201
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Ollis AA, Zhang S, Fisher AC, DeLisa MP. Engineered oligosaccharyltransferases with greatly relaxed acceptor-site specificity. Nat Chem Biol 2014; 10:816-22. [PMID: 25129029 DOI: 10.1038/nchembio.1609] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 06/12/2014] [Indexed: 01/23/2023]
Abstract
The Campylobacter jejuni protein glycosylation locus (pgl) encodes machinery for asparagine-linked (N-linked) glycosylation and serves as the archetype for bacterial N-linked glycosylation. This machinery has been functionally transferred into Escherichia coli, enabling convenient mechanistic dissection of the N-linked glycosylation process in this genetically tractable host. Here we sought to identify sequence determinants in the oligosaccharyltransferase PglB that restrict its specificity to only those glycan acceptor sites containing a negatively charged residue at the -2 position relative to asparagine. This involved creation of a genetic assay, glycosylation of secreted N-linked acceptor proteins (glycoSNAP), that facilitates high-throughput screening of glycophenotypes in E. coli. Using this assay, we isolated several C. jejuni PglB variants that could glycosylate an array of noncanonical acceptor sequences, including one in a eukaryotic N-glycoprotein. These results underscore the utility of glycoSNAP for shedding light on poorly understood aspects of N-linked glycosylation and for engineering designer N-linked glycosylation biocatalysts.
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Affiliation(s)
- Anne A Ollis
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, USA
| | - Sheng Zhang
- Proteomics and Mass Spectrometry Core Facility, Cornell University, Ithaca, New York, USA
| | | | - Matthew P DeLisa
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York, USA
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202
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Comparative Analysis of Protein Glycosylation Pathways in Humans and the Fungal Pathogen Candida albicans. Int J Microbiol 2014; 2014:267497. [PMID: 25104959 PMCID: PMC4106090 DOI: 10.1155/2014/267497] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/06/2014] [Indexed: 11/30/2022] Open
Abstract
Protein glycosylation pathways are present in all kingdoms of life and are metabolic pathways found in all the life kingdoms. Despite sharing commonalities in their synthesis, glycans attached to glycoproteins have species-specific structures generated by the presence of different sets of enzymes and acceptor substrates in each organism. In this review, we present a comparative analysis of the main glycosylation pathways shared by humans and the fungal pathogen Candida albicans: N-linked glycosylation, O-linked mannosylation and glycosylphosphatidylinositol-anchorage. The knowledge of similarities and divergences between these metabolic pathways could help find new pharmacological targets for C. albicans infection.
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203
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Byun H, Gou Y, Zook A, Lozano MM, Dudley JP. ERAD and how viruses exploit it. Front Microbiol 2014; 5:330. [PMID: 25071743 PMCID: PMC4080680 DOI: 10.3389/fmicb.2014.00330] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 06/16/2014] [Indexed: 01/09/2023] Open
Abstract
Endoplasmic reticulum (ER)-associated degradation (ERAD) is a universally important process among eukaryotic cells. ERAD is necessary to preserve cell integrity since the accumulation of defective proteins results in diseases associated with neurological dysfunction, cancer, and infections. This process involves recognition of misfolded or misassembled proteins that have been translated in association with ER membranes. Recognition of ERAD substrates leads to their extraction through the ER membrane (retrotranslocation or dislocation), ubiquitination, and destruction by cytosolic proteasomes. This review focuses on ERAD and its components as well as how viruses use this process to promote their replication and to avoid the immune response.
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Affiliation(s)
- Hyewon Byun
- Department of Molecular Biosciences, Center for Infectious Diseases and Institute for Cellular and Molecular Biology, The University of Texas at Austin Austin, TX, USA
| | - Yongqiang Gou
- Department of Molecular Biosciences, Center for Infectious Diseases and Institute for Cellular and Molecular Biology, The University of Texas at Austin Austin, TX, USA
| | - Adam Zook
- Department of Molecular Biosciences, Center for Infectious Diseases and Institute for Cellular and Molecular Biology, The University of Texas at Austin Austin, TX, USA
| | - Mary M Lozano
- Department of Molecular Biosciences, Center for Infectious Diseases and Institute for Cellular and Molecular Biology, The University of Texas at Austin Austin, TX, USA
| | - Jaquelin P Dudley
- Department of Molecular Biosciences, Center for Infectious Diseases and Institute for Cellular and Molecular Biology, The University of Texas at Austin Austin, TX, USA
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204
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Abstract
An essential step during the intracellular life cycle of many positive-strand RNA viruses is the rearrangement of host cell membranes to generate membrane-bound replication platforms. For example, Nidovirales and Flaviviridae subvert the membrane of the endoplasmic reticulum (ER) for their replication. However, the absence of conventional ER and secretory pathway markers in virus-induced ER-derived membranes has for a long time hampered a thorough understanding of their biogenesis. Recent reports highlight the analogies between mouse hepatitis virus-, equine arteritis virus-, and Japanese encephalitis virus-induced replication platforms and ER-associated degradation (ERAD) tuning vesicles (or EDEMosomes) that display nonlipidated LC3 at their cytosolic face and segregate the ERAD factors EDEM1, OS-9, and SEL1L from the ER lumen. In this Gem, we briefly summarize the current knowledge on ERAD tuning pathways and how they might be hijacked for viral genome replication. As ERAD tuning components, such as SEL1L and nonlipidated LC3, appear to contribute to viral infection, these cellular pathways represent novel candidate drug targets to combat positive-strand RNA viruses.
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205
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Naegeli A, Michaud G, Schubert M, Lin CW, Lizak C, Darbre T, Reymond JL, Aebi M. Substrate specificity of cytoplasmic N-glycosyltransferase. J Biol Chem 2014; 289:24521-32. [PMID: 24962585 DOI: 10.1074/jbc.m114.579326] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
N-Linked protein glycosylation is a very common post-translational modification that can be found in all kingdoms of life. The classical, highly conserved pathway entails the assembly of a lipid-linked oligosaccharide and its transfer to an asparagine residue in the sequon NX(S/T) of a secreted protein by the integral membrane protein oligosaccharyltransferase. A few species in the class of γ-proteobacteria encode a cytoplasmic N-glycosylation system mediated by a soluble N-glycosyltransferase (NGT). This enzyme uses nucleotide-activated sugars to modify asparagine residues with single monosaccharides. As these enzymes are not related to oligosaccharyltransferase, NGTs constitute a novel class of N-glycosylation catalyzing enzymes. To characterize the NGT-catalyzed reaction, we developed a sensitive and quantitative in vitro assay based on HPLC separation and quantification of fluorescently labeled substrate peptides. With this assay we were able to directly quantify glycopeptide formation by Actinobacillus pleuropneumoniae NGT and determine its substrate specificities: NGT turns over a number of different sugar donor substrates and allows for activation by both UDP and GDP. Quantitative analysis of peptide substrate turnover demonstrated a strikingly similar specificity as the classical, oligosaccharyltransferase-catalyzed N-glycosylation, with NX(S/T) sequons being the optimal NGT substrates.
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Affiliation(s)
- Andreas Naegeli
- From the Department of Biology, Institute of Microbiology, ETH Zurich, CH-8093 Zurich
| | - Gaëlle Michaud
- the Department of Chemistry and Biochemistry, University of Berne, 3012 Berne, and
| | - Mario Schubert
- the Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Chia-Wei Lin
- From the Department of Biology, Institute of Microbiology, ETH Zurich, CH-8093 Zurich
| | - Christian Lizak
- the Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Tamis Darbre
- the Department of Chemistry and Biochemistry, University of Berne, 3012 Berne, and
| | - Jean-Louis Reymond
- the Department of Chemistry and Biochemistry, University of Berne, 3012 Berne, and
| | - Markus Aebi
- From the Department of Biology, Institute of Microbiology, ETH Zurich, CH-8093 Zurich,
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206
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Dersh D, Jones SM, Eletto D, Christianson JC, Argon Y. OS-9 facilitates turnover of nonnative GRP94 marked by hyperglycosylation. Mol Biol Cell 2014; 25:2220-34. [PMID: 24899641 PMCID: PMC4116297 DOI: 10.1091/mbc.e14-03-0805] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
ER quality control factors GRP94 and OS-9 associate not for the disposal of ERAD substrates but
instead because OS-9 sequesters and degrades aberrant forms of GRP94, which are hyperglycosylated at
cryptic acceptor sites and have altered structure and activity. This highlights a novel mechanism of
quality control of an ER-resident chaperone. The tight coupling of protein folding pathways with disposal mechanisms promotes the efficacy of
protein production in the endoplasmic reticulum (ER). It has been hypothesized that the ER-resident
molecular chaperone glucose-regulated protein 94 (GRP94) is part of this quality control coupling
because it supports folding of select client proteins yet also robustly associates with the lectin
osteosarcoma amplified 9 (OS-9), a component involved in ER-associated degradation (ERAD). To
explore this possibility, we investigated potential functions for the GRP94/OS-9 complex in ER
quality control. Unexpectedly, GRP94 does not collaborate with OS-9 in ERAD of misfolded substrates,
nor is the chaperone required directly for OS-9 folding. Instead, OS-9 binds preferentially to a
subpopulation of GRP94 that is hyperglycosylated on cryptic N-linked glycan acceptor sites.
Hyperglycosylated GRP94 forms have nonnative conformations and are less active. As a result, these
species are degraded much faster than the major, monoglycosylated form of GRP94 in an
OS-9–mediated, ERAD-independent, lysosomal-like mechanism. This study therefore clarifies
the role of the GRP94/OS-9 complex and describes a novel pathway by which glycosylation of cryptic
acceptor sites influences the function and fate of an ER-resident chaperone.
