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Muñoz SM, Vallejos-Baccelliere G, Manubens A, Salazar ML, Nascimento AFZ, Tapia-Reyes P, Meneses C, Ambrosio ALB, Becker MI, Guixé V, Castro-Fernandez V. Structural insights into a functional unit from an immunogenic mollusk hemocyanin. Structure 2024; 32:812-823.e4. [PMID: 38513659 DOI: 10.1016/j.str.2024.02.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 01/30/2024] [Accepted: 02/23/2024] [Indexed: 03/23/2024]
Abstract
Mollusk hemocyanins, among the largest known proteins, are used as immunostimulants in biomedical and clinical applications. The hemocyanin of the Chilean gastropod Concholepas concholepas (CCH) exhibits unique properties, which makes it safe and effective for human immunotherapy, as observed in animal models of bladder cancer and melanoma, and dendritical cell vaccine trials. Despite its potential, the structure and amino acid sequence of CCH remain unknown. This study reports two sequence fragments of CCH, representing three complete functional units (FUs). We also determined the high-resolution (1.5 Å) X-ray crystal structure of an "FU-g type" from the CCHB subunit. This structure enables in-depth analysis of chemical interactions at the copper-binding center and unveils an unusual, truncated N-glycosylation pattern. These features are linked to eliciting more robust immunological responses in animals, offering insights into CCH's enhanced immunostimulatory properties and opening new avenues for its potential applications in biomedical research and therapies.
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Affiliation(s)
- Sebastián M Muñoz
- Laboratorio de Bioquímica y Biología Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 780003, Chile
| | - Gabriel Vallejos-Baccelliere
- Laboratorio de Bioquímica y Biología Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 780003, Chile
| | - Augusto Manubens
- Departamento de Investigación y Desarrollo, Biosonda Corp., Santiago 7750629, Chile; Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750629, Chile
| | - Michelle L Salazar
- Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750629, Chile
| | - Andrey F Z Nascimento
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, Sao Paulo 13083-970, Brazil
| | - Patricio Tapia-Reyes
- Escuela de Biotecnología, Facultad de Ciencias, Universidad Santo Tomás, Santiago 8370003, Chile; Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | - Claudio Meneses
- Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile; Departamento de Fruticultura y Enología, Facultad de Agronomía y Sistemas Naturales, Pontificia Universidad Católica de Chile, Santiago 7820436, Chile; Millennium Nucleus Development of Super Adaptable Plants (MN-SAP), Santiago 8331150, Chile; Millennium Institute Center for Genome Regulation (CRG), Santiago 8331150, Chile
| | - Andre L B Ambrosio
- Sao Carlos Institute of Physics (IFSC), University of Sao Paulo (USP), Sao Carlos, Sao Paulo 13563-120, Brazil
| | - María Inés Becker
- Departamento de Investigación y Desarrollo, Biosonda Corp., Santiago 7750629, Chile; Fundación Ciencia y Tecnología para el Desarrollo (FUCITED), Santiago 7750629, Chile
| | - Victoria Guixé
- Laboratorio de Bioquímica y Biología Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 780003, Chile.
| | - Victor Castro-Fernandez
- Laboratorio de Bioquímica y Biología Molecular, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago 780003, Chile.
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2
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Toustou C, Walet-Balieu ML, Kiefer-Meyer MC, Houdou M, Lerouge P, Foulquier F, Bardor M. Towards understanding the extensive diversity of protein N-glycan structures in eukaryotes. Biol Rev Camb Philos Soc 2021; 97:732-748. [PMID: 34873817 PMCID: PMC9300197 DOI: 10.1111/brv.12820] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 11/04/2021] [Accepted: 11/24/2021] [Indexed: 12/12/2022]
Abstract
N‐glycosylation is an important post‐translational modification of proteins that has been highly conserved during evolution and is found in Eukaryota, Bacteria and Archaea. In eukaryotes, N‐glycan processing is sequential, involving multiple specific steps within the secretory pathway as proteins travel through the endoplasmic reticulum and the Golgi apparatus. In this review, we first summarize the different steps of the N‐glycan processing and further describe recent findings regarding the diversity of N‐glycan structures in eukaryotic clades. This comparison allows us to explore the different regulation mechanisms of N‐glycan processing among eukaryotic clades. Recent findings regarding the regulation of protein N‐glycosylation are highlighted, especially the regulation of the biosynthesis of complex‐type N‐glycans through manganese and calcium homeostasis and the specific role of transmembrane protein 165 (TMEM165) for which homologous sequences have been identified in several eukaryotic clades. Further research will be required to characterize the function of TMEM165 homologous sequences in different eukaryotic clades.
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Affiliation(s)
- Charlotte Toustou
- Normandie Univ, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire végétale (Glyco-MEV) EA4358, Mont-Saint-Aignan, 76821, France
| | - Marie-Laure Walet-Balieu
- Normandie Univ, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire végétale (Glyco-MEV) EA4358, Mont-Saint-Aignan, 76821, France
| | - Marie-Christine Kiefer-Meyer
- Normandie Univ, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire végétale (Glyco-MEV) EA4358, Mont-Saint-Aignan, 76821, France
| | - Marine Houdou
- Univ Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, Lille, F-59000, France.,Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, Box 802, Leuven, 3000, Belgium
| | - Patrice Lerouge
- Normandie Univ, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire végétale (Glyco-MEV) EA4358, Mont-Saint-Aignan, 76821, France
| | - François Foulquier
- Univ Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, Lille, F-59000, France
| | - Muriel Bardor
- Normandie Univ, UNIROUEN, Laboratoire Glycobiologie et Matrice Extracellulaire végétale (Glyco-MEV) EA4358, Mont-Saint-Aignan, 76821, France.,Univ Lille, CNRS, UMR 8576 - UGSF - Unité de Glycobiologie Structurale et Fonctionnelle, Lille, F-59000, France
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3
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Mollusc N-glycosylation: Structures, Functions and Perspectives. Biomolecules 2021; 11:biom11121820. [PMID: 34944464 PMCID: PMC8699351 DOI: 10.3390/biom11121820] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/01/2021] [Accepted: 12/01/2021] [Indexed: 12/22/2022] Open
Abstract
Molluscs display a sophisticated N-glycan pattern on their proteins, which is, in terms of involved structural features, even more diverse than that of vertebrates. This review summarises the current knowledge of mollusc N-glycan structures, with a focus on the functional aspects of the corresponding glycoproteins. Furthermore, the potential of mollusc-derived biomolecules for medical applications is addressed, emphasising the importance of mollusc research.
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4
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Dolashka P, Daskalova A, Dolashki A, Voelter W. De Novo Structural Determination of the Oligosaccharide Structure of Hemocyanins from Molluscs. Biomolecules 2020; 10:biom10111470. [PMID: 33105875 PMCID: PMC7690630 DOI: 10.3390/biom10111470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 09/22/2020] [Accepted: 09/23/2020] [Indexed: 12/04/2022] Open
Abstract
A number of studies have shown that glycosylation of proteins plays diverse functions in the lives of organisms, has crucial biological and physiological roles in pathogen–host interactions, and is involved in a large number of biological events in the immune system, and in virus and bacteria recognition. The large amount of scientific interest in glycoproteins of molluscan hemocyanins is due not only to their complex quaternary structures, but also to the great diversity of their oligosaccharide structures with a high carbohydrate content (2–9%). This great variety is due to their specific monosaccharide composition and different side chain composition. The determination of glycans and glycopeptides was performed with the most commonly used methods for the analysis of biomolecules, including peptides and proteins, including Matrix Assisted Laser Desorption/Ionisation–Time of Flight (MALDI-TOF-TOF), Liquid Chromatography - Electrospray Ionization-Mass Spectrometry (LC/ESI-MS), Liquid Chromatography (LC-Q-trap-MS/MS) or Nano- Electrospray Ionization-Mass Spectrometry (nano-ESI-MS) and others. The molluscan hemocyanins have complex carbohydrate structures with predominant N-linked glycans. Of interest are identified structures with methylated hexoses and xyloses arranged at different positions in the carbohydrate moieties of molluscan hemocyanins. Novel acidic glycan structures with specific glycosylation positions, e.g., hemocyanins that enable a deeper insight into the glycosylation process, were observed in Rapana venosa, Helix lucorum, and Haliotis tuberculata. Recent studies demonstrate that glycosylation plays a crucial physiological role in the immunostimulatory and therapeutic effect of glycoproteins. The remarkable diversity of hemocyanin glycan content is an important feature of their immune function and provides a new concept in the antibody–antigen interaction through clustered carbohydrate epitopes.
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Affiliation(s)
- Pavlina Dolashka
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria or (A.D.); (A.D.)
- Correspondence: or ; Tel.:+359-887193423
| | - Asya Daskalova
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria or (A.D.); (A.D.)
| | - Aleksandar Dolashki
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria or (A.D.); (A.D.)
| | - Wolfgang Voelter
- Interfacultary Institute of Biochemistry, University of Tuebingen, 72074 Tuebingen, Germany;
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Tjondro HC, Loke I, Chatterjee S, Thaysen-Andersen M. Human protein paucimannosylation: cues from the eukaryotic kingdoms. Biol Rev Camb Philos Soc 2019; 94:2068-2100. [PMID: 31410980 DOI: 10.1111/brv.12548] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 07/10/2019] [Accepted: 07/17/2019] [Indexed: 12/11/2022]
Abstract
Paucimannosidic proteins (PMPs) are bioactive glycoproteins carrying truncated α- or β-mannosyl-terminating asparagine (N)-linked glycans widely reported across the eukaryotic domain. Our understanding of human PMPs remains limited, despite findings documenting their existence and association with human disease glycobiology. This review comprehensively surveys the structures, biosynthetic routes and functions of PMPs across the eukaryotic kingdoms with the aim of synthesising an improved understanding on the role of protein paucimannosylation in human health and diseases. Convincing biochemical, glycoanalytical and biological data detail a vast structural heterogeneity and fascinating tissue- and subcellular-specific expression of PMPs within invertebrates and plants, often comprising multi-α1,3/6-fucosylation and β1,2-xylosylation amongst other glycan modifications and non-glycan substitutions e.g. O-methylation. Vertebrates and protists express less-heterogeneous PMPs typically only comprising variable core fucosylation of bi- and trimannosylchitobiose core glycans. In particular, the Manα1,6Manβ1,4GlcNAc(α1,6Fuc)β1,4GlcNAcβAsn glycan (M2F) decorates various human neutrophil proteins reportedly displaying bioactivity and structural integrity demonstrating that they are not degradation products. Less-truncated paucimannosidic glycans (e.g. M3F) are characteristic glycosylation features of proteins expressed by human cancer and stem cells. Concertedly, these observations suggest the involvement of human PMPs in processes related to innate immunity, tumorigenesis and cellular differentiation. The absence of human PMPs in diverse bodily fluids studied under many (patho)physiological conditions suggests extravascular residence and points to localised functions of PMPs in peripheral tissues. Absence of PMPs in Fungi indicates that paucimannosylation is common, but not universally conserved, in eukaryotes. Relative to human PMPs, the expression of PMPs in plants, invertebrates and protists is more tissue-wide and constitutive yet, similar to their human counterparts, PMP expression remains regulated by the physiology of the producing organism and PMPs evidently serve essential functions in development, cell-cell communication and host-pathogen/symbiont interactions. In most PMP-producing organisms, including humans, the N-acetyl-β-hexosaminidase isoenzymes and linkage-specific α-mannosidases are glycoside hydrolases critical for generating PMPs via N-acetylglucosaminyltransferase I (GnT-I)-dependent and GnT-I-independent truncation pathways. However, the identity and structure of many species-specific PMPs in eukaryotes, their biosynthetic routes, strong tissue- and development-specific expression, and diverse functions are still elusive. Deep exploration of these PMP features involving, for example, the characterisation of endogenous PMP-recognising lectins across a variety of healthy and N-acetyl-β-hexosaminidase-deficient human tissue types and identification of microbial adhesins reactive to human PMPs, are amongst the many tasks required for enhanced insight into the glycobiology of human PMPs. In conclusion, the literature supports the notion that PMPs are significant, yet still heavily under-studied biomolecules in human glycobiology that serve essential functions and create structural heterogeneity not dissimilar to other human N-glycoprotein types. Human PMPs should therefore be recognised as bioactive glycoproteins that are distinctly different from the canonical N-glycoprotein classes and which warrant a more dedicated focus in glycobiological research.
