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The in silico characterization of neutral alpha-glucosidase C (GANC) and its evolution from GANAB. Gene X 2020; 726:144192. [DOI: 10.1016/j.gene.2019.144192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 07/26/2019] [Accepted: 10/20/2019] [Indexed: 11/21/2022] Open
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2
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Satoh T, Kato K. Structural Aspects of ER Glycoprotein Quality-Control System Mediated by Glucose Tagging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1104:149-169. [PMID: 30484248 DOI: 10.1007/978-981-13-2158-0_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
N-linked oligosaccharides attached to proteins act as tags for glycoprotein quality control, ensuring their appropriate folding and trafficking in cells. Interactions with a variety of intracellular lectins determine glycoprotein fates. Monoglucosylated glycoforms are the hallmarks of incompletely folded glycoproteins in the protein quality-control system, in which glucosidase II and UDP-glucose/glycoprotein glucosyltransferase are, respectively, responsible for glucose trimming and attachment. In this review, we summarize a recently emerging view of the structural basis of the functional mechanisms of these key enzymes as well as substrate N-linked oligosaccharides exhibiting flexible structures, as revealed by applying a series of biophysical techniques including small-angle X-ray scattering, X-ray crystallography, high-speed atomic force microscopy , electron microscopy , and computational simulation in conjunction with NMR spectroscopy.
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Affiliation(s)
- Tadashi Satoh
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Aichi, Japan
| | - Koichi Kato
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Aichi, Japan. .,Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki, Aichi, Japan.
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3
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Satoh T, Toshimori T, Noda M, Uchiyama S, Kato K. Interaction mode between catalytic and regulatory subunits in glucosidase II involved in ER glycoprotein quality control. Protein Sci 2016; 25:2095-2101. [PMID: 27576940 DOI: 10.1002/pro.3031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 08/28/2016] [Accepted: 08/29/2016] [Indexed: 12/18/2022]
Abstract
The glycoside hydrolase family 31 (GH31) α-glucosidases play vital roles in catabolic and regulated degradation, including the α-subunit of glucosidase II (GIIα), which catalyzes trimming of the terminal glucose residues of N-glycan in glycoprotein processing coupled with quality control in the endoplasmic reticulum (ER). Among the known GH31 enzymes, only GIIα functions with its binding partner, regulatory β-subunit (GIIβ), which harbors a lectin domain for substrate recognition. Although the structural data have been reported for GIIα and the GIIβ lectin domain, the interaction mode between GIIα and GIIβ remains unknown. Here, we determined the structure of a complex formed between GIIα and the GIIα-binding domain of GIIβ, thereby providing a structural basis underlying the functional extension of this unique GH31 enzyme.
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Affiliation(s)
- Tadashi Satoh
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan. .,JST, PRESTO, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan.
| | - Takayasu Toshimori
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan.,Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.,Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan
| | - Masanori Noda
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Susumu Uchiyama
- Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.,Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Koichi Kato
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan. .,Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan. .,Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.
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4
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D'Alessio C, Dahms NM. Glucosidase II and MRH-domain containing proteins in the secretory pathway. Curr Protein Pept Sci 2015; 16:31-48. [PMID: 25692846 DOI: 10.2174/1389203716666150213160438] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Revised: 08/25/2014] [Accepted: 11/13/2014] [Indexed: 12/24/2022]
Abstract
N-glycosylation in the endoplasmic reticulum (ER) consists of the transfer of a preassembled glycan conserved among species (Glc3Man9GlcNAc2) from a lipid donor to a consensus sequence within a nascent protein that is entering the ER. The protein-linked glycans are then processed by glycosidases and glycosyltransferases in the ER producing specific structures that serve as signalling molecules for the fate of the folding glycoprotein: to stay in the ER during the folding process, to be retrotranslocated to the cytosol for proteasomal degradation if irreversibly misfolded, or to pursue transit through the secretory pathway as a mature glycoprotein. In the ER, each glycan signalling structure is recognized by a specific lectin. A domain similar to that of the mannose 6-phosphate receptors (MPRs) has been identified in several proteins of the secretory pathway. These include the beta subunit of glucosidase II (GII), a key enzyme in the early processing of the transferred glycan that removes middle and innermost glucoses and is involved in quality control of glycoprotein folding in the ER (QC), the lectins OS-9 and XTP3-B, proteins involved in the delivery of ER misfolded proteins to degradation (ERAD), the gamma subunit of the Golgi GlcNAc-1-phosphotransferase, an enzyme involved in generating the mannose 6-phosphate (M6P) signal for sorting acidic hydrolases to lysosomes, and finally the MPRs that deliver those hydrolytic enzymes to the lysosome. Each of the MRH-containing proteins recognizes a different signalling N-glycan structure. Three-dimensional structures of some of the MRH domains have been solved, providing the basis to understand recognition mechanisms.