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Affiliation(s)
- Devin Dersh
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Stephanie M Jones
- Ludwig Institute for Cancer Research, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Davide Eletto
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104
| | - John C Christianson
- Ludwig Institute for Cancer Research, University of Oxford, Oxford OX3 7DQ, United Kingdom
| | - Yair Argon
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
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207
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Zhang Y, Kong D, Reichl L, Vogt N, Wolf F, Großhans J. The glucosyltransferase Xiantuan of the endoplasmic reticulum specifically affects E-Cadherin expression and is required for gastrulation movements in Drosophila. Dev Biol 2014; 390:208-20. [DOI: 10.1016/j.ydbio.2014.03.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 03/13/2014] [Accepted: 03/17/2014] [Indexed: 11/24/2022]
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208
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Klug L, Tarazona P, Gruber C, Grillitsch K, Gasser B, Trötzmüller M, Köfeler H, Leitner E, Feussner I, Mattanovich D, Altmann F, Daum G. The lipidome and proteome of microsomes from the methylotrophic yeast Pichia pastoris. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:215-26. [PMID: 24246743 DOI: 10.1016/j.bbalip.2013.11.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 11/05/2013] [Accepted: 11/08/2013] [Indexed: 11/28/2022]
Abstract
The methylotrophic yeast Pichia pastoris is a popular yeast expression system for the production of heterologous proteins in biotechnology. Interestingly, cell organelles which play an important role in this process have so far been insufficiently investigated. For this reason, we started a systematic approach to isolate and characterize organelles from P. pastoris. In this study, we present a procedure to isolate microsomal membranes at high purity. These samples represent endoplasmic reticulum (ER) fractions which were subjected to molecular analysis of lipids and proteins. Organelle lipidomics included a detailed analysis of glycerophospholipids, fatty acids, sterols and sphingolipids. The microsomal proteome analyzed by mass spectrometry identified typical proteins of the ER known from other cell types, especially Saccharomyces cerevisiae, but also a number of unassigned gene products. The lipidome and proteome analysis of P. pastoris microsomes are prerequisite for a better understanding of functions of this organelle and for modifying this compartment for biotechnological applications.
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209
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Suzuki T, Harada Y. Non-lysosomal degradation pathway for N-linked glycans and dolichol-linked oligosaccharides. Biochem Biophys Res Commun 2014; 453:213-9. [PMID: 24866240 DOI: 10.1016/j.bbrc.2014.05.075] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 05/16/2014] [Indexed: 01/11/2023]
Abstract
There is growing evidence that asparagine (N)-linked glycans play pivotal roles in protein folding and intra- or intercellular trafficking of N-glycosylated proteins. During the N-glycosylation of proteins, significant amounts of free oligosaccharides (fOSs) and phosphorylated oligosaccharides (POSs) are generated at the endoplasmic reticulum (ER) membrane by unclarified mechanisms. fOSs are also formed in the cytosol by the enzymatic deglycosylation of misfolded glycoproteins destined for proteasomal degradation. This article summarizes the current knowledge of the molecular and regulatory mechanisms underlying the formation of fOSs and POSs in mammalian cells and Saccharomyces cerevisiae.
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Affiliation(s)
- Tadashi Suzuki
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Japan.
| | - Yoichiro Harada
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Japan
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210
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Halperin L, Jung J, Michalak M. The many functions of the endoplasmic reticulum chaperones and folding enzymes. IUBMB Life 2014; 66:318-26. [PMID: 24839203 DOI: 10.1002/iub.1272] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Accepted: 04/24/2014] [Indexed: 12/12/2022]
Abstract
Endoplasmic reticulum (ER) is an essential sub-cellular compartment of the eukaryotic cell performing many diverse functions essential for the cell and the whole organism. ER molecular chaperones and folding enzymes are multidomain proteins that are designed to support nascent proteins entering ER lumen to achieve their native conformation, mediate post-translational modification, prevent misfolded protein aggregation, and facilitate exit from the ER. Typically the role of ER chaperones expands beyond protein folding. Here, we illustrate the multifunctional nature of many ER associated molecular chaperones and folding enzymes and unique functional overlap of these proteins all designed to support the many functions of the ER membrane.
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Affiliation(s)
- Laura Halperin
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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211
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Lackman JJ, Markkanen PMH, Hogue M, Bouvier M, Petäjä-Repo UE. N-Glycan-dependent and -independent quality control of human δ opioid receptor N-terminal variants. J Biol Chem 2014; 289:17830-42. [PMID: 24798333 DOI: 10.1074/jbc.m114.566273] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Quality control (QC) in the endoplasmic reticulum (ER) scrutinizes newly synthesized proteins and directs them either to ER export or ER-associated degradation (ERAD). Here, we demonstrate that the human δ-opioid receptor (hδOR) is subjected to ERQC in both N-glycan-dependent and -independent manners. This was shown by investigating the biosynthesis and trafficking of wild-type and non-N-glycosylated F27C variants in metabolic pulse-chase assays coupled with flow cytometry and cell surface biotinylation. Both QC mechanisms distinguished the minute one-amino acid difference between the variants, targeting a large fraction of hδOR-Cys(27) to ERAD. However, the N-glycan-independent QC was unable to compensate the N-glycan-dependent pathway, and some incompletely folded non-N-glycosylated hδOR-Cys(27) reached the cell surface in conformation incompatible with ligand binding. The turnover of receptors associating with the molecular chaperone calnexin (CNX) was significantly slower for the hδOR-Cys(27), pointing to an important role of CNX in the hδOR N-glycan-dependent QC. This was further supported by the fact that inhibiting the co-translational interaction of hδOR-Cys(27) precursors with CNX led to their ERAD. Opioid receptor pharmacological chaperones released the CNX-bound receptors to ER export and, furthermore, were able to rescue the Cys(27) variant from polyubiquitination and retrotranslocation to the cytosol whether carrying N-glycans or not. Taken together, the hδOR appears to rely primarily on the CNX-mediated N-glycan-dependent QC that has the capacity to assist in folding, whereas the N-glycan-independent mechanism constitutes an alternative, although less accurate, system for directing misfolded/incompletely folded receptors to ERAD, possibly in altered cellular conditions.
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Affiliation(s)
- Jarkko J Lackman
- From the Department of Anatomy and Cell Biology and the Medical Research Center Oulu, Institute of Biomedicine, University of Oulu, FI-90014 Oulu, Finland and
| | - Piia M H Markkanen
- From the Department of Anatomy and Cell Biology and the Medical Research Center Oulu, Institute of Biomedicine, University of Oulu, FI-90014 Oulu, Finland and
| | - Mireille Hogue
- the Department of Biochemistry, Institute for Research in Immunology and Cancer and Groupe de Recherche Universitaire sur le Médicament, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Michel Bouvier
- the Department of Biochemistry, Institute for Research in Immunology and Cancer and Groupe de Recherche Universitaire sur le Médicament, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Ulla E Petäjä-Repo
- From the Department of Anatomy and Cell Biology and the Medical Research Center Oulu, Institute of Biomedicine, University of Oulu, FI-90014 Oulu, Finland and
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212
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Denks K, Vogt A, Sachelaru I, Petriman NA, Kudva R, Koch HG. The Sec translocon mediated protein transport in prokaryotes and eukaryotes. Mol Membr Biol 2014; 31:58-84. [DOI: 10.3109/09687688.2014.907455] [Citation(s) in RCA: 123] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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213
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Hofherr A, Wagner C, Fedeles S, Somlo S, Köttgen M. N-glycosylation determines the abundance of the transient receptor potential channel TRPP2. J Biol Chem 2014; 289:14854-67. [PMID: 24719335 DOI: 10.1074/jbc.m114.562264] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycosylation plays a critical role in the biogenesis and function of membrane proteins. Transient receptor potential channel TRPP2 is a nonselective cation channel that is mutated in autosomal dominant polycystic kidney disease. TRPP2 has been shown to be heavily N-glycosylated, but the glycosylation sites and the biological role of N-linked glycosylation have not been investigated. Here we show, using a combination of mass spectrometry and biochemical approaches, that native TRPP2 is glycosylated at five asparagines in the first extracellular loop. Glycosylation is required for the efficient biogenesis of TRPP2 because mutations of the glycosylated asparagines result in strongly decreased protein expression of the ion channel. Wild-type and N-glycosylation-deficient TRPP2 is degraded in lysosomes, as shown by increased TRPP2 protein levels upon chemical inhibition of lysosomal degradation. In addition, using pharmacological and genetic approaches, we demonstrate that glucosidase II (GII) mediates glycan trimming of TRPP2. The non-catalytic β subunit of glucosidase II (GIIβ) is encoded by PRKCSH, one of the genes causing autosomal dominant polycystic liver disease (ADPLD). The impaired GIIβ-dependent glucose trimming of TRPP2 glycosylation in ADPLD may explain the decreased TRPP2 protein expression in Prkcsh(-/-) mice and the genetic interaction observed between TRPP2 and PRKCSH in ADPLD. These results highlight the biological importance of N-linked glycosylation and GII-mediated glycan trimming in the control of biogenesis and stability of TRPP2.