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Affiliation(s)
- Harry C Tjondro
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Ian Loke
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia.,Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Sayantani Chatterjee
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Morten Thaysen-Andersen
- Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
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González A, Nova E, Del Campo M, Manubens A, De Ioannes A, Ferreira J, Becker MI. The oxygen-binding properties of hemocyanin from the mollusk Concholepas concholepas. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:1746-1757. [DOI: 10.1016/j.bbapap.2017.08.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Revised: 05/29/2017] [Accepted: 08/07/2017] [Indexed: 01/18/2023]
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7
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Velkova L, Dolashka P, Van Beeumen J, Devreese B. N-glycan structures of β-HlH subunit of Helix lucorum hemocyanin. Carbohydr Res 2017; 449:1-10. [PMID: 28672164 DOI: 10.1016/j.carres.2017.06.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 06/20/2017] [Accepted: 06/21/2017] [Indexed: 10/19/2022]
Abstract
The carbohydrate structures of molluscan hemocyanins have recently received particular interest due to their specific monosaccharide composition, as well as their immunostimulatory properties and application in clinical studies. For the first time, we investigated N-glycans of the structural subunit β-HlH of hemocyanin isolated from Helix lucorum. In total, 32 different glycans were enzymatically liberated and characterized by tandem mass spectrometry using a Q-Trap mass spectrometer. Our study revealed a highly heterogeneous mixture of glycans with composition Hex3-7HexNAc2-5MeHex0-4Pent0-1Fuc0-1. The oligosaccharide chains are mostly modified at the inner core by β1-2-linked xylose to β-mannose, by α1-6-fucosylation of the innermost GlcNAc residue (the Asn-bound GlcNAc), and by methylation. The glycans of β-HlH mainly contain a terminal MeHex residue; in some cases even two, three or four of these residues occur. Several carbohydrate chains in β-HlH are core-fucosylated without Xyl and also possess a high degree of methylation. This study shows the presence of mono- and bi-antennary N-glycans as well as hybrid type structures with or without core-fucosylation.
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Affiliation(s)
- Lyudmila Velkova
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 9 G. Bonchev St., Sofia 1113, Bulgaria.
| | - Pavlina Dolashka
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 9 G. Bonchev St., Sofia 1113, Bulgaria
| | - Jozef Van Beeumen
- Laboratory of Protein Biochemistry and Biomolecular Engineering, Ghent University, KL Ledeganckstraat 35, Ghent 9000, Belgium
| | - Bart Devreese
- Laboratory of Protein Biochemistry and Biomolecular Engineering, Ghent University, KL Ledeganckstraat 35, Ghent 9000, Belgium
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8
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VLIEGENTHART JFG. The complexity of glycoprotein-derived glycans. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2017; 93:64-86. [PMID: 28190870 PMCID: PMC5422628 DOI: 10.2183/pjab.93.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 12/09/2016] [Indexed: 05/31/2023]
Abstract
A brief review is presented of our studies on the structure of glycoprotein-derived glycans. The emphasis is on the introduction of high-resolution 1H-NMR spectroscopy for the unambiguous determination of primary structures. For this purpose, we developed the structural reporter group concept. Structural reporters are defined as unique markers of structural elements in the NMR spectra. Application of this concept led to the discovery of numerous new structures. Furthermore, a number of structures presented in the literature could be corrected. The results are relevant for insight in the various steps in glycan metabolism in health and disease, for the function and mode of action of glycans in vivo and for the interpretation of structural information obtained through other techniques. The strength of the approach is further shown for several highly complex glycoproteins, carrying very heterogeneous and complicated glycans.
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N-linked glycosite profiling and use of Skyline as a platform for characterization and relative quantification of glycans in differentiating xylem of Populus trichocarpa. Anal Bioanal Chem 2016; 409:487-497. [PMID: 27491298 DOI: 10.1007/s00216-016-9776-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 06/28/2016] [Accepted: 07/06/2016] [Indexed: 01/02/2023]
Abstract
Our greater understanding of the importance of N-linked glycosylation in biological systems has spawned the field of glycomics and development of analytical tools to address the many challenges regarding our ability to characterize and quantify this complex and important modification as it relates to biological function. One of the unmet needs of the field remains a systematic method for characterization of glycans in new biological systems. This study presents a novel workflow for identification of glycans using Individuality Normalization when Labeling with Isotopic Glycan Hydrazide Tags (INLIGHT™) strategy developed in our lab. This consists of monoisotopic mass extraction followed by peak pair identification of tagged glycans from a theoretical library using an in-house program. Identification and relative quantification could then be performed using the freely available bioinformatics tool Skyline. These studies were performed in the biological context of studying the N-linked glycome of differentiating xylem of the poplar tree, a widely studied model woody plant, particularly with respect to understanding lignin biosynthesis during wood formation. Through our workflow, we were able to identify 502 glycosylated proteins including 12 monolignol enzymes and 1 peroxidase (PO) through deamidation glycosite analysis. Finally, our novel semi-automated workflow allowed for rapid identification of 27 glycans by intact mass and by NAT/SIL peak pairing from a library containing 1573 potential glycans, eliminating the need for extensive manual analysis. Implementing Skyline for relative glycan quantification allowed for improved accuracy and precision of quantitative measurements over current processing tools which we attribute to superior algorithms correction for baseline variation and MS1 peak filtering. Graphical abstract Workflow for FANGS-INLIGHT glycosite profiling of plant xylem and monolignol proteins followed by INLIGHT tagging with semi-automated identification of glycans by light-heavy peak pairs. Finally, manual validation and relative quantification was performed in Skyline.
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10
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Eckmair B, Jin C, Abed-Navandi D, Paschinger K. Multistep Fractionation and Mass Spectrometry Reveal Zwitterionic and Anionic Modifications of the N- and O-glycans of a Marine Snail. Mol Cell Proteomics 2015; 15:573-97. [PMID: 26598642 DOI: 10.1074/mcp.m115.051573] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Indexed: 12/11/2022] Open
Abstract
Various studies in the past have revealed that molluscs can produce a wide range of rather complex N-glycan structures, which vary from those occurring in other invertebrate animals; particularly methylated glycans have been found in gastropods, and there are some reports of anionic glycans in bivalves. Due to the high variability in terms of previously described structures and methodologies, it is a major challenge to establish glycomic workflows that yield the maximum amount of detailed structural information from relatively low quantities of sample. In this study, we apply differential release with peptide:N-glycosidases F and A followed by solid-phase extraction on graphitized carbon and reversed-phase materials to examine the glycome of Volvarina rubella (C. B. Adams, 1845), a margin snail of the clade Neogastropoda. The resulting four pools of N-glycans were fractionated on a fused core RP-HPLC column and subject to MALDI-TOF MS and MS/MS in conjunction with chemical and enzymatic treatments. In addition, selected N-glycan fractions, as well as O-glycans released by β-elimination, were analyzed by porous graphitized carbon-LC-MS and MS(n). This comprehensive approach enabled us to determine a number of novel modifications of protein-linked glycans, including N-methyl-2-aminoethylphosphonate on mannose and N-acetylhexosamine residues, core β1,3-linked mannose, zwitterionic moieties on core Galβ1,4Fuc motifs, additional mannose residues on oligomannosidic glycans, and bisubstituted antennal fucose; furthermore, typical invertebrate N-glycans with sulfate and core fucose residues are present in this gastropod.
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Affiliation(s)
- Barbara Eckmair
- From the ‡Department für Chemie, Universität für Bodenkultur Wien, 1190 Wien, Austria
| | - Chunsheng Jin
- §Institutionen för Biomedicin, Göteborgs universitet, 405 30 Göteborg, Sweden
| | | | - Katharina Paschinger
- From the ‡Department für Chemie, Universität für Bodenkultur Wien, 1190 Wien, Austria;
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11
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Pietrzyk AJ, Bujacz A, Mak P, Potempa B, Niedziela T. Structural studies of Helix aspersa agglutinin complexed with GalNAc: A lectin that serves as a diagnostic tool. Int J Biol Macromol 2015; 81:1059-68. [PMID: 26416237 DOI: 10.1016/j.ijbiomac.2015.09.044] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Revised: 09/22/2015] [Accepted: 09/23/2015] [Indexed: 02/07/2023]
Abstract
Lectins belong to a differentiated group of proteins known to possess sugar-binding properties. Due to this fact, they are interesting research targets in medical diagnostics. Helix aspersa agglutinin (HAA) is a lectin that recognizes the epitopes containing α-d-N-acetylgalactosamine (GalNAc), which is present at the surface of metastatic cancer cells. Although several reports have already described the use of HAA as a diagnostic tool, this protein was not characterized on the molecular level. Here, we present for the first time the structural information about lectin isolated from mucus of Helix aspersa (garden snail). The amino acid sequence of this agglutinin was determined by Edman degradation and tertiary as well as quaternary structure by X-ray crystallography. The high resolution crystal structure (1.38Å) and MALDI-TOF mass spectrometry analysis provide the detailed information about a large part of the HAA natural glycan chain. The topology of the GalNAc binding cleft and interaction with lectin are very well defined in the structure and fully confirmed by STD HSQC NMR spectroscopy. Together, this provides structural clues regarding HAA specificity and opens possibilities to rational modifications of this important diagnostic tool.