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Affiliation(s)
| | - Nancy M Dahms
- Laboratory of Glycobiology, Fundación Instituto Leloir - Instituto de Investigaciones Bioquimicas de Buenos Aires-CONICET, Av. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina, and School of Sciences, University of Buenos Aires, C1428EHA, Buenos Aires, Argentina.
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5
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Anji A, Miller H, Raman C, Phillips M, Ciment G, Kumari M. Expression of α-subunit of α-glucosidase II in adult mouse brain regions and selected organs. J Neurosci Res 2014; 93:82-93. [PMID: 25131991 DOI: 10.1002/jnr.23470] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 05/22/2014] [Accepted: 07/16/2014] [Indexed: 01/14/2023]
Abstract
α-Glucosidase II (GII), a resident of endoplasmic reticulum (ER) and an important enzyme in the folding of nascent glycoproteins, is heterodimeric, consisting of α (GIIα) and β (GIIβ) subunits. The catalytic GIIα subunit, with the help of mannose 6-phosphate receptor homology domain of GIIβ, sequentially hydrolyzes two α1-3-linked glucose residues in the second step of N-linked oligosaccharide-mediated protein folding. The soluble GIIα subunit is retained in the ER through its interaction with the HDEL-containing GIIβ subunit. N-glycosylation and correct protein folding are crucial for protein stability and trafficking and cell surface expression of several proteins in the brain. Alterations in N-glycosylation lead to abnormalities in neuronal migration and mental retardation, various neurodegenerative diseases, and invasion of malignant gliomas. Inhibitors of GII are used to inhibit cell proliferation and migration in a variety of different pathologies, such as viral infection, cancer, and diabetes. Despite the widespread use of GIIα inhibitory drugs and the role of GIIα in brain function, little is known about its expression in brain and other tissues. Here, we report generation of a highly specific chicken antibody to the GIIα subunit and its characterization by Western blotting and immunoprecipitation using cerebral cortical extracts. By using this antibody, we showed that the GIIα protein is highly expressed in testis, kidney, and lung, with the lowest amount in heart. GIIα polypeptide levels in whole brain were comparable to those in spleen. However, a higher expression of GIIα protein was detected in the cerebral cortex, reflecting its continuous requirement in correct folding of cell surface proteins.
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Affiliation(s)
- Antje Anji
- Department of Anatomy and Physiology, CVM, Kansas State University, Manhattan, Kansas
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6
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Olson LJ, Orsi R, Alculumbre SG, Peterson FC, Stigliano ID, Parodi AJ, D'Alessio C, Dahms NM. Structure of the lectin mannose 6-phosphate receptor homology (MRH) domain of glucosidase II, an enzyme that regulates glycoprotein folding quality control in the endoplasmic reticulum. J Biol Chem 2013; 288:16460-16475. [PMID: 23609449 DOI: 10.1074/jbc.m113.450239] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Here we report for the first time the three-dimensional structure of a mannose 6-phosphate receptor homology (MRH) domain present in a protein with enzymatic activity, glucosidase II (GII). GII is involved in glycoprotein folding in the endoplasmic reticulum. GII removes the two innermost glucose residues from the Glc3Man9GlcNAc2 transferred to nascent proteins and the glucose added by UDP-Glc:glycoprotein glucosyltransferase. GII is composed of a catalytic GIIα subunit and a regulatory GIIβ subunit. GIIβ participates in the endoplasmic reticulum localization of GIIα and mediates in vivo enhancement of N-glycan trimming by GII through its C-terminal MRH domain. We determined the structure of a functional GIIβ MRH domain by NMR spectroscopy. It adopts a β-barrel fold similar to that of other MRH domains, but its binding pocket is the most shallow known to date as it accommodates a single mannose residue. In addition, we identified a conserved residue outside the binding pocket (Trp-409) present in GIIβ but not in other MRHs that influences GII glucose trimming activity.