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Affiliation(s)
- Alexis Hofherr
- From the Renal Division, Department of Medicine, University Medical Center Freiburg, Hugstetter Straβe 55, 79106 Freiburg, Germany, the Spemann Graduate School of Biology and Medicine (SGBM) and Faculty of Biology, Albert-Ludwigs-University Freiburg, 79106 Freiburg, Germany, and
| | - Claudius Wagner
- From the Renal Division, Department of Medicine, University Medical Center Freiburg, Hugstetter Straβe 55, 79106 Freiburg, Germany
| | - Sorin Fedeles
- the Departments of Medicine and Genetics, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Stefan Somlo
- the Departments of Medicine and Genetics, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Michael Köttgen
- From the Renal Division, Department of Medicine, University Medical Center Freiburg, Hugstetter Straβe 55, 79106 Freiburg, Germany,
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214
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Ferris SP, Kodali VK, Kaufman RJ. Glycoprotein folding and quality-control mechanisms in protein-folding diseases. Dis Model Mech 2014; 7:331-41. [PMID: 24609034 PMCID: PMC3944493 DOI: 10.1242/dmm.014589] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 01/14/2014] [Indexed: 12/31/2022] Open
Abstract
Biosynthesis of proteins--from translation to folding to export--encompasses a complex set of events that are exquisitely regulated and scrutinized to ensure the functional quality of the end products. Cells have evolved to capitalize on multiple post-translational modifications in addition to primary structure to indicate the folding status of nascent polypeptides to the chaperones and other proteins that assist in their folding and export. These modifications can also, in the case of irreversibly misfolded candidates, signal the need for dislocation and degradation. The current Review focuses on the glycoprotein quality-control (GQC) system that utilizes protein N-glycosylation and N-glycan trimming to direct nascent glycopolypeptides through the folding, export and dislocation pathways in the endoplasmic reticulum (ER). A diverse set of pathological conditions rooted in defective as well as over-vigilant ER quality-control systems have been identified, underlining its importance in human health and disease. We describe the GQC pathways and highlight disease and animal models that have been instrumental in clarifying our current understanding of these processes.
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Affiliation(s)
- Sean P. Ferris
- Department of Biological Chemistry and Medical Scientist Training Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Vamsi K. Kodali
- Center for Neuroscience, Aging and Stem Cell Research, Sanford-Burnham Medical Research Institute, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Randal J. Kaufman
- Center for Neuroscience, Aging and Stem Cell Research, Sanford-Burnham Medical Research Institute, 10901 N. Torrey Pines Road, La Jolla, CA 92037, USA
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215
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Imamura K, Maeda S, Kawamura I, Matsuyama K, Shinohara N, Yahiro Y, Nagano S, Setoguchi T, Yokouchi M, Ishidou Y, Komiya S. Human immunodeficiency virus type 1 enhancer-binding protein 3 is essential for the expression of asparagine-linked glycosylation 2 in the regulation of osteoblast and chondrocyte differentiation. J Biol Chem 2014; 289:9865-79. [PMID: 24563464 DOI: 10.1074/jbc.m113.520585] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Human immunodeficiency virus type 1 enhancer-binding protein 3 (Hivep3) suppresses osteoblast differentiation by inducing proteasomal degradation of the osteogenesis master regulator Runx2. In this study, we tested the possibility of cooperation of Hivep1, Hivep2, and Hivep3 in osteoblast and/or chondrocyte differentiation. Microarray analyses with ST-2 bone stroma cells demonstrated that expression of any known osteochondrogenesis-related genes was not commonly affected by the three Hivep siRNAs. Only Hivep3 siRNA promoted osteoblast differentiation in ST-2 cells, whereas all three siRNAs cooperatively suppressed differentiation in ATDC5 chondrocytes. We further used microarray analysis to identify genes commonly down-regulated in both MC3T3-E1 osteoblasts and ST-2 cells upon knockdown of Hivep3 and identified asparagine-linked glycosylation 2 (Alg2), which encodes a mannosyltransferase residing on the endoplasmic reticulum. The Hivep3 siRNA-mediated promotion of osteoblast differentiation was negated by forced Alg2 expression. Alg2 suppressed osteoblast differentiation and bone formation in cultured calvarial bone. Alg2 was immunoprecipitated with Runx2, whereas the combined transfection of Runx2 and Alg2 interfered with Runx2 nuclear localization, which resulted in suppression of Runx2 activity. Chondrocyte differentiation was promoted by Hivep3 overexpression, in concert with increased expression of Creb3l2, whose gene product is the endoplasmic reticulum stress transducer crucial for chondrogenesis. Alg2 silencing suppressed Creb3l2 expression and chondrogenesis of ATDC5 cells, whereas infection of Alg2-expressing virus promoted chondrocyte maturation in cultured cartilage rudiments. Thus, Alg2, as a downstream mediator of Hivep3, suppresses osteogenesis, whereas it promotes chondrogenesis. To our knowledge, this study is the first to link a mannosyltransferase gene to osteochondrogenesis.
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216
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Aikawa JI, Takeda Y, Matsuo I, Ito Y. Trimming of glucosylated N-glycans by human ER α1,2-mannosidase I. ACTA ACUST UNITED AC 2014; 155:375-84. [DOI: 10.1093/jb/mvu008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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217
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Satoh T, Suzuki K, Yamaguchi T, Kato K. Structural basis for disparate sugar-binding specificities in the homologous cargo receptors ERGIC-53 and VIP36. PLoS One 2014; 9:e87963. [PMID: 24498414 PMCID: PMC3912170 DOI: 10.1371/journal.pone.0087963] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 12/30/2013] [Indexed: 12/19/2022] Open
Abstract
ERGIC-53 and VIP36 are categorized as leguminous type (L-type) lectins, and they function as cargo receptors for trafficking certain N-linked glycoproteins in the secretory pathway in animal cells. They share structural similarities in their carbohydrate recognition domains (CRDs) but exhibit distinct sugar-binding specificities and affinities. VIP36 specifically interacts with the α1,2-linked D1 mannosyl arm without terminal glucosylation, while ERGIC-53 shows a broader specificity and lower binding affinity to the high-mannose-type oligosaccharides, irrespective of the presence or absence of the non-reducing terminal glucose residue at the D1 arm. In this study, we determined the crystal structure of ERGIC-53-CRD in complex with their binding partner, MCFD2 and the α1,2 mannotriose which corresponds to the trisaccharide of the D1 arm of high-mannose-type glycans. ERGIC-53 can interact with the D1 trimannosyl arm in two alternative modes, one of which is similar but distinct from that previously observed for VIP36. ERGIC-53 has a shallower sugar-binding pocket than VIP36 because of the single amino acid substitution, Asp-to-Gly. This enables ERGIC-53 to accommodate the non-reducing terminal glucose of the D1 arm in its CRD. In the other interaction mode, the 3-OH group of the terminal mannose was situated outward with respect to the sugar binding pocket, also enabling the Glcα1-3 linkage formation without steric hindrance. Our findings thus provide a structural basis for the broad sugar-binding specificity of the ERGIC-53/MCFD2 cargo receptor complex.
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Affiliation(s)
- Tadashi Satoh
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Mizuho-ku, Nagoya, Japan
- JST, PRESTO, Mizuho-ku, Nagoya, Japan
| | - Kousuke Suzuki
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Mizuho-ku, Nagoya, Japan
- Okazaki Institute for Integrative Bioscience and Institute for Molecular Science, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi, Japan
| | - Takumi Yamaguchi
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Mizuho-ku, Nagoya, Japan
- Okazaki Institute for Integrative Bioscience and Institute for Molecular Science, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi, Japan
| | - Koichi Kato
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Mizuho-ku, Nagoya, Japan
- Okazaki Institute for Integrative Bioscience and Institute for Molecular Science, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi, Japan
- * E-mail:
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218
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Tan NY, Bailey UM, Jamaluddin MF, Mahmud SHB, Raman SC, Schulz BL. Sequence-based protein stabilization in the absence of glycosylation. Nat Commun 2014; 5:3099. [DOI: 10.1038/ncomms4099] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 12/12/2013] [Indexed: 12/12/2022] Open
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219
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Protein quality control and elimination of protein waste: The role of the ubiquitin–proteasome system. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:182-96. [DOI: 10.1016/j.bbamcr.2013.06.031] [Citation(s) in RCA: 292] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 06/28/2013] [Accepted: 06/29/2013] [Indexed: 01/26/2023]
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220
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Liu Y, Li J. Endoplasmic reticulum-mediated protein quality control in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2014; 5:162. [PMID: 24817869 PMCID: PMC4012192 DOI: 10.3389/fpls.2014.00162] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 04/07/2014] [Indexed: 05/19/2023]
Abstract
A correct three-dimensional structure is crucial for the physiological functions of a protein, yet the folding of proteins to acquire native conformation is a fundamentally error-prone process. Eukaryotic organisms have evolved a highly conserved endoplasmic reticulum-mediated protein quality control (ERQC) mechanism to monitor folding processes of secretory and membrane proteins, allowing export of only correctly folded proteins to their physiological destinations, retaining incompletely/mis-folded ones in the ER for additional folding attempts, marking and removing terminally misfolded ones via a unique multiple-step degradation process known as ER-associated degradation (ERAD). Most of our current knowledge on ERQC and ERAD came from genetic and biochemical investigations in yeast and mammalian cells. Recent studies in the reference plant Arabidopsis thaliana uncovered homologous components and similar mechanisms in plants for monitoring protein folding and for retaining, repairing, and removing misfolded proteins. These studies also revealed critical roles of the plant ERQC/ERAD systems in regulating important biochemical/physiological processes, such as abiotic stress tolerance and plant defense. In this review, we discuss our current understanding about the molecular components and biochemical mechanisms of the plant ERQC/ERAD system in comparison to yeast and mammalian systems.
