51
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Yoshimura Y, Nudelman AS, Levery SB, Wandall HH, Bennett EP, Hindsgaul O, Clausen H, Nishimura SI. Elucidation of the sugar recognition ability of the lectin domain of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase 3 by using unnatural glycopeptide substrates. Glycobiology 2012; 22:429-38. [PMID: 22042768 DOI: 10.1093/glycob/cwr159] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
Mucin-type glycosylation [α-N-acetyl-D-galactosamine (α-GalNAc)-O-Ser/Thr] on proteins is initiated biosynthetically by 16 homologous isoforms of GalNAc-Ts (uridine diphosphate-GalNAc:polypeptide N-acetylgalactosaminyltransferases). All the GalNAc-Ts consist of a catalytic domain and a lectin domain. Previous reports of GalNAc-T assays toward peptides and α-GalNAc glycopeptides showed that the lectin domain recognized the sugar on the substrates and affected the reaction; however, the details are not clear. Here, we report a new strategy to give insight on the sugar recognition ability and the function of the GalNAc-T3 lectin domain using chemically synthesized natural-type (α-GalNAc-O-Thr) and unnatural-type [β-GalNAc-O-Thr, α-Fuc-O-Thr and β-GlcNAc-O-Thr] MUC5AC glycopeptides. GalNAc-T3 is one of isoforms expressed in various organs, its substrate specificity extensively characterized and its anomalous expression has been identified in several types of cancer (e.g. pancreas and stomach). The glycopeptides used in this study were designed based on a preliminary peptide assay with a sequence derived from the MUC5AC tandem repeat. Through GalNAc-T3 and lectin-inactivated GalNAc-T3, competition assays between the glycopeptide substrates and product analyses (MALDI-TOF MS, RP-HPLC and ETD-MS/MS), we show that the lectin domain strictly recognized GalNAc on the substrate and this specificity controlled the glycosylation pathway.
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Affiliation(s)
- Yayoi Yoshimura
- Graduate School of Life Science and Research Center for Post-Genome Science and Technology, Hokkaido University, Sapporo 001-0021, Japan.
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2007-2008. MASS SPECTROMETRY REVIEWS 2012; 31:183-311. [PMID: 21850673 DOI: 10.1002/mas.20333] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 01/04/2011] [Accepted: 01/04/2011] [Indexed: 05/31/2023]
Abstract
This review is the fifth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2008. The first section of the review covers fundamental studies, fragmentation of carbohydrate ions, use of derivatives and new software developments for analysis of carbohydrate spectra. Among newer areas of method development are glycan arrays, MALDI imaging and the use of ion mobility spectrometry. The second section of the review discusses applications of MALDI MS to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, biopharmaceuticals, glycated proteins, glycolipids, glycosides and various other natural products. There is a short section on the use of MALDI mass spectrometry for the study of enzymes involved in glycan processing and a section on the use of MALDI MS to monitor products of the chemical synthesis of carbohydrates with emphasis on carbohydrate-protein complexes and glycodendrimers. Corresponding analyses by electrospray ionization now appear to outnumber those performed by MALDI and the amount of literature makes a comprehensive review on this technique impractical. However, most of the work relating to sample preparation and glycan synthesis is equally relevant to electrospray and, consequently, those proposing analyses by electrospray should also find material in this review of interest.
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Affiliation(s)
- David J Harvey
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
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Horynová M, Takahashi K, Hall S, Renfrow MB, Novak J, Raška M. Production of N-acetylgalactosaminyl-transferase 2 (GalNAc-T2) fused with secretory signal Igκ in insect cells. Protein Expr Purif 2012; 81:175-80. [PMID: 22033505 PMCID: PMC3637031 DOI: 10.1016/j.pep.2011.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 10/12/2011] [Accepted: 10/13/2011] [Indexed: 01/29/2023]
Abstract
The human UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyl-transferase 2 (GalNAc-T2) is one of the key enzymes that initiate synthesis of hinge-region O-linked glycans of human immunoglobulin A1 (IgA1). We designed secreted soluble form of human GalNAc-T2 as a fusion protein containing mouse immunoglobulin light chain kappa secretory signal and expressed it using baculovirus and mammalian expression vectors. The recombinant protein was secreted by insect cells Sf9 and human HEK 293T cells in the culture medium. The protein was purified from the media using affinity Ni-NTA chromatography followed by stabilization of purified protein in 50mM Tris-HCl buffer at pH 7.4. Although the purity of recombinant GalNAc-T2 was comparable in both expression systems, the yield was higher in Sf9 insect expression system (2.5mg of GalNAc-T2 protein per 1L culture medium). The purified soluble recombinant GalNAc-T2 had an estimated molecular mass of 65.8kDa and its amino-acid sequence was confirmed by mass-spectrometric analysis. The enzymatic activity of Sf9-produced recombinant GalNAc-T2 was determined by the quantification of enzyme-mediated attachment of GalNAc to synthetic IgA1 hinge-region peptide as the acceptor and UDP-GalNAc as the donor. In conclusion, murine immunoglobulin kappa secretory signal was used for production of secreted enzymatically active GalNAc-T2 in insect baculovirus expression system.
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Affiliation(s)
- Milada Horynová
- Department of Immunology, Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Kazuo Takahashi
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Stacy Hall
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Matthew B. Renfrow
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jan Novak
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Milan Raška
- Department of Immunology, Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
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54
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Gerken TA. O-glycoprotein biosynthesis: site localization by Edman degradation and site prediction based on random peptide substrates. Methods Mol Biol 2012; 842:81-108. [PMID: 22259131 DOI: 10.1007/978-1-61779-513-8_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The characterization of mucin-type O-glycosylation is fraught with extreme difficulty at almost every level of analysis: from difficulties in obtaining glycopeptides suitable for study, their structural heterogeneity, lack of broad acting glycosidase tools capable of simplifying the glycans, and finally the vast complexity of performing analysis on multiply glycosylated glycopeptides. This, along with a lack of known peptide sequence motif(s) for the transferases that initiate mucin-type O-glycosylation, significantly hinders our understanding of mucin-type O-glycosylation at almost every level from their biosynthesis to their biological and biophysical properties. In this chapter, the use of partial chemical deglycosylation coupled with Edman amino acid sequencing is described to quantify sites of O-glycosylation. In addition, the use of oriented random peptide substrates is described for providing the specificities of the polypeptide α-N-acetylgalactosaminyltransferases, which can be used to estimate transferase-specific sites of O-glycosylation.
