoplasmic reticulum (ER) of mammals. In addition to its essential role in protein folding, Grp94 was proposed to participate in the ER-associated degradation quality control pathway by interacting with the lectin OS-9, a sensor for terminally misfolded proteins. To understand how OS-9 interacts with ER chaperone proteins, we mapped its interaction with Grp94. Glycosylation of the full-length Grp94 protein was essential for OS-9 binding, although deletion of the Grp94 N-terminal domain relieved this requirement suggesting that the effect was allosteric rather than direct. Although yeast OS-9 is composed of a well-established N-terminal mannose recognition homology lectin domain and a C-terminal dimerization domain, we find that the C-terminal domain of OS-9 in higher eukaryotes contains "mammalian-specific insets" that are specifically recognized by the middle and C-terminal domains of Grp94. Additionally, the Grp94 binding domain in OS-9 was found to be intrinsically disordered. The biochemical analysis of the interacting regions provides insight into the manner by which the two associate and it additionally hints at a plausible biological role for the Grp94/OS-9 complex.
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Affiliation(s)
- Paul M Seidler
- Department of Structural Biology, University at Buffalo, 700 Ellicott Street, Buffalo, NY 14203, USA; Hauptman Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203, USA
| | - Stephen A Shinsky
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, 766 Irving Aveenue, Syracuse, NY 13210, USA
| | - Feng Hong
- Department of Microbiology and Immunology, Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Zihai Li
- Department of Microbiology and Immunology, Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA
| | - Michael S Cosgrove
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, 766 Irving Aveenue, Syracuse, NY 13210, USA
| | - Daniel T Gewirth
- Department of Structural Biology, University at Buffalo, 700 Ellicott Street, Buffalo, NY 14203, USA; Hauptman Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203, USA.
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8
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Smith MH, Rodriguez EH, Weissman JS. Misfolded proteins induce aggregation of the lectin Yos9. J Biol Chem 2014; 289:25670-7. [PMID: 25086047 DOI: 10.1074/jbc.m114.583344] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A substantial fraction of nascent proteins delivered into the endoplasmic reticulum (ER) never reach their native conformations. Eukaryotes use a series of complementary pathways to efficiently recognize and dispose of these terminally misfolded proteins. In this process, collectively termed ER-associated degradation (ERAD), misfolded proteins are retrotranslocated to the cytosol, polyubiquitinated, and degraded by the proteasome. Although there has been great progress in identifying ERAD components, how these factors accurately identify substrates remains poorly understood. The targeting of misfolded glycoproteins in the ER lumen for ERAD requires the lectin Yos9, which recognizes the glycan species found on terminally misfolded proteins. In a role that remains poorly characterized, Yos9 also binds the protein component of ERAD substrates. Here, we identified a 45-kDa domain of Yos9, consisting of residues 22-421, that is proteolytically stable, highly structured, and able to fully support ERAD in vivo. In vitro binding studies show that Yos9(22-421) exhibits sequence-specific recognition of linear peptides from the ERAD substrate, carboxypeptidase Y G255R (CPY*), and binds a model unfolded peptide ΔEspP and protein Δ131Δ in solution. Binding of Yos9 to these substrates results in their cooperative aggregation. Although the physiological consequences of this substrate-induced aggregation remain to be seen, it has the potential to play a role in the regulation of ERAD.
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Affiliation(s)
- Melanie H Smith
- From the Department of Cellular and Molecular Pharmacology, Graduate Group in Biophysics, California Institute for Quantitative Biosciences, Center for RNA Systems Biology, and Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158
| | - Edwin H Rodriguez
- From the Department of Cellular and Molecular Pharmacology, Graduate Group in Biophysics, California Institute for Quantitative Biosciences, Center for RNA Systems Biology, and Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158
| | - Jonathan S Weissman
- From the Department of Cellular and Molecular Pharmacology, Graduate Group in Biophysics, California Institute for Quantitative Biosciences, Center for RNA Systems Biology, and Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94158
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Heinemann U, Arumughan A, Hanna J, Roske Y, Schütz A, Wanker EE. 213 Structures and interactions of proteins involved in ER-associated protein degradation. J Biomol Struct Dyn 2013. [DOI: 10.1080/07391102.2013.790144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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10
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Hebert DN, Molinari M. Flagging and docking: dual roles for N-glycans in protein quality control and cellular proteostasis. Trends Biochem Sci 2012; 37:404-10. [PMID: 22921611 PMCID: PMC3459134 DOI: 10.1016/j.tibs.2012.07.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 07/17/2012] [Accepted: 07/20/2012] [Indexed: 12/02/2022]
Abstract
Nascent polypeptides entering the endoplasmic reticulum (ER) are covalently modified with pre-assembled oligosaccharides. The terminal glucose and mannose residues are immediately removed after transfer of the oligosaccharide onto newly synthesized polypeptides. This processing determines whether the polypeptide will be retained in the ER, transported along the secretory pathway, or dislocated across the ER membrane for destruction. New avenues of research and some issues of controversy have recently been opened by the discovery that lectin–oligosaccharide interactions stabilize supramolecular complexes between regulators of ER-associated degradation (ERAD). In this Opinion article, we propose a unified model that depicts carbohydrates acting both as flags signaling the fitness of a maturing protein and as docking sites that regulate the assembly and stability of the ERAD machinery.
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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, MA 01003, USA.
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Role of the SEL1L:LC3-I complex as an ERAD tuning receptor in the mammalian ER. Mol Cell 2012; 46:809-19. [PMID: 22633958 DOI: 10.1016/j.molcel.2012.04.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 09/01/2011] [Accepted: 04/12/2012] [Indexed: 11/21/2022]
Abstract
Several regulators of endoplasmic reticulum (ER)-associated degradation (ERAD) have a shorter half-life compared to conventional ER chaperones. At steady state, they are selectively removed from the ER by poorly defined events collectively referred to as ERAD tuning. Here we identify the complex comprising the type-I transmembrane protein SEL1L and the cytosolic protein LC3-I as an ERAD tuning receptor regulating the COPII-independent, vesicle-mediated removal of the lumenal ERAD regulators EDEM1 and OS-9 from the ER. Expression of folding-defective polypeptides enhances the lumenal content of EDEM1 and OS-9 by inhibiting their SEL1L:LC3-I-mediated segregation. This raises ERAD activity in the absence of UPR-induction. The mouse hepatitis virus (MHV) subverts ERAD tuning for replication. Consistently, SEL1L or LC3 silencing impair the MHV life cycle. Collectively, our data provide new molecular information about the ERAD tuning mechanisms that regulate ERAD in mammalian cells at the post translational level and how these mechanisms are hijacked by a pathogen.
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