1
|
Hagströmer CJ, Hyld Steffen J, Kreida S, Al-Jubair T, Frick A, Gourdon P, Törnroth-Horsefield S. Structural and functional analysis of aquaporin-2 mutants involved in nephrogenic diabetes insipidus. Sci Rep 2023; 13:14674. [PMID: 37674034 PMCID: PMC10482962 DOI: 10.1038/s41598-023-41616-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 08/29/2023] [Indexed: 09/08/2023] Open
Abstract
Aquaporins are water channels found in the cell membrane, where they allow the passage of water molecules in and out of the cells. In the kidney collecting duct, arginine vasopressin-dependent trafficking of aquaporin-2 (AQP2) fine-tunes reabsorption of water from pre-urine, allowing precise regulation of the final urine volume. Point mutations in the gene for AQP2 may disturb this process and lead to nephrogenic diabetes insipidus (NDI), whereby patients void large volumes of highly hypo-osmotic urine. In recessive NDI, mutants of AQP2 are retained in the endoplasmic reticulum due to misfolding. Here we describe the structural and functional characterization of three AQP2 mutations associated with recessive NDI: T125M and T126M, situated close to a glycosylation site and A147T in the transmembrane region. Using a proteoliposome assay, we show that all three mutants permit the transport of water. The crystal structures of T125M and T126M together with biophysical characterization of all three mutants support that they retain the native structure, but that there is a significant destabilization of A147T. Our work provides unique molecular insights into the mechanisms behind recessive NDI as well as deepens our understanding of how misfolded proteins are recognized by the ER quality control system.
Collapse
Affiliation(s)
| | - Jonas Hyld Steffen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stefan Kreida
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Tamim Al-Jubair
- Department of Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Anna Frick
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Pontus Gourdon
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | | |
Collapse
|
2
|
Papadopoulos N, Nédélec A, Derenne A, Şulea TA, Pecquet C, Chachoua I, Vertenoeil G, Tilmant T, Petrescu AJ, Mazzucchelli G, Iorga BI, Vertommen D, Constantinescu SN. Oncogenic CALR mutant C-terminus mediates dual binding to the thrombopoietin receptor triggering complex dimerization and activation. Nat Commun 2023; 14:1881. [PMID: 37019903 PMCID: PMC10076285 DOI: 10.1038/s41467-023-37277-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 03/04/2023] [Indexed: 04/07/2023] Open
Abstract
Calreticulin (CALR) frameshift mutations represent the second cause of myeloproliferative neoplasms (MPN). In healthy cells, CALR transiently and non-specifically interacts with immature N-glycosylated proteins through its N-terminal domain. Conversely, CALR frameshift mutants turn into rogue cytokines by stably and specifically interacting with the Thrombopoietin Receptor (TpoR), inducing its constitutive activation. Here, we identify the basis of the acquired specificity of CALR mutants for TpoR and define the mechanisms by which complex formation triggers TpoR dimerization and activation. Our work reveals that CALR mutant C-terminus unmasks CALR N-terminal domain, rendering it more accessible to bind immature N-glycans on TpoR. We further find that the basic mutant C-terminus is partially α-helical and define how its α-helical segment concomitantly binds acidic patches of TpoR extracellular domain and induces dimerization of both CALR mutant and TpoR. Finally, we propose a model of the tetrameric TpoR-CALR mutant complex and identify potentially targetable sites.
Collapse
Affiliation(s)
- Nicolas Papadopoulos
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
| | - Audrey Nédélec
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
| | - Allison Derenne
- Spectralys Biotech SRL, rue Auguste Piccard 48, 6041, Gosselies, Belgium
| | - Teodor Asvadur Şulea
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, Bucharest, 060031, Romania
| | - Christian Pecquet
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
| | - Ilyas Chachoua
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
- Department of Molecular Biology and Genetics, Bilkent University, Ankara, Turkey
| | - Gaëlle Vertenoeil
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
| | - Thomas Tilmant
- Mass Spectrometry Laboratory, MolSys Research Unit, Universiy of Liège, 4000, Liège, Belgium
| | - Andrei-Jose Petrescu
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, Bucharest, 060031, Romania
| | - Gabriel Mazzucchelli
- Mass Spectrometry Laboratory, MolSys Research Unit, Universiy of Liège, 4000, Liège, Belgium
| | - Bogdan I Iorga
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, Gif-sur-Yvette, France
| | - Didier Vertommen
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium
- de Duve Institute and MASSPROT platform, Brussels, Belgium
| | - Stefan N Constantinescu
- Ludwig Institute for Cancer Research Brussels, Brussels, Belgium.
- Université catholique de Louvain and de Duve Institute, Brussels, Belgium.
- Walloon Excelence in Life Sciences and Biotechnology, WELBIO, avenue Pasteur, 6, 1300, Wavre, Belgium.
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, Oxford University, Oxford, UK.
| |
Collapse
|
3
|
Montpetit J, Clúa J, Hsieh YF, Vogiatzaki E, Müller J, Abel S, Strasser R, Poirier Y. Endoplasmic reticulum calnexins participate in the primary root growth response to phosphate deficiency. PLANT PHYSIOLOGY 2023; 191:1719-1733. [PMID: 36567484 PMCID: PMC10022610 DOI: 10.1093/plphys/kiac595] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 12/08/2022] [Indexed: 06/17/2023]
Abstract
Accumulation of incompletely folded proteins in the endoplasmic reticulum (ER) leads to ER stress, activates ER protein degradation pathways, and upregulates genes involved in protein folding. This process is known as the unfolded protein response (UPR). The role of ER protein folding in plant responses to nutrient deficiencies is unclear. We analyzed Arabidopsis (Arabidopsis thaliana) mutants affected in ER protein quality control and established that both CALNEXIN (CNX) genes function in the primary root response to phosphate (Pi) deficiency. CNX1 and CNX2 are homologous ER lectins promoting protein folding of N-glycosylated proteins via the recognition of the GlcMan9GlcNAc2 glycan. Growth of cnx1-1 and cnx2-2 single mutants was similar to that of the wild type under high and low Pi conditions, but the cnx1-1 cnx2-2 double mutant showed decreased primary root growth under low Pi conditions due to reduced meristematic cell division. This phenotype was specific to Pi deficiency; the double mutant responded normally to osmotic and salt stress. Expression of CNX2 mutated in amino acids involved in binding the GlcMan9GlcNAc2 glycan failed to complement the cnx1-1 cnx2-2 mutant. The root growth phenotype was Fe-dependent and was associated with root apoplastic Fe accumulation. Two genes involved in Fe-dependent inhibition of primary root growth under Pi deficiency, the ferroxidase LOW PHOSPHATE 1 (LPR1) and P5-type ATPase PLEIOTROPIC DRUG RESISTANCE 2 (PDR2) were epistatic to CNX1/CNX2. Overexpressing PDR2 failed to complement the cnx1-1 cnx2-2 root phenotype. The cnx1-1 cnx2-2 mutant showed no evidence of UPR activation, indicating a limited effect on ER protein folding. CNX might process a set of N-glycosylated proteins specifically involved in the response to Pi deficiency.
Collapse
Affiliation(s)
- Jonatan Montpetit
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015 Lausanne, Switzerland
| | - Joaquín Clúa
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015 Lausanne, Switzerland
| | - Yi-Fang Hsieh
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015 Lausanne, Switzerland
| | - Evangelia Vogiatzaki
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015 Lausanne, Switzerland
| | - Jens Müller
- Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Steffen Abel
- Department of Molecular Signal Processing, Leibniz Institute of Plant Biochemistry, 06120 Halle, Germany
| | - Richard Strasser
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Yves Poirier
- Department of Plant Molecular Biology, Biophore Building, University of Lausanne, 1015 Lausanne, Switzerland
| |
Collapse
|
4
|
Chen W, Zhong Y, Shu J, Yu H, Chen Z, Ren X, Hui Z, Li Z. Characterization of glucose-binding proteins isolated from health volunteers and human type 2 diabetes mellitus patients. Proteins 2021; 89:1413-1424. [PMID: 34165207 DOI: 10.1002/prot.26163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 05/09/2021] [Accepted: 06/15/2021] [Indexed: 11/11/2022]
Abstract
Glucose is one of the most important monosaccharides. Although hyperglycemia in type 2 diabetes mellitus (T2DM) lead to a series of changes; however, little is known about the alterations of serum proteins in T2DM, especially those proteins with glucose affinity. In this study, the glucose-binding proteins (GlcBPs) of serum were isolated from 30 health volunteer (HV) and 30 T2DM patients by glucose-magnetic particle conjugates (GMPC) and identified by mass spectrum analysis. Gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) indicated the main gene annotations and pathways of this GlcBPs, while Motif-X webtool provided the potential glucose-binding domains. Further docking analysis and glycan microarray were used to understand the interaction between the glucose and glucose-binding domains. A total of 149 and 119 GlcBPs were identified from HV and T2DM cases. Four hundred and sixty-eight GO annotations in 165 identified GlcBPs were available, while the majority involved in cellular processes and binding function. A short peptide, EGDEEITCLNGFWLE, which was derived from the Motif-X analysis, presented a high-binding ability to the glucose from both docking analysis and glycan analysis. GMPC provides a powerful tool for GlcBPs isolation and indicates the alteration of GlcBPs in T2DM.