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Affiliation(s)
| | - Jianming Li
- *Correspondence: Jianming Li, Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 4085 Natural Science Building, 830 North University, Ann Arbor, MI 48109-1048, USA e-mail:
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221
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Cytoplasm: ER Stress. Mol Biol 2014. [DOI: 10.1007/978-1-4939-0263-7_9-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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222
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Howell S. ER Stress Signaling in Plants. Mol Biol 2014. [DOI: 10.1007/978-1-4614-7570-5_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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223
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Petäjä-Repo UE, Lackman JJ. Targeting opioid receptors with pharmacological chaperones. Pharmacol Res 2013; 83:52-62. [PMID: 24355364 DOI: 10.1016/j.phrs.2013.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 12/05/2013] [Accepted: 12/05/2013] [Indexed: 11/29/2022]
Abstract
G protein-coupled receptors (GPCRs) are polytopic membrane proteins that have a pivotal role in cellular signaling. Like other membrane proteins, they fold in the endoplasmic reticulum (ER) before they are transported to the plasma membrane. The ER quality control monitors the folding process and misfolded proteins and slowly folding intermediates are targeted to degradation in the cytosol via the ubiquitin-proteasome pathway. The high efficiency of the quality control machinery may lead to the disposal of potentially functional receptors. This is the major underlying course for loss-of-function conformational diseases, such as retinitis pigmentosa, nephrogenic diabetes insipidus and early onset obesity, which involve mutant GPCRs. During the past decade, it has become increasingly evident that small-molecular lipophilic and pharmacologically selective receptor ligands, called pharmacological chaperones (PCs), can rescue these mutant receptors from degradation by stabilizing newly synthesized receptors in the ER and enhancing their transport to the cell surface. This has raised the interesting prospect that PCs might have therapeutic value for the treatment of conformational diseases. At the same time, accumulating evidence has indicated that wild-type receptors might also be targeted by PCs, widening their therapeutic potential. This review focuses on one GPCR subfamily, opioid receptors that have been useful models to unravel the mechanism of action of PCs. In contrast to most other GPCRs, compounds that act as PCs for opioid receptors, including widely used opioid drugs, target wild-type receptors and their common natural variants.
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Affiliation(s)
- Ulla E Petäjä-Repo
- Department of Anatomy and Cell Biology and Medical Research Center Oulu, Institute of Biomedicine, University of Oulu, FI-90014 Oulu, Finland.
| | - Jarkko J Lackman
- Department of Anatomy and Cell Biology and Medical Research Center Oulu, Institute of Biomedicine, University of Oulu, FI-90014 Oulu, Finland
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224
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Allele-specific N-glycosylation delays human surfactant protein B secretion in vitro and associates with decreased protein levels in vivo. Pediatr Res 2013; 74:646-51. [PMID: 24002332 DOI: 10.1038/pr.2013.151] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 04/18/2013] [Indexed: 11/09/2022]
Abstract
BACKGROUND Surfactant protein B (SP-B) is essential for normal lung function, and decreased concentrations of SP-B have a deleterious effect on pulmonary outcome. SP-B levels may correlate with variations in the encoding gene (SFTPB). SFTPB single-nucleotide polymorphism Ile131Thr affects proSP-B N-glycosylation in humans and the glycosylated Thr variant associates with pulmonary diseases. METHODS We analyzed SP-B levels in amniotic fluid samples for associations with SFTPB polymorphisms and generated cell lines expressing either proSP-B/131Ile or proSP-B/131Thr for examining the effect of glycosylation on proSP-B secretion kinetics. To determine any transcription preference between Ile131Thr allelic variants, we used heterozygous human lungs for allelic expression imbalance assays. RESULTS Protein levels correlated with Ile131Thr genotype and the lowest SP-B levels were observed in Thr/Thr homozygotes. Our results suggest that Ile131Thr variation-dependent N-glycosylation associates with decreased levels of SP-B, which is secreted from fetal lung to amniotic fluid. Glycosylated proSP-B/131Thr was secreted from transfected cells at a lower rate than nonglycosylated proSP-B/131Ile. Expression levels of the mRNA variants were equal. Secretion of the glycosylated variant was thus delayed in vitro by a posttranscriptional mechanism. CONCLUSION These data support the hypothesis that proSP-B glycosylation due to Ile131Thr variation may have a causal role in genetic susceptibility to acute respiratory distress.
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225
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Naegeli A, Neupert C, Fan YY, Lin CW, Poljak K, Papini AM, Schwarz F, Aebi M. Molecular analysis of an alternative N-glycosylation machinery by functional transfer from Actinobacillus pleuropneumoniae to Escherichia coli. J Biol Chem 2013; 289:2170-9. [PMID: 24275653 DOI: 10.1074/jbc.m113.524462] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
N-Linked protein glycosylation is a frequent post-translational modification that can be found in all three domains of life. In a canonical, highly conserved pathway, an oligosaccharide is transferred by a membrane-bound oligosaccharyltransferase from a lipid donor to asparagines in the sequon NX(S/T) of secreted polypeptides. The δ-proteobacterium Actinobacillus pleuropneumoniae encodes an unusual pathway for N-linked protein glycosylation. This pathway takes place in the cytoplasm and is mediated by a soluble N-glycosyltransferase (NGT) that uses nucleotide-activated monosaccharides to glycosylate asparagine residues. To characterize the process of cytoplasmic N-glycosylation in more detail, we studied the glycosylation in A. pleuropneumoniae and functionally transferred the glycosylation system to Escherichia coli. N-Linked glucose specific human sera were used for the analysis of the glycosylation process. We identified autotransporter adhesins as the preferred protein substrate of NGT in vivo, and in depth analysis of the modified sites in E. coli revealed a surprisingly relaxed peptide substrate specificity. Although NX(S/T) is the preferred acceptor sequon, we detected glycosylation of alternative sequons, including modification of glutamine and serine residues. We also demonstrate the use of NGT to glycosylate heterologous proteins. Therefore, our study could provide the basis for a novel route for the engineering of N-glycoproteins in bacteria.
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Affiliation(s)
- Andreas Naegeli
- From the Institute of Microbiology, Swiss Federal Institute of Technology, ETH Zurich, CH-8093 Zurich, Switzerland and
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226
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Barry C, Cocinero EJ, Çarçabal P, Gamblin D, Stanca-Kaposta EC, Remmert SM, Fernández-Alonso MC, Rudić S, Simons JP, Davis BG. 'Naked' and hydrated conformers of the conserved core pentasaccharide of N-linked glycoproteins and its building blocks. J Am Chem Soc 2013; 135:16895-903. [PMID: 24127839 PMCID: PMC3901393 DOI: 10.1021/ja4056678] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Indexed: 12/11/2022]
Abstract
N-glycosylation of eukaryotic proteins is widespread and vital to survival. The pentasaccharide unit -Man3GlcNAc2- lies at the protein-junction core of all oligosaccharides attached to asparagine side chains during this process. Although its absolute conservation implies an indispensable role, associated perhaps with its structure, its unbiased conformation and the potential modulating role of solvation are unknown; both have now been explored through a combination of synthesis, laser spectroscopy, and computation. The proximal -GlcNAc-GlcNAc- unit acts as a rigid rod, while the central, and unusual, -Man-β-1,4-GlcNAc- linkage is more flexible and is modulated by the distal Man-α-1,3- and Man-α-1,6- branching units. Solvation stiffens the 'rod' but leaves the distal residues flexible, through a β-Man pivot, ensuring anchored projection from the protein shell while allowing flexible interaction of the distal portion of N-glycosylation with bulk water and biomolecular assemblies.
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Affiliation(s)
- Conor
S. Barry
- Department
of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Emilio J. Cocinero
- Department
of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ United Kingdom
| | - Pierre Çarçabal
- Institut
des Sciences Moléculaire d’Orsay-CNRS, Université Paris Sud, Bâtiment 210, 91405 Orsay Cedex, France
| | - David
P. Gamblin
- Department
of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - E. Cristina Stanca-Kaposta
- Department
of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ United Kingdom
| | - Sarah M. Remmert
- Department
of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ United Kingdom
| | | | - Svemir Rudić
- Department
of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
- Department
of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ United Kingdom
| | - John P. Simons
- Department
of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ United Kingdom
| | - Benjamin G. Davis
- Department
of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom
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227
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Kolb AR, Needham PG, Rothenberg C, Guerriero CJ, Welling PA, Brodsky JL. ESCRT regulates surface expression of the Kir2.1 potassium channel. Mol Biol Cell 2013; 25:276-89. [PMID: 24227888 PMCID: PMC3890348 DOI: 10.1091/mbc.e13-07-0394] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Kir2.1 potassium channel is targeted by endoplasmic reticulum–associated degradation in yeast. To identify other Kir2.1 quality control factors, a novel yeast screen was performed. ESCRT components were among the strongest hits from the screen. Consistent with these data, ESCRT also regulates Kir2.1 stability in human cells. Protein quality control (PQC) is required to ensure cellular health. PQC is recognized for targeting the destruction of defective polypeptides, whereas regulated protein degradation mechanisms modulate the concentration of specific proteins in concert with physiological demands. For example, ion channel levels are physiologically regulated within tight limits, but a system-wide approach to define which degradative systems are involved is lacking. We focus on the Kir2.1 potassium channel because altered Kir2.1 levels lead to human disease and Kir2.1 restores growth on low-potassium medium in yeast mutated for endogenous potassium channels. Using this system, first we find that Kir2.1 is targeted for endoplasmic reticulum–associated degradation (ERAD). Next a synthetic gene array identifies nonessential genes that negatively regulate Kir2.1. The most prominent gene family that emerges from this effort encodes members of endosomal sorting complex required for transport (ESCRT). ERAD and ESCRT also mediate Kir2.1 degradation in human cells, with ESCRT playing a more prominent role. Thus multiple proteolytic pathways control Kir2.1 levels at the plasma membrane.