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Affiliation(s)
- Agnieszka J Pietrzyk
- Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 4/10, Lodz 90-924, Poland
| | - Anna Bujacz
- Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 4/10, Lodz 90-924, Poland.
| | - Paweł Mak
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7A, 30-387 Krakow, Poland; Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Krakow, Poland
| | - Barbara Potempa
- University of Louisville School of Dentistry, Department of Oral Immunology and Infectious Diseases, 501 South Preston Street, Louisville, KY 40202, USA
| | - Tomasz Niedziela
- Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla 12, Wrocław 53-114, Poland
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12
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Ichimiya T, Maeda M, Sakamura S, Kanazawa M, Nishihara S, Kimura Y. Identification of β1,3-galactosyltransferases responsible for biosynthesis of insect complex-type N-glycans containing a T-antigen unit in the honeybee. Glycoconj J 2015; 32:141-51. [PMID: 25931033 DOI: 10.1007/s10719-015-9585-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 03/20/2015] [Accepted: 03/24/2015] [Indexed: 11/29/2022]
Abstract
Honeybees (Apis mellifera) produce unique complex-type N-glycans bearing a Galβ1-3GalNAc (T-antigen) unit, and honeybee-specific N-glycans are linked to royal jelly glycoproteins. In this study, we identified two novel honeybee β1,3-galactosyltransferase (β1,3-GalT) genes responsible for biosynthesis of the T-antigen in insect N-glycans. The products of the two putative β1,3-GalT genes (β1,3-GalT1 and β1,3-GalT2), which were expressed in Sf21 insect cells, transferred galactose (Gal) residues to GalNAc2GlcNAc2Man3GlcNAc2-PA to form the Galβ1-3GalNAc unit, indicating that the identified genes were involved in biosynthesis of the β1-3 Gal-containing N-glycan. Therefore, using biochemistry and molecular biology techniques, we revealed a unique N-glycan biosynthesis mechanism in the cephalic region of honeybees, which has not previously been found in other animal or plant cells.
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Affiliation(s)
- Tomomi Ichimiya
- Department of Bioinformatics, Faculty of Engineering, Soka University, 1-236 Tangi-cho, Tokyo, Japan
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13
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Velkova L, Todorov D, Dimitrov I, Shishkov S, Beeumen JV, Dolashka-Angelova P. Rapana Venosa Hemocyanin with Antiviral Activity. BIOTECHNOL BIOTEC EQ 2014. [DOI: 10.1080/13102818.2009.10818498] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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14
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Solomon EI, Heppner DE, Johnston EM, Ginsbach JW, Cirera J, Qayyum M, Kieber-Emmons MT, Kjaergaard CH, Hadt RG, Tian L. Copper active sites in biology. Chem Rev 2014; 114:3659-853. [PMID: 24588098 PMCID: PMC4040215 DOI: 10.1021/cr400327t] [Citation(s) in RCA: 1138] [Impact Index Per Article: 113.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | - David E. Heppner
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Jordi Cirera
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Munzarin Qayyum
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | | | - Ryan G. Hadt
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Li Tian
- Department of Chemistry, Stanford University, Stanford, CA, 94305
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15
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Kurz S, Jin C, Hykollari A, Gregorich D, Giomarelli B, Vasta GR, Wilson IBH, Paschinger K. Hemocytes and plasma of the eastern oyster (Crassostrea virginica) display a diverse repertoire of sulfated and blood group A-modified N-glycans. J Biol Chem 2013; 288:24410-28. [PMID: 23824194 DOI: 10.1074/jbc.m113.478933] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The eastern oyster (Crassostrea virginica) has become a useful model system for glycan-dependent host-parasite interactions due to the hijacking of the oyster galectin CvGal1 for host entry by the protozoan parasite Perkinsus marinus, the causative agent of Dermo disease. In this study, we examined the N-glycans of both the hemocytes, which via CvGal1 are the target of the parasite, and the plasma of the oyster. In combination with HPLC fractionation, exoglycosidase digestion, and fragmentation of the glycans, mass spectrometry revealed that the major N-glycans of plasma are simple hybrid structures, sometimes methylated and core α1,6-fucosylated, with terminal β1,3-linked galactose; a remarkable high degree of sulfation of such glycans was observed. Hemocytes express a larger range of glycans, including core-difucosylated paucimannosidic forms, whereas bi- and triantennary glycans were found in both sources, including structures carrying sulfated and methylated variants of the histo-blood group A epitope. The primary features of the oyster whole hemocyte N-glycome were also found in dominin, the major plasma glycoprotein, which had also been identified as a CvGal1 glycoprotein ligand associated with hemocytes. The occurrence of terminal blood group moieties on oyster dominin and on hemocyte surfaces can account in part for their affinity for the endogenous CvGal1.
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Affiliation(s)
- Simone Kurz
- Department für Chemie, Universität für Bodenkultur, A-1190 Wien, Austria
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16
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Staudacher E. Methylation--an uncommon modification of glycans. Biol Chem 2013; 393:675-85. [PMID: 22944672 DOI: 10.1515/hsz-2012-0132] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 03/27/2012] [Indexed: 11/15/2022]
Abstract
A methyl (Me) group on a sugar residue is a rarely reported event. Until now, this type of modification has been found in the animal kingdom only in worms and molluscs, whereas it is more frequently present in some species of bacteria, fungi, algae and plants, but not in mammals. The monosaccharides involved as well as the positions of the Me groups on the sugar vary with species. Methylation appears to play a role in some recognition events, but details are still unknown. This review summarises the current knowledge on methylation of sugars in all types of organism.
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Affiliation(s)
- Erika Staudacher
- Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
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17
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Schiller B, Hykollari A, Yan S, Paschinger K, Wilson IBH. Complicated N-linked glycans in simple organisms. Biol Chem 2013; 393:661-73. [PMID: 22944671 DOI: 10.1515/hsz-2012-0150] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 04/07/2012] [Indexed: 11/15/2022]
Abstract
Although countless genomes have now been sequenced, the glycomes of the vast majority of eukaryotes still present a series of unmapped frontiers. However, strides are being made in a few groups of invertebrate and unicellular organisms as regards their N-glycans and N-glycosylation pathways. Thereby, the traditional classification of glycan structures inevitably approaches its boundaries. Indeed, the glycomes of these organisms are rich in surprises, including a multitude of modifications of the core regions of N-glycans and unusual antennae. From the actually rather limited glycomic information we have, it is nevertheless obvious that the biotechnological, developmental and immunological relevance of these modifications, especially in insect cell lines, model organisms and parasites means that deciphering unusual glycomes is of more than just academic interest.
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Affiliation(s)
- Birgit Schiller
- Department für Chemie, Universität für Bodenkultur, A-1190 Wien, Austria
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18
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Kostadinova E, Dolashka P, Kaloyanova S, Velkova L, Deligeorgiev T, Voelter W, Petkov I. Method for analysis of different oligosacchiride structures. J Fluoresc 2012; 22:1609-15. [PMID: 22825362 DOI: 10.1007/s10895-012-1102-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 06/27/2012] [Indexed: 11/26/2022]
Abstract
In this study, an improved, rapid, high yield synthesis of N,N'-4,4'-bis(benzyl-2-boronic acid)-bipyridinium dibromide (o-BBV) is described. The obtained o-BVV is applied in a two-component saccharide sensing system (complex) where it serves as a fluorescence quencher and a saccharide receptor. This system was applied to different natural oligosaccharides isolated from molluscan Rapana venosa (RvH1-a) and arthropodan Carcinus aestuarii (CaeH) hemocyanins (Hcs) and cyclodextrins (CDs). The carbohydrate contents of both Hcs were calculated in our previous work to be 1,6 % and 7 % for CaeH and RvH1-a, respectively. We propose that the difference in fluorescence increase of the native CaeH and RvH1-a when titrating them with the complex is due to the fact that the carbohydrate content of CaeH is lower and the carbohydrate chains are buried in between the structural subunits of the native molecule, while the glycans of the functional unit RvH1-a are exposed on the surface of the molecule leading to a 4-fold fluorescence's intensity change.
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19
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Arancibia S, Del Campo M, Nova E, Salazar F, Becker MI. Enhanced structural stability of Concholepas hemocyanin increases its immunogenicity and maintains its non-specific immunostimulatory effects. Eur J Immunol 2012; 42:688-99. [PMID: 22144228 DOI: 10.1002/eji.201142011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Hemocyanins, which boost the immune system of mammals, have been used as carrier-adjuvants to promote Ab production against haptens and peptides, as immunostimulants during therapy for bladder carcinoma and as a component in therapeutic vaccines for cancer. These biomedical applications have led to growing interest in obtaining hemocyanins with high immunogenicity. Here, we study the immunological properties of a modified oxidized Concholepas concholepas hemocyanin (Ox-CCH) obtained by the oxidation of its carbohydrates using sodium periodate. We assessed the internalization of Ox-CCH into DCs and its immunogenicity and antitumor effects. Transmission electron microscopy showed no changes in Ox-CCH quaternary structure with respect to native CCH, although proteolytic treatment followed by SDS-PAGE analysis demonstrated that Schiff bases were formed. Interestingly, DCs internalized Ox-CCH faster than CCH, mainly through macropinocytosis. During this process, Ox-CCH remained inside endosome-like structures for a longer period. Mouse immunization experiments demonstrated that Ox-CCH is more immunogenic and a better carrier than CCH. Moreover, Ox-CCH showed a significant antitumor effect in the B16F10 melanoma model similar to that produced by CCH, inducing IFN-γ secretion. Together, these data demonstrate that the aldehydes formed by the periodate oxidation of sugar moieties stabilizes the CCH structure, increasing its adjuvant/immunostimulatory carrier effects.