Collapse
Affiliation(s)
- Wentian Chen
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an, China
| | - Yaogang Zhong
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an, China
| | - Jian Shu
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an, China
| | - Hanjie Yu
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an, China
| | - Zhuo Chen
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an, China
| | - Xiameng Ren
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an, China
| | - Ziye Hui
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an, China
| | - Zheng Li
- Laboratory for Functional Glycomics, College of Life Sciences, Northwest University, Xi'an, China
| |
Collapse
|
5
|
Hematoxylin binds to mutant calreticulin and disrupts its abnormal interaction with thrombopoietin receptor. Blood 2021; 137:1920-1931. [PMID: 33202418 DOI: 10.1182/blood.2020006264] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 11/05/2020] [Indexed: 12/21/2022] Open
Abstract
Somatic mutations of calreticulin (CALR) have been identified as a main disease driver of myeloproliferative neoplasms, suggesting that development of drugs targeting mutant CALR is of great significance. Site-directed mutagenesis in the N-glycan binding domain (GBD) abolishes the ability of mutant CALR to oncogenically activate the thrombopoietin receptor (MPL). We therefore hypothesized that a small molecule targeting the GBD might inhibit the oncogenicity of the mutant CALR. Using an in silico molecular docking study, we identified candidate binders to the GBD of CALR. Further experimental validation of the hits identified a group of catechols inducing a selective growth inhibitory effect on cells that depend on oncogenic CALR for survival and proliferation. Apoptosis-inducing effects by the compound were significantly higher in the CALR-mutated cells than in CALR wild-type cells. Additionally, knockout or C-terminal truncation of CALR eliminated drug hypersensitivity in CALR-mutated cells. We experimentally confirmed the direct binding of the selected compound to CALR, disruption of the mutant CALR-MPL interaction, inhibition of the JAK2-STAT5 pathway, and reduction at the intracellular level of mutant CALR upon drug treatment. Our data indicate that small molecules targeting the GBD of CALR can selectively kill CALR-mutated cells by disrupting the CALR-MPL interaction and inhibiting oncogenic signaling.
Collapse
|
6
|
Doğan C, Hänniger S, Heckel DG, Coutu C, Hegedus DD, Crubaugh L, Groves RL, Bayram Ş, Toprak U. Two calcium-binding chaperones from the fat body of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) involved in diapause. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2021; 106:e21755. [PMID: 33118236 DOI: 10.1002/arch.21755] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/13/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
Molecular chaperones are crucial for the correct folding of newly synthesized polypeptides, in particular, under stress conditions. Various studies have revealed the involvement of molecular chaperones, such as heat shock proteins, in diapause maintenance and starvation; however, the role of other chaperones in diapause and starvation relatively is unknown. In the current study, we identified two lectin-type chaperones with calcium affinity, a calreticulin (LdCrT) and a calnexin (LdCnX), that were present in the fat body of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) during diapause. Both proteins possessed an N-globular domain, a P-arm domain, and a highly charged C-terminal domain, while an additional transmembrane domain was present in LdCnX. Phylogenetic analysis revealed distinction at the order level. Both genes were expressed in multiple tissues in larval and adult stages, and constitutively throughout development, though a starvation response was detected only for LdCrT. In females, diapause-related expression analysis in the whole body revealed an upregulation of both genes by post-diapause, but a downregulation by diapause only for LdCrT. By contrast, males revealed no alteration in their diapause-related expression pattern in the entire body for both genes. Fat body-specific expression analysis of both genes in relation to diapause revealed the same expression pattern with no alteration in females and downregulation in males by post-diapause. This study suggests that calcium-binding chaperones play similar and possibly gender-specific roles during diapause.
Collapse
Affiliation(s)
- Cansu Doğan
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan, Canada
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sabine Hänniger
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - David G Heckel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Cathy Coutu
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan, Canada
| | - Dwayne D Hegedus
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan, Canada
| | - Linda Crubaugh
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Russell L Groves
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Şerife Bayram
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
| | - Umut Toprak
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
| |
Collapse
|
7
|
Kozlov G, Gehring K. Calnexin cycle - structural features of the ER chaperone system. FEBS J 2020; 287:4322-4340. [PMID: 32285592 PMCID: PMC7687155 DOI: 10.1111/febs.15330] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/31/2020] [Accepted: 04/08/2020] [Indexed: 12/21/2022]
Abstract
The endoplasmic reticulum (ER) is the major folding compartment for secreted and membrane proteins and is the site of a specific chaperone system, the calnexin cycle, for folding N-glycosylated proteins. Recent structures of components of the calnexin cycle have deepened our understanding of quality control mechanisms and protein folding pathways in the ER. In the calnexin cycle, proteins carrying monoglucosylated glycans bind to the lectin chaperones calnexin and calreticulin, which recruit a variety of function-specific chaperones to mediate protein disulfide formation, proline isomerization, and general protein folding. Upon trimming by glucosidase II, the glycan without an inner glucose residue is no longer able to bind to the lectin chaperones. For proteins that have not yet folded properly, the enzyme UDP-glucose:glycoprotein glucosyltransferase (UGGT) acts as a checkpoint by adding a glucose back to the N-glycan. This allows the misfolded proteins to re-associate with calnexin and calreticulin for additional rounds of chaperone-mediated refolding and prevents them from exiting the ERs. Here, we review progress in structural studies of the calnexin cycle, which reveal common features of how lectin chaperones recruit function-specific chaperones and how UGGT recognizes misfolded proteins.
Collapse
Affiliation(s)
- Guennadi Kozlov
- From the Department of Biochemistry & Centre for Structural BiologyMcGill UniversityMontréalQCCanada
| | - Kalle Gehring
- From the Department of Biochemistry & Centre for Structural BiologyMcGill UniversityMontréalQCCanada
| |
Collapse
|
8
|
Lin B, Qing X, Liao J, Zhuo K. Role of Protein Glycosylation in Host-Pathogen Interaction. Cells 2020; 9:E1022. [PMID: 32326128 PMCID: PMC7226260 DOI: 10.3390/cells9041022] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/11/2020] [Accepted: 04/16/2020] [Indexed: 02/07/2023] Open
Abstract
Host-pathogen interactions are fundamental to our understanding of infectious diseases. Protein glycosylation is one kind of common post-translational modification, forming glycoproteins and modulating numerous important biological processes. It also occurs in host-pathogen interaction, affecting host resistance or pathogen virulence often because glycans regulate protein conformation, activity, and stability, etc. This review summarizes various roles of different glycoproteins during the interaction, which include: host glycoproteins prevent pathogens as barriers; pathogen glycoproteins promote pathogens to attack host proteins as weapons; pathogens glycosylate proteins of the host to enhance virulence; and hosts sense pathogen glycoproteins to induce resistance. In addition, this review also intends to summarize the roles of lectin (a class of protein entangled with glycoprotein) in host-pathogen interactions, including bacterial adhesins, viral lectins or host lectins. Although these studies show the importance of protein glycosylation in host-pathogen interaction, much remains to be discovered about the interaction mechanism.
Collapse
Affiliation(s)
- Borong Lin
- Laboratory of Plant Nematology, South China Agricultural University, Guangzhou 510642, China; (B.L.); (J.L.)
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China
| | - Xue Qing
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China;
| | - Jinling Liao
- Laboratory of Plant Nematology, South China Agricultural University, Guangzhou 510642, China; (B.L.); (J.L.)