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Affiliation(s)
- Thomas A Gerken
- Department of Pediatrics and Biochemistry, Case Western Reserve University, School of Medicine, Cleveland, OH, USA,
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55
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Takahashi K, Smith AD, Poulsen K, Kilian M, Julian BA, Mestecky J, Novak J, Renfrow MB. Naturally occurring structural isomers in serum IgA1 o-glycosylation. J Proteome Res 2011; 11:692-702. [PMID: 22067045 DOI: 10.1021/pr200608q] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
IgA is the most abundantly produced antibody and plays an important role in the mucosal immune system. Human IgA is represented by two isotypes, IgA1 and IgA2. The major structural difference between these two subclasses is the presence of nine potential sites of O-glycosylation in the hinge region between the first and second constant region domains of the heavy chain. Thr(225), Thr(228), Ser(230), Ser(232) and Thr(236) have been identified as the predominant sites of O-glycan attachment. The range and distribution of O-glycan chains at each site within the context of adjacent sites in this clustered region create a complex heterogeneity of surface epitopes that is incompletely defined. We previously described the analysis of IgA1 O-glycan heterogeneity by use of high resolution LC-MS and electron capture dissociation tandem MS to unambiguously localize all amino acid attachment sites in IgA1 (Ale) myeloma protein. Here, we report the identification and elucidation of IgA1 O-glycopeptide structural isomers that occur based on amino acid position of the attached glycans (positional isomers) and the structure of the O-glycan chains at individual sites (glycan isomers). These isomers are present in a model IgA1 (Mce1) myeloma protein and occur naturally in normal human serum IgA1. Variable O-glycan chains attached to Ser(230), Thr(233) or Thr(236) produce the predominant positional isomers, including O-glycans composed of a single GalNAc residue. These findings represent the first definitive identification of structural isomeric IgA1 O-glycoforms, define the single-site heterogeneity for all O-glycan sites in a single sample, and have implications for defining epitopes based on clustered O-glycan variability.
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Affiliation(s)
- Kazuo Takahashi
- UAB Biomedical FT-ICR MS Laboratory, MCLM 570, 1530 3rd Avenue South, Birmingham, AL 35294, USA
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56
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Pedersen JW, Bennett EP, Schjoldager KTBG, Meldal M, Holmér AP, Blixt O, Cló E, Levery SB, Clausen H, Wandall HH. Lectin domains of polypeptide GalNAc transferases exhibit glycopeptide binding specificity. J Biol Chem 2011; 286:32684-96. [PMID: 21768105 PMCID: PMC3173194 DOI: 10.1074/jbc.m111.273722] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 07/09/2011] [Indexed: 11/06/2022] Open
Abstract
UDP-GalNAc:polypeptide α-N-acetylgalactosaminyltransferases (GalNAc-Ts) constitute a family of up to 20 transferases that initiate mucin-type O-glycosylation. The transferases are structurally composed of catalytic and lectin domains. Two modes have been identified for the selection of glycosylation sites by GalNAc-Ts: confined sequence recognition by the catalytic domain alone, and concerted recognition of acceptor sites and adjacent GalNAc-glycosylated sites by the catalytic and lectin domains, respectively. Thus far, only the catalytic domain has been shown to have peptide sequence specificity, whereas the primary function of the lectin domain is to increase affinity to previously glycosylated substrates. Whether the lectin domain also has peptide sequence selectivity has remained unclear. Using a glycopeptide array with a library of synthetic and recombinant glycopeptides based on sequences of mucins MUC1, MUC2, MUC4, MUC5AC, MUC6, and MUC7 as well as a random glycopeptide bead library, we examined the binding properties of four different lectin domains. The lectin domains of GalNAc-T1, -T2, -T3, and -T4 bound different subsets of small glycopeptides. These results indicate an additional level of complexity in the initiation step of O-glycosylation by GalNAc-Ts.
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Affiliation(s)
| | - Eric P. Bennett
- School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N and
| | | | - Morten Meldal
- the Carlsberg Laboratory and Nano Science Center, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | | | - Ola Blixt
- From the Department of Cellular and Molecular Medicine and
| | - Emiliano Cló
- From the Department of Cellular and Molecular Medicine and
| | | | - Henrik Clausen
- From the Department of Cellular and Molecular Medicine and
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57
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Zlocowski N, Sendra VG, Lorenz V, Villarreal MA, Jorge A, Núñez Y, Bennett EP, Clausen H, Nores GA, Irazoqui FJ. Catalytic and glycan-binding abilities of ppGalNAc-T2 are regulated by acetylation. Biochem Biophys Res Commun 2011; 410:140-5. [PMID: 21651894 DOI: 10.1016/j.bbrc.2011.05.125] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 05/21/2011] [Indexed: 01/12/2023]
Abstract
Post-translational acetylation is an important molecular regulatory mechanism affecting the biological activity of proteins. Polypeptide GalNAc transferases (ppGalNAc-Ts) are a family of enzymes that catalyze initiation of mucin-type O-glycosylation. All ppGalNAc-Ts in mammals are type II transmembrane proteins having a Golgi lumenal region that contains a catalytic domain with glycosyltransferase activity, and a C-terminal R-type ("ricin-like") lectin domain. We investigated the effect of acetylation on catalytic activity of glycosyltransferase, and on fine carbohydrate-binding specificity of the R-type lectin domain of ppGalNAc-T2. Acetylation effect on ppGalNAc-T2 biological activity in vitro was studied using a purified human recombinant ppGalNAc-T2. Mass spectrometric analysis of acetylated ppGalNAc-T2 revealed seven acetylated amino acids (K103, S109, K111, K363, S373, K521, and S529); the first five are located in the catalytic domain. Specific glycosyltransferase activity of ppGalNAc-T2 was reduced 95% by acetylation. The last two amino acids, K521 and S529, are located in the lectin domain, and their acetylation results in alteration of the carbohydrate-binding ability of ppGalNAc-T2. Direct binding assays showed that acetylation of ppGalNAc-T2 enhances the recognition to αGalNAc residue of MUC1αGalNAc, while competitive assays showed that acetylation modifies the fine GalNAc-binding form of the lectin domain. Taken together, these findings clearly indicate that biological activity (catalytic capacity and glycan-binding ability) of ppGalNAc-T2 is regulated by acetylation.