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Affiliation(s)
- Alexander R Kolb
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15261 Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201
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228
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Metabolically programmed quality control system for dolichol-linked oligosaccharides. Proc Natl Acad Sci U S A 2013; 110:19366-71. [PMID: 24218558 DOI: 10.1073/pnas.1312187110] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The glycolipid Glc3Man9GlcNAc2-pyrophosphate-dolichol serves as the precursor for asparagine (N)-linked protein glycosylation in mammals. The biosynthesis of dolichol-linked oligosaccharides (DLOs) is arrested in low-glucose environments via unknown mechanisms, resulting in abnormal N-glycosylation. Here, we show that under glucose deprivation, DLOs are prematurely degraded during the early stages of DLO biosynthesis by pyrophosphatase, leading to the release of singly phosphorylated oligosaccharides into the cytosol. We identified that the level of GDP-mannose (Man), which serves as a donor substrate for DLO biosynthesis, is substantially reduced under glucose deprivation. We provide evidence that the selective shutdown of the GDP-Man biosynthetic pathway is sufficient to induce the release of phosphorylated oligosaccharides. These results indicate that glucose-regulated metabolic changes in the GDP-Man biosynthetic pathway cause the biosynthetic arrest of DLOs and facilitate their premature degradation by pyrophosphatase. We propose that this degradation system may avoid abnormal N-glycosylation with premature oligosaccharides under conditions that impair efficient DLO biosynthesis.
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229
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Canales A, Mallagaray A, Pérez-Castells J, Boos I, Unverzagt C, André S, Gabius HJ, Cañada FJ, Jiménez-Barbero J. Breaking Pseudo-Symmetry in Multiantennary Complex N-Glycans Using Lanthanide-Binding Tags and NMR Pseudo-Contact Shifts. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201307845] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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230
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Canales A, Mallagaray A, Pérez-Castells J, Boos I, Unverzagt C, André S, Gabius HJ, Cañada FJ, Jiménez-Barbero J. Breaking Pseudo-Symmetry in Multiantennary Complex N-Glycans Using Lanthanide-Binding Tags and NMR Pseudo-Contact Shifts. Angew Chem Int Ed Engl 2013; 52:13789-93. [DOI: 10.1002/anie.201307845] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Indexed: 01/24/2023]
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231
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Crystal structures of an archaeal oligosaccharyltransferase provide insights into the catalytic cycle of N-linked protein glycosylation. Proc Natl Acad Sci U S A 2013; 110:17868-73. [PMID: 24127570 DOI: 10.1073/pnas.1309777110] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Oligosaccharyltransferase transfers an oligosaccharide chain to the asparagine residues in proteins. The archaeal and eubacterial oligosaccharyltransferases are single subunit membrane enzymes, referred to as "AglB" (archaeal glycosylation B) and "PglB" (protein glycosylation B), respectively. Only one crystal structure of a full-length PglB has been solved. Here we report the crystal structures of the full-length AglB from a hyperthermophilic archaeon, Archaeoglobus fulgidus. The AglB and PglB proteins share the common overall topology of the 13 transmembrane helices, and a characteristic long plastic loop in the transmembrane region. This is the structural basis for the formation of the catalytic center, consisting of conserved acidic residues coordinating a divalent metal ion. In one crystal form, a sulfate ion was bound next to the metal ion. This structure appears to represent a dolichol-phosphate binding state, and suggests the release mechanism for the glycosylated product. The structure in the other crystal form corresponds to the resting state conformation with the well-ordered plastic loop in the transmembrane region. The overall structural similarity between the distantly related AglB and PglB proteins strongly indicates the conserved catalytic mechanism in the eukaryotic counterpart, the STT3 (stauroporine and temperature sensitivity 3) protein. The detailed structural comparison provided the dynamic view of the N-glycosylation reaction, involving the conversion between the structured and unstructured states of the plastic loop in the transmembrane region and the formation and collapse of the Ser/Thr-binding pocket in the C-terminal globular domain.
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232
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Allan G, Ouadid-Ahidouch H, Sanchez-Fernandez EM, Risquez-Cuadro R, Fernandez JMG, Ortiz-Mellet C, Ahidouch A. New castanospermine glycoside analogues inhibit breast cancer cell proliferation and induce apoptosis without affecting normal cells. PLoS One 2013; 8:e76411. [PMID: 24124558 PMCID: PMC3790671 DOI: 10.1371/journal.pone.0076411] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 08/30/2013] [Indexed: 12/15/2022] Open
Abstract
sp2-Iminosugar-type castanospermine analogues have been shown to exhibit anti-tumor activity. However, their effects on cell proliferation and apoptosis and the molecular mechanism at play are not fully understood. Here, we investigated the effect of two representatives, namely the pseudo-S- and C-octyl glycoside 2-oxa-3-oxocastanospermine derivatives SO-OCS and CO-OCS, on MCF-7 and MDA-MB-231 breast cancer and MCF-10A mammary normal cell lines. We found that SO-OCS and CO-OCS inhibited breast cancer cell viability in a concentration- and time-dependent manner. This effect is specific to breast cancer cells as both molecules had no impact on normal MCF-10A cell proliferation. Both drugs induced a cell cycle arrest. CO-OCS arrested cell cycle at G1 and G2/M in MCF-7 and MDA-MB-231cells respectively. In MCF-7 cells, the G1 arrest is associated with a reduction of CDK4 (cyclin-dependent kinase 4), cyclin D1 and cyclin E expression, pRb phosphorylation, and an overexpression of p21Waf1/Cip1. In MDA-MB-231 cells, CO-OCS reduced CDK1 but not cyclin B1 expression. SO-OCS accumulated cells in G2/M in both cell lines and this blockade was accompanied by a decrease of CDK1, but not cyclin B1 expression. Furthermore, both drugs induced apoptosis as demonstrated by the increased percentage of annexin V positive cells and Bax/Bcl-2 ratio. Interestingly, in normal MCF-10A cells the two drugs failed to modify cell proliferation, cell cycle progression, cyclins, or CDKs expression. These results demonstrate that the effect of CO-OCS and SO-OCS is triggered by both cell cycle arrest and apoptosis, suggesting that these castanospermine analogues may constitute potential anti-cancer agents against breast cancer.
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Affiliation(s)
- Ghada Allan
- Laboratory of Cellular and Molecular Physiology (EA 4667), SFR CAP-SANTE (FED 4132), UFR of Sciences, UPJV, Amiens, France
| | - Halima Ouadid-Ahidouch
- Laboratory of Cellular and Molecular Physiology (EA 4667), SFR CAP-SANTE (FED 4132), UFR of Sciences, UPJV, Amiens, France
- * E-mail: (HOA); (AA)
| | | | - Rocío Risquez-Cuadro
- Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, Sevilla, Spain
| | | | - Carmen Ortiz-Mellet
- Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, Sevilla, Spain
| | - Ahmed Ahidouch
- Laboratory of Cellular and Molecular Physiology (EA 4667), SFR CAP-SANTE (FED 4132), UFR of Sciences, UPJV, Amiens, France
- Department of Biology, Faculty of Sciences, University Ibn Zohr, Agadir, Morocco
- * E-mail: (HOA); (AA)
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233
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Morgan GW, Kail M, Hollinshead M, Vaux DJ. Combined biochemical and cytological analysis of membrane trafficking using lectins. Anal Biochem 2013; 441:21-31. [PMID: 23756734 DOI: 10.1016/j.ab.2013.05.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 05/30/2013] [Accepted: 05/31/2013] [Indexed: 02/03/2023]
Abstract
We have tested the application of high-mannose-binding lectins as analytical reagents to identify N-glycans in the early secretory pathway of HeLa cells during subcellular fractionation and cytochemistry. Post-endoplasmic reticulum (ER) pre-Golgi intermediates were separated from the ER on Nycodenz-sucrose gradients, and the glycan composition of each gradient fraction was profiled using lectin blotting. The fractions containing the post-ER pre-Golgi intermediates are found to contain a subset of N-linked α-mannose glycans that bind the lectins Galanthus nivalis agglutinin (GNA), Pisum sativum agglutinin (PSA), and Lens culinaris agglutinin (LCA) but not lectins binding Golgi-modified glycans. Cytochemical analysis demonstrates that high-mannose-containing glycoproteins are predominantly localized to the ER and the early secretory pathway. Indirect immunofluorescence microscopy revealed that GNA colocalizes with the ER marker protein disulfide isomerase (PDI) and the COPI coat protein β-COP. In situ competition with concanavalin A (ConA), another high-mannose specific lectin, and subsequent GNA lectin histochemistry refined the localization of N-glyans containing nonreducing mannosyl groups, accentuating the GNA vesicular staining. Using GNA and treatments that perturb ER-Golgi transport, we demonstrate that lectins can be used to detect changes in membrane trafficking pathways histochemically. Overall, we find that conjugated plant lectins are effective tools for combinatory biochemical and cytological analysis of membrane trafficking of glycoproteins.
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Affiliation(s)
- Gareth W Morgan
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
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234
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Harada Y, Buser R, Ngwa EM, Hirayama H, Aebi M, Suzuki T. Eukaryotic oligosaccharyltransferase generates free oligosaccharides during N-glycosylation. J Biol Chem 2013; 288:32673-32684. [PMID: 24062310 DOI: 10.1074/jbc.m113.486985] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Asparagine (N)-linked glycosylation regulates numerous cellular activities, such as glycoprotein quality control, intracellular trafficking, and cell-cell communications. In eukaryotes, the glycosylation reaction is catalyzed by oligosaccharyltransferase (OST), a multimembrane protein complex that is localized in the endoplasmic reticulum (ER). During N-glycosylation in the ER, the protein-unbound form of oligosaccharides (free oligosaccharides; fOSs), which is structurally related to N-glycan, is released into the ER lumen. However, the enzyme responsible for this process remains unidentified. Here, we demonstrate that eukaryotic OST generates fOSs. Biochemical and genetic analyses using mutant strains of Saccharomyces cerevisiae revealed that the generation of fOSs is tightly correlated with the N-glycosylation activity of OST. Furthermore, we present evidence that the purified OST complex can generate fOSs by hydrolyzing dolichol-linked oligosaccharide, the glycan donor substrate for N-glycosylation. The heterologous expression of a single subunit of OST from the protozoan Leishmania major in S. cerevisiae demonstrated that this enzyme functions both in N-glycosylation and generation of fOSs. This study provides insight into the mechanism of PNGase-independent formation of fOSs.