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China
- Guangdong Eco-Engineering Polytechnic, Guangzhou 510520, China
| | - Kan Zhuo
- Laboratory of Plant Nematology, South China Agricultural University, Guangzhou 510642, China; (B.L.); (J.L.)
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China
| |
Collapse
|
9
|
Yang H, Ahmad ZA, Song Y. Molecular insight for the role of key residues of calreticulin in its binding activities: A computational study. Comput Biol Chem 2020; 85:107228. [DOI: 10.1016/j.compbiolchem.2020.107228] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/28/2020] [Accepted: 02/01/2020] [Indexed: 12/26/2022]
|
10
|
Ihara Y, Ikezaki M, Takatani M, Ito Y. Calnexin/Calreticulin and Assays Related to N-Glycoprotein Folding In Vitro. Methods Mol Biol 2020; 2132:295-308. [PMID: 32306337 DOI: 10.1007/978-1-0716-0430-4_29] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Calnexin (CNX) and calreticulin (CRT) are ER-resident lectin-like molecular chaperones involved in the quality control of secretory or membrane glycoproteins. They can exert molecular chaperone functions via specific binding to the early processing intermediates of Glc1Man9GlcNAc2 oligosaccharides of N-glycoproteins. CNX and CRT have similar N-terminal luminal domains and share the same jelly roll tertiary structure as legume lectins. In addition to the lectin-like interactions, CNX and CRT also suppress the aggregation of non-glycosylated substrates through interaction with hydrophobic peptide parts, suggesting a general chaperone function in glycan-dependent and glycan-independent manners. This chapter describes the isolation and purification of CRT produced in a bacterial expression system. We also introduce in vitro assays to estimate the molecular chaperone functions of CRT via the interaction with monoglucosylated N-glycans using Jack bean α-mannosidase as a target substrate. These assays are valuable in assessing quality control events related to the CNX/CRT chaperone cycle and lectin functions.
Collapse
Affiliation(s)
- Yoshito Ihara
- Department of Biochemistry, Wakayama Medical University, Wakayama, Japan.
| | - Midori Ikezaki
- Department of Biochemistry, Wakayama Medical University, Wakayama, Japan
| | - Maki Takatani
- Synthetic Cellular Chemistry Laboratory, RIKEN, Saitama, Japan
| | - Yukishige Ito
- Synthetic Cellular Chemistry Laboratory, RIKEN, Saitama, Japan
| |
Collapse
|
11
|
Defining the requirements for the pathogenic interaction between mutant calreticulin and MPL in MPN. Blood 2017; 131:782-786. [PMID: 29288169 DOI: 10.1182/blood-2017-08-800896] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 12/18/2017] [Indexed: 01/09/2023] Open
Abstract
Mutations in calreticulin (CALR) are phenotypic drivers in the pathogenesis of myeloproliferative neoplasms. Mechanistic studies have demonstrated that mutant CALR binds to the thrombopoietin receptor MPL, and that the positive electrostatic charge of the mutant CALR C terminus is required for mutant CALR-mediated activation of JAK-STAT signaling. Here we demonstrate that although binding between mutant CALR and MPL is required for mutant CALR to transform hematopoietic cells; binding alone is insufficient for cytokine independent growth. We further show that the threshold of positive charge in the mutant CALR C terminus influences both binding of mutant CALR to MPL and activation of MPL signaling. We find that mutant CALR binds to the extracellular domain of MPL and that 3 tyrosine residues within the intracellular domain of MPL are required to activate signaling. With respect to mutant CALR function, we show that its lectin-dependent function is required for binding to MPL and for cytokine independent growth, whereas its chaperone and polypeptide-binding functionalities are dispensable. Together, our findings provide additional insights into the mechanism of the pathogenic mutant CALR-MPL interaction in myeloproliferative neoplasms.
Collapse
|
12
|
Neerincx A, Hermann C, Antrobus R, van Hateren A, Cao H, Trautwein N, Stevanović S, Elliott T, Deane JE, Boyle LH. TAPBPR bridges UDP-glucose:glycoprotein glucosyltransferase 1 onto MHC class I to provide quality control in the antigen presentation pathway. eLife 2017; 6:e23049. [PMID: 28425917 PMCID: PMC5441866 DOI: 10.7554/elife.23049] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 04/14/2017] [Indexed: 11/24/2022] Open
Abstract
Recently, we revealed that TAPBPR is a peptide exchange catalyst that is important for optimal peptide selection by MHC class I molecules. Here, we asked whether any other co-factors associate with TAPBPR, which would explain its effect on peptide selection. We identify an interaction between TAPBPR and UDP-glucose:glycoprotein glucosyltransferase 1 (UGT1), a folding sensor in the calnexin/calreticulin quality control cycle that is known to regenerate the Glc1Man9GlcNAc2 moiety on glycoproteins. Our results suggest the formation of a multimeric complex, dependent on a conserved cysteine at position 94 in TAPBPR, in which TAPBPR promotes the association of UGT1 with peptide-receptive MHC class I molecules. We reveal that the interaction between TAPBPR and UGT1 facilities the reglucosylation of the glycan on MHC class I molecules, promoting their recognition by calreticulin. Our results suggest that in addition to being a peptide editor, TAPBPR improves peptide optimisation by promoting peptide-receptive MHC class I molecules to associate with the peptide-loading complex.
Collapse
Affiliation(s)
- Andreas Neerincx
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Clemens Hermann
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Robin Antrobus
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Andy van Hateren
- Faculty of Medicine, University of Southampton, Southampton, United Kingdom
- Institute for Life Science, University of Southampton, Southampton, United Kingdom
| | - Huan Cao
- Division of Applied Medicine, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Nico Trautwein
- Department of Immunology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Stefan Stevanović
- Department of Immunology, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Tim Elliott
- Faculty of Medicine, University of Southampton, Southampton, United Kingdom
- Institute for Life Science, University of Southampton, Southampton, United Kingdom
| | - Janet E Deane
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Louise H Boyle
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| |
Collapse
|
13
|
The Distribution of Lectins across the Phylum Nematoda: A Genome-Wide Search. Int J Mol Sci 2017; 18:ijms18010091. [PMID: 28054982 PMCID: PMC5297725 DOI: 10.3390/ijms18010091] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 12/20/2016] [Accepted: 12/28/2016] [Indexed: 12/13/2022] Open
Abstract
Nematodes are a very diverse phylum that has adapted to nearly every ecosystem. They have developed specialized lifestyles, dividing the phylum into free-living, animal, and plant parasitic species. Their sheer abundance in numbers and presence in nearly every ecosystem make them the most prevalent animals on earth. In this research nematode-specific profiles were designed to retrieve predicted lectin-like domains from the sequence data of nematode genomes and transcriptomes. Lectins are carbohydrate-binding proteins that play numerous roles inside and outside the cell depending on their sugar specificity and associated protein domains. The sugar-binding properties of the retrieved lectin-like proteins were predicted in silico. Although most research has focused on C-type lectin-like, galectin-like, and calreticulin-like proteins in nematodes, we show that the lectin-like repertoire in nematodes is far more diverse. We focused on C-type lectins, which are abundantly present in all investigated nematode species, but seem to be far more abundant in free-living species. Although C-type lectin-like proteins are omnipresent in nematodes, we have shown that only a small part possesses the residues that are thought to be essential for carbohydrate binding. Curiously, hevein, a typical plant lectin domain not reported in animals before, was found in some nematode species.