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Affiliation(s)
- Natacha Zlocowski
- Centro de Investigaciones en Química Biológica de Córdoba, UNC-CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina
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58
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Yao J, Nellas RB, Glover MM, Shen T. Stability and sugar recognition ability of ricin-like carbohydrate binding domains. Biochemistry 2011; 50:4097-104. [PMID: 21510689 DOI: 10.1021/bi102021p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Lectins are a class of proteins known for their novel binding to saccharides. Understanding this sugar recognition process can be crucial in creating structure-based designs of proteins with various biological roles. We focus on the sugar binding of a particular lectin, ricin, which has two β-trefoil carbohydrate-binding domains (CRDs) found in several plant protein toxins. The binding ability of possible sites of ricin-like CRD has been puzzling. The apo and various (multiple) ligand-bound forms of the sugar-binding domains of ricin were studied by molecular dynamics simulations. By evaluating structural stability, hydrogen bond dynamics, flexibility, and binding energy, we obtained a detailed picture of the sugar recognition of the ricin-like CRD. Unlike what was previously believed, we found that the binding abilities of the two known sites are not independent of each other. The binding ability of one site is positively affected by the other site. While the mean positions of different binding scenarios are not altered significantly, the flexibility of the binding pockets visibly decreases upon multiple ligand binding. This change in flexibility seems to be the origin of the binding cooperativity. All the hydrogen bonds that are strong in the monoligand state are also strong in the double-ligand complex, although the stability is much higher in the latter form due to cooperativity. These strong hydrogen bonds in a monoligand state are deemed to be the essential hydrogen bonds. Furthermore, by examining the structural correlation matrix, the two domains are structurally one entity. Galactose hydroxyl groups, OH4 and OH3, are the most critical parts in both site 1α and site 2γ recognition.
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Affiliation(s)
- Jianzhuang Yao
- Department of Biochemistry, Cellular & Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, United States
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59
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Gill DJ, Clausen H, Bard F. Location, location, location: new insights into O-GalNAc protein glycosylation. Trends Cell Biol 2011; 21:149-58. [PMID: 21145746 DOI: 10.1016/j.tcb.2010.11.004] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 11/10/2010] [Accepted: 11/11/2010] [Indexed: 01/04/2023]
Abstract
O-GalNAc glycosylation of proteins confers essential structural, protective and signaling roles in eumetazoans. Addition of O-glycans onto proteins is an extremely complex process that regulates both sites of attachment and the types of oligosaccharides added. Twenty distinct polypeptide GalNAc-transferases (GalNAc-Ts) initiate O-glycosylation and fine-tuning their expression provides a mechanism for regulating this action. Recently, a new mode of regulation has emerged where activation of Src kinase selectively redistributes Golgi-localized GalNAc-Ts to the ER. This relocalization results in a strong increase in the density of O-glycan decoration. In this review, we discuss how different mechanisms can regulate the number and the types of O-glycans decorating proteins. In addition, we speculate how Src-dependent relocation of GalNAc-Ts could play an important role in cancerous cellular transformation.
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Affiliation(s)
- David J Gill
- Institute of Molecular and Cell Biology (IMCB), Proteos, 61 Biopolis Drive, Singapore, 138673
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60
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Gerken TA, Jamison O, Perrine CL, Collette JC, Moinova H, Ravi L, Markowitz SD, Shen W, Patel H, Tabak LA. Emerging paradigms for the initiation of mucin-type protein O-glycosylation by the polypeptide GalNAc transferase family of glycosyltransferases. J Biol Chem 2011; 286:14493-507. [PMID: 21349845 DOI: 10.1074/jbc.m111.218701] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mammalian mucin-type O-glycosylation is initiated by a large family of ∼20 UDP-GalNAc:polypeptide α-N-acetylgalactosaminyltransferases (ppGalNAc Ts) that transfer α-GalNAc from UDP-GalNAc to Ser and Thr residues of polypeptide acceptors. Characterizing the peptide substrate specificity of each isoform is critical to understanding their properties, biological roles, and significance. Presently, only the specificities of ppGalNAc T1, T2, and T10 and the fly orthologues of T1 and T2 have been systematically characterized utilizing random peptide substrates. We now extend these studies to ppGalNAc T3, T5, and T12, transferases variously associated with human disease. Our results reveal several common features; the most striking is the similar pattern of enhancements for the three residues C-terminal to the site of glycosylation for those transferases that contain a common conserved Trp. In contrast, residues N-terminal to the site of glycosylation show a wide range of isoform-specific enhancements, with elevated preferences for Pro, Val, and Tyr being the most common at the -1 position. Further analysis reveals that the ratio of positive (Arg, Lys, and His) to negative (Asp and Glu) charged residue enhancements varied among transferases, thus further modulating substrate preference in an isoform-specific manner. By utilizing the obtained transferase-specific preferences, the glycosylation patterns of the ppGalNAc Ts against a series of peptide substrates could roughly be reproduced, demonstrating the potential for predicting isoform-specific glycosylation. We conclude that each ppGalNAc T isoform may be uniquely sensitive to peptide sequence and overall charge, which together dictates the substrate sites that will be glycosylated.
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Affiliation(s)
- Thomas A Gerken
- Department of Pediatrics (W. A. Bernbaum Center for Cystic Fibrosis Research), Case Western Reserve University, Cleveland, Ohio 44106, USA.
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61
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Corzana F, Busto JH, Marcelo F, García de Luis M, Asensio JL, Martín‐Santamaría S, Jiménez‐Barbero J, Avenoza A, Peregrina JM. Engineering
O
‐Glycosylation Points in Non‐extended Peptides: Implications for the Molecular Recognition of Short Tumor‐Associated Glycopeptides. Chemistry 2011; 17:3105-10. [DOI: 10.1002/chem.201003124] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Indexed: 12/15/2022]
Affiliation(s)
- Francisco Corzana
- Departmento de Química, Universidad de La Rioja, Madre de Dios, 51, 26006 Logroño (Spain), Fax: (+34) 941‐299‐621
| | - Jesús H. Busto
- Departmento de Química, Universidad de La Rioja, Madre de Dios, 51, 26006 Logroño (Spain), Fax: (+34) 941‐299‐621
| | - Filipa Marcelo
- Centro de Investigaciones Biológicas (CSIC), Madrid (Spain)
| | - Marisa García de Luis
- Departmento de Química, Universidad de La Rioja, Madre de Dios, 51, 26006 Logroño (Spain), Fax: (+34) 941‐299‐621
| | | | | | | | - Alberto Avenoza
- Departmento de Química, Universidad de La Rioja, Madre de Dios, 51, 26006 Logroño (Spain), Fax: (+34) 941‐299‐621
| | - Jesús M. Peregrina
- Departmento de Química, Universidad de La Rioja, Madre de Dios, 51, 26006 Logroño (Spain), Fax: (+34) 941‐299‐621
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62
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Hashimoto R, Fujitani N, Takegawa Y, Kurogochi M, Matsushita T, Naruchi K, Ohyabu N, Hinou H, Gao XD, Manri N, Satake H, Kaneko A, Sakamoto T, Nishimura SI. An Efficient Approach for the Characterization of Mucin-Type Glycopeptides: The Effect of O-Glycosylation on the Conformation of Synthetic Mucin Peptides. Chemistry 2011; 17:2393-404. [DOI: 10.1002/chem.201002754] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2010] [Indexed: 01/19/2023]
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63
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Van Elssen CHMJ, Clausen H, Germeraad WTV, Bennet EP, Menheere PP, Bos GMJ, Vanderlocht J. Flow cytometry-based assay to evaluate human serum MUC1-Tn antibodies. J Immunol Methods 2010; 365:87-94. [PMID: 21194532 DOI: 10.1016/j.jim.2010.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 11/22/2010] [Accepted: 12/13/2010] [Indexed: 01/27/2023]
Abstract
Mucin-1 (MUC1) is a heavily O-glycosylated, transmembrane protein that is expressed on the apical surface of most secretory epithelia. In malignantly transformed epithelia, MUC1 has lost its apical distribution, is underglycosylated and is secreted into the circulation. Due to the underglycosylation of MUC1, cancer-specific MUC1-Tn/STn antigens, which are highly immunogenic, become exposed. We aimed at developing a system that allows detection of antibodies directed to the native form of MUC1 and the underglycosylated MUC1-Tn epitopes. To this end, we made use of the Chinese Hamster Ovary (CHO) ldlD cell line stably transfected with MUC1. This cell line has a glycosylation defect, which can be reversed by addition of different monosaccharides to the cell culture and enables the production of cells expressing the MUC1-Tn glycoforms. After validation with glycospecific antibodies, the CHO-ldlD MUC1 system was used to detect serum MUC1 and MUC1-Tn antibodies. Using this system, we could confirm the presence of MUC1-Tn antibodies in the serum of a patient vaccinated with a truncated MUC1 peptide. This indicates that the CHO-ldlD MUC1 system represents a flow cytometry-based technique to detect antibodies binding to the underglycosylated MUC1 protein. This cellular system is complementary to the previously published methods to detect MUC1 serum antibodies, since the antibodies to the native protein are evaluated and therefore it can be effectively used for MUC1 antibody monitoring in vaccination studies as well as for functional assays.