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20
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Stepan H, Pabst M, Altmann F, Geyer H, Geyer R, Staudacher E. O-Glycosylation of snails. Glycoconj J 2012; 29:189-98. [PMID: 22581130 PMCID: PMC3372779 DOI: 10.1007/s10719-012-9391-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 04/26/2012] [Indexed: 11/04/2022]
Abstract
The glycosylation abilities of snails deserve attention, because snail species serve as intermediate hosts in the developmental cycles of some human and cattle parasites. In analogy to many other host-pathogen relations, the glycosylation of snail proteins may likewise contribute to these host-parasite interactions. Here we present an overview on the O-glycan structures of 8 different snails (land and water snails, with or without shell): Arion lusitanicus, Achatina fulica, Biomphalaria glabrata, Cepaea hortensis, Clea helena, Helix pomatia, Limax maximus and Planorbarius corneus. The O-glycans were released from the purified snail proteins by β-elimination. Further analysis was carried out by liquid chromatography coupled to electrospray ionization mass spectrometry and – for the main structures – by gas chromatography/mass spectrometry. Snail O-glycans are built from the four monosaccharide constituents: N-acetylgalactosamine, galactose, mannose and fucose. An additional modification is a methylation of the hexoses. The common trisaccharide core structure was determined in Arion lusitanicus to be N-acetylgalactosamine linked to the protein elongated by two 4-O-methylated galactose residues. Further elongations by methylated and unmethylated galactose and mannose residues and/or fucose are present. The typical snail O-glycan structures are different to those so far described. Similar to snail N-glycan structures they display methylated hexose residues.
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Affiliation(s)
- Herwig Stepan
- Department of Chemistry, Glycobiology, University of Natural Resources and Life Sciences Vienna, 1190, Vienna, Austria
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21
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The cDNA sequence of three hemocyanin subunits from the garden snail Helix lucorum. Gene 2011; 487:118-28. [PMID: 21851852 DOI: 10.1016/j.gene.2011.07.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 07/22/2011] [Accepted: 07/31/2011] [Indexed: 11/20/2022]
Abstract
Hemocyanins are blue copper containing respiratory proteins residing in the hemolymph of many molluscs and arthropods. They can have different molecular masses and quaternary structures. Moreover, several molluscan hemocyanins are isolated with one, two or three isoforms occurring as decameric, didecameric, multidecameric or tubule aggregates. We could recently isolate three different hemocyanin isopolypeptides from the hemolymph of the garden snail Helix lucorum (HlH). These three structural subunits were named α(D)-HlH, α(N)-HlH and β-HlH. We have cloned and sequenced their cDNA which is the first result ever reported for three isoforms of a molluscan hemocyanin. Whereas the complete gene sequence of α(D)-HlH and β-HlH was obtained, including the 5' and 3' UTR, 180bp of the 5' end and around 900bp at the 3' end are missing for the third subunit. The subunits α(D)-HlH and β-HlH comprise a signal sequence of 19 amino acids plus a polypeptide of 3409 and 3414 amino acids, respectively. We could determine 3031 residues of the α(N)-HLH subunit. Sequence comparison with other molluscan hemocyanins shows that α(D)-HlH is more related to Aplysia californicum hemocyanin than to each of its own isopolypeptides. The structural subunits comprise 8 different functional units (FUs: a, b, c, d, e, f, g, h) and each functional unit possesses a highly conserved copper-A and copper-B site for reversible oxygen binding. Potential N-glycosylation sites are present in all three structural subunits. We confirmed that all three different isoforms are effectively produced and secreted in the hemolymph of H. lucorum by analyzing a tryptic digest of the purified native hemocyanin by MALDI-TOF and LC-FTICR mass spectrometry.
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22
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Levy-Ontman O, Arad SM, Harvey DJ, Parsons TB, Fairbanks A, Tekoah Y. Unique N-glycan moieties of the 66-kDa cell wall glycoprotein from the red microalga Porphyridium sp. J Biol Chem 2011; 286:21340-52. [PMID: 21515680 PMCID: PMC3122194 DOI: 10.1074/jbc.m110.175042] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 04/11/2011] [Indexed: 11/06/2022] Open
Abstract
We report here the structural determination of the N-linked glycans in the 66-kDa glycoprotein, part of the unique sulfated complex cell wall polysaccharide of the red microalga Porphyridium sp. Structures were elucidated by a combination of normal phase/reverse phase HPLC, positive ion MALDI-TOF MS, negative ion electrospray ionization, and MS/MS. The sugar moieties of the glycoprotein consisted of at least four fractions of N-linked glycans, each composed of the same four monosaccharides, GlcNAc, Man, 6-O-MeMan, and Xyl, with compositions Man(8-9)Xyl(1-2)Me(3)GlcNAc(2). The present study is the first report of N-glycans with the terminal Xyl attached to the 6-mannose branch of the 6-antenna and to the 3-oxygen of the penultimate (core) GlcNAc. Another novel finding was that all four glycans contain three O-methylmannose residues in positions that have never been reported before. Although it is known that some lower organisms are able to methylate terminal monosaccharides in glycans, the present study on Porphyridium sp. is the first describing an organism that is able to methylate non-terminal mannose residues. This study will thus contribute to understanding of N-glycosylation in algae and might shed light on the evolutionary development from prokaryotes to multicellular organisms. It also may contribute to our understanding of the red algae polysaccharide formation. The additional importance of this research lies in its potential for biotechnological applications, especially in evaluating the use of microalgae as cell factories for the production of therapeutic proteins.
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Affiliation(s)
- Oshrat Levy-Ontman
- Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
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23
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Velkova L, Dolashka P, Lieb B, Dolashki A, Voelter W, Van Beeumen J, Devreese B. Glycan structures of the structural subunit (HtH1) of Haliotis tuberculata hemocyanin. Glycoconj J 2011; 28:385-95. [PMID: 21660411 DOI: 10.1007/s10719-011-9337-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 04/16/2011] [Accepted: 05/24/2011] [Indexed: 11/26/2022]
Abstract
The oligosaccharide structures of the structural subunit HtH1 of Haliotis tuberculata hemocyanin (HtH) were studied by mass spectral sequence analysis of the glycans. The proposed structures are based on MALDI-TOF-MS data before and after treatment with the specific exoglycosidases β1-3,4,6-galactosidase and α1-6(>2,3,4) fucosidase followed by sequence analysis via electrospray ionization MS/MS-spectra. In total, 15 glycans were identified as a highly heterogeneous group of structures. As in most molluscan hemocyanins, the glycans of HtH1 contain a terminal MeHex, but more interestingly, a novel structural motif was observed: MeHex[Fuc(α1-3)-]GlcNAc, including thus MeHex and (α1-3)-Fuc residues being linked to an internal GlcNAc residue. While the functional unit (FU) c (HtH1-c) is completely lacking any potential glycosylation site, FU-h possesses a second exposed sugar attachment site between beta-strands 8 and 9 within the beta sandwich domain compared to the other FUs. The glycosylation pattern/sites show a high degree of conservation. In FU-h two prominent potential glycosylation sites can be detected. The finding that HtH1 is not able to form multidecameric structures in vivo could be explained by the presence of the exposed glycan on the surface of FU-h.
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Affiliation(s)
- Lyudmila Velkova
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia
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24
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Dolashka P, Velkova L, Iliev I, Beck A, Dolashki A, Yossifova L, Toshkova R, Voelter W, Zacharieva S. Antitumor activity of glycosylated molluscan hemocyanins via Guerin ascites tumor. Immunol Invest 2010; 40:130-49. [PMID: 20923331 DOI: 10.3109/08820139.2010.513408] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
As observed in most molluscan hemocyanins, high-mannose type glycans were identified in hemocyanins from Rapana venosa (RvH), Helix lucorum (HlH) and keyhole limpet (Megatura crenulata). In addition, a glycan with a branching structure containing xylose, fucose and terminal methyl hexose was identified in β-HlH. We have examined the immuno-adjuvant properties of hemocyanins, their derivatives and conjugates associated with the cell mediated immunity in experimental tumor-bearing animals with ascites tumor of Guerin. After immunization of the animals with the experimental vaccine preparations, the highest values of splenic lymphocytes were observed in groups immunized with the conjugates RvH-TAg, β-HlH-TAg and KLH-TAg (42.3%; 40.8% and 40.58%, respectively) than with the native hemocyanins (36.5%; 35.1% and 32.4%, respectively). The immunization of rats with the hemocyanins β-HlH, RvH and KLH and their conjugates, prolonged the median survival time of tumor-bearing animals compared with non-immunized animals (39, 33, 31 and 7 days, respectively). Both hemocyanins β-HlH and RvH activate the immune system of the experimental animals and therefore could be a good alternative for KLH. For this reason they could be included into the composition of non-specific anti-tumor vaccines to enhance their effectiveness.
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Affiliation(s)
- Pavlina Dolashka
- Institute of Organic Chemistry, Bulgarian Academy of Sciences, G. Bonchev 9, Sofia 1113, Bulgaria. pda54@ abv.bg
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25
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Dolashka P, Velkova L, Shishkov S, Kostova K, Dolashki A, Dimitrov I, Atanasov B, Devreese B, Voelter W, Van Beeumen J. Glycan structures and antiviral effect of the structural subunit RvH2 of Rapana hemocyanin. Carbohydr Res 2010; 345:2361-7. [PMID: 20863484 DOI: 10.1016/j.carres.2010.08.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Revised: 07/22/2010] [Accepted: 08/12/2010] [Indexed: 11/24/2022]
Abstract
Molluscan hemocyanins are very large biological macromolecules and they act as oxygen-transporting glycoproteins. Most of them are glycoproteins with molecular mass around 9000 kDa. The oligosaccharide structures of the structural subunit RvH2 of Rapana venosa hemocyanin (RvH) were studied by sequence analysis of glycans using MALDI-TOF-MS and tandem mass spectrometry on a Q-Trap mass spectrometer after enzymatical liberation of the N-glycans from the polypeptides. Our study revealed a highly heterogeneous mixture of glycans of the compositions Hex(0-9) HexNAc(2-4) Hex(0-3) Pent(0-3) Fuc(0-3). A novel type of N-glycan, with an internal fucose residue connecting one GalNAc(β1-2) and one hexuronic acid, was detected, as also occurs in subunit RvH1. A glycan with the same structure but with two deoxyhexose residues was observed as a doubly charged ion. Antiviral effects of the native molecules of RvH and also of Helix lucorum hemocyanin (HlH), of their structural subunits, and of the glycosylated functional unit RvH2-e and the non-glycosylated unit RvH2-c on HSV virus type 1 were investigated. Only glycosylated FU RvH2-e exhibits this antiviral activity. The carbohydrate chains of the FU are likely to interact with specific regions of glycoproteins of HSV, through van der Waals interactions in general or with certain amino acid residues in particular. Several clusters of these residues can be identified on the surface of RvH2-e.
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Affiliation(s)
- Pavlina Dolashka
- Institute of Organic Chemistry, Bulgarian Academy of Sciences, G. Bonchev 9, Sofia 1113, Bulgaria.