Collapse
|
14
|
Lum R, Ahmad S, Hong SJ, Chapman DC, Kozlov G, Williams DB. Contributions of the Lectin and Polypeptide Binding Sites of Calreticulin to Its Chaperone Functions in Vitro and in Cells. J Biol Chem 2016; 291:19631-41. [PMID: 27413183 DOI: 10.1074/jbc.m116.746321] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Indexed: 11/06/2022] Open
Abstract
Calreticulin is a lectin chaperone of the endoplasmic reticulum that interacts with newly synthesized glycoproteins by binding to Glc1Man9GlcNAc2 oligosaccharides as well as to the polypeptide chain. In vitro, the latter interaction potently suppresses the aggregation of various non-glycosylated proteins. Although the lectin-oligosaccharide association is well understood, the polypeptide-based interaction is more controversial because the binding site on calreticulin has not been identified, and its significance in the biogenesis of glycoproteins in cells remains unknown. In this study, we identified the polypeptide binding site responsible for the in vitro aggregation suppression function by mutating four candidate hydrophobic surface patches. Mutations in only one patch, P19K/I21E and Y22K/F84E, impaired the ability of calreticulin to suppress the thermally induced aggregation of non-glycosylated firefly luciferase. These mutants also failed to bind several hydrophobic peptides that act as substrate mimetics and compete in the luciferase aggregation suppression assay. To assess the relative contributions of the glycan-dependent and -independent interactions in living cells, we expressed lectin-deficient, polypeptide binding-deficient, and doubly deficient calreticulin constructs in calreticulin-negative cells and monitored the effects on the biogenesis of MHC class I molecules, the solubility of mutant forms of α1-antitrypsin, and interactions with newly synthesized glycoproteins. In all cases, we observed a profound impairment in calreticulin function when its lectin site was inactivated. Remarkably, inactivation of the polypeptide binding site had little impact. These findings indicate that the lectin-based mode of client interaction is the predominant contributor to the chaperone functions of calreticulin within the endoplasmic reticulum.
Collapse
Affiliation(s)
- Ronnie Lum
- From the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada and
| | - Samar Ahmad
- From the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada and
| | - Seo Jung Hong
- From the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada and
| | - Daniel C Chapman
- From the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada and
| | - Guennadi Kozlov
- the Groupe de Recherche Axé sur la Structure des Proteines, Department of Biochemistry, McGill University, Montréal, Québec H3G 0B1, Canada
| | - David B Williams
- From the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada and
| |
Collapse
|
15
|
Izumi M, Oka Y, Okamoto R, Seko A, Takeda Y, Ito Y, Kajihara Y. Synthesis of Glc1
Man9
-Glycoprotein Probes by a Misfolding/Enzymatic Glucosylation/Misfolding Sequence. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201511491] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Masayuki Izumi
- Department of Chemistry; Graduate School of Science; Osaka University; 1-1 Machikaneyama, Toyonaka Osaka 560-0043 Japan
| | - Yukiho Oka
- Department of Chemistry; Graduate School of Science; Osaka University; 1-1 Machikaneyama, Toyonaka Osaka 560-0043 Japan
| | - Ryo Okamoto
- Department of Chemistry; Graduate School of Science; Osaka University; 1-1 Machikaneyama, Toyonaka Osaka 560-0043 Japan
| | - Akira Seko
- ERATO Ito glycotrilogy project Japan Science and Technology Agency (JST); 2-1 Hirosawa, Wako Saitama 351-0198 Japan
| | - Yoichi Takeda
- ERATO Ito glycotrilogy project Japan Science and Technology Agency (JST); 2-1 Hirosawa, Wako Saitama 351-0198 Japan
| | - Yukishige Ito
- ERATO Ito glycotrilogy project Japan Science and Technology Agency (JST); 2-1 Hirosawa, Wako Saitama 351-0198 Japan
- Synthetic Cellular Chemistry Laboratory; RIKEN; 2-1 Hirosawa, Wako Saitama 351-0198 Japan
| | - Yasuhiro Kajihara
- Department of Chemistry; Graduate School of Science; Osaka University; 1-1 Machikaneyama, Toyonaka Osaka 560-0043 Japan
- ERATO Ito glycotrilogy project Japan Science and Technology Agency (JST); 2-1 Hirosawa, Wako Saitama 351-0198 Japan
| |
Collapse
|
16
|
Izumi M, Oka Y, Okamoto R, Seko A, Takeda Y, Ito Y, Kajihara Y. Synthesis of Glc1Man9-Glycoprotein Probes by a Misfolding/Enzymatic Glucosylation/Misfolding Sequence. Angew Chem Int Ed Engl 2016; 55:3968-71. [PMID: 26890995 DOI: 10.1002/anie.201511491] [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: 12/10/2015] [Indexed: 12/12/2022]
Abstract
Glycoproteins in non-native conformations are often toxic to cells and may cause diseases, thus the quality control (QC) system eliminates these unwanted species. Lectin chaperone calreticulin and glucosidase II, both of which recognize the Glc1 Man9 oligosaccharide on glycoproteins, are important components of the glycoprotein QC system. Reported herein is the preparation of Glc1 Man9 -glycoproteins in both native and non-native conformations by using the following sequence: misfolding of chemically synthesized Man9 -glycoprotein, enzymatic glucosylation, and another misfolding step. By using synthetic glycoprotein probes, calreticulin was found to bind preferentially to a hydrophobic non-native glycoprotein whereas glucosidase II activity was not affected by glycoprotein conformation. The results demonstrate the ability of chemical synthesis to deliver homogeneous glycoproteins in several non-native conformations for probing the glycoprotein QC system.
Collapse
Affiliation(s)
- Masayuki Izumi
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Yukiho Oka
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Ryo Okamoto
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Akira Seko
- ERATO Ito glycotrilogy project Japan Science and Technology Agency (JST), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Yoichi Takeda
- ERATO Ito glycotrilogy project Japan Science and Technology Agency (JST), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Yukishige Ito
- ERATO Ito glycotrilogy project Japan Science and Technology Agency (JST), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan. .,Synthetic Cellular Chemistry Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
| | - Yasuhiro Kajihara
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan. .,ERATO Ito glycotrilogy project Japan Science and Technology Agency (JST), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
| |
Collapse
|
17
|
Abstract
The endoplasmic reticulum (ER) supports many cellular processes and performs diverse functions, including protein synthesis, translocation across the membrane, integration into the membrane, folding, and posttranslational modifications including N-linked glycosylation; and regulation of Ca2+ homeostasis. In mammalian systems, the majority of proteins synthesized by the rough ER have N-linked glycans critical for protein maturation. The N-linked glycan is used as a quality control signal in the secretory protein pathway. A series of chaperones, folding enzymes, glucosidases, and carbohydrate transferases support glycoprotein synthesis and processing. Perturbation of ER-associated functions such as disturbed ER glycoprotein quality control, protein glycosylation and protein folding results in activation of an ER stress coping response. Collectively this ER stress coping response is termed the unfolded protein response (UPR), and occurs through the activation of complex cytoplasmic and nuclear signaling pathways. Cellular and ER homeostasis depends on balanced activity of the ER protein folding, quality control, and degradation pathways; as well as management of the ER stress coping response.
Collapse
|
18
|
Tannous A, Pisoni GB, Hebert DN, Molinari M. N-linked sugar-regulated protein folding and quality control in the ER. Semin Cell Dev Biol 2015; 41:79-89. [PMID: 25534658 PMCID: PMC4474783 DOI: 10.1016/j.semcdb.2014.12.001] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 12/02/2014] [Indexed: 11/18/2022]
Abstract
Asparagine-linked glycans (N-glycans) are displayed on the majority of proteins synthesized in the endoplasmic reticulum (ER). Removal of the outermost glucose residue recruits the lectin chaperone malectin possibly involved in a first triage of defective polypeptides. Removal of a second glucose promotes engagement of folding and quality control machineries built around the ER lectin chaperones calnexin (CNX) and calreticulin (CRT) and including oxidoreductases and peptidyl-prolyl isomerases. Deprivation of the last glucose residue dictates the release of N-glycosylated polypeptides from the lectin chaperones. Correctly folded proteins are authorized to leave the ER. Non-native polypeptides are recognized by the ER quality control key player UDP-glucose glycoprotein glucosyltransferase 1 (UGT1), re-glucosylated and re-addressed to the CNX/CRT chaperone binding cycle to provide additional opportunity for the protein to fold in the ER. Failure to attain the native structure determines the selection of the misfolded polypeptides for proteasome-mediated degradation.