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Affiliation(s)
- Yoichiro Harada
- From the Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Reto Buser
- the Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Elsy M Ngwa
- the Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Hiroto Hirayama
- From the Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Markus Aebi
- the Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Tadashi Suzuki
- From the Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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Olzmann JA, Kopito RR, Christianson JC. The mammalian endoplasmic reticulum-associated degradation system. Cold Spring Harb Perspect Biol 2013; 5:cshperspect.a013185. [PMID: 23232094 DOI: 10.1101/cshperspect.a013185] [Citation(s) in RCA: 253] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The endoplasmic reticulum (ER) is the site of synthesis for nearly one-third of the eukaryotic proteome and is accordingly endowed with specialized machinery to ensure that proteins deployed to the distal secretory pathway are correctly folded and assembled into native oligomeric complexes. Proteins failing to meet this conformational standard are degraded by ER-associated degradation (ERAD), a complex process through which folding-defective proteins are selected and ultimately degraded by the ubiquitin-proteasome system. ERAD proceeds through four tightly coupled steps involving substrate selection, dislocation across the ER membrane, covalent conjugation with polyubiquitin, and proteasomal degradation. The ERAD machinery shows a modular organization with central ER membrane-embedded ubiquitin ligases linking components responsible for recognition in the ER lumen to the ubiquitin-proteasome system in the cytoplasm. The core ERAD machinery is highly conserved among eukaryotes and much of our basic understanding of ERAD organization has been derived from genetic and biochemical studies of yeast. In this article we discuss how the core ERAD machinery is organized in mammalian cells.
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Affiliation(s)
- James A Olzmann
- Department of Biology, Stanford University, Stanford, California 94305, USA
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236
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Carneiro P, Figueiredo J, Bordeira-Carriço R, Fernandes MS, Carvalho J, Oliveira C, Seruca R. Therapeutic targets associated to E-cadherin dysfunction in gastric cancer. Expert Opin Ther Targets 2013; 17:1187-201. [PMID: 23957294 DOI: 10.1517/14728222.2013.827174] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Epithelial cadherin (E-cadherin) plays a key role in epithelial cell-cell adhesion, contributing to tissue differentiation and homeostasis. Throughout the past decades, research has shed light on the molecular mechanisms underlying E-cadherin's role in tumor progression, namely in invasion and metastization. Emerging evidence established E-cadherin as a tumor suppressor and suggests that targeting E-cadherin or downstream signaling molecules may constitute effective cancer therapeutics. AREAS COVERED This review aims to cover E-cadherin-mediated signaling during cancer development and progression and highlight putative therapeutic targets. EXPERT OPINION Reconstitution of E-cadherin expression or targeting of E-cadherin downstream molecules holds promise in cancer therapies. Considering the high frequency of CDH1 promoter hypermethylation as a second hit in malignant lesions from hereditary diffuse gastric cancer patients, histone deacetylase inhibitors are potential therapeutic agents in combination with conventional chemotherapy, specifically in initial tumor stages. Concerning E-cadherin-mediated signaling, we propose that HER receptors (as epidermal growth factor receptor) and Notch downstream targets are clinically relevant and should be considered in gastric cancer therapeutics and control.
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Affiliation(s)
- Patrícia Carneiro
- IPATIMUP, Institute of Molecular Pathology and Immunology of the University of Porto , Rua Dr. Roberto Frias s/n, 4200-465 Porto , Portugal +00351 225570700 ; +00351 225570799 ;
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237
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Santos CN, Alves M, Oliveira A, Ferreira RB. β-N-Acetylhexosaminidase involvement in α-conglutin mobilization in Lupinus albus. JOURNAL OF PLANT PHYSIOLOGY 2013; 170:1047-1056. [PMID: 23602380 DOI: 10.1016/j.jplph.2013.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 02/26/2013] [Accepted: 03/07/2013] [Indexed: 06/02/2023]
Abstract
Glycosylation is an important post-translational modification involved in the modulation of a wide variety of cellular processes. Because glycosydases are central, the aim of this study was to investigate the glycosyl activity present in the cotyledons of the seeds of an important crop legume, Lupinus albus, as well as potential natural substrates of the detected enzymes. The glycosyl activity detected in the cotyledons beginning at seed imbibition and continuing until 9 days after, was due to a β-N-acetylhexosaminidase (β-NAHase), which was molecularly and biochemically characterized after purification. Two isoenzymes with molecular masses of 64 and 61 kDa were detected, each having five isoenzymes with pIs 5.3-5.6. The 64 and 61 kDa isoenzymes had the same protein core showing different degrees of glycosylation. The N-terminal sequence of the enzyme protein core was determined [VDSEDLI(EN)AFKIYVEDDNEHLQGSVD] and to our knowledge, is the first reported protein sequence from a plant β-NAHase. L. albus β-NAHase had Km values of 2.59 mM and 2.94 mM and V values of 18.40 μM min(-1) and 2.73 μM min(-1), for pNP-GlcNAc and pNP-GalNAc, an optimum pH of 5.0 and 4.0 and temperature of 50 °C and 60 °C were detected toward pNP-GlcNAc and pNP-GalNAc. In the presence of AgNO3, CoCl2, CuSO4, FeCl3, CdCl2 and ZnCl2 the enzymatic activity decreased more than 50%, and when in the presence of sugars, an activity reduction of no more than 25% was observed. A physiological role for β-NAHase in L. albus storage protein mobilization was investigated. β-NAHase has already been implicated in several biological processes, namely in glycoprotein processing during seed germination and seedling growth. However, the natural substrates used by this enzyme are not yet completely clarified. By gathering in vivo and in vitro data for β-NAHase activity together with globulin degradation, we suggest that L. albus β-NAHase is involved in the mobilization of storage protein degradation, with α-conglutin being a potential natural substrate for this enzyme.
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Affiliation(s)
- Cláudia N Santos
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127, 2781-901 Oeiras, Portugal
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238
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Pan S, Cheng X, Chen H, Castro PD, Ittmann MM, Hutson AW, Zapata SK, Sifers RN. ERManI is a target of miR-125b and promotes transformation phenotypes in hepatocellular carcinoma (HCC). PLoS One 2013; 8:e72829. [PMID: 23940818 PMCID: PMC3733964 DOI: 10.1371/journal.pone.0072829] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 07/14/2013] [Indexed: 02/07/2023] Open
Abstract
The MAN1B1 gene product, designated ER alpha-1, 2-mannosidase (ERManI), is an enzyme localized in the Golgi complex of mammalian cells. By functioning as a "gate keeper" to prevent the inappropriate secretion of misfolded glycoproteins, it plays a critical role in maintaining protein homeostasis in the mammalian secretory pathway. In the present study, we identified that a conserved motif within the 3'UTR of ERManI is a target of miR-125b, a microRNA frequently down-regulated in numerous types of cancers, including hepatocellular carcinoma (HCC). As predicted, the expression of ERManI is significantly elevated in HCC, as measured by immunohistochemistry in a liver spectrum tissue microarray. Additional analyses using several hepatoma cell lines demonstrated that the elevated ERManI inversely correlates with a diminished intracellular concentration of miR-125b. Moreover, functional studies indicated that RNAi-mediated knock-down of endogenous ERManI was sufficient to inhibit proliferation, migration, and invasion of hepatoma cells. These phenotypical changes occurred in the absence of alterations in global glycoprotein secretion or ER-stress status. Together, these results revealed a novel post-transcriptional regulatory mechanism for ERManI and implied that this molecule contributes to the regulation of carcinogenesis in HCC independent of its function in glycoprotein quality control.
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Affiliation(s)
- Shujuan Pan
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Xiaoyun Cheng
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Lymphoma & Myeloma, University of Texas-M D Anderson Cancer Center, Houston, Texas, United States of America
| | - Hongan Chen
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Participant in the Baylor College of Medicine Summer Medical and Research Training Program, Baylor College of Medicine, Houston, Texas, United States of America
| | - Patricia D. Castro
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Michael M. Ittmann
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Anne W. Hutson
- Department of Pediatrics-Gastroenterology, Hepatology & Nutrition, Baylor College of Medicine, Houston, Texas, United States of America
| | - Susan K. Zapata
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Richard N. Sifers
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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239
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Breitling J, Aebi M. N-linked protein glycosylation in the endoplasmic reticulum. Cold Spring Harb Perspect Biol 2013; 5:a013359. [PMID: 23751184 DOI: 10.1101/cshperspect.a013359] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The attachment of glycans to asparagine residues of proteins is an abundant and highly conserved essential modification in eukaryotes. The N-glycosylation process includes two principal phases: the assembly of a lipid-linked oligosaccharide (LLO) and the transfer of the oligosaccharide to selected asparagine residues of polypeptide chains. Biosynthesis of the LLO takes place at both sides of the endoplasmic reticulum (ER) membrane and it involves a series of specific glycosyltransferases that catalyze the assembly of the branched oligosaccharide in a highly defined way. Oligosaccharyltransferase (OST) selects the Asn-X-Ser/Thr consensus sequence on polypeptide chains and generates the N-glycosidic linkage between the side-chain amide of asparagine and the oligosaccharide. This ER-localized pathway results in a systemic modification of the proteome, the basis for the Golgi-catalyzed modification of the N-linked glycans, generating the large diversity of N-glycoproteome in eukaryotic cells. This article focuses on the processes in the ER. Based on the highly conserved nature of this pathway we concentrate on the mechanisms in the eukaryotic model organism Saccharomyces cerevisiae.