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26
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Velkova L, Dimitrov I, Schwarz H, Stevanovic S, Voelter W, Salvato B, Dolashka-Angelova P. Structure of hemocyanin from garden snail Helix lucorum. Comp Biochem Physiol B Biochem Mol Biol 2010; 157:16-25. [PMID: 20433940 DOI: 10.1016/j.cbpb.2010.04.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 04/21/2010] [Accepted: 04/22/2010] [Indexed: 10/19/2022]
Abstract
Hemocyanins are giant extracellular oxygen carriers in the hemolymph of many molluscs and arthropods with different quaternary structure. They are represented in the hemolymph of molluscs with one, two or three isoforms, as decameric, didecameric, multidecameric and tubules aggregates. We describe here the structure of the hemocyanin Helix lucorum (HlH), species in the series of molluscan hemocyanins. In contrast with other molluscan hemocyanins, three different hemocyanin isopolypeptides were isolated from the hemolymph of the garden snail H. lucorum, named as beta-HlH, alpha(D)-HlH and alpha(N)-HlH. Their molecular masses were determined by size exclusion chromatography to be 1068 kDa (beta-HlH) and 1079 kDa (alpha(D)-HlH, and alpha(N)-HlH). Native HlH exhibits a predominant didecameric structure as revealed by electron microscopy and additionally few tridecamers are shown in the electron micrographs of HlH resulting from the association of a further decamer with one didecamer. The three isoforms are represented mainly as homogeneous didecamers, but they have different behaviour after dissociation and reassociation in the pH-stabilizing buffer, containing 20 mM CaCl(2). All isoforms were reassociated into didecamers and tubules with different length, but in contrast to alpha(D)-HlH isoform, longer tubules were observed in beta-HlH. Moreover the structure of beta-HlH was analysed after limited proteolysis with trypsin followed by FPLC and HPLC separation of the cleavage products. Eight different functional units were identified by their N-terminal sequences and molecular masses. The protein characteristics, including UV absorption at 340 nm, fluorescence and CD spectra of the native molecule and its units confirmed the structure of multimer protein complexes.
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Affiliation(s)
- Ludmila Velkova
- Institute of Organic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str bl.9, Sofia 1113, Bulgaria
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27
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Stepan H, Bleckmann C, Geyer H, Geyer R, Staudacher E. Determination of 3-O- and 4-O-methylated monosaccharide constituents in snail glycans. Carbohydr Res 2010; 345:1504-7. [PMID: 20400065 DOI: 10.1016/j.carres.2010.03.027] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 03/12/2010] [Accepted: 03/19/2010] [Indexed: 11/25/2022]
Abstract
The N- and O-glycans of Arianta arbustorum, Achatina fulica, Arion lusitanicus and Planorbarius corneus were analysed for their monosaccharide pattern by reversed-phase HPLC after labelling with 2-aminobenzoic acid or 3-methyl-1-phenyl-2-pyrazolin-5-one and by gas chromatography-mass spectrometry. Glucosamine, galactosamine, mannose, galactose, glucose, fucose and xylose were identified. Furthermore, three different methylated sugars were detected: 3-O-methyl-mannose and 3-O-methyl-galactose were confirmed to be a common snail feature; 4-O-methyl-galactose was detected for the first time in snails.
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Affiliation(s)
- Herwig Stepan
- Department of Chemistry, University of Natural Resources and Applied Life Sciences, Vienna, Austria
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28
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Dolashka-Angelova P, Stefanova T, Livaniou E, Velkova L, Klimentzou P, Stevanovic S, Salvato B, Neychev H, Voelter W. Immunological potential of Helix vulgaris and Rapana venosa hemocyanins. Immunol Invest 2009; 37:822-40. [PMID: 18991098 DOI: 10.1080/08820130802403366] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A new hemocyanin was isolated from the hemolymph of garden snails Helix vulgaris, composed of two isoforms, HvH1 and HvH2 separated on an ion exchange column DEAE-Sepharose 6CL. Structural and immunological properties of Helix vulgaris hemocyanin were studied in comparison with molluscan Hcs Rapana venosa and Megathura crenulata. The possibility of using HvH and RvH as carriers of small molecules (haptens) in immunizing protocols was studied in comparison with KLH, which is a widely used, highly immunogenic carrier protein. By using HvH as a carrier of the well-known hapten TNBS (2,4,6-trinitrobenzene sulfonic acid), an increasing with time production of hapten-specific TFN-gamma was detected in splenocyte cultures of mice, which lasted longer than in case of KLH and RvH carriers. Also, use of HvH or RvH as a carrier of the hapten ProT alpha[101-109] (i.e., the synthetic C-terminal fragment of the poorly immunogenic protein prothymosin alpha) showed that antisera of higher titres than that of the control conjugate (ProT alpha[101-109]-KLH) were obtained immediately after the second bleeding. HvH and RvH may prove to be useful for the development of new antiviral, antibacterial and antitumor vaccines, since they seem to launch strong and specific immune response against the conjugated antigens.
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Affiliation(s)
- Pavlina Dolashka-Angelova
- Institute of Organic Chemistry with Center of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria.
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29
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Jin C, Hantusch B, Hemmer W, Stadlmann J, Altmann F. Affinity of IgE and IgG against cross-reactive carbohydrate determinants on plant and insect glycoproteins. J Allergy Clin Immunol 2007; 121:185-190.e2. [PMID: 17881041 DOI: 10.1016/j.jaci.2007.07.047] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Revised: 07/26/2007] [Accepted: 07/27/2007] [Indexed: 12/14/2022]
Abstract
BACKGROUND Cross-reactive carbohydrate determinants (CCDs) are probably the most widely occurring IgE epitopes. Approximately one fifth of patients with allergy develop IgE antibodies against such glycans. However, they appear to be of low clinical significance. OBJECTIVE We wanted to elucidate the reasons for this lack of clinical symptoms on contact with CCD allergens by determination of the binding affinities of patients' IgE and IgG antibodies. METHODS IgE and IgG against CCDs were affinity-purified from sera of selected patients. The binding affinity to defined glyco-epitopes was measured by surface plasmon resonance. RESULTS From a pool of CCD-positive sera, we isolated 0.1 and 25 microg CCD-specific IgE and IgG, respectively. The binding affinity of purified IgE antibodies to core alpha1,3-fucosylated glycans was in the 10(-10) mol/L range. The affinity was highest when both fucose and xylose were present, whereas xylosylation alone did not cause IgE binding. CCD-specific IgG exhibited a dissociation constant of approximately 10(-8) mol/L. IgG(4) amounted to only 20% of the CCD-specific IgG (as well as total IgG). CONCLUSION Low binding affinity of anti-CCD IgE cannot be the reason for the observed clinical insignificance of IgE against plant/insect glycan epitopes. Notably, the affinity of IgG to CCDs is higher than that to protein allergens, and it may therefore function as blocking antibody.
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Affiliation(s)
- Chunsheng Jin
- Department of Chemistry, University of Natural Resources and Applied Life Sciences, Vienna, Austria
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Beck A, Hillen N, Dolashki A, Stevanovic S, Salvato B, Voelter W, Dolashka-Angelova P. Oligosaccharide structure of a functional unit RvH1-b of Rapana venosa hemocyanin using HPLC/electrospray ionization mass spectrometry. Biochimie 2007; 89:938-49. [PMID: 17400357 DOI: 10.1016/j.biochi.2007.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Accepted: 02/06/2007] [Indexed: 11/24/2022]
Abstract
In the present study the structures of two glycopeptides (G1 and G1'), isolated from FU RvH(1)-b and two glycopeptides (G2 and G3), isolated from the structural subunit RvH(1) of Rapana venosa hemocyanin, were determined. To structurally characterize the site-specific carbohydrate heterogeneity and binding site of the N-linked glycopeptide(s), a combination of capillary reversed-phase chromatography and ion trap mass spectrometry was used. The amino acid sequences of glycopeptides G1 and G1' determined by Edman degradation and MS/MS sequencing demonstrated that the oligosaccharides are linked to N-glycosylation sites. Two peptides (a glycosylated (G1) and non-glycosylated one) were identified in this fraction and no linkage sites were observed in the latter one. Based on the sequencing of the glycosylated fractions G1, G1', G2 and G3, the carbohydrate structure Man(alpha1-6)Man(alpha1-3)Man(beta1-4)GlcNAc(beta1-4)[Fuc(alpha1-6)]GlcNAc-R could be identified for glycopeptides G1 and G3, and only the typical core structure Man(alpha1-6)Man(alpha1-3)Man(beta1-4)GlcNAc(beta1-4)GlcNAc-R was found for G1' and G2. The Fuc residue found in glycopeptides G1 and G3 is attached to N-acetyl-glucosamine of the carbohydrate core, as often found in other glycoproteins.
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Affiliation(s)
- Alexander Beck
- Klinisch-chemisches Zentrallaboratorium der Universitätskliniken, Abteilung Innere Medizin IV, Universität Tübingen, Otfried-Müller-Strasse 10, D-72076 Tübingen, Germany
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31
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Gutternigg M, Bürgmayr S, Pöltl G, Rudolf J, Staudacher E. Neutral N-glycan patterns of the gastropods Limax maximus, Cepaea hortensis, Planorbarius corneus, Arianta arbustorum and Achatina fulica. Glycoconj J 2007; 24:475-89. [PMID: 17516162 DOI: 10.1007/s10719-007-9040-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2006] [Revised: 02/27/2007] [Accepted: 04/11/2007] [Indexed: 11/28/2022]
Abstract
The N-glycosylation potentials of Limax maximus, Cepaea hortensis, Planorbarius corneus, Arianta arbustorum and Achatina fulica were analysed by investigation of the N-glycan structures of the skin and viscera glycoproteins by a combination of HPLC and mass-spectrometry methods. It is one of the first steps to enlarge the knowledge on the glycosylation abilities of gastropods, which may help to establish new cell culture systems, to uncover new means for pest control for some species, and to identify carbohydrate-epitopes which may be relevant for immune response. All snails analysed contained mainly oligomannosidic and small paucimannosidic structures, often terminated with 3-O-methylated mannoses. The truncated structures carried modifications by beta1-2-linked xylose to the beta-mannose residue, and/or an alpha-fucosylation, mainly alpha1,6-linked to the innermost N-acetylglucosaminyl residue of the core. Many of these structures were missing the terminal N-acetylglucosamine, which has been shown to be a prerequisite for processing to complex N-glycans in the Golgi. In some species (Planorbarius corneus and Achatina fulica) traces of large structures, terminated by 3-O-methylated galactoses and carrying xylose and/or fucose residues, were also detected. In Planorbarius viscera low amounts of terminal alpha1-2-fucosylation were determined. Combining these results, gastropods seem to be capable to produce all kinds of structures ranging from those typical in mammals through to structures similar to those found in plants, insects or nematodes. The detailed knowledge of this very complex glycosylation system of the gastropods will be a valuable tool to understand the principle rules of glycosylation in all organisms.