Collapse
Affiliation(s)
- Abla Tannous
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | | | - Daniel N Hebert
- Department of Biochemistry and Molecular Biology, Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003, USA.
| | - Maurizio Molinari
- Università della Svizzera italiana, CH-6900 Lugano, Switzerland; Institute for Research in Biomedicine, Protein Folding and Quality Control, CH-6500 Bellinzona, Switzerland; Ecole Polytechnique Fédérale de Lausanne, School of Life Sciences, CH-1015 Lausanne, Switzerland.
| |
Collapse
|
19
|
Lin Q, Cao Y, Gao J. Serum calreticulin is a negative biomarker in patients with Alzheimer's disease. Int J Mol Sci 2014; 15:21740-53. [PMID: 25429433 PMCID: PMC4284675 DOI: 10.3390/ijms151221740] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 11/03/2014] [Accepted: 11/10/2014] [Indexed: 11/16/2022] Open
Abstract
Calreticulin is down-regulated in the cortical neurons of patients with Alzheimer's disease (AD) and may be a potential biomarker for the diagnosis of AD. A total of 128 AD patients were randomly recruited from May 2012 to July 2013. The mRNA levels of calreticulin were measured from the serum of tested subjects using real-time quantitative reverse transcriptase-PCR (real-time qRT-PCR). Serum levels of calreticulin were determined by ELISA and Western Blot. Serum levels of calreticulin in AD patients were significantly lower than those from a healthy group (p < 0.01). The baseline characters indicated that sample size, gender, mean age, diabetes and BMI (body mass index) were not major sources of heterogeneity. The serum levels of mRNA and protein of calreticulin were lower in AD patients than those from a healthy group, and negatively associated with the progression of AD according to CDR scores (p < 0.01). Thus, there is a trend toward decreased serum levels of calreticulin in the patients with progression of AD. Serum levels of calreticulin can be a negative biomarker for the diagnosis of AD patients.
Collapse
Affiliation(s)
- Qiao Lin
- Department of Internal Medicine, the Fourth Affiliated Hospital of China Medical University, Shenyang 110005, China.
| | - Yunpeng Cao
- Neural Department of Internal Medicine, the First Affiliated Hospital of China Medical University, Shenyang 110001, China.
| | - Jie Gao
- Department of Anatomy, the First Affiliated Hospital of China Medical University, Shenyang 110001, China.
| |
Collapse
|
20
|
Calreticulin molecular evolution: a strong purifying and episodic diversifying selection result. Biologia (Bratisl) 2014. [DOI: 10.2478/s11756-013-0327-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
21
|
Huang SH, Zhao LX, Hong C, Duo CC, Guo BN, Zhang LJ, Gong Z, Xiong SD, Gong FY, Gao XM. Self-oligomerization is essential for enhanced immunological activities of soluble recombinant calreticulin. PLoS One 2013; 8:e64951. [PMID: 23762269 PMCID: PMC3677884 DOI: 10.1371/journal.pone.0064951] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 04/19/2013] [Indexed: 12/11/2022] Open
Abstract
We have recently reported that calreticulin (CRT), a luminal resident protein, can be found in the sera of patients with rheumatoid arthritis and also that recombinant CRT (rCRT) exhibits extraordinarily strong immunological activities. We herein further demonstrate that rCRT fragments 18-412 (rCRT/18-412), rCRT/39-272, rCRT/120-308 and rCRT/120-250 can self-oligomerize in solution and are 50-100 fold more potent than native CRT (nCRT, isolated from mouse livers) in activating macrophages in vitro. We narrowed down the active site of CRT to residues 150-230, the activity of which also depends on dimerization. By contrast, rCRT/18-197 is almost completely inactive. When rCRT/18-412 is fractionated into oligomers and monomers by gel filtration, the oligomers maintain most of their immunological activities in terms of activating macrophages in vitro and inducing specific antibodies in vivo, while the monomers were much less active by comparison. Additionally, rCRT/18-412 oligomers are much better than monomers in binding to, and uptake by, macrophages. Inhibition of macrophage endocytosis partially blocks the stimulatory effect of rCRT/18-412. We conclude that the immunologically active site of CRT maps between residues 198-230 and that soluble CRT could acquire potent immuno-pathological activities in microenvironments favoring its oligomerization.
Collapse
Affiliation(s)
- Shang-Hui Huang
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province, China
| | - Li-Xiang Zhao
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province, China
| | - Chao Hong
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province, China
| | - Cui-Cui Duo
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province, China
| | - Bing-Nan Guo
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province, China
| | - Li-Juan Zhang
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province, China
| | - Zheng Gong
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province, China
| | - Si-Dong Xiong
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province, China
| | - Fang-Yuan Gong
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province, China
- * E-mail: (XMG); (FYG)
| | - Xiao-Ming Gao
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, Jiangsu Province, China
- * E-mail: (XMG); (FYG)
| |
Collapse
|
22
|
Liu Y, Li J. An in vivo investigation of amino acid residues critical for the lectin function of Arabidopsis calreticulin 3. MOLECULAR PLANT 2013; 6:985-7. [PMID: 23288863 PMCID: PMC3660953 DOI: 10.1093/mp/sss163] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 12/26/2012] [Indexed: 05/26/2023]
Affiliation(s)
| | - Jianming Li
- To whom correspondence should be addressed. E-mail , tel. +1 734–763–4253, fax +1 734–647–0884
| |
Collapse
|
23
|
Liu Y, Li J. A conserved basic residue cluster is essential for the protein quality control function of the Arabidopsis calreticulin 3. PLANT SIGNALING & BEHAVIOR 2013; 8:e23864. [PMID: 23425854 PMCID: PMC3956487 DOI: 10.4161/psb.23864] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Calreticulin (CRT) is a highly conserved chaperone-like lectin that regulates Ca(2+) homeostasis and participates in protein quality control in the endoplasmic reticulum (ER). Most of our CRT knowledge came from mammalian studies, but our understanding of plant CRTs is limited. Many plants contain more than two CRTs that form two distinct groups: CRT1/CRT2 and CRT3. Previous studies on plant CRTs were focused on their Ca(2+)-binding function, but recent studies revealed a crucial role for the Arabidopsis CRT3 in ER retention of a mutant brassinosteroid receptor, brassinosteroid-insensitive 1-9 (bri1-9) and in complete folding of a plant immunity receptor EF-Tu Receptor (EFR). However, little is known about the molecular basis of the functional specification of the CRTs. We have recently shown that the C-terminal domain of CRT3, which is rich in basic residues, is essential for retaining bri1-9 in the ER; however, its role in assisting EFR folding has not been studied. Here, we used an insertional mutant of CRT3, ebs2-8 (EMS mutagenized bri1 suppressor 2-8), in the bri1-9 background as a genetic system to investigate the functional importance of two basic residue clusters in the CRT3's C-terminal domain. Complementation experiments of ebs2-8 bri1-9 with mutant CRT3(M) transgenes showed that a highly conserved basic tetrapeptide Arg(392)Arg (393)Arg(394)Lys(395) is essential but a less conserved basic tetrapeptide Arg(401)Arg(402)Arg(403)Arg(404) is dispensable for the quality control function of CRT3 that retains bri1-9 in the ER and facilitates the complete folding of EFR.
Collapse
|
24
|
Qiu X, Hong C, Zhong Z, Li Y, Zhang T, Bao W, Xiong S, Gao XM. Modulation of cellular immunity by antibodies against calreticulin. Eur J Immunol 2012; 42:2419-30. [PMID: 22685035 DOI: 10.1002/eji.201142320] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 05/02/2012] [Accepted: 05/30/2012] [Indexed: 12/26/2022]
Abstract
Although caltreticulin (CRT) is mainly a residential ER protein, it is also expressed on the membrane surface of various types of cells exhibiting multiple functions. We report here that intraperitoneal administration of a soluble recombinant CRT fragment (rCRT/39-272) led to a substantial decrease in delayed type hypersensitivity (DTH) responses in BALB/c mice and EAE in C57BL/6 mice. In the recall response against keyhole limpet hemocyanin (KLH) in vitro, draining lymph node cells from the rCRT/39-272-treated mice produced less IFN-γ but more IL-4 as compared with the cells from the control group. The immunomodulating effect of intraperitoneally administered rCRT/39-272 was attributed to anti-CRT Abs thereby induced, because, in passive transfer experiments, the CRT-specific antiserum could suppress DTH in BALB/c mice. B-cell-deficient μMT mice were not susceptible to rCRT/39-272-mediated DTH suppression. Furthermore, CRT appears on the surface of murine T cells soon after activation and remains detectable (at relatively low level) by flow cytometry for approximately 5 days in vitro. Anti-CRT Abs were able to inhibit AKT phosphorylation, proliferation, and cytokine production by activated murine T cells. We propose that cell surface CRT could play a role in the function of effector T cells and may be considered a target for immunological manipulation.