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Affiliation(s)
- Jörg Breitling
- Institute of Microbiology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
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240
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Lakkaraju A, van der Goot F. Calnexin Controls the STAT3-Mediated Transcriptional Response to EGF. Mol Cell 2013; 51:386-96. [DOI: 10.1016/j.molcel.2013.07.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 06/10/2013] [Accepted: 06/26/2013] [Indexed: 01/05/2023]
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241
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Bestebroer J, V'kovski P, Mauthe M, Reggiori F. Hidden behind autophagy: the unconventional roles of ATG proteins. Traffic 2013; 14:1029-41. [PMID: 23837619 PMCID: PMC7169877 DOI: 10.1111/tra.12091] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/03/2013] [Accepted: 07/09/2013] [Indexed: 12/27/2022]
Abstract
Macroautophagy (hereafter referred to as autophagy) is an evolutionarily conserved intracellular catabolic transport route that generally allows the lysosomal degradation of cytoplasmic components, including bulk cytosol, protein aggregates, damaged or superfluous organelles and invading microbes. Target structures are sequestered by double‐membrane vesicles called autophagosomes, which are formed through the concerted action of the autophagy (ATG)‐related proteins. Until recently it was assumed that ATG proteins were exclusively involved in autophagy. A growing number of studies, however, have attributed functions to some of them that are distinct from their classical role in autophagosome biogenesis. Autophagy‐independent roles of the ATG proteins include the maintenance of cellular homeostasis and resistance to pathogens. For example, they assist and enhance the turnover of dead cells and microbes upon their phagocytic engulfment, and inhibit murine norovirus replication. Moreover, bone resorption by osteoclasts, innate immune regulation triggered by cytoplasmic DNA and the ER‐associated degradation regulation all have in common the requirement of a subset of ATG proteins. Microorganisms such as coronaviruses, Chlamydia trachomatis or Brucella abortus have even evolved ways to manipulate autophagy‐independent functions of ATG proteins in order to ensure the completion of their intracellular life cycle. Taken together these novel mechanisms add to the repertoire of functions and extend the number of cellular processes involving the ATG proteins.
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Affiliation(s)
- Jovanka Bestebroer
- Department of Medical Microbiology, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands; Department of Cell Biology and Institute of Biomembranes, University Medical Centre Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands
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242
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Xu J, Xu M, Brown T, Rossi GC, Hurd YL, Inturrisi CE, Pasternak GW, Pan YX. Stabilization of the μ-opioid receptor by truncated single transmembrane splice variants through a chaperone-like action. J Biol Chem 2013; 288:21211-21227. [PMID: 23760268 DOI: 10.1074/jbc.m113.458687] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The μ-opioid receptor gene, OPRM1, undergoes extensive alternative pre-mRNA splicing, as illustrated by the identification of an array of splice variants generated by both 5' and 3' alternative splicing. The current study reports the identification of another set of splice variants conserved across species that are generated through exon skipping or insertion that encodes proteins containing only a single transmembrane (TM) domain. Using a Tet-Off system, we demonstrated that the truncated single TM variants can dimerize with the full-length 7-TM μ-opioid receptor (MOR-1) in the endoplasmic reticulum, leading to increased expression of MOR-1 at the protein level by a chaperone-like function that minimizes endoplasmic reticulum-associated degradation. In vivo antisense studies suggested that the single TM variants play an important role in morphine analgesia, presumably through modulation of receptor expression levels. Our studies suggest the functional roles of truncated receptors in other G protein-coupled receptor families.
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Affiliation(s)
- Jin Xu
- From the Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Ming Xu
- From the Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Taylor Brown
- From the Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065
| | - Grace C Rossi
- the Department of Psychology, CW Post College, Long Island University, Brookville, New York 11568
| | - Yasmin L Hurd
- the Department of Psychiatry and Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York 10029, and
| | - Charles E Inturrisi
- the Department of Pharmacology, Weill Cornell Medical College, New York, New York 10065
| | - Gavril W Pasternak
- From the Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065,; the Department of Pharmacology, Weill Cornell Medical College, New York, New York 10065.
| | - Ying-Xian Pan
- From the Department of Neurology and the Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065,.
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243
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Hecht KA, Wytiaz VA, Ast T, Schuldiner M, Brodsky JL. Characterization of an M28 metalloprotease family member residing in the yeast vacuole. FEMS Yeast Res 2013; 13:471-84. [PMID: 23679341 DOI: 10.1111/1567-1364.12050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 04/29/2013] [Accepted: 05/09/2013] [Indexed: 11/26/2022] Open
Abstract
The systematic and complete characterization of the Saccharomyces cerevisiae genome and proteome has been stalled in some cases by misannotated genes. One such gene is YBR074W, which was initially annotated as two independent open reading frames (ORFs). We now report on Ybr074, a metalloprotease family member that was initially predicted to reside in the endoplasmic reticulum (ER). Therefore, we tested the hypothesis that Ybr074 may be an ER quality control protease. Instead, indirect immunofluorescence images indicate that Ybr074 is a vacuolar protein, and by employing protease protection assays, we demonstrate that a conserved M28 metalloprotease domain is oriented within the lumen. Involvement of Ybr074 in ER protein quality control was ruled out by examining the stabilities of several well-characterized substrates in strains lacking Ybr074. Finally, using a proteomic approach, we show that disrupting Ybr074 function affects the levels of select factors implicated in vacuolar trafficking and osmoregulation. Together, our data indicate that Ybr074 is the only multispanning vacuolar membrane protease found in the yeast Saccharomyces cerevisiae.
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Affiliation(s)
- Karen A Hecht
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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244
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Unique N-linked glycosylation of CasBrE Env influences its stability, processing, and viral infectivity but not its neurotoxicity. J Virol 2013; 87:8372-87. [PMID: 23698308 DOI: 10.1128/jvi.00392-13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The envelope protein (Env) from the CasBrE murine leukemia virus (MLV) can cause acute spongiform neurodegeneration analogous to that induced by prions. Upon central nervous system (CNS) infection, Env is expressed as multiple isoforms owing to differential asparagine (N)-linked glycosylation. Because N-glycosylation can affect protein folding, stability, and quality control, we explored whether unique CasBrE Env glycosylation features could influence neurovirulence. CasBrE Env possesses 6/8 consensus MLV glycosylation sites (gs) but is missing gs3 and gs5 and contains a putative site (gs*). Twenty-nine mutants were generated by modifying these three sites, individually or in combination, to mimic the amino acid sequence in the nonneurovirulent Friend 57 MLV. Three basic viral phenotypes were observed: replication defective (dead; titer < 1 focus-forming unit [FFU]/ml), replication compromised (RC) (titer = 10(2) to 10(5) FFU/ml); and wild-type-like (WTL) (titer > 10(5) FFU/ml). Env protein was undetectable in dead mutants, while RC and WTL mutants showed variations in Env expression, processing, virus incorporation, virus entry, and virus spread. The newly introduced gs3 and gs5 sites were glycosylated, whereas gs* was not. Six WTL mutants tested in mice showed no clear attenuation in disease onset or severity versus controls. Furthermore, three RC viruses tested by neural stem cell (NSC)-mediated brainstem dissemination also induced acute spongiosis. Thus, while unique N-glycosylation affected structural features of Env involved in protein stability, proteolytic processing, and virus assembly and entry, these changes had minimal impact on CasBrE Env neurotoxicity. These findings suggest that the Env protein domains responsible for spongiogenesis represent highly stable elements upon which the more variable viral functional domains have evolved.
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245
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de la Morena-Barrio ME, Buil A, Antón AI, Martínez-Martínez I, Miñano A, Gutiérrez-Gallego R, Navarro-Fernández J, Aguila S, Souto JC, Vicente V, Soria JM, Corral J. Identification of antithrombin-modulating genes. Role of LARGE, a gene encoding a bifunctional glycosyltransferase, in the secretion of proteins? PLoS One 2013; 8:e64998. [PMID: 23705025 PMCID: PMC3660365 DOI: 10.1371/journal.pone.0064998] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 04/22/2013] [Indexed: 12/26/2022] Open
Abstract
The haemostatic relevance of antithrombin together with the low genetic variability of SERPINC1, and the high heritability of plasma levels encourage the search for modulating genes. We used a hypothesis-free approach to identify these genes, evaluating associations between plasma antithrombin and 307,984 polymorphisms in the GAIT study (352 individuals from 21 Spanish families). Despite no SNP reaching the genome wide significance threshold, we verified milder positive associations in 307 blood donors from a different cohort. This validation study suggested LARGE, a gene encoding a protein with xylosyltransferase and glucuronyltransferase activities that forms heparin-like linear polysaccharides, as a potential modulator of antithrombin based on the significant association of one SNPs, rs762057, with anti-FXa activity, particularly after adjustment for age, sex and SERPINC1 rs2227589 genotype, all factors influencing antithrombin levels (p = 0.02). Additional results sustained this association. LARGE silencing inHepG2 and HEK-EBNA cells did not affect SERPINC1 mRNA levels but significantly reduced the secretion of antithrombin with moderate intracellular retention. Milder effects were observed on α1-antitrypsin, prothrombin and transferrin. Our study suggests LARGE as the first known modifier of plasma antithrombin, and proposes a new role for LARGE in modulating extracellular secretion of certain glycoproteins.