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64
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Mariño K, Bones J, Kattla JJ, Rudd PM. A systematic approach to protein glycosylation analysis: a path through the maze. Nat Chem Biol 2010; 6:713-23. [PMID: 20852609 DOI: 10.1038/nchembio.437] [Citation(s) in RCA: 479] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Protein glycosylation is an important post-translational modification. It is a feature that enhances the functional diversity of proteins and influences their biological activity. A wide range of functions for glycans have been described, from structural roles to participation in molecular trafficking, self-recognition and clearance. Understanding the basis of these functions is challenging because the biosynthetic machinery that constructs glycans executes sequential and competitive steps that result in a mixture of glycosylated variants (glycoforms) for each glycoprotein. Additionally, naturally occurring glycoproteins are often present at low levels, putting pressure on the sensitivity of the analytical technologies. No universal method for the rapid and reliable identification of glycan structure is currently available; hence, research goals must dictate the best method or combination of methods. To this end, we introduce some of the major technologies routinely used for structural N- and O-glycan analysis, describing the complementary information that each provides.
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Affiliation(s)
- Karina Mariño
- Dublin-Oxford Glycobiology Laboratory, National Institute for Bioprocessing, Research and Training, University College Dublin Conway Institute, University College Dublin, Belfield, Ireland
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65
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Takahashi K, Wall SB, Suzuki H, Smith AD, Hall S, Poulsen K, Kilian M, Mobley JA, Julian BA, Mestecky J, Novak J, Renfrow MB. Clustered O-glycans of IgA1: defining macro- and microheterogeneity by use of electron capture/transfer dissociation. Mol Cell Proteomics 2010; 9:2545-57. [PMID: 20823119 DOI: 10.1074/mcp.m110.001834] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
IgA nephropathy (IgAN) is the most common primary glomerulonephritis in the world. Aberrantly glycosylated IgA1, with galactose (Gal)-deficient hinge region (HR) O-glycans, plays a pivotal role in the pathogenesis of the disease. It is not known whether the glycosylation defect occurs randomly or preferentially at specific sites. We have described the utility of activated ion-electron capture dissociation (AI-ECD) mass spectrometric analysis of IgA1 O-glycosylation. However, locating and characterizing the entire range of O-glycan attachment sites are analytically challenging due to the clustered serine and threonine residues in the HR of IgA1 heavy chain. To address this problem, we analyzed all glycoforms of the HR glycopeptides of a Gal-deficient IgA1 myeloma protein, mimicking the aberrant IgA1 in patients with IgAN, by use of a combination of IgA-specific proteases + trypsin and AI-ECD Fourier transform ion cyclotron resonance (FT-ICR) tandem mass spectrometry (MS/MS). The IgA-specific proteases provided a variety of IgA1 HR fragments that allowed unambiguous localization of all O-glycosylation sites in the six most abundant glycoforms, including the sites deficient in Gal. Additionally, this protocol was adapted for on-line liquid chromatography (LC)-AI-ECD MS/MS and LC-electron transfer dissociation MS/MS analysis. Our results thus represent a new clinically relevant approach that requires ECD/electron transfer dissociation-type fragmentation to define the molecular events leading to pathogenesis of a chronic kidney disease. Furthermore, this work offers generally applicable principles for the analysis of clustered sites of O-glycosylation.
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Affiliation(s)
- Kazuo Takahashi
- Biomedical FT-ICR MS Laboratory, Department of Biochemistry and Molecular Genetics, University of Alabama, Birmingham, Alabama 35294-0005, USA
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66
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Yoshimura Y, Matsushita T, Fujitani N, Takegawa Y, Fujihira H, Naruchi K, Gao XD, Manri N, Sakamoto T, Kato K, Hinou H, Nishimura SI. Unexpected tolerance of glycosylation by UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferase revealed by electron capture dissociation mass spectrometry: carbohydrate as potential protective groups. Biochemistry 2010; 49:5929-41. [PMID: 20540529 DOI: 10.1021/bi100623g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferases (ppGalNAcTs, EC 2.4.1.41), a family of key enzymes that initiate posttranslational modification with O-glycans in mucin synthesis by introduction of alpha-GalNAc residues, are structurally composed of a catalytic domain and a lectin domain. It has been known that multiple Ser/Thr residues are assigned in common mucin glycoproteins as potential O-glycosylation sites and more than 20 distinct isoforms of this enzyme family contribute to produce densely O-glycosylated mucin glycoproteins. However, it seems that the functional role of the lectin domain of ppGalNAcTs remains unclear. We considered that electron capture dissociation mass spectrometry (ECD-MS), a promising method for highly selective fragmentation at peptide linkages of glycopeptides to generate unique c and z series of ions, should allow for precise structural characterization to uncover the mechanism in O-glycosylation of mucin peptides by ppGalNAcTs. In the present study, it was demonstrated that a system composed of an electrospray source, a linear RFQ ion trap that isolates precursor ions, the ECD device, and a TOF mass spectrometer is a nice tool to identify the preferential O-glycosylation sites without any decomposition of the carbohydrate moiety. It should be noted that electrons used for ECD are accelerated within a range from 1.75 to 9.75 eV depending on the structures of glycopeptides of interest. We revealed for the first time that additional installation of a alpha-GalNAc residue at potential glycosylation sites by ppGalNAcT2 proceeds smoothly in various unnatural glycopeptides having alpha-Man, alpha-Fuc, and beta-Gal residues as well as alpha-GalNAc residues. The results may suggest that ppGalNAcT2 did not differentiate totally presubstituted sugar residues in terms of configuration of functional groups, d-, l-configuration, and even alpha-, beta-stereochemistry at an anomeric carbon atom when relatively short synthetic peptides were employed for the acceptor substrates. Unexpected characteristics of ppGalNAcT2 motivated us to challenge site-directed installation of alpha-GalNAc residues at desired position(s) by protecting some hydroxyl groups of Thr/Ser residues with selectively removable sugars, notably a novel concept as "carbohydrate as protective groups", toward a goal of the systematic chemical and enzymatic synthesis of biologically important mucin glycopeptides.
