| 1. |
- D'Arrigo, I., et al.
(author)
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Diverse IgG serum response to novel glycopeptide epitopes detected within immunodominant stretches of Epstein-Barr virus glycoprotein 350/220: diagnostic potential of O-glycopeptide microarrays
- 2013
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In: Glycoconjugate Journal. - : Springer Science and Business Media LLC. - 0282-0080 .- 1573-4986. ; 30:7, s. 633-640
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Journal article (peer-reviewed)abstract
- The Epstein-Barr virus (EBV) envelope glycoprotein 350/220 (gp350/220) is the most abundant molecule on the viral surface and it is responsible for the initial viral attachment to cell surface of the host. As many other viral envelope proteins, it is highly glycosylated, not least with O-linked glycans, most of which essential for EBV life cycle. EBV gp350/220 is also a primary target for neutralizing antibodies in the human hosts and a promising candidate for an EBV vaccine. Here we showed that recombinant GalNAc transferases can glycosylate scan peptides of the EBV gp350/220 envelope protein immobilized on microarray glass slides. We also identified serum IgG antibodies to a selection of peptides and O-glycopeptides, whereas sera from EBV-IgG negative individuals remained negative. We here describe novel glycopeptide epitopes present within immunodominant stretches of EBV gp350/220 and demonstrate a remarkable variability between individual samples with respect to their reactivity patterns to peptides and glycopeptides. The study provides additional insights into the complex B-cell response towards the EBV gp350/220 envelope protein, which may have implications for diagnostic and vaccine developments.
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| 2. |
- Gaunitz, Stefan, et al.
(author)
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Avian influenza H5 hemagglutinin binds with high avidity to sialic acid on different O-linked core structures on mucin-type fusion proteins
- 2014
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In: Glycoconjugate Journal. - : Springer Science and Business Media LLC. - 0282-0080 .- 1573-4986. ; 31:2, s. 145-159
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Journal article (peer-reviewed)abstract
- The interaction between P-selectin glycoprotein ligand-1/mouse IgG(2b) (PSGL-1/mIgG(2b)) fusion protein carrying multiple copies of the influenza hemagglutinin receptor Sia alpha 2-3Gal on different O-glycan chains and recombinant human influenza H5N1 A/Vietnam/1203/04 hemagglutinin was investigated with a Biacore biosensor. The fusion protein was produced by stable cell lines in large scale cultures and purified with affinity- and gel filtration chromatography. The C-P55 and 293-P cell lines were established by transfecting the Chinese hamster ovary (CHO)-K1 and Human embryonic kidney (HEK)-293 cell lines with plasmids encoding the PSGL-1/mIgG(2b) fusion protein, while the C-PSLex cell line was engineered by transfecting CHO-K1 cells with the plasmids encoding the core 2 beta 1,6GnT-I and FUT-VII glycosyltransferases. Glycosylation was characterized by lectin Western blotting of the proteins and liquid chromatography - mass spectrometry of released non-derivatized O-glycans. Biacore experiments revealed that PSGL-1/mIgG(2b) is a good binding partner of H5. The binding curves displayed a slow dissociation indicating a multivalent binding. The H5 hemagglutinin binds with similar strength to PSGL-1/mIgG(2b) carrying mostly sialylated core 1 (clone C-P55), a mix of sialylated core 1 and sialylated lactosamine (clone 293-P) or mainly sialylated lactosamine (clone C-PSLex) O-glycans, indicating that this hemagglutinin is unable to discriminate between these structures. The potential use of the large, flexible PSGL-1/mIgG(2b) mucin-type fusion protein carrying Sia alpha 2-3Gal as a multivalent inhibitor of influenza virus is discussed.
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| 3. |
- Harrison, Amanda L., et al.