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Affiliation(s)
- Martin Gutternigg
- Department of Chemistry, University of Natural Resources and Applied Life Sciences Vienna, Muthgasse 18, 1190 Vienna, Austria
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32
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Dolashka-Angelova P, Stevanovic S, Dolashki A, Devreese B, Tzvetkova B, Voelter W, Van Beeumen J, Salvato B. A challenging insight on the structural unit 1 of molluscan Rapana venosa hemocyanin. Arch Biochem Biophys 2007; 459:50-8. [PMID: 17291443 DOI: 10.1016/j.abb.2006.12.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Revised: 11/20/2006] [Accepted: 12/07/2006] [Indexed: 10/23/2022]
Abstract
Hemocyanins of mollusks are high molecular mass glycoproteins with a complex quaternary structure which still remains to be defined in detail for most of its species as far as number, spatial distribution and interactions of their structural units is concerned. In the present study, we isolated the functional units of the structural subunit RvH1 of Rapana venosa hemocyanin, combining enzymatic and non-enzymatic methods. Our results suggest that Hc's carbohydrate moieties play a basic role in the organization of the structural units, resulting from post-translational polymerization of the 50 kDa functional units and involving sugar moieties that link between them.
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Di Patrizi L, Rosati F, Guerranti R, Pagani R, Gerwig GJ, Kamerling JP. Structural characterization of the N-glycans of gpMuc from Mucuna pruriens seeds. Glycoconj J 2006; 23:599-609. [PMID: 17006651 DOI: 10.1007/s10719-006-8715-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 04/06/2006] [Accepted: 04/07/2006] [Indexed: 10/24/2022]
Abstract
Mucuna pruriens seeds are used in some countries as a human prophylactic oral anti-snake remedy. Aqueous extracts of M. pruriens seeds possess in vivo activity against cobra and viper venoms, and protect mice against Echis carinatus venom. It was recently demonstrated that the seed immunogen generating the antibody that cross-reacts with the venom proteins is a multiform glycoprotein (gpMuc), and the immunogenic properties of gpMuc seemed to mainly reside in its glycan chains. In the present study, gpMuc was found to contain only N-glycans. Part of the N-glycans could be released with peptide-(N (4)-(N-acetyl-beta -glucosaminyl)asparagine amidase F (PNGase F-sensitive N-glycans); the PNGase F-resistant N-glycans were PNGase A-sensitive. The oligosaccharides released were analyzed by a combination of MALDI-TOF mass spectrometry, HPLC profiling of 2-aminobenzamide-labelled derivatives and (1)H NMR spectroscopy. The PNGase F-sensitive N-glycans comprised a mixture of oligomannose-type structures ranging from Man(5)GlcNAc(2) to Man(9)GlcNAc(2), and two xylosylated structures, Xyl(1)Man(3)GlcNAc(2) and Xyl(1)Man(4)GlcNAc(2). The PNGase A-sensitive N-glycans, containing (alpha 1-3)-linked fucose, were identified as Fuc(1)Xyl(1)Man(2)GlcNAc(2) and Fuc(1)Xyl(1)Man(3)GlcNAc(2). In view of the determined N-glycan ensemble, the immunoreactivity of gpMuc was ascribed to the presence of core (beta 1-2)-linked xylose- and core alpha (1-3)-linked fucose-modified N-glycan chains.
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Affiliation(s)
- Lisa Di Patrizi
- Department of Evolutionary Biology, University of Siena, via A. Moro 4, 53100, Siena, Italy
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Sandra K, Dolashka-Angelova P, Devreese B, Van Beeumen J. New insights in Rapana venosa hemocyanin N-glycosylation resulting from on-line mass spectrometric analyses. Glycobiology 2006; 17:141-56. [PMID: 17068122 DOI: 10.1093/glycob/cwl063] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The N-glycosylation of structural unit 1 of Rapana venosa hemocyanin was studied. Enzymatically liberated N-glycans were analyzed by matrix-assisted laser desorption ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS) and capillary electrophoresis (CE)-MS following 8-aminopyrene-1,3,6-trisulfonate labeling and labeling with 3-aminopyrazole, a new dedicated sugar reagent. Structural information was obtained by exoglycosidase sequencing, on-line MS/MS, permethylation, and amidation. A mixture of high-mannose and complex glycans with so far unknown and unusual acidic terminal structures was revealed. As the hemocyanin protein sequence is currently unknown, de novo sequencing of the glycopeptides had to be carried out. The N-glycans were therefore enzymatically removed with simultaneous partial (50%) (18)O-labeling of glycosylated asparagine residues prior to proteolysis. Following nano-liquid chromatography-MALDI-TOF-MS, the originally glycosylated peptides could be revealed and their sequences determined by MS/MS. The site occupancies were subsequently elucidated by precursor ion scanning of the intact glycopeptides using a Q-Trap mass spectrometer.
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Affiliation(s)
- Koen Sandra
- Laboratory of Protein Biochemistry and Protein Engineering, Ghent University, KL Ledeganckstraat 35, B-9000 Ghent, Belgium.
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35
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Abstract
The asparagine-linked carbohydrate moieties of plant and insect glycoproteins are the most abundant environmental immune determinants. They are the structural basis of what is known as cross-reactive carbohydrate determinants (CCDs). Despite some structural variation, the two main motifs are the xylose and the core-3-linked fucose, which form the essential part of two independent epitopes. Plants contain both epitopes, insect glycoproteins only fucose. These epitopes and other fucosylated determinants are also found in helminth parasites where they exert remarkable immunomodulatory effects. About 20% or more of allergic patients generate specific anti-glycan IgE, which is often accompanied by IgG. Even though antibody-binding glycoproteins are widespread in pollens, foods and insect venoms, CCDs do not appear to cause clinical symptoms in most, if not all patients. When IgE binding is solely due to CCDs, a glycoprotein allergen thus can be rated as clinical irrelevant allergen. Low binding affinity between IgE and plant N-glycans now drops out as a plausible explanation for the benign nature of CCDs. This rather may result from blocking antibodies induced by an incidental 'immune therapy' ('glyco-specific immune therapy') exerted by everyday contact with plant materials, e.g. fruits or vegetables. The need to detect and suppress anti-CCD IgE without interference from peptide epitopes can be best met by artificial glycoprotein allergens. Hydroxyproline-linked arabinose (single beta-arabinofuranosyl residues) has been identified as a new IgE-binding carbohydrate epitope in the major mugwort allergen. However, currently the occurrence of this O-glycan determinant appears to be rather restricted.
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Affiliation(s)
- Friedrich Altmann
- Divison of Biochemistry, Department of Chemistry, University of Natural Resources and Applied Life Sciences, Vienna, Austria.
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Lehr T, Geyer H, Maass K, Doenhoff MJ, Geyer R. Structural characterization of N-glycans from the freshwater snail Biomphalaria glabrata cross-reacting with Schistosoma mansoni glycoconjugates. Glycobiology 2006; 17:82-103. [PMID: 16971380 DOI: 10.1093/glycob/cwl048] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The human parasitic trematode Schistosoma mansoni has a complex life cycle that includes the freshwater snail Biomphalaria glabrata as intermediate host. Within each stage, the parasite synthesizes a wide array of glycoconjugates, exhibiting, in part, unique carbohydrate structures. In addition, the parasite expresses definitive host-like sugar epitopes, such as Lewis X determinants, supporting the concept of carbohydrate-mediated molecular mimicry as an invasion and survival strategy. In the present study, we investigated whether common carbohydrate determinants occur also at the level of the intermediate host. To this end, a structural characterization of hemolymph glycoprotein-N-glycans of B. glabrata was performed. N-glycans were released from tryptic glycopeptides and labeled with 2-aminopyridine. Sugar chains serologically cross-reacting with S. mansoni glycoconjugates were isolated by immunoaffinity chromatography using a polyclonal antiserum directed against schistosomal egg antigens and fractionated by Aleuria aurantia lectin affinity chromatography and high-performance liquid chromatography. Obtained glycans were analyzed by different mass spectrometric techniques as well as by monosaccharide constituent and linkage analysis. The results revealed a highly heterogeneous oligosaccharide pattern. Cross-reacting species represented about 5% of the total glycans and exhibited a terminal Fuc(alpha1-3)GalNAc unit, a (1-2)-linked xylosyl residue, or both types of structural motifs. In conclusion, our study demonstrates the presence of common carbohydrate epitopes also at the level of S. mansoni and its intermediate host.
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Affiliation(s)
- Tobias Lehr
- Institute of Biochemistry, Faculty of Medicine, University of Giessen, Friedrichstrasse 24, D-35392 Giessen, Germany
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Sanchez JF, Lescar J, Chazalet V, Audfray A, Gagnon J, Alvarez R, Breton C, Imberty A, Mitchell EP. Biochemical and Structural Analysis of Helix pomatia Agglutinin. J Biol Chem 2006; 281:20171-80. [PMID: 16704980 DOI: 10.1074/jbc.m603452200] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Helix pomatia agglutinin (HPA) is a N-acetylgalactosamine (GalNAc) binding lectin found in the albumen gland of the roman snail. As a constituent of perivitelline fluid, HPA protects fertilized eggs from bacteria and is part of the innate immunity system of the snail. The peptide sequence deduced from gene cloning demonstrates that HPA belongs to a family of carbohydrate-binding proteins recently identified in several invertebrates. This domain is also present in discoidin from the slime mold Dictyostelium discoideum. Investigation of the lectin specificity was performed with the use of glycan arrays, demonstrating that several GalNAc-containing oligosaccharides are bound and rationalizing the use of this lectin as a cancer marker. Titration microcalorimetry performed on the interaction between HPA and GalNAc indicates an affinity in the 10(-4) M range with an enthalpy-driven binding mechanism. The crystal structure of HPA demonstrates the occurrence of a new beta-sandwich lectin fold. The hexameric quaternary state was never observed previously for a lectin. The high resolution structure complex of HPA with GalNAc characterizes a new carbohydrate binding site and rationalizes the observed preference for alphaGalNAc-containing oligosaccharides.