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Affiliation(s)
- Yayoi Yoshimura
- Graduate School of Life Science and Research Center for Post-Genome Science and Technology, Hokkaido University, Sapporo 001-0021, Japan
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67
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Gill DJ, Chia J, Senewiratne J, Bard F. Regulation of O-glycosylation through Golgi-to-ER relocation of initiation enzymes. J Cell Biol 2010; 189:843-58. [PMID: 20498016 PMCID: PMC2878949 DOI: 10.1083/jcb.201003055] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 04/27/2010] [Indexed: 12/25/2022] Open
Abstract
After growth factor stimulation, kinases are activated to regulate multiple aspects of cell physiology. Activated Src is present on Golgi membranes, but its function here remains unclear. We find that Src regulates mucin-type protein O-glycosylation through redistribution of the initiating enzymes, polypeptide N-acetylgalactosaminyl transferases (GalNac-Ts), from the Golgi to the ER. Redistribution occurs after stimulation with EGF or PDGF in a Src-dependent manner and in cells with constitutively elevated Src activity. All GalNac-T family enzymes tested are affected, whereas multiple other glycosylation enzymes are not displaced from the Golgi. Upon Src activation, the COP-I coat is also redistributed in punctate structures that colocalize with GalNac-Ts and a dominant-negative Arf1 isoform, Arf1(Q71L), efficiently blocks GalNac-T redistribution, indicating that Src activates a COP-I-dependent trafficking event. Finally, Src activation increases O-glycosylation initiation as seen by lectin staining and metabolic labeling. We propose that growth factor stimulation regulates O-glycosylation initiation in a Src-dependent fashion by GalNac-T redistribution to the ER.
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Affiliation(s)
- David J. Gill
- Institute of Molecular and Cell Biology, Proteos, Singapore 138673
| | - Joanne Chia
- Institute of Molecular and Cell Biology, Proteos, Singapore 138673
| | | | - Frederic Bard
- Institute of Molecular and Cell Biology, Proteos, Singapore 138673
- National University of Singapore, Singapore 119077
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68
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69
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Bennett EP, Chen YW, Schwientek T, Mandel U, Schjoldager KTBG, Cohen SM, Clausen H. Rescue of Drosophila Melanogaster l(2)35Aa lethality is only mediated by polypeptide GalNAc-transferase pgant35A, but not by the evolutionary conserved human ortholog GalNAc-transferase-T11. Glycoconj J 2010; 27:435-44. [PMID: 20422447 DOI: 10.1007/s10719-010-9290-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 04/07/2010] [Accepted: 04/07/2010] [Indexed: 01/02/2023]
Abstract
The Drosophila l(2)35Aa gene encodes a UDP-N-acetylgalactosamine: Polypeptide N-acetylgalactosaminyltransferase, essential for embryogenesis and development (J. Biol. Chem. 277, 22623-22638; J. Biol. Chem. 277, 22616-22). l(2)35Aa, also known as pgant35A, is a member of a large evolutionarily conserved family of genes encoding polypeptide GalNAc-transferases. Phylogenetic and functional analyses have proposed that subfamilies of orthologous GalNAc-transferase genes are conserved in species, suggesting that they serve distinct functions in vivo. Based on sequence alignments, pgant35A and human GALNT11 are thought to belong to a distinct subfamily. Recent in vitro studies have shown that pgant35A and pgant7, encoding enzymes from different subfamilies, prefer different acceptor substrates, whereas the orthologous pgant35A and human GALNT11 gene products possess, 1) conserved substrate preferences and 2) similar acceptor site preferences in vitro. In line with the in vitro pgant7 studies, we show that l(2)35Aa lethality is not rescued by ectopic pgant7 expression. Remarkably and in contrast to this observation, the human pgant35A ortholog, GALNT11, was shown not to support rescue of the l(2)35Aa lethality. By use of genetic "domain swapping" experiments we demonstrate, that lack of rescue was not caused by inappropriate sub-cellular targeting of functionally active GalNAc-T11. Collectively our results show, that fly embryogenesis specifically requires functional pgant35A, and that the presence of this gene product during fly embryogenesis is functionally distinct from other Drosophila GalNAc-transferase isoforms and from the proposed human ortholog GALNT11.
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Affiliation(s)
- Eric P Bennett
- Copenhagen Center for Glycomics, University of Copenhagen, Nørre Alle 20, 2200 Copenhagen N, Denmark.
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70
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Miwa HE, Gerken TA, Jamison O, Tabak LA. Isoform-specific O-glycosylation of osteopontin and bone sialoprotein by polypeptide N-acetylgalactosaminyltransferase-1. J Biol Chem 2010; 285:1208-19. [PMID: 19880513 PMCID: PMC2801249 DOI: 10.1074/jbc.m109.035436] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 10/08/2009] [Indexed: 11/06/2022] Open
Abstract
Mucin-type O-glycan biosynthesis is regulated by the family of UDP-GalNAc polypeptide:N-acetylgalactosaminlytransfersases (ppGalNAcTs) that catalyzes the first step in the pathway by transferring GalNAc to Ser or Thr residues in a protein from the sugar donor UDP-GalNAc. Because not all Ser/Thr residues are glycosylated, rules must exist that signal which hydroyxamino acids acquire sugar. To date, no universal consensus signal has emerged. Therefore, strategies to deduce the subset of proteins that will be glycosylated by distinct ppGalNAcTs must be developed. Mucin-type O-glycoproteins are present abundantly in bone, where we found multiple ppGalNAcT isoforms, including ppGalNAcT-1, to be highly expressed. Thus, we compared glycoproteins expressed in wild-type and Galnt1-null mice to identify bone-associated proteins that were glycosylated in a ppGalNAcT-1-dependent manner. A reduction in the apparent molecular masses of two SIBLINGs (small integrin binding ligand N-linked glycoproteins), osteopontin (OPN) and bone sialoprotein (BSP) in the Galnt1-null mice relative to those of the wild-type was observed. Several synthetic peptides derived from OPN and BSP sequences were designed to include either known or predicted (in silico) glycosylation sites. In vitro glycosylation assays of these peptides with recombinant ppGalNAcT-1, ppGalNAcT-2, or ppGalNAcT-3 demonstrated that both SIBLINGs contained Thr/Ser residues that were preferentially glycosylated by ppGalNAcT-1. In addition, lysates prepared from wild-type, but not those from Galnt1-null derived osteoblasts, could glycosylate these peptides efficiently, suggesting that OPN and BSP contain sites that are specific for ppGalNAcT-1. Our study presents a novel and systematic approach for identification of isoform-specific substrates of the ppGalNAcT family and suggests ppGalNAcT-1 to be indispensable for O-glycosylation at specific sites of the bone glycoproteins OPN and BSP.