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Affiliation(s)
- Linda J Olson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Ramiro Orsi
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, C1405BWE Buenos Aires, Argentina
| | - Solana G Alculumbre
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, C1405BWE Buenos Aires, Argentina
| | - Francis C Peterson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Ivan D Stigliano
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, C1405BWE Buenos Aires, Argentina
| | - Armando J Parodi
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, C1405BWE Buenos Aires, Argentina
| | - Cecilia D'Alessio
- Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, C1405BWE Buenos Aires, Argentina; School of Sciences, University of Buenos Aires, C1428EHA Buenos Aires, Argentina.
| | - Nancy M Dahms
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
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Orlean P. Architecture and biosynthesis of the Saccharomyces cerevisiae cell wall. Genetics 2012; 192:775-818. [PMID: 23135325 PMCID: PMC3522159 DOI: 10.1534/genetics.112.144485] [Citation(s) in RCA: 303] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 08/06/2012] [Indexed: 01/02/2023] Open
Abstract
The wall gives a Saccharomyces cerevisiae cell its osmotic integrity; defines cell shape during budding growth, mating, sporulation, and pseudohypha formation; and presents adhesive glycoproteins to other yeast cells. The wall consists of β1,3- and β1,6-glucans, a small amount of chitin, and many different proteins that may bear N- and O-linked glycans and a glycolipid anchor. These components become cross-linked in various ways to form higher-order complexes. Wall composition and degree of cross-linking vary during growth and development and change in response to cell wall stress. This article reviews wall biogenesis in vegetative cells, covering the structure of wall components and how they are cross-linked; the biosynthesis of N- and O-linked glycans, glycosylphosphatidylinositol membrane anchors, β1,3- and β1,6-linked glucans, and chitin; the reactions that cross-link wall components; and the possible functions of enzymatic and nonenzymatic cell wall proteins.
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Affiliation(s)
- Peter Orlean
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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De Pourcq K, Tiels P, Van Hecke A, Geysens S, Vervecken W, Callewaert N. Engineering Yarrowia lipolytica to produce glycoproteins homogeneously modified with the universal Man3GlcNAc2 N-glycan core. PLoS One 2012; 7:e39976. [PMID: 22768188 PMCID: PMC3386995 DOI: 10.1371/journal.pone.0039976] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 05/30/2012] [Indexed: 11/18/2022] Open
Abstract
Yarrowia lipolytica is a dimorphic yeast that efficiently secretes various heterologous proteins and is classified as “generally recognized as safe.” Therefore, it is an attractive protein production host. However, yeasts modify glycoproteins with non-human high mannose-type N-glycans. These structures reduce the protein half-life in vivo and can be immunogenic in man. Here, we describe how we genetically engineered N-glycan biosynthesis in Yarrowia lipolytica so that it produces Man3GlcNAc2 structures on its glycoproteins. We obtained unprecedented levels of homogeneity of this glycanstructure. This is the ideal starting point for building human-like sugars. Disruption of the ALG3 gene resulted in modification of proteins mainly with Man5GlcNAc2 and GlcMan5GlcNAc2 glycans, and to a lesser extent with Glc2Man5GlcNAc2 glycans. To avoid underoccupancy of glycosylation sites, we concomitantly overexpressed ALG6. We also explored several approaches to remove the terminal glucose residues, which hamper further humanization of N-glycosylation; overexpression of the heterodimeric Apergillus niger glucosidase II proved to be the most effective approach. Finally, we overexpressed an α-1,2-mannosidase to obtain Man3GlcNAc2 structures, which are substrates for the synthesis of complex-type glycans. The final Yarrowia lipolytica strain produces proteins glycosylated with the trimannosyl core N-glycan (Man3GlcNAc2), which is the common core of all complex-type N-glycans. All these glycans can be constructed on the obtained trimannosyl N-glycan using either in vivo or in vitro modification with the appropriate glycosyltransferases. The results demonstrate the high potential of Yarrowia lipolytica to be developed as an efficient expression system for the production of glycoproteins with humanized glycans.