Collapse
Affiliation(s)
- Xiang Qiu
- Department of Immunology, Peking University Health Science Center, Beijing, China
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Hariprasad G, Kumar M, Rani K, Kaur P, Srinivasan A. Aminoglycoside induced nephrotoxicity: molecular modeling studies of calreticulin-gentamicin complex. J Mol Model 2011; 18:2645-52. [DOI: 10.1007/s00894-011-1289-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 10/20/2011] [Indexed: 12/11/2022]
|
26
|
Brodsky JL, Skach WR. Protein folding and quality control in the endoplasmic reticulum: Recent lessons from yeast and mammalian cell systems. Curr Opin Cell Biol 2011; 23:464-75. [PMID: 21664808 DOI: 10.1016/j.ceb.2011.05.004] [Citation(s) in RCA: 181] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 04/29/2011] [Accepted: 05/17/2011] [Indexed: 12/16/2022]
Abstract
The evolution of eukaryotes was accompanied by an increased need for intracellular communication and cellular specialization. Thus, a more complex collection of secreted and membrane proteins had to be synthesized, modified, and folded. The endoplasmic reticulum (ER) thereby became equipped with devoted enzymes and associated factors that both catalyze the production of secreted proteins and remove damaged proteins. A means to modify ER function to accommodate and destroy misfolded proteins also evolved. Not surprisingly, a growing number of human diseases are linked to various facets of ER function. Each of these topics will be discussed in this article, with an emphasis on recent reports in the literature that employed diverse models.
Collapse
Affiliation(s)
- Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA.
| | | |
Collapse
|
27
|
Pocanschi CL, Kozlov G, Brockmeier U, Brockmeier A, Williams DB, Gehring K. Structural and functional relationships between the lectin and arm domains of calreticulin. J Biol Chem 2011; 286:27266-77. [PMID: 21652723 DOI: 10.1074/jbc.m111.258467] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calreticulin and calnexin are key components in maintaining the quality control of glycoprotein folding within the endoplasmic reticulum. Although their lectin function of binding monoglucosylated sugar moieties of glycoproteins is well documented, their chaperone activity in suppressing protein aggregation is less well understood. Here, we use a series of deletion mutants of calreticulin to demonstrate that its aggregation suppression function resides primarily within its lectin domain. Using hydrophobic peptides as substrate mimetics, we show that aggregation suppression is mediated through a single polypeptide binding site that exhibits a K(d) for peptides of 0.5-1 μM. This site is distinct from the oligosaccharide binding site and differs from previously identified sites of binding to thrombospondin and GABARAP (4-aminobutyrate type A receptor-associated protein). Although the arm domain of calreticulin was incapable of suppressing aggregation or binding hydrophobic peptides on its own, it did contribute to aggregation suppression in the context of the whole molecule. The high resolution x-ray crystal structure of calreticulin with a partially truncated arm domain reveals a marked difference in the relative orientations of the arm and lectin domains when compared with calnexin. Furthermore, a hydrophobic patch was detected on the arm domain that mediates crystal packing and may contribute to calreticulin chaperone function.
Collapse
Affiliation(s)
- Cosmin L Pocanschi
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | | | | | | | | | | |
Collapse
|
28
|
Chouquet A, Païdassi H, Ling WL, Frachet P, Houen G, Arlaud GJ, Gaboriaud C. X-ray structure of the human calreticulin globular domain reveals a peptide-binding area and suggests a multi-molecular mechanism. PLoS One 2011; 6:e17886. [PMID: 21423620 PMCID: PMC3057994 DOI: 10.1371/journal.pone.0017886] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 02/15/2011] [Indexed: 11/23/2022] Open
Abstract
In the endoplasmic reticulum, calreticulin acts as a chaperone and a
Ca2+-signalling protein. At the cell surface, it mediates
numerous important biological effects. The crystal structure of the human
calreticulin globular domain was solved at 1.55 Å resolution. Interactions
of the flexible N-terminal extension with the edge of the lectin site are
consistently observed, revealing a hitherto unidentified peptide-binding site. A
calreticulin molecular zipper, observed in all crystal lattices, could further
extend this site by creating a binding cavity lined by hydrophobic residues.
These data thus provide a first structural insight into the lectin-independent
binding properties of calreticulin and suggest new working hypotheses, including
that of a multi-molecular mechanism.
Collapse
Affiliation(s)
- Anne Chouquet
- Institut de Biologie Structurale Jean-Pierre
Ebel, CEA, Grenoble, France
| | - Helena Païdassi
- Institut de Biologie Structurale Jean-Pierre
Ebel, CEA, Grenoble, France
| | - Wai Li Ling
- Institut de Biologie Structurale Jean-Pierre
Ebel, CEA, Grenoble, France
| | - Philippe Frachet
- Institut de Biologie Structurale Jean-Pierre
Ebel, UJF Grenoble 1, Grenoble, France
| | - Gunnar Houen
- Department of Clinical Biochemistry and
Immunology, Statens Serum Institut, Copenhagen, Denmark
| | - Gérard J. Arlaud
- Institut de Biologie Structurale Jean-Pierre
Ebel, CNRS, Grenoble, France
| | - Christine Gaboriaud
- Institut de Biologie Structurale Jean-Pierre
Ebel, CEA, Grenoble, France
- * E-mail:
| |
Collapse
|
29
|
Essential glycan-dependent interactions optimize MHC class I peptide loading. Proc Natl Acad Sci U S A 2011; 108:4950-5. [PMID: 21383180 DOI: 10.1073/pnas.1102524108] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In this study we sought to better understand the role of the glycoprotein quality control machinery in the assembly of MHC class I molecules with high-affinity peptides. The lectin-like chaperone calreticulin (CRT) and the thiol oxidoreductase ERp57 participate in the final step of this process as part of the peptide-loading complex (PLC). We provide evidence for an MHC class I/CRT intermediate before PLC engagement and examine the nature of that chaperone interaction in detail. To investigate the mechanism of peptide loading and roles of individual components, we reconstituted a PLC subcomplex, excluding the Transporter Associated with Antigen Processing, from purified, recombinant proteins. ERp57 disulfide linked to the class I-specific chaperone tapasin and CRT were the minimal PLC components required for MHC class I association and peptide loading. Mutations disrupting the interaction of CRT with ERp57 or the class I glycan completely eliminated PLC activity in vitro. By using the purified system, we also provide direct evidence for a role for UDP-glucose:glycoprotein glucosyltransferase 1 in MHC class I assembly. The recombinant Drosophila enzyme reglucosylated MHC class I molecules associated with suboptimal ligands and allowed PLC reengagement and high-affinity peptide exchange. Collectively, the data indicate that CRT in the PLC enhances weak tapasin/class I interactions in a manner that is glycan-dependent and regulated by UDP-glucose:glycoprotein glucosyltransferase 1.
Collapse
|
30
|
Kozlov G, Pocanschi CL, Rosenauer A, Bastos-Aristizabal S, Gorelik A, Williams DB, Gehring K. Structural basis of carbohydrate recognition by calreticulin. J Biol Chem 2010; 285:38612-20. [PMID: 20880849 PMCID: PMC2992293 DOI: 10.1074/jbc.m110.168294] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 09/06/2010] [Indexed: 11/06/2022] Open
Abstract
The calnexin cycle is a process by which glycosylated proteins are subjected to folding cycles in the endoplasmic reticulum lumen via binding to the membrane protein calnexin (CNX) or to its soluble homolog calreticulin (CRT). CNX and CRT specifically recognize monoglucosylated Glc(1)Man(9)GlcNAc(2) glycans, but the structural determinants underlying this specificity are unknown. Here, we report a 1.95-Å crystal structure of the CRT lectin domain in complex with the tetrasaccharide α-Glc-(1→3)-α-Man-(1→2)-α-Man-(1→2)-Man. The tetrasaccharide binds to a long channel on CRT formed by a concave β-sheet. All four sugar moieties are engaged in the protein binding via an extensive network of hydrogen bonds and hydrophobic contacts. The structure explains the requirement for glucose at the nonreducing end of the carbohydrate; the oxygen O(2) of glucose perfectly fits to a pocket formed by CRT side chains while forming direct hydrogen bonds with the carbonyl of Gly(124) and the side chain of Lys(111). The structure also explains a requirement for the Cys(105)-Cys(137) disulfide bond in CRT/CNX for efficient carbohydrate binding. The Cys(105)-Cys(137) disulfide bond is involved in intimate contacts with the third and fourth sugar moieties of the Glc(1)Man(3) tetrasaccharide. Finally, the structure rationalizes previous mutagenesis of CRT and lays a structural groundwork for future studies of the role of CNX/CRT in diverse biological pathways.