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Affiliation(s)
- Hazuki E. Miwa
- From the Section on Biological Chemistry, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892 and
| | - Thomas A. Gerken
- the Departments of Pediatrics and Biochemistry, W. A. Bernbaum Center for Cystic Fibrosis Research, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Oliver Jamison
- the Departments of Pediatrics and Biochemistry, W. A. Bernbaum Center for Cystic Fibrosis Research, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Lawrence A. Tabak
- From the Section on Biological Chemistry, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892 and
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71
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Nilsson T, Au CE, Bergeron JJM. Sorting out glycosylation enzymes in the Golgi apparatus. FEBS Lett 2009; 583:3764-9. [PMID: 19878678 DOI: 10.1016/j.febslet.2009.10.064] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 10/20/2009] [Indexed: 11/26/2022]
Abstract
The study of glycosylation and glycosylation enzymes has been instrumental for the advancement of Cell Biology. After Neutra and Leblond showed that the Golgi apparatus is the main site of glycosylation, elucidation of oligosaccharide structures by Baenziger and Kornfeld and subsequent mapping of glycosylation enzymes followed. This enabled development of anin vitrotransport assay by Rothman and co-workers using glycosylation to monitor intra Golgi transport which, complemented by yeast genetics by Schekman and co-workers, provided much of the fundamental insights and key components of the secretory pathway that we today take for granted. Glycobiology continues to play a key role in Cell Biology and here, we look at the use of glycosylation enzymes to elucidate intra Golgi transport.
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Affiliation(s)
- Tommy Nilsson
- The Research Institute of the McGill University Health Centre, Department of Medicine, McGill University, 687 Pine Avenue West, Montreal, Quebec, Canada H3A 1A1.
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72
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Brockhausen I, Dowler T, Paulsen H. Site directed processing: role of amino acid sequences and glycosylation of acceptor glycopeptides in the assembly of extended mucin type O-glycan core 2. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1790:1244-57. [PMID: 19524017 DOI: 10.1016/j.bbagen.2009.05.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 05/21/2009] [Accepted: 05/29/2009] [Indexed: 12/15/2022]
Abstract
BACKGROUND The assembly of Ser/Thr-linked O-glycans of mucins with core 2 structures is initiated by polypeptide GalNAc-transferase (ppGalNAc-T), followed by the action of core 1 beta3-Gal-transferase (C1GalT) and core 2 beta6-GlcNAc-transferase (C2GnT). Beta4-Gal-transferase (beta4GalT) extends core 2 and forms the backbone structure for biologically important epitopes. O-glycan structures are often abnormal in chronic diseases. The goal of this work is to determine if the activity and specificity of these enzymes are directed by the sequences and glycosylation of substrates. METHODS We studied the specificities of four enzymes that synthesize extended O-glycan core 2 using as acceptor substrates synthetic mucin derived peptides and glycopeptides, substituted with GalNAc or O-glycan core structures 1, 2, 3, 4 and 6. RESULTS Specific Thr residues were found to be preferred sites for the addition of GalNAc, and Pro in the +3 position was found to especially enhance primary glycosylation. An inverse relationship was found between the size of adjacent glycans and the rate of GalNAc addition. All four enzymes could distinguish between substrates having different amino acid sequences and O-glycosylated sites. A short glycopeptide Galbeta1-3GalNAcalpha-TAGV was identified as an efficient C2GnT substrate. CONCLUSIONS The activities of four enzymes assembling the extended core 2 structure are affected by the amino acid sequence and presence of carbohydrates on nearby residues in acceptor glycopeptides. In particular, the sequences and O-glycosylation patterns direct the addition of the first and second sugar residues by ppGalNAc-T and C1GalT which act in a site directed fashion. GENERAL SIGNIFICANCE Knowledge of site directed processing enhances our understanding of the control of O-glycosylation in normal cells and in disease.
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Affiliation(s)
- Inka Brockhausen
- Department of Medicine, Division of Rheumatology, Queen's University, Kingston, Ontario, Canada K7L 3N6.
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73
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Mercier KA, Cort JR, Kennedy MA, Lockert EE, Ni S, Shortridge MD, Powers R. Structure and function of Pseudomonas aeruginosa protein PA1324 (21-170). Protein Sci 2009; 18:606-18. [PMID: 19241370 DOI: 10.1002/pro.62] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Pseudomonas aeruginosa is the prototypical biofilm-forming gram-negative opportunistic human pathogen. P. aeruginosa is causatively associated with nosocomial infections and with cystic fibrosis. Antibiotic resistance in some strains adds to the inherent difficulties that result from biofilm formation when treating P. aeruginosa infections. Transcriptional profiling studies suggest widespread changes in the proteome during quorum sensing and biofilm development. Many of the proteins found to be upregulated during these processes are poorly characterized from a functional standpoint. Here, we report the solution NMR structure of PA1324, a protein of unknown function identified in these studies, and provide a putative biological functional assignment based on the observed prealbumin-like fold and FAST-NMR ligand screening studies. PA1324 is postulated to be involved in the binding and transport of sugars or polysaccharides associated with the peptidoglycan matrix during biofilm formation.