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Affiliation(s)
- María Eugenia de la Morena-Barrio
- Centro Regional de Hemodonación, Servicio de Hematología y Oncología Médica, HU Morales Meseguer, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Murcia, Spain
| | - Alfonso Buil
- Unitat de Genòmica de Malalties Complexes, Institutd'Investigació Sant Pau (IIB-Sant), Barcelona, Spain
| | - Ana Isabel Antón
- Centro Regional de Hemodonación, Servicio de Hematología y Oncología Médica, HU Morales Meseguer, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Murcia, Spain
| | - Irene Martínez-Martínez
- Centro Regional de Hemodonación, Servicio de Hematología y Oncología Médica, HU Morales Meseguer, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Murcia, Spain
| | - Antonia Miñano
- Centro Regional de Hemodonación, Servicio de Hematología y Oncología Médica, HU Morales Meseguer, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Murcia, Spain
| | - Ricardo Gutiérrez-Gallego
- Bio-analysis group, Neurosciences Research Program, IMIM Parc Salut Mar, PRBB, Barcelona, Spain
- Department of Experimental and Health Sciences, Pompeu Fabra University, PRBB, Barcelona, Spain
| | - José Navarro-Fernández
- Centro Regional de Hemodonación, Servicio de Hematología y Oncología Médica, HU Morales Meseguer, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Murcia, Spain
| | - Sonia Aguila
- Centro Regional de Hemodonación, Servicio de Hematología y Oncología Médica, HU Morales Meseguer, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Murcia, Spain
| | - Juan Carlos Souto
- Unitat d'Hemostasia i Trombosis. Institut d'Investigació Sant Pau (IIB-Sant), Barcelona, Spain
| | - Vicente Vicente
- Centro Regional de Hemodonación, Servicio de Hematología y Oncología Médica, HU Morales Meseguer, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Murcia, Spain
| | - José Manuel Soria
- Unitat de Genòmica de Malalties Complexes, Institutd'Investigació Sant Pau (IIB-Sant), Barcelona, Spain
| | - Javier Corral
- Centro Regional de Hemodonación, Servicio de Hematología y Oncología Médica, HU Morales Meseguer, Regional Campus of International Excellence "Campus Mare Nostrum" University of Murcia, Murcia, Spain
- * E-mail:
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Takeda Y, Seko A, Sakono M, Hachisu M, Koizumi A, Fujikawa K, Ito Y. Parallel quantification of lectin-glycan interaction using ultrafiltration. Carbohydr Res 2013; 375:112-7. [PMID: 23701871 DOI: 10.1016/j.carres.2013.04.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 04/24/2013] [Accepted: 04/26/2013] [Indexed: 01/23/2023]
Abstract
Using ultrafiltration membrane, a simple method for screening protein-ligand interaction was developed. The procedure comprises three steps: mixing ligand with protein, ultrafiltration of the solution, and quantification of unbound ligands by HPLC. By conducting analysis with variable protein concentrations, affinity constants were easily obtained. Multiple ligands can be analyzed simultaneously as a mixture, when concentration of ligands was controlled. Feasibility of this method for lectin-glycan interaction analysis was examined using fluorescently labeled high-mannose-type glycans and recombinant intracellular lectins or endo-α-mannosidase mutants. Estimated Ka values of malectin and VIP36 were in good agreement indeed with those evaluated by conventional methods such as isothermal titration calorimetry (ITC) or frontal affinity chromatography (FAC). Finally, several mutants of endo-α-mannosidase were produced and their affinities to monoglucosylated glycans were evaluated.
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Affiliation(s)
- Yoichi Takeda
- Japan Science and Technology Agency (JST), ERATO, Ito Glycotrilogy Project, Wako, Saitama, Japan.
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247
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Guerriero CJ, Weiberth KF, Brodsky JL. Hsp70 targets a cytoplasmic quality control substrate to the San1p ubiquitin ligase. J Biol Chem 2013; 288:18506-20. [PMID: 23653356 DOI: 10.1074/jbc.m113.475905] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Accumulation of misfolded proteins in cellular compartments can result in stress-induced cell death. In the endoplasmic reticulum (ER), ER-associated degradation clears aberrant proteins from the secretory pathway. In the cytoplasm and nucleus, this job is left to the cytoplasmic quality control (CytoQC) machinery. Both processes utilize chaperones and the ubiquitin-proteasome system to aid in protein elimination. Previous studies in yeast have drawn comparisons between these processes using data from structurally and topologically different substrates. We sought to draw a direct comparison between ERAD and CytoQC by studying the elimination of a single misfolded domain that, depending on its residence, is disposed by either of these pathways. The truncated, second nucleotide binding domain (NBD2*) from a yeast ERAD substrate, Ste6p*, resides at the cytoplasmic face of the ER. We show that a soluble form of NBD2* is cytoplasmic and unlike wild-type NBD2 is targeted for proteasome-mediated degradation. In contrast to Ste6p*, which employs the ER-localized Doa10p ubiquitin ligase, NBD2* is ubiquitinated by a nuclear E3 ligase San1p, a factor that is also required for its degradation. Although the yeast cytoplasmic Hsp70 chaperone, Ssa1p, has been thought to facilitate the nuclear import or to maintain the solubility of most CytoQC substrates, we discovered that Ssa1p facilitates the interaction between San1p and NBD2*, demonstrating that chaperones can aid in substrate recognition and San1p-dependent protein degradation. These results emphasize the diverse action of molecular chaperones during CytoQC.
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Affiliation(s)
- Christopher J Guerriero
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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Buck TM, Plavchak L, Roy A, Donnelly BF, Kashlan OB, Kleyman TR, Subramanya AR, Brodsky JL. The Lhs1/GRP170 chaperones facilitate the endoplasmic reticulum-associated degradation of the epithelial sodium channel. J Biol Chem 2013; 288:18366-80. [PMID: 23645669 DOI: 10.1074/jbc.m113.469882] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epithelial sodium channel, ENaC, plays a critical role in maintaining salt and water homeostasis, and not surprisingly defects in ENaC function are associated with disease. Like many other membrane-spanning proteins, this trimeric protein complex folds and assembles inefficiently in the endoplasmic reticulum (ER), which results in a substantial percentage of the channel being targeted for ER-associated degradation (ERAD). Because the spectrum of factors that facilitates the degradation of ENaC is incomplete, we developed yeast expression systems for each ENaC subunit. We discovered that a conserved Hsp70-like chaperone, Lhs1, is required for maximal turnover of the ENaC α subunit. By expressing Lhs1 ATP binding mutants, we also found that the nucleotide exchange properties of this chaperone are dispensable for ENaC degradation. Consistent with the precipitation of an Lhs1-αENaC complex, Lhs1 holdase activity was instead most likely required to support the ERAD of αENaC. Moreover, a complex containing the mammalian Lhs1 homolog GRP170 and αENaC co-precipitated, and GRP170 also facilitated ENaC degradation in human, HEK293 cells, and in a Xenopus oocyte expression system. In both yeast and higher cell types, the effect of Lhs1 on the ERAD of αENaC was selective for the unglycosylated form of the protein. These data establish the first evidence that Lhs1/Grp170 chaperones can act as mediators of ERAD substrate selection.
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Affiliation(s)
- Teresa M Buck
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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Dumax-Vorzet A, Roboti P, High S. OST4 is a subunit of the mammalian oligosaccharyltransferase required for efficient N-glycosylation. J Cell Sci 2013; 126:2595-606. [PMID: 23606741 PMCID: PMC3687696 DOI: 10.1242/jcs.115410] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The eukaryotic oligosaccharyltransferase (OST) is a membrane-embedded protein complex that catalyses the N-glycosylation of nascent polypeptides in the lumen of the endoplasmic reticulum (ER), a highly conserved biosynthetic process that enriches protein structure and function. All OSTs contain a homologue of the catalytic STT3 subunit, although in many cases this is assembled with several additional components that influence function. In S. cerevisiae, one such component is Ost4p, an extremely small membrane protein that appears to stabilise interactions between subunits of assembled OST complexes. OST4 has been identified as a putative human homologue, but to date neither its relationship to the OST complex, nor its role in protein N-glycosylation, have been directly addressed. Here, we establish that OST4 is assembled into native OST complexes containing either the catalytic STT3A or STT3B isoforms. Co-immunoprecipitation studies suggest that OST4 associates with both STT3 isoforms and with ribophorin I, an accessory subunit of mammalian OSTs. These presumptive interactions are perturbed by a single amino acid change in the transmembrane region of OST4. Using siRNA knockdowns and native gel analysis, we show that OST4 plays an important role in maintaining the stability of native OST complexes. Hence, upon OST4 depletion well-defined OST complexes are partially destabilised and a novel ribophorin I-containing subcomplex can be detected. Strikingly, cells depleted of either OST4 or STT3A show a remarkably similar defect in the N-glycosylation of endogenous prosaposin. We conclude that OST4 most likely promotes co-translational N-glycosylation by stabilising STT3A-containing OST isoforms.
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Affiliation(s)
- Audrey Dumax-Vorzet
- Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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250
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Merulla J, Fasana E, Soldà T, Molinari M. Specificity and Regulation of the Endoplasmic Reticulum-Associated Degradation Machinery. Traffic 2013; 14:767-77. [DOI: 10.1111/tra.12068] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/18/2013] [Accepted: 03/23/2013] [Indexed: 02/05/2023]
Affiliation(s)
| | - Elisa Fasana
- Institute for Research in Biomedicine; Protein Folding and Quality Control; CH-6500; Bellinzona; Switzerland
| | - Tatiana Soldà
- Institute for Research in Biomedicine; Protein Folding and Quality Control; CH-6500; Bellinzona; Switzerland
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