Collapse
Affiliation(s)
- Guennadi Kozlov
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - Cosmin L. Pocanschi
- the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Angelika Rosenauer
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - Sara Bastos-Aristizabal
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - Alexei Gorelik
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| | - David B. Williams
- the Departments of Biochemistry and Immunology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Kalle Gehring
- From the Department of Biochemistry, Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montréal, Québec H3G 0B1, Canada and
| |
Collapse
|
31
|
Participation of lectin chaperones and thiol oxidoreductases in protein folding within the endoplasmic reticulum. Curr Opin Cell Biol 2010; 23:157-66. [PMID: 21094034 DOI: 10.1016/j.ceb.2010.10.011] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 10/05/2010] [Accepted: 10/21/2010] [Indexed: 01/21/2023]
Abstract
Protein folding within the endoplasmic reticulum occurs in conjunction with a complex array of molecular chaperones and folding catalysts that assist the folding process as well as function in quality control processes to monitor the outcome. In this review, we summarize recent advances in the calnexin/calreticulin chaperone system that is directed primarily toward Asn-linked glycoproteins, as well as the protein disulfide isomerase family of enzymes that catalyze disulfide formation, reduction, and isomerization. We highlight issues related to function and substrate specificity as well as the functional interplay between the two systems.
Collapse
|
32
|
Hong C, Qiu X, Li Y, Huang Q, Zhong Z, Zhang Y, Liu X, Sun L, Lv P, Gao XM. Functional analysis of recombinant calreticulin fragment 39-272: implications for immunobiological activities of calreticulin in health and disease. THE JOURNAL OF IMMUNOLOGY 2010; 185:4561-9. [PMID: 20855873 DOI: 10.4049/jimmunol.1000536] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although calreticulin (CRT) is a major Ca(2+)-binding luminal resident protein, it can also appear on the surface of various types of cells and it functions as an immunopotentiating molecule. However, molecular mechanisms underlying the potent immunobiological activity of cell surface CRT are still unclear. In the present study, a recombinant fragment (rCRT/39-272) covering the lectin-like N domain and partial P domain of murine CRT has been expressed in Escherichia coli. The affinity-purified rCRT/39-272 assembles into homodimers and oligomers in solution and exhibits high binding affinity to various glycans, including carrageenan, alginic acids, and hyaluronic acids. Functionally, rCRT/39-272 is capable of driving the activation and maturation of B cells and cytokine production by macrophages in a TLR-4-dependent manner in vitro. It specifically binds recombinant mouse CD14, but not BAFFR and CD40. It is also able to trigger Ig class switching by B cells in the absence of T cell help both in vitro and in vivo. Furthermore, this fragment of CRT exhibits strong adjuvanticity when conjugated to polysaccharides or expressed as part of a fusion protein. Soluble CRT can be detected in the sera of patients with rheumatoid arthritis or systemic lupus erythematosus, but not in healthy subjects. We argue that CRT, either on the membrane surface of cells or in soluble form, is a potent stimulatory molecule to B cells and macrophages via the TLR-4/CD14 pathway and plays important roles in the pathogenesis of autoimmune diseases.
Collapse
Affiliation(s)
- Chao Hong
- Department of Immunology, Peking University Health Science Center, Beijing, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Del Cid N, Jeffery E, Rizvi SM, Stamper E, Peters LR, Brown WC, Provoda C, Raghavan M. Modes of calreticulin recruitment to the major histocompatibility complex class I assembly pathway. J Biol Chem 2009; 285:4520-35. [PMID: 19959473 DOI: 10.1074/jbc.m109.085407] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Major histocompatibility complex (MHC) class I molecules are ligands for T-cell receptors of CD8(+) T cells and inhibitory receptors of natural killer cells. Assembly of the heavy chain, light chain, and peptide components of MHC class I molecules occurs in the endoplasmic reticulum (ER). Specific assembly factors and generic ER chaperones, collectively called the MHC class I peptide loading complex (PLC), are required for MHC class I assembly. Calreticulin has an important role within the PLC and induces MHC class I cell surface expression, but the interactions and mechanisms involved are incompletely understood. We show that interactions with the thiol oxidoreductase ERp57 and substrate glycans are important for the recruitment of calreticulin into the PLC and for its functional activities in MHC class I assembly. The glycan and ERp57 binding sites of calreticulin contribute directly or indirectly to complexes between calreticulin and the MHC class I assembly factor tapasin and are important for maintaining steady-state levels of both tapasin and MHC class I heavy chains. A number of destabilizing conditions and mutations induce generic polypeptide binding sites on calreticulin and contribute to calreticulin-mediated suppression of misfolded protein aggregation in vitro. We show that generic polypeptide binding sites per se are insufficient for stable recruitment of calreticulin to PLC substrates in cells. However, such binding sites could contribute to substrate stabilization in a step that follows the glycan and ERp57-dependent recruitment of calreticulin to the PLC.
Collapse
Affiliation(s)
- Natasha Del Cid
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Dong G, Wearsch PA, Peaper DR, Cresswell P, Reinisch KM. Insights into MHC class I peptide loading from the structure of the tapasin-ERp57 thiol oxidoreductase heterodimer. Immunity 2009; 30:21-32. [PMID: 19119025 DOI: 10.1016/j.immuni.2008.10.018] [Citation(s) in RCA: 228] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 10/17/2008] [Accepted: 10/22/2008] [Indexed: 11/19/2022]
Abstract
Tapasin is a glycoprotein critical for loading major histocompatibility complex (MHC) class I molecules with high-affinity peptides. It functions within the multimeric peptide-loading complex (PLC) as a disulfide-linked, stable heterodimer with the thiol oxidoreductase ERp57, and this covalent interaction is required to support optimal PLC activity. Here, we present the 2.6 A resolution structure of the tapasin-ERp57 core of the PLC. The structure revealed that tapasin interacts with both ERp57 catalytic domains, accounting for the stability of the heterodimer, and provided an example of a protein disulfide isomerase family member interacting with substrate. Mutational analysis identified a conserved surface on tapasin that interacted with MHC class I molecules and was critical for peptide loading and editing functions of the tapasin-ERp57 heterodimer. By combining the tapasin-ERp57 structure with those of other defined PLC components, we present a molecular model that illuminates the processes involved in MHC class I peptide loading.
Collapse
Affiliation(s)
- Gang Dong
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06520, USA
| | | | | | | | | |
Collapse
|
35
|
Zhang Y, Kozlov G, Pocanschi CL, Brockmeier U, Ireland BS, Maattanen P, Howe C, Elliott T, Gehring K, Williams DB. ERp57 does not require interactions with calnexin and calreticulin to promote assembly of class I histocompatibility molecules, and it enhances peptide loading independently of its redox activity. J Biol Chem 2009; 284:10160-73. [PMID: 19196713 DOI: 10.1074/jbc.m808356200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ERp57 is a thiol oxidoreductase that catalyzes disulfide formation in heavy chains of class I histocompatibility molecules. It also forms a mixed disulfide with tapasin within the class I peptide loading complex, stabilizing the complex and promoting efficient binding of peptides to class I molecules. Since ERp57 associates with the lectin chaperones calnexin and calreticulin, it is thought that ERp57 requires these chaperones to gain access to its substrates. To test this idea, we examined class I biogenesis in cells lacking calnexin or calreticulin or that express an ERp57 mutant that fails to bind to these chaperones. Remarkably, heavy chain disulfides formed at the same rate in these cells as in wild type cells. Moreover, ERp57 formed a mixed disulfide with tapasin and promoted efficient peptide loading in the absence of interactions with calnexin and calreticulin. These findings suggest that ERp57 has the capacity to recognize its substrates directly in addition to being recruited through lectin chaperones. We also found that calreticulin could be recruited into the peptide loading complex in the absence of interactions with both ERp57 and substrate oligosaccharides, demonstrating the importance of its polypeptide binding site in substrate recognition. Finally, by inactivating the redox-active sites of ERp57, we demonstrate that its enzymatic activity is dispensable in stabilizing the peptide loading complex and in supporting efficient peptide loading. Thus, ERp57 appears to play a structural rather than catalytic role within the peptide loading complex.