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Affiliation(s)
- Kelly A Mercier
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA
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74
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Perrine CL, Ganguli A, Wu P, Bertozzi CR, Fritz TA, Raman J, Tabak LA, Gerken TA. Glycopeptide-preferring polypeptide GalNAc transferase 10 (ppGalNAc T10), involved in mucin-type O-glycosylation, has a unique GalNAc-O-Ser/Thr-binding site in its catalytic domain not found in ppGalNAc T1 or T2. J Biol Chem 2009; 284:20387-97. [PMID: 19460755 PMCID: PMC2740463 DOI: 10.1074/jbc.m109.017236] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 05/05/2009] [Indexed: 02/05/2023] Open
Abstract
Mucin-type O-gly co sy la tion is initiated by a large family of UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferases (ppGalNAc Ts) that transfer GalNAc from UDP-GalNAc to the Ser and Thr residues of polypeptide acceptors. Some members of the family prefer previously gly co sylated peptides (ppGalNAc T7 and T10), whereas others are inhibited by neighboring gly co sy la tion (ppGalNAc T1 and T2). Characterizing their peptide and glycopeptide substrate specificity is critical for understanding the biological role and significance of each isoform. Utilizing a series of random peptide and glycopeptide substrates, we have obtained the peptide and glycopeptide specificities of ppGalNAc T10 for comparison with ppGalNAc T1 and T2. For the glycopeptide substrates, ppGalNAc T10 exhibited a single large preference for Ser/Thr-O-GalNAc at the +1 (C-terminal) position relative to the Ser or Thr acceptor site. ppGalNAc T1 and T2 revealed no significant enhancements suggesting Ser/Thr-O-GalNAc was inhibitory at most positions for these isoforms. Against random peptide substrates, ppGalNAc T10 revealed no significant hydrophobic or hydrophilic residue enhancements, in contrast to what has been reported previously for ppGalNAc T1 and T2. Our results reveal that these transferases have unique peptide and glycopeptide preferences demonstrating their substrate diversity and their likely roles ranging from initiating transferases to filling-in transferases.
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Affiliation(s)
| | | | - Peng Wu
- the Departments of Chemistry and
| | - Carolyn R. Bertozzi
- the Departments of Chemistry and
- Molecular and Cell Biology and
- Howard Hughes Medical Institute, University of California, Berkeley, California 94720
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and
| | - Timothy A. Fritz
- Section on Biological Chemistry, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892
| | - Jayalakshmi Raman
- Section on Biological Chemistry, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892
| | - Lawrence A. Tabak
- Section on Biological Chemistry, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892
| | - Thomas A. Gerken
- From the Departments ofChemistry
- Biochemistry, and
- Pediatrics and
- the W. A. Bernbaum Center for Cystic Fibrosis Research, Case Western Reserve University, Cleveland, Ohio 44106
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75
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Rich JR, Withers SG. Emerging methods for the production of homogeneous human glycoproteins. Nat Chem Biol 2009; 5:206-15. [PMID: 19295526 DOI: 10.1038/nchembio.148] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Most circulating human proteins exist as heterogeneously glycosylated variants (glycoforms) of an otherwise homogeneous polypeptide. Though glycan heterogeneity is most likely important to glycoprotein function, the preparation of homogeneous glycoforms is important both for the study of the consequences of glycosylation and for therapeutic purposes. This review details selected approaches to the production of homogeneous human N- and O-linked glycoproteins with human-type glycans. Particular emphasis is placed on recent developments in the engineering of glycosylation pathways within yeast and bacteria for in vivo production, and on the in vitro remodeling of glycoproteins by enzymatic means. The future of this field is very exciting.
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Affiliation(s)
- Jamie R Rich
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
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76
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Gerken TA, Ten Hagen KG, Jamison O. Conservation of peptide acceptor preferences between Drosophila and mammalian polypeptide-GalNAc transferase ortholog pairs. Glycobiology 2008; 18:861-70. [PMID: 18669915 PMCID: PMC2574660 DOI: 10.1093/glycob/cwn073] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Revised: 07/18/2008] [Accepted: 07/29/2008] [Indexed: 12/22/2022] Open
Abstract
UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltrans- ferases (ppGalNAc Ts) comprise a large family of glycosyltransferases that initiate mucin-type protein O-glycosylation, transferring alpha-GalNAc to Thr and Ser residues of polypeptide acceptors. Families of ppGalNAc Ts are found across diverse eukaryotes with orthologs identifiable from mammals to single-cell organisms. The peptide substrate specificity and specific protein targets of the individual ppGalNAc T family members remain poorly understood. Previously, we reported a series of oriented random peptide substrate libraries for quantitatively determining the peptide substrate specificities of the mammalian ppGalNAc T1 and T2 (Gerken TA, Raman J, Fritz TA, Jamison O. 2006. Identification of common and unique peptide substrate preferences for the UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferases T1 & T2 (ppGalNAc T1 & T2) derived from oriented random peptide substrates. J Biol Chem. 281:32403-32416). With these substrates, previously unknown features of the transferases were revealed. Utilizing these and a new lengthened set of random peptides, studies have now been performed on PGANT5 and PGANT2, the Drosophila orthologs of T1 and T2. The results from these studies suggest that the major peptide substrate determinants for these transferases are contained within 2 to 3 residues flanking the site of glycosylation. It is further found that the mammalian and fly T1 orthologs display very similar peptide substrate preferences, while the T2 orthologs are nearly indistinguishable, suggesting similar peptide preferences amongst orthologous pairs have been maintained across evolution. This conclusion is further supported by sequence homology comparisons of each of the transferase orthologs, showing that the peptide substrate and UDP binding site residues are more highly conserved between species relative to their remaining catalytic and lectin domain residues.
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Affiliation(s)
- Thomas A Gerken
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
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77
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Raman J, Fritz TA, Gerken TA, Jamison O, Live D, Liu M, Tabak LA. The catalytic and lectin domains of UDP-GalNAc:polypeptide alpha-N-Acetylgalactosaminyltransferase function in concert to direct glycosylation site selection. J Biol Chem 2008; 283:22942-51. [PMID: 18562306 PMCID: PMC2517002 DOI: 10.1074/jbc.m803387200] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Revised: 06/17/2008] [Indexed: 11/06/2022] Open
Abstract
UDP-GalNAc:polypeptide alpha-N-Acetylgalactosaminyltransferases (ppGalNAcTs), a family (EC 2.4.1.41) of enzymes that initiate mucin-type O-glycosylation, are structurally composed of a catalytic domain and a lectin domain. Previous studies have suggested that the lectin domain modulates the glycosylation of glycopeptide substrates and may underlie the strict glycopeptide specificity of some isoforms (ppGalNAcT-7 and -10). Using a set of synthetic peptides and glycopeptides based upon the sequence of the mucin, MUC5AC, we have examined the activity and glycosylation site preference of lectin domain deletion and exchange constructs of the peptide/glycopeptide transferase ppGalNAcT-2 (hT2) and the glycopeptide transferase ppGalNAcT-10 (hT10). We demonstrate that the lectin domain of hT2 directs glycosylation site selection for glycopeptide substrates. Pre-steady-state kinetic measurements show that this effect is attributable to two mechanisms, either lectin domain-aided substrate binding or lectin domain-aided product release following glycosylation. We find that glycosylation of peptide substrates by hT10 requires binding of existing GalNAcs on the substrate to either its catalytic or lectin domain, thereby resulting in its apparent strict glycopeptide specificity. These results highlight the existence of two modes of site selection used by these ppGalNAcTs: local sequence recognition by the catalytic domain and the concerted recognition of distal sites of prior glycosylation together with local sequence binding mediated, respectively, by the lectin and catalytic domains. The latter mode may facilitate the glycosylation of serine or threonine residues, which occur in sequence contexts that would not be efficiently glycosylated by the catalytic domain alone. Local sequence recognition by the catalytic domain differs between hT2 and hT10 in that hT10 requires a pre-existing GalNAc residue while hT2 does not.