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Affiliation(s)
- Karen De Pourcq
- Unit for Medical Biotechnology, Department for Molecular Biomedical Research, VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Petra Tiels
- Unit for Medical Biotechnology, Department for Molecular Biomedical Research, VIB, Ghent, Belgium
- L-Probe, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Annelies Van Hecke
- Unit for Medical Biotechnology, Department for Molecular Biomedical Research, VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Steven Geysens
- Unit for Medical Biotechnology, Department for Molecular Biomedical Research, VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
- Oxyrane Belgium, Ghent, Belgium
| | - Wouter Vervecken
- Unit for Medical Biotechnology, Department for Molecular Biomedical Research, VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
- Oxyrane Belgium, Ghent, Belgium
| | - Nico Callewaert
- Unit for Medical Biotechnology, Department for Molecular Biomedical Research, VIB, Ghent, Belgium
- L-Probe, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
- * E-mail:
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9
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Hüttner S, Veit C, Schoberer J, Grass J, Strasser R. Unraveling the function of Arabidopsis thaliana OS9 in the endoplasmic reticulum-associated degradation of glycoproteins. PLANT MOLECULAR BIOLOGY 2012; 79:21-33. [PMID: 22328055 PMCID: PMC3332353 DOI: 10.1007/s11103-012-9891-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 01/29/2012] [Indexed: 05/18/2023]
Abstract
In the endoplasmic reticulum, immature polypeptides coincide with terminally misfolded proteins. Consequently, cells need a well-balanced quality control system, which decides about the fate of individual proteins and maintains protein homeostasis. Misfolded and unassembled proteins are sent for destruction via the endoplasmic reticulum-associated degradation (ERAD) machinery to prevent the accumulation of potentially toxic protein aggregates. Here, we report the identification of Arabidopsis thaliana OS9 as a component of the plant ERAD pathway. OS9 is an ER-resident glycoprotein containing a mannose-6-phosphate receptor homology domain, which is also found in yeast and mammalian lectins involved in ERAD. OS9 fused to the C-terminal domain of YOS9 can complement the ERAD defect of the corresponding yeast Δyos9 mutant. An A. thaliana OS9 loss-of-function line suppresses the severe growth phenotype of the bri1-5 and bri1-9 mutant plants, which harbour mutated forms of the brassinosteroid receptor BRI1. Co-immunoprecipitation studies demonstrated that OS9 associates with Arabidopsis SEL1L/HRD3, which is part of the plant ERAD complex and with the ERAD substrates BRI1-5 and BRI1-9, but only the binding to BRI1-5 occurs in a glycan-dependent way. OS9-deficiency results in activation of the unfolded protein response and reduces salt tolerance, highlighting the role of OS9 during ER stress. We propose that OS9 is a component of the plant ERAD machinery and may act specifically in the glycoprotein degradation pathway.
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Affiliation(s)
- Silvia Hüttner
- Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Christiane Veit
- Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Jennifer Schoberer
- Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
- Present Address: Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford, OX3 0BP UK
| | - Josephine Grass
- Department of Chemistry, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
| | - Richard Strasser
- Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
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Stigliano ID, Alculumbre SG, Labriola CA, Parodi AJ, D'Alessio C. Glucosidase II and N-glycan mannose content regulate the half-lives of monoglucosylated species in vivo. Mol Biol Cell 2011; 22:1810-23. [PMID: 21471007 PMCID: PMC3103398 DOI: 10.1091/mbc.e11-01-0019] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
A decrease in N-glycan mannose content significantly diminishes in vivo glucosidase II–mediated deglucosylation rates but does not affect in vivo UDP-glucose:glycoprotein glucosyltransferase–mediated glucosylation, thus increasing the possibility of displaying monoglucosylated structures able to interact with calnexin/calreticulin for longer time periods. Glucosidase II (GII) sequentially removes the two innermost glucose residues from the glycan (Glc3Man9GlcNAc2) transferred to proteins. GII also participates in cycles involving the lectin/chaperones calnexin (CNX) and calreticulin (CRT) as it removes the single glucose unit added to folding intermediates and misfolded glycoproteins by the UDP-Glc:glycoprotein glucosyltransferase (UGGT). GII is a heterodimer in which the α subunit (GIIα) bears the active site, and the β subunit (GIIβ) modulates GIIα activity through its C-terminal mannose 6-phosphate receptor homologous (MRH) domain. Here we report that, as already described in cell-free assays, in live Schizosaccharomyces pombe cells a decrease in the number of mannoses in the glycan results in decreased GII activity. Contrary to previously reported cell-free experiments, however, no such effect was observed in vivo for UGGT. We propose that endoplasmic reticulum α-mannosidase–mediated N-glycan demannosylation of misfolded/slow-folding glycoproteins may favor their interaction with the lectin/chaperone CNX present in S. pombe by prolonging the half-lives of the monoglucosylated glycans (S. pombe lacks CRT). Moreover, we show that even N-glycans bearing five mannoses may interact in vivo with the GIIβ MRH domain and that the N-terminal GIIβ G2B domain is involved in the GIIα–GIIβ interaction. Finally, we report that protists that transfer glycans with low mannose content to proteins have nevertheless conserved the possibility of displaying relatively long-lived monoglucosylated glycans by expressing GIIβ MRH domains with a higher specificity for glycans with high mannose content.