Collapse
Affiliation(s)
- Yinan Zhang
- Departments of Biochemistry and Immunology, University of Toronto, Toronto M5S 1A8, Canada
| | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Michalak M, Groenendyk J, Szabo E, Gold L, Opas M. Calreticulin, a multi-process calcium-buffering chaperone of the endoplasmic reticulum. Biochem J 2009; 417:651-666. [DOI: 10.1042/bj20081847] [Citation(s) in RCA: 522] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
Calreticulin is an ER (endoplasmic reticulum) luminal Ca2+-buffering chaperone. The protein is involved in regulation of intracellular Ca2+ homoeostasis and ER Ca2+ capacity. The protein impacts on store-operated Ca2+ influx and influences Ca2+-dependent transcriptional pathways during embryonic development. Calreticulin is also involved in the folding of newly synthesized proteins and glycoproteins and, together with calnexin (an integral ER membrane chaperone similar to calreticulin) and ERp57 [ER protein of 57 kDa; a PDI (protein disulfide-isomerase)-like ER-resident protein], constitutes the ‘calreticulin/calnexin cycle’ that is responsible for folding and quality control of newly synthesized glycoproteins. In recent years, calreticulin has been implicated to play a role in many biological systems, including functions inside and outside the ER, indicating that the protein is a multi-process molecule. Regulation of Ca2+ homoeostasis and ER Ca2+ buffering by calreticulin might be the key to explain its multi-process property.
Collapse
Affiliation(s)
- Marek Michalak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Jody Groenendyk
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Eva Szabo
- Laboratory of Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8
| | - Leslie I. Gold
- Departments of Medicine and Pathology, New York University School of Medicine, New York, NY 10016, U.S.A
| | - Michal Opas
- Laboratory of Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8
| |
Collapse
|
37
|
Ireland BS, Brockmeier U, Howe CM, Elliott T, Williams DB. Lectin-deficient calreticulin retains full functionality as a chaperone for class I histocompatibility molecules. Mol Biol Cell 2008; 19:2413-23. [PMID: 18337472 DOI: 10.1091/mbc.e07-10-1055] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Calreticulin is a molecular chaperone of the endoplasmic reticulum that uses both a lectin site specific for Glc(1)Man(5-9)GlcNAc(2) oligosaccharides and a polypeptide binding site to interact with nascent glycoproteins. The latter mode of substrate recognition is controversial. To examine the relevance of polypeptide binding to protein folding in living cells, we prepared lectin-deficient mutants of calreticulin and examined their abilities to support the assembly and quality control of mouse class I histocompatibility molecules. In cells lacking calreticulin, class I molecules exhibit inefficient loading of peptide ligands, reduced cell surface expression and aberrantly rapid export from the endoplasmic reticulum. Remarkably, expression of calreticulin mutants that are completely devoid of lectin function fully complemented all of the class I biosynthetic defects. We conclude that calreticulin can use nonlectin-based modes of substrate interaction to effect its chaperone and quality control functions on class I molecules in living cells. Furthermore, pulse-chase coimmunoisolation experiments revealed that lectin-deficient calreticulin bound to a similar spectrum of client proteins as wild-type calreticulin and dissociated with similar kinetics, suggesting that lectin-independent interactions are commonplace in cells and that they seem to be regulated during client protein maturation.
Collapse
Affiliation(s)
- Breanna S Ireland
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | | | | | | | | |
Collapse
|
38
|
How sugars convey information on protein conformation in the endoplasmic reticulum. Semin Cell Dev Biol 2007; 18:732-42. [PMID: 17997334 DOI: 10.1016/j.semcdb.2007.09.006] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Revised: 07/24/2007] [Accepted: 09/05/2007] [Indexed: 11/21/2022]
Abstract
The N-glycan-dependent quality control of glycoprotein folding prevents endoplasmic reticulum to Golgi exit of folding intermediates, irreparably misfolded glycoproteins and not completely 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 and a glucosidase that creates monoglucosylated epitopes in glycans transferred in protein N-glycosylation or 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 purpose of the review is to describe the most significant recent findings on the mechanism of glycoprotein folding and assembly quality control and to discuss the main still unanswered questions.
Collapse
|
39
|
Sandhu N, Duus K, Jørgensen CS, Hansen PR, Bruun SW, Pedersen LØ, Højrup P, Houen G. Peptide binding specificity of the chaperone calreticulin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2007; 1774:701-13. [PMID: 17499031 DOI: 10.1016/j.bbapap.2007.03.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 03/28/2007] [Accepted: 03/29/2007] [Indexed: 10/23/2022]
Abstract
Calreticulin is a molecular chaperone with specificity for polypeptides and N-linked monoglucosylated glycans. In order to determine the specificity of polypeptide binding, the interaction of calreticulin with polypeptides was investigated using synthetic peptides of different length and composition. A large set of available synthetic peptides (n=127) was tested for binding to calreticulin and the results analysed by multivariate data analysis. The parameter that correlated best with binding was hydrophobicity while beta-turn potential disfavoured binding. Only hydrophobic peptides longer than 5 amino acids showed binding and a clear correlation with hydrophobicity was demonstrated for oligomers of different hydrophobic amino acids. Insertion of hydrophilic amino acids in a hydrophobic sequence diminished or abolished binding. In conclusion our results show that calreticulin has a peptide-binding specificity for hydrophobic sequences and delineate the fine specificity of calreticulin for hydrophobic amino acid residues.
Collapse
Affiliation(s)
- Noreen Sandhu
- Department of Autoimmunology, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen, Denmark
| | | | | | | | | | | | | | | |
Collapse
|
40
|
Gopalakrishnapai J, Gupta G, Karthikeyan T, Sinha S, Kandiah E, Gemma E, Oscarson S, Surolia A. Isothermal titration calorimetric study defines the substrate binding residues of calreticulin. Biochem Biophys Res Commun 2006; 351:14-20. [PMID: 17049488 DOI: 10.1016/j.bbrc.2006.09.164] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Accepted: 09/25/2006] [Indexed: 11/22/2022]
Abstract
Earlier we established using modeling studies the residues in calreticulin (CRT) important for sugar-binding (M. Kapoor, H. Srinivas, K. Eaazhisai, E. Gemma, L. Ellgaard, S. Oscarson, A. Helenius, A. Surolia, Interactions of substrate with calreticulin, an endoplasmic reticulum chaperone, J. Biol. Chem. 278 (8) (2003) 6194-6200). Here, we discuss the relative roles of Trp-319, Asp-317, and Asp-160 for sugar-binding by using site-directed mutagenesis and isothermal titration calorimetry (ITC). Residues corresponding to Asp-160 and Asp-317 in CNX play important role towards sugar-binding. From the present study we demonstrate that the residue Asp-160 is not involved in sugar-binding, while Asp-317 plays a crucial role. Further, it is also validated that cation-pi interactions of the sugar with Trp-319 dictate sugar-binding in CRT. This study not only defines further the binding site of CRT but also highlights its subtle differences with that of calnexin.
Collapse
|
41
|
Williams DB. Beyond lectins: the calnexin/calreticulin chaperone system of the endoplasmic reticulum. J Cell Sci 2006; 119:615-23. [PMID: 16467570 DOI: 10.1242/jcs.02856] [Citation(s) in RCA: 337] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Calnexin and calreticulin are related proteins that comprise an ER chaperone system that ensures the proper folding and quality control of newly synthesized glycoproteins. The specificity for glycoproteins is conferred by a lectin site that recognizes an early oligosaccharide processing intermediate on the folding glycoprotein, Glc1Man9GlcNAc2. In addition, calnexin and calreticulin possess binding sites for ATP, Ca2+, non-native polypeptides and ERp57, an enzyme that catalyzes disulfide bond formation, reduction and isomerization. Recent studies have revealed the locations of some of these ligand-binding sites and have provided insights into how they contribute to overall chaperone function. In particular, the once controversial non-native-polypeptide-binding site has now been shown to function both in vitro and in cells. Furthermore, there is clear evidence that ERp57 participates in glycoprotein biogenesis either alone or in tandem with calnexin and calreticulin.
Collapse
Affiliation(s)
- David B Williams
- Department of Biochemistry and Immunology, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.
| |
Collapse
|