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Affiliation(s)
- Jayalakshmi Raman
- Section on Biological Chemistry, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA
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Herr P, Korniychuk G, Yamamoto Y, Grubisic K, Oelgeschläger M. Regulation of TGF-(beta) signalling by N-acetylgalactosaminyltransferase-like 1. Development 2008; 135:1813-22. [PMID: 18417620 DOI: 10.1242/dev.019323] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The TGF-beta superfamily of secreted signalling molecules plays a pivotal role in the regulation of early embryogenesis, organogenesis and adult tissue homeostasis. Here we report the identification of Xenopus N-acetylgalactosaminyltransferase-like 1 (xGalntl-1) as a novel important regulator of TGF-beta signalling. N-acetylgalactosaminyltransferases mediate the first step of mucin-type glycosylation, adding N-acetylgalactose to serine or threonine side chains. xGalntl-1 is expressed in the anterior mesoderm and neural crest territory at neurula stage, and in the anterior neural crest, notochord and the mediolateral spinal cord at tailbud stage. Inhibition of endogenous xGalntl-1 protein synthesis, using specific morpholino oligomers, interfered with the formation of anterior neural crest, anterior notochord and the spinal cord. Xenopus and mammalian Galntl-1 inhibited Activin as well as BMP signalling in the early Xenopus embryo and in human HEK 293T cells. Gain- and loss-of-function experiments showed that xGalntl-1 interferes with the activity of the common TGF-beta type II receptor ActR-IIB in vivo. In addition, our biochemical data demonstrated that xGalntl-1 specifically interferes with the binding of ActR-IIB to Activin- and BMP-specific type I receptors. This inhibitory activity of xGalntl-1 was dependent on mucin-type glycosylation, as it was sensitive to the chemical inhibitor benzyl-GalNAc. These studies reveal an important role of a N-acetylgalactosaminyltransferase in the regulation of TGF-beta signalling. This novel regulatory mechanism is evolutionarily conserved and, thus, might provide a new paradigm for the regulation of TGF-beta signalling in vertebrates.
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Affiliation(s)
- Patrick Herr
- Max-Planck Institute of Immunobiology, Stübeweg 51, D-79108 Freiburg, Germany
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79
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Tarp MA, Clausen H. Mucin-type O-glycosylation and its potential use in drug and vaccine development. BIOCHIMICA ET BIOPHYSICA ACTA 2008; 1780:546-63. [PMID: 17988798 DOI: 10.1016/j.bbagen.2007.09.010] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 09/14/2007] [Indexed: 01/03/2023]
Abstract
Mucin-type O-glycans are found on mucins as well as many other glycoproteins. The initiation step in synthesis is catalyzed by a large family of polypeptide GalNAc-transferases attaching the first carbohydrate residue, GalNAc, to selected serine and threonine residues in proteins. During the last decade an increasing number of GalNAc-transferase isoforms have been cloned and their substrate-specificities partly characterized. These differences in substrate specificities have been exploited for in vitro site-directed O-glycosylation. In GlycoPEGylation, polyehylene glycol (PEG) is transferred to recombinant therapeutics to specific acceptor sites directed by GalNAc-transferases. GalNAc-transferases have also been used to control density of glycosylation in the development of glycopeptide-based cancer vaccines. The membrane-associated mucin-1 (MUC1) has long been considered a target for immunotherapeutic and immunodiagnostic measures, since it is highly overexpressed and aberrantly O-glycosylated in most adenocarcinomas, including breast, ovarian, and pancreatic cancers. By using vaccines mimicking the glycosylation pattern of cancer-cells, it is possible to overcome tolerance in transgenic animals expressing the human MUC1 protein as a self-antigen providing important clues for an improved MUC1 vaccine design. The present review will highlight some of the potential applications of site-directed O-glycosylation.
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Affiliation(s)
- Mads Agervig Tarp
- Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, The Panum Institute, 6.4, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
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Napoletano C, Rughetti A, Agervig Tarp MP, Coleman J, Bennett EP, Picco G, Sale P, Denda-Nagai K, Irimura T, Mandel U, Clausen H, Frati L, Taylor-Papadimitriou J, Burchell J, Nuti M. Tumor-associated Tn-MUC1 glycoform is internalized through the macrophage galactose-type C-type lectin and delivered to the HLA class I and II compartments in dendritic cells. Cancer Res 2007; 67:8358-67. [PMID: 17804752 DOI: 10.1158/0008-5472.can-07-1035] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The type of interaction between tumor-associated antigens and specialized antigen-presenting cells such as dendritic cells (DCs) is critical for the type of immunity that will be generated. MUC1, a highly O-glycosylated mucin, is overexpressed and aberrantly glycosylated in several tumor histotypes. This results in the expression of tumor-associated glycoforms and in MUC1 carrying the tumor-specific glycan Tn (GalNAcalpha1-O-Ser/Thr). Glycopeptides corresponding to three tandem repeats of MUC1, enzymatically glycosylated with 9 or 15 mol of GalNAc, were shown to specifically bind and to be internalized by immature monocyte-derived DCs (iDCs). Binding required calcium and the GalNAc residue and was competed out by GalNAc polymer and Tn-MUC1 or Tn-MUC2 glycopeptides. The macrophage galactose-type C-type lectin (MGL) receptor expressed on iDCs was shown to be responsible for the binding. Confocal analysis and ELISA done on subcellular fractions of iDCs showed that the Tn-MUC1 glycopeptides colocalized with HLA class I and II compartments after internalization. Importantly, although Tn-MUC1 recombinant protein was bound and internalized by MGL, the glycoprotein entered the HLA class II compartment, but not the HLA class I pathway. These data indicate that MGL expressed on iDCs is an optimal receptor for the internalization of short GalNAcs carrying immunogens to be delivered into HLA class I and II compartments. Such glycopeptides therefore represent a new way of targeting the HLA class I and II pathways of DCs. These results have possible implications in designing cancer vaccines.
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Affiliation(s)
- Chiara Napoletano
- Department of Experimental Medicine, University of Rome Sapienza, IRCCS San Raffaele Pisana, Rome, Italy
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