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Affiliation(s)
- Jean-Frederic Sanchez
- Centre de Recherches sur les Macromolécules Végétales, CNRS, Université Joseph Fourier, 38041 Grenoble, France
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Geyer H, Wuhrer M, Resemann A, Geyer R. Identification and Characterization of Keyhole Limpet Hemocyanin N-Glycans Mediating Cross-reactivity with Schistosoma mansoni. J Biol Chem 2005; 280:40731-48. [PMID: 16135511 DOI: 10.1074/jbc.m505985200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Keyhole limpet hemocyanin (KLH) of the mollusc Megathura crenulata is known to serologically cross-react with Schistosoma mansoni glycoconjugates in a carbohydrate-dependent manner. To elucidate the structural basis for this cross-reactivity, KLH glycans were released from tryptic glycopeptides and fluorescently labeled. Cross-reacting glycans were identified using a polyclonal antiserum reacting with soluble S. mansoni egg antigens, isolated by a three-dimensional fractionation scheme and analyzed by different mass spectrometric techniques as well as linkage analysis and exoglycosidase treatment. The results revealed that cross-reacting species comprise approximately 4.5% of released glycans. They all represent novel types of N-glycans with a Fuc(alpha1-3)GalNAc(beta1-4)[Fuc(alpha1-3)]GlcNAc motif, which is known to occur also in schistosomal glycoconjugates. The tetrasaccharide unit is attached to the 3-linked antenna of a trimannosyl core, which can be further decorated by galactosyl residues, a xylose residue in 2-position of the central mannose and/or a fucose at the innermost N-acetylglucosamine. This study provides for the first time detailed structural data on the KLH carbohydrate entities responsible for cross-reactivity with glycoconjugates from S. mansoni.
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Affiliation(s)
- Hildegard Geyer
- Institute of Biochemistry, Faculty of Medicine, University of Giessen, Friedrichstrasse 24, D-35392 Giessen, Germany
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Idakieva K, Stoeva S, Voelter W, Gielens C. Glycosylation of Rapana thomasiana hemocyanin. Comparison with other prosobranch (gastropod) hemocyanins. Comp Biochem Physiol B Biochem Mol Biol 2005; 138:221-8. [PMID: 15253870 DOI: 10.1016/j.cbpc.2004.02.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Revised: 02/27/2004] [Accepted: 02/29/2004] [Indexed: 11/28/2022]
Abstract
The carbohydrate content and composition of hemocyanins (Hcs) of three prosobranchs (gastropods), Rapana thomasiana, Megathura crenulata and Haliotis tuberculata, were compared. The analyses were performed by gas-liquid chromatography after methanolysis, re-N-acetylation and trimethylsilylation. The two structural subunits of R. thomasiana Hc, RtH1 and RtH2, both showed 2.6% (w/w) carbohydrate content with very similar monosaccharide composition, indicative for N-glycosylation. The two isoforms of M. crenulata Hc (KLH), KLH1 and KLH2, on the other hand, definitely differed in glycosylation: KLH2 (3.4% carbohydrate, w/w) comprised relatively less mannose and more N-acetylgalactosamine than KLH1 (3.0% carbohydrate, w/w), in agreement with the fact that O-glycosylation has been observed in a functional unit (FU) of KLH2. For the Hc of the abalone H. tuberculata, with 4.5% (w/w) carbohydrate, appreciable amounts of 3-O-methyl-d-mannose and 3-O-methyl-d-galactose were detected, showing that the occurrence of methylated sugars is not restricted to the Hcs of pulmonates. From the structural subunit RtH2 of Rapana Hc the FUs RtH2-b and RtH2-d were isolated. On the basis of amino acid sequence analysis and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of the respective native and PNGase-F-treated glycopeptides, one N-glycosylation site was found for each FU. This site was located at Asn-405 for RtH2-b and at Asn-394 for RtH2-d; the carbohydrate moiety corresponded to GlcNAc2Man6 and GlcNAc2Man5, respectively. A comparison was made with the N-glycosylation sites of other FUs of Rapana Hc.
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Affiliation(s)
- Krassimira Idakieva
- Institute of Organic Chemistry, Bulgarian Academy of Sciences, Akad. G. Bonchev-Str. bl. 9, Sofia 1113, Bulgaria.
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Gielens C, Idakieva K, Van den Bergh V, Siddiqui NI, Parvanova K, Compernolle F. Mass spectral evidence for N-glycans with branching on fucose in a molluscan hemocyanin. Biochem Biophys Res Commun 2005; 331:562-70. [PMID: 15850797 DOI: 10.1016/j.bbrc.2005.03.217] [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: 03/25/2005] [Indexed: 11/26/2022]
Abstract
Glycopeptides, isolated from a trypsinolysate of functional unit (FU) RtH2-e of Rapana thomasiana hemocyanin subunit 2, were analysed by electrospray ionization mass spectrometry and MS/MS. From the molecular mass observed after deglycosylation, it was inferred that all glycopeptides shared the same peptide stretch 92-143 of FU RtH2-e with a glycosylation site at Asn-127. Besides the core structure Man(3)GlcNAc(2) for N-glycosylation, structures with a supplementary GlcNAc linked to either the Man(alpha1-3) or the Man(alpha1-6) arm and/or an additional tetrasaccharide unit connected to the other Man arm were observed, indicating the existence of microheterogeneity at the glycan level. The tetrasaccharide unit contains a central fucose moiety substituted with 3-O-methylgalactose and N-acetylgalactosamine, and linked to GlcNAc at the reducing end. This structure represents a novel N-glycan motif and is likely to be immunogenic. A second potential site for N-glycosylation in FU RtH2-e at Asn-17 was shown to be not glycosylated.
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Affiliation(s)
- Constant Gielens
- Laboratory of Biochemistry, Chemistry Department, Katholieke Universiteit Leuven, Celestijnenlaan 200 G, 3001 Leuven-Heverlee, Belgium.
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Gutternigg M, Ahrer K, Grabher-Meier H, Bürgmayr S, Staudacher E. Neutral N-glycans of the gastropod Arion lusitanicus. ACTA ACUST UNITED AC 2004; 271:1348-56. [PMID: 15030485 DOI: 10.1111/j.1432-1033.2004.04045.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The neutral N-glycan structures of Arion lusitanicus (gastropod) skin, viscera and egg glycoproteins were examined after proteolytic digestion, release of the glycans from the peptides, fluorescent labelling with 2-aminopyridine and fractionation by charge, size and hydrophobicity to obtain pure glycan structures. The positions and linkages of the sugars in the glycan were analysed by two dimensional HPLC (size and hydrophobicity) and MALDI-TOF mass spectrometry before and after digestion with specific exoglycosidases. The most striking feature in the adult tissues was the high amount of oligomannosidic and small paucimannosidic glycans terminated with 3-O-methylated mannoses. The truncated structures often contained modifications of the inner core by beta1,2-linked xylose to the beta-mannose residue and/or an alpha-fucosylation (mainly alpha1,6-) of the innermost GlcNAc residue. Skin and viscera showed predominantly the same glycans, however, in different amounts. Traces of large structures carrying 3-O-methylated galactoses were also detected. The egg glycans contained mainly (approximately 75%) oligomannosidic structures and some paucimannosidic structures modified by xylose or alpha1,6-fucose, but in this case no methylation of any monosaccharide was detected. Thus, gastropods seem to be capable of producing many types of structures ranging from those typical in human to structures similar to those found in nematodes, and therefore will be a valuable model to understand the regulation of glycosylation. Furthermore, this opens the way for using this organism as a host for the production of recombinant proteins. The detailed knowledge on glycosylation also may help to identify targets for pest control.
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Affiliation(s)
- Martin Gutternigg
- Department für Chemie, Universität für Bodenkultur Wien, Vienna, Austria
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Gielens C, De Geest N, Compernolle F, Préaux G. Glycosylation sites of hemocyanins of Helix pomatia and Sepia officinalis. Micron 2004; 35:99-100. [PMID: 15036305 DOI: 10.1016/j.micron.2003.10.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glycopeptides were isolated from functional units of two molluscan hemocyanins (Hcs). They were analyzed and localized in the sequences. A comparison with potential N-glycosylation sites of two other molluscan Hcs was made. An immunological cross-reactivity was observed between the beta-Hc and the alpha-macroglobulin of Helix pomotia. ELISA experiments with glycopeptide fractions indicated a competition.
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Affiliation(s)
- Constant Gielens
- Laboratory of Biochemistry, Department of Chemistry, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium.
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Marxen JC, Nimtz M, Becker W, Mann K. The major soluble 19.6 kDa protein of the organic shell matrix of the freshwater snail Biomphalaria glabrata is an N-glycosylated dermatopontin. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1650:92-8. [PMID: 12922172 DOI: 10.1016/s1570-9639(03)00203-6] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The major Biomphalaria glabrata shell matrix protein of 19.6 kDa was isolated by preparative electrophoresis and sequenced. The sequence of 148 amino acids showed 32% sequence identity to mammalian dermatopontin sequences and 34-37% identity to two invertebrate dermatopontins described previously. A unique feature of the shell matrix dermatopontin was the presence of a single N-glycosylation consensus sequence, the asparagine of which was completely modified with a pentasaccharide. Sequence analysis of this short N-glycan by mass spectrometry and carbohydrate composition analysis indicated that it was the ubiquitous N-glycan core oligosaccharide with the exception that the terminal mannoses were 3-O-methylated. Dermatopontin is widespread in mammalian extracellular matrices, including the matrix of biominerals such as bone and teeth. Its occurrence in an invertebrate biomineral indicates that such phylogenetically distant biomineral-forming systems as vertebrate bone and mollusk shell share components which have undergone surprisingly few changes during a long evolution.