(author)
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A synthetic globotriaosylceramide analogue inhibits HIV-1 infection in vitro by two mechanisms
- 2010
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In: Glycoconjugate Journal. - : Springer Science and Business Media LLC. - 1573-4986 .- 0282-0080. ; 27:5, s. 515-524
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Journal article (peer-reviewed)abstract
- Previously, it was shown that the cell-membrane-expressed glycosphingolipid, globotriaosylceramide (Gb(3)/P-k/CD77), protects against HIV-1 infection and may be a newly described natural resistance factor against HIV infection. We have now investigated the potential of a novel, water soluble, non-toxic and completely synthetic analogue of Gb(3)/P-k (FSL-Gb(3)) to inhibit HIV-1 infection in vitro. A uniquely designed analogue, FSL-Gb(3), of the natural Gb(3)/P-k molecule was synthesized. HIV-1(IIIB) (X4 virus) and HIV-1(Ba-L) (R5 virus) infection of PHA/interleukin-2-activated, peripheral blood mononuclear cells (PBMCs) and Jurkat T cells in vitro was assessed, as well as infection of U87.CD4.CCR5 by various clinical R5 tropic viruses after treatment with FSL-Gb(3). We monitored Gb(3), CD4 and CXCR4 expression by fluorescent antibody cell sorting and viral replication by p24 (gag) ELISA. Total cellular Gb(3) was examined by glycosphingolipid extraction and thin layer chromatography. In vivo toxicity was monitored in mice by histological assessment of vital organs and lymphoid tissue. FSL-Gb(3) blocked X4 and R5 of both lab and clinical viral strains in activated PBMCs or the U87.CD4.CCR5 cell line with a 50% inhibitory concentration (IC50) of approximately 200-250 mu M. FACS and TLC overlay showed that FSL-Gb(3) can insert itself into cellular plasma membranes and that cellular membrane-absorbed FSL-Gb(3) is able to inhibit subsequent HIV-1 infection. There was no effect of FSL-Gb(3) on cell surface levels of CD4 or CXCR4. Thus, FSL-Gb(3) can inhibit HIV-1 by two mechanisms: direct inhibition of virus and inhibition of viral entry. Infusion of FSL-Gb(3) into laboratory mice at doses well in excess of theoretical therapeutic doses was tolerated with no untoward reactions. Our results demonstrate the potential utility of using a completely synthetic, water soluble globotriaosylceramide analogue, FSL-Gb(3), having low toxicity, for possible future use as a novel therapeutic approach for the systemic treatment of HIV/AIDS.
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| 4. |
- Hoja-Łukowicz, Dorota, et al.
(author)
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L1CAM from human melanoma carries a novel type of N-glycan with Galβ1-4Galβ1- motif : Involvement of N-linked glycans in migratory and invasive behaviour of melanoma cells
- 2013
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In: Glycoconjugate Journal. - : Springer Netherlands. - 0282-0080 .- 1573-4986. ; 30:3, s. 205-225
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Journal article (peer-reviewed)abstract
- Dramatic changes in glycan biosynthesis during oncogenic transformation result in the emergence of marker glycans on the cell surface. We analysed the N- linked glycans of L1CAM from different stages of melanoma progression, using high-performance liquid chromatography combined with exoglycosidase sequencing, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, and lectin probes. L1CAM oligosaccharides are heavily sialylated, mainly digalactosylated, biantennary complex-type structures with galactose β1-4/3-linked to GlcNAc and with or without fucose α1-3/6-linked to GlcNAc. Hybrid, bisected hybrid, bisected triantennary and tetraantennary complex oligosaccharides, and β1-6-branched complex-type glycans with or without lactosamine extensions are expresses at lower abundance. We found that metastatic L1CAM possesses only α2-6-linked sialic acid and the loss of α2-3-linked sialic acid in L1CAM is a phenomenon observed during the transition of melanoma cells from VGP to a metastatic stage. Unexpectedly, we found a novel monoantennary complex-type oligosaccharide with a Galβ1-4Galβ1- epitope capped with sialic acid residues A1[3]G(4)2S 2-3 . To our knowledge this is the first report documenting the presence of this oligosaccharide in human cancer. The novel and unique N- glycan should be recognised as a new class of human melanoma marker. In functional tests we demonstrated that the presence of cell surface α2-3-linked sialic acid facilitates the migratory behaviour and increases the invasiveness of primary melanoma cells, and it enhances the motility of metastatic cells. The presence of cell surface α2-6-linked sialic acid enhances the invasive potential of both primary and metastatic melanoma cells. Complex-type oligosaccharides in L1CAM enhance the invasiveness of metastatic melanoma cells.