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Affiliation(s)
- Ivan D Stigliano
- Laboratory of Glycobiology, Fundación Instituto Leloir and Instituto de Investigaciones Bioquímicas de Buenos Aires-CONICET, C1405BWE, Buenos Aires, Argentina
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D'Alessio C, Caramelo JJ, Parodi AJ. UDP-GlC:glycoprotein glucosyltransferase-glucosidase II, the ying-yang of the ER quality control. Semin Cell Dev Biol 2010; 21:491-9. [PMID: 20045480 DOI: 10.1016/j.semcdb.2009.12.014] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 12/17/2009] [Indexed: 12/22/2022]
Abstract
The N-glycan-dependent quality control of glycoprotein folding prevents endoplasmic to Golgi exit of folding intermediates, irreparably misfolded glycoproteins and incompletely assembled multimeric complexes. It also enhances folding efficiency by preventing aggregation and facilitating formation of proper disulfide bonds. The control mechanism essentially involves four components, resident lectin-chaperones that recognize monoglucosylated polymannose glycans, a lectin-associated oxidoreductase acting on monoglucosylated glycoproteins, a glucosyltransferase that creates monoglucosytlated epitopes in protein-linked glycans and a glucosidase that removes the glucose units added by the glucosyltransferase. This last enzyme is the only mechanism component sensing glycoprotein conformations as it creates monoglucosylated glycans exclusively in not properly folded species or in not completely assembled complexes. The glucosidase is a dimeric heterodimer composed of a catalytic subunit and an additional one that is partially responsible for the ER localization of the enzyme and for the enhancement of the deglucosylation rate as its mannose 6-phosphate receptor homologous domain presents the substrate to the catalytic site. This review deals with our present knowledge on the glucosyltransferase and the glucosidase.
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Affiliation(s)
- Cecilia D'Alessio
- Laboratory of Glycobiology, Fundación Instituto Leloir, Avda. Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
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Pearse BR, Hebert DN. Lectin chaperones help direct the maturation of glycoproteins in the endoplasmic reticulum. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1803:684-93. [PMID: 19891995 DOI: 10.1016/j.bbamcr.2009.10.008] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 10/09/2009] [Accepted: 10/20/2009] [Indexed: 02/06/2023]
Abstract
Eukaryotic secretory pathway cargo fold to their native structures within the confines of the endoplasmic reticulum (ER). To ensure a high degree of folding fidelity, a multitude of covalent and noncovalent constraints are imparted upon nascent proteins. These constraints come in the form of topological restrictions or membrane tethers, covalent modifications, and interactions with a series of molecular chaperones. N-linked glycosylation provides inherent benefits to proper folding and creates a platform for interactions with specific chaperones and Cys modifying enzymes. Recent insights into this timeline of protein maturation have revealed mechanisms for protein glycosylation and iterative targeting of incomplete folding intermediates, which provides nurturing interactions with molecular chaperones that assist in the efficient maturation of proteins in the eukaryotic secretory pathway.
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Affiliation(s)
- Bradley R Pearse
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
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