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Affiliation(s)
- Julia C Marxen
- Zoologisches Institut und Museum der Universität Hamburg, D-20146 Hamburg, Germany
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Dolashka-Angelova P, Beck A, Dolashki A, Beltramini M, Stevanovic S, Salvato B, Voelter W. Characterization of the carbohydrate moieties of the functional unit RvH1-a of Rapana venosa haemocyanin using HPLC/electrospray ionization MS and glycosidase digestion. Biochem J 2003; 374:185-92. [PMID: 12732096 PMCID: PMC1223564 DOI: 10.1042/bj20030291] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2003] [Revised: 04/09/2003] [Accepted: 05/01/2003] [Indexed: 11/17/2022]
Abstract
The primary structures of two biantennary N -glycans of the glycoprotein Rapana venosa (marine snail) haemocyanin were determined. Two different structural subunits have been found in R. venosa haemocyanin: RvH1 and RvH2. The carbohydrate content of the N-terminal functional unit RvH1-a of RvH1 was studied and compared with the N-terminal functional unit RvH2-a of RvH2. Oligosaccharide fragments were released from the glycoprotein by Smith degradation of a haemocyanin pronase digest and separated on a Superdex 300 column. The glycopeptide fragments, giving a positive reaction for the orcinol/H2SO4 method, were separated by HPLC. In order to determine the linked sugar chains to the hinge glycopeptides isolated from the functional unit RvH1-a, several techniques were applied, including capillary electrophoresis, matrix-assisted laser desorption ionization-MS and electrospray ionization-MS in combination with glycosidase digestion. On the basis of these results and amino acid sequence analysis, we concluded that the functional unit RvH1-a contains 7% oligosaccharides N-glycosidically attached to Asn262 and Asn401, and the following structures were suggested:[structure: see text]
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Lommerse JPM, van Rooijen JJM, Kroon-Batenburg LMJ, Kamerling JP, Vliegenthart JFG. Conformational analysis of two xylose-containing N-glycans in aqueous solution by using 1H NMR ROESY and NOESY spectroscopy in combination with MD simulations. Carbohydr Res 2002; 337:2279-99. [PMID: 12433493 DOI: 10.1016/s0008-6215(02)00212-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The conformational behavior of the synthetic hexa- and heptasaccharide methyl beta-glycosides alpha-D-Manp-(1 --> 6)-[alpha-D-Manp-(1 --> 3)-][beta-D-Xylp-(1 --> 2)-]beta-D-Manp-(1 --> 4)-beta-D-GlcpNAc-(1 --> 4)-beta-D-GlcpNAc-(1 --> OMe and alpha-D-Manp-(1 --> 6)-[alpha-D-Manp-(1 --> 3)-][beta-D-Xylp-(1 --> 2)-]beta-D-Manp-(1 --> 4)-beta-D-GlcpNAc-(1 --> 4)-[alpha-L-Fucp-(1 --> 6)-]beta-D-GlcpNAc-(1 --> OMe, representing the xylosylated and the xylosylated alpha-(1 --> 6)-fucosylated core structures of N-glycans in alpha(D)-hemocyanin of the snail Helix pomatia, respectively, were investigated by 1H NMR spectroscopy in combination with molecular dynamics (MD) simulations in water. 1H and 13C chemical shifts of the oligosaccharides were assigned using 1H-(1)H COSY, TOCSY, and NOESY, and 1H-(13)C HMQC techniques. Experimental 2D 1H cross-peak intensities from one series of NOESY and one series of ROESY experiments of the two oligosaccharides were compared with calculated values derived from MD trajectories using the CROSREL program, yielding information about the conformation of each glycosidic linkage of the methyl glycosides. The flexibility of the linkages was described by generalized order parameters and internal rotation correlation times. Analysis of the data indicated that several conformations are likely to exist for the alpha-D-Man-(1 --> 6)-beta-D-Man, the alpha-L-Fuc-(1 --> 6)-beta-D-GlcNAc, and the alpha-D-Man-(1 --> 3)-beta-D-Man linkage, whereas the beta-D-Xyl-(1 --> 2)-beta-D-Man-(1 --> 4)-beta-D-GlcNAc-(1 --> 4)-beta-D-GlcNAc fragment occurs in one rigid conformation. No significant differences were found between the corresponding structural elements in both methyl glycosides. NOESY and ROESY experiments proved to be suitable for providing the experimental data required, however, due to more overlap within the ROESY spectra, reducing the accuracy of the analysis, NOESY spectral analysis is preferred.
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Affiliation(s)
- Jos P M Lommerse
- Bijvoet Center, Department of Bio-Organic Chemistry, Section of Glycoscience and Biocatalysis, Utrecht University, Padualaan 8, NL-3584 CH Utrecht, The Netherlands
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Kurokawa T, Wuhrer M, Lochnit G, Geyer H, Markl J, Geyer R. Hemocyanin from the keyhole limpet Megathura crenulata (KLH) carries a novel type of N-glycans with Gal(beta1-6)Man-motifs. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:5459-73. [PMID: 12423344 DOI: 10.1046/j.1432-1033.2002.03244.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Keyhole limpet (Megathura crenulata) hemocyanin (KLH), an extracellular respiratory protein, is widely used as hapten carrier and immune stimulant. Although it is generally accepted that the sugar constituents of this glycoprotein are likely to be implicated in the antigenicity and biomedical properties of KLH, knowledge of its carbohydrate structure is still limited. Therefore, we have investigated the N-linked oligosaccharides of KLH. Glycan chains were enzymatically liberated from tryptic glycopeptides, pyridylaminated and separated by two-dimensional HPLC. Only neutral oligosaccharides were obtained and characterized by carbohydrate constituent and methylation analyses, MALDI-TOF-MS, ESI-ion trap-MS and sequential exoglycosidase digestion. The results revealed that KLH is carrying high mannose-type glycans and truncated sugar chains derived thereof. As a characteristic feature, a number of the studied N-glycans contained a Gal(beta1-6)Man-unit which has not been found in glycoprotein-N-glycans so far. Hence, our studies demonstrate that this marine mollusk glycoprotein is characterized by a unique oligosaccharide pattern comprising, in part, novel structural elements.
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Affiliation(s)
- Tomofumi Kurokawa
- Pharmaceutical Discovery Center, Pharmaceutical Research Division, Takeda Chemical Industries, Ltd, Osaka, Japan
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Stoeva S, Idakieva K, Betzel C, Genov N, Voelter W. Amino acid sequence and glycosylation of functional unit RtH2-e from Rapana thomasiana (gastropod) hemocyanin. Arch Biochem Biophys 2002; 399:149-58. [PMID: 11888200 DOI: 10.1006/abbi.2001.2741] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The complete amino acid sequence of Rapana thomasiana hemocyanin functional unit RtH2-e was determined by direct sequencing and matrix-assisted laser desorption ionization mass spectrometry of peptides obtained by cleavage with EndoLysC proteinase, chymotrypsin, and trypsin. The single-polypeptide chain of RtH2-e consists of 413 amino acid residues and contains two consensus sequences NXS/T (positions 11-19 and 127-129), potential sites for N-glycosylation. Monosaccharide analysis of RtH2-e revealed a carbohydrate content of about 1.1% and the presence of xylose, fucose, mannose, and N-acetylglucosamine, demonstrating that only N-linked carbohydrate chains of high-mannose type seem to be present. On basis of the monosaccharide composition and MALDI-MS analysis of native and PNGase-F-treated chymotryptic glycopeptide fragment of RtH2-e the oligosaccharide Man(5)GlcNAc(2), attached to Asn(127), is suggested. Multiple sequence alignments with other molluscan hemocyanin e functional units revealed an identity of 63% to the cephalopod Octopus dofleini and of 69% to the gastropod Haliotis tuberculata. The present results are discussed in view of the recently determined X-ray structure of the functional unit g of the O. dofleini hemocyanin.
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Affiliation(s)
- Stanka Stoeva
- Department of Physical Biochemistry, Institute of Physiological Chemistry, University of Tuebingen, Hoppe-Seyler-Strasse 4, D-72076 Tuebingen, Germany.
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Abstract
The occurrence of N-acetylneuraminic acid and N-glycolylneuraminic acid residues in preparations of the slug Arion lusitanicus (Gastropoda) was determined by sodium dodecyl sulphate electrophoresis of the proteins followed by lectin blots stained with the sialic acid specific lectin from Maackia amurensis, by the sensitivity of this binding to sialidase from Clostridium perfringens, by specific fluorescent labelling of sialic acids with 1,2-diamino-4,5-methylenedioxybenzene, by the determination of the sensitivity to sialate-pyruvate-lyase, by co-migration with standards on high performance anion exchange chromatography with pulsed amperometric detection and by identification of the typical masses in the fragmentation patterns of the trimethylsilyl derivatives after gas chromatography. It is the first time sialic acids are identified in gastropods.
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Affiliation(s)
- S Bürgmayr
- Glycobiology, Institut für Chemie, Universität für Bodenkultur, Muthgasse 18, A-1190 Vienna, Austria
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Dolashka-Angelova P, Beltramini M, Dolashki A, Salvato B, Hristova R, Voelter W. Carbohydrate composition of Carcinus aestuarii hemocyanin. Arch Biochem Biophys 2001; 389:153-8. [PMID: 11339803 DOI: 10.1006/abbi.2000.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The hemocyanin of the crab Carcinus aestuarii contains a carbohydrate moiety that represents 1.6% of protein mass. This carbohydrate content is higher than that exhibited by other arthropod hemocyanins so far investigated. By combination of FPLC ion exchange chromatography and reverse-phase HPLC, the native oligomeric protein can be resolved into three major and one minor electrophoretically pure fractions that are found to be homogeneous by N-terminal sequencing and correspond to the subunit polypeptide chains. Sugar analysis on the different subunits reveals that the subunit referred to as Ca2 is glycosylated, with a carbohydrate content of 6.3%. By Ca2 trypsin digestion, separation of glycopeptides, and amino acid sequencing, three consensus sequences for O-glycosylation and one for N-glycosylation were found. MALDI-MS was applied for the determination of the molecular masses of the various glycopeptides and peptides after removal of carbohydrates by neuraminidase and alpha-N-acetylgalactosaminidase.
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Affiliation(s)
- P Dolashka-Angelova
- Institute of Organic Chemistry, Bulgarian Academy of Sciences, Sofia, 1113, Bulgaria.
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Yigzaw Y, Gielens C, Préaux G. Isolation and characterization of an alpha-macroglobulin from the gastropod mollusc Helix pomatia with tetrameric structure and preserved activity after methylamine treatment. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1545:104-13. [PMID: 11342036 DOI: 10.1016/s0167-4838(00)00267-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A proteinase inhibitor with M(r) 697000 and 20.3% (w/w) carbohydrate was isolated from the haemolymph of the snail Helix pomatia and characterized. It was shown to have a tetrameric structure with subunits disulphide linked by two. It inhibited the activity of several types of proteinases against large substrates but not that of trypsin against N-alpha-benzoyl-DL-arginine-4-nitroanilide. This indicated a nonspecific and steric hindrance mode of inhibition. The ratio of trypsin molecules inactivated per inhibitor amounted to 1.5. This interaction led to a cleavage of the subunits into two equal fragments and to a slow to fast conformational change of the whole molecules. Experiments with 125I-labelled trypsin indicated that the proteinase had become covalently linked to one of the fragments. Heating of the inhibitor led to autolytic cleavage products but not when methylamine treated. Thiol titration after trypsin or methylamine treatment indicated the presence of one thiol ester bond per subunit. These facts are all indicative of an alpha-macroglobulin type of inhibitor. However, unlike for most of them the methylamine treatment did not induce a conformational change nor suppress its proteinase inhibitory activity. Moreover, invertebrate alpha-macroglobulins are mostly dimeric in structure but tetramers likewise do occur in Biomphalaria glabrata.
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Affiliation(s)
- Y Yigzaw
- Laboratorium voor Biochemie, Katholieke Universiteit Leuven, Celestijnenlaan 200 G, B-3001, Leuven-Heverlee, Belgium
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