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| 5. |
- Landström, Jens, et al.
(author)
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Small molecules containing hetero-bicyclic ring systems compete with UDP-Glc for binding to WaaG glycosyltransferase
- 2012
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In: Glycoconjugate Journal. - : Springer. - 0282-0080 .- 1573-4986. ; 29:7, s. 491-502
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Journal article (peer-reviewed)abstract
- The α-1,3-glucosyltransferase WaaG is involved in the synthesis of the core region of lipopolysaccharides in E. coli. A fragment-based screening for inhibitors of the WaaG glycosyltrasferase donor site has been performed using NMR spectroscopy. Docking simulations were performed for three of the compounds of the fragment library that had shown binding activity towards WaaG and yielded 3D models for the respective complexes. The three ligands share a hetero-bicyclic ring system as a common structural motif and they compete with UDP-Glc for binding. Interestingly, one of the compounds promoted binding of uridine to WaaG, as seen from STD NMR titrations, suggesting a different binding mode for this ligand. We propose these compounds as scaffolds for the design of selective high-affinity inhibitors of WaaG. Binding of natural substrates, enzymatic activity and donor substrate selectivity were also investigated by NMR spectroscopy. Molecular dynamics simulations of WaaG were carried out with and without bound UDP and revealed structural changes compared to the crystal structure and also variations in flexibility for some amino acid residues between the two WaaG systems studied.
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| 6. |
- Nilsson, Jonas, 1970, et al.
(author)
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Targeting the glycoproteome.
- 2013
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In: Glycoconjugate journal. - : Springer Science and Business Media LLC. - 1573-4986 .- 0282-0080. ; 30:2, s. 119-36
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Journal article (peer-reviewed)abstract
- Despite numerous original publications describing the structural complexity of N- and O-linked glycans on glycoproteins, only very few answer the basic question of which particular glycans are linked to which amino acid residues along the polypeptide chain. Such structural information is of fundamental importance for understanding the biological roles of complex glycosylations as well as deciphering their non-template driven biosynthesis. This review focuses on presenting and commenting on recent strategies, specifically aimed at identifying the glycoproteome of cultured cells and biological samples, using targeted and global enrichment procedures and utilizing the high resolution power, high through-put capacity and complementary fragmentation techniques of tandem mass spectrometry. The goal is to give an update of this emerging field of protein and glyco-sciences and suggest routes to bridge the data gap between the two aspects of glycoprotein characteristics, i.e. glycan structures and their attachment sites.
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| 7. |
- Rademacher, Christoph, et al.
(author)
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NMR-based exploration of the acceptor binding site of human blood group B galactosyltransferase with molecular fragments
- 2010
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In: Glycoconjugate Journal. - : Springer. - 0282-0080 .- 1573-4986. ; 27:3, s. 349-358
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Journal article (peer-reviewed)abstract
- A substantial body of work has been devoted to the design and synthesis of glycosyltransferase inhibitors. A major obstacle has always been the demanding chemistry. Therefore, only few potent and selective inhibitors are known to date. Glycosyltransferases possess two distinct binding sites, one for the donor substrate, and one for the acceptor substrate. In many cases binding to the donor site is well defined but data for acceptor binding is sparse. In particular, acceptor binding sites are often shallow, and in many cases the dimensions of the binding pocket are not well defined. One approach to glycosyltransferase inhibitors is to chemically link donor site and acceptor site ligands to generate high affinity binders. Here, we describe a novel approach to identify acceptor site ligands from a fragment library. We have chosen human blood group B galactosyltransferase (GTB) as a biologically important model target. The approach utilizes a combination of STD NMR, spin-lock filtered NMR experiments and surface plasmon resonance measurements. Following this route we have identified molecular fragments from a fragment library that bind to the acceptor site of GTB with affinities of the order of a natural acceptor substrate. Unlike natural substrates these fragments allow for straightforward chemical modifications and, therefore will serve as scaffolds for potent GTB inhibitors. In general, the approach described is applicable to any glycosyltransferase and may assist in the development of novel glycosyltransferase inhibitors.
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