Special Issue "Challenges in Glycan, Glycoprotein and Proteoglycan Research"

Guest Editor
Prof. Dr. Hans Vliegenthart
Bijvoet Center, Division Bioorganic Chemistry, Utrecht University, Padualaan 8, NL 3584 CH Utrecht, The Netherlands
Website: http://www.bijvoet-center.nl/boc2/contact/vliegenthart
E-Mail: j.f.g.vliegenthart@uu.nl
Phone: +3130 253 2168/2281
Interests: carbohydrates; glycoconjugates; unsaturated fatty acids; lipoxygenase and related enzymes

Dear Colleagues,

In the past decades Glycoscience has evolved tremendously. The progress that has been made in the analytical and synthetic aspects is spectacular. The introduction of high resolution NMR spectroscopy and Mass spectrometry has enabled the unravelling of the structure of glycans derived from glycoconjugates like glycoproteins, proteoglycans and glycolipids as well as of oligo- and polysaccharides. Improvements in the synthetic procedures, e.g., the development of solid state synthesis and of oligosaccharide synthesizers have rendered the synthesis of complex glycans possible in a reasonable period of time. Intriguing are the roles glycans can play at the molecular level in a large diversity of biological processes like normal and abnormal cell growth and development, recognition and interaction phenomena, adhesion of pathogens.

The biological features imply that the borders with (micro)biology, medicine, immunology, vaccines etc. have definitively been crossed. Many new challenges are waiting in the field.

To illustrate for the readers of “Biomolecules” the importance of Glycoscience as a multidisciplinary field of research, this special issue is intended to show the various aspects, possibilities, applications and challenges of glycans and related compounds.

We look forward to reading your contributions,

Prof. Dr. Hans Vliegenthart
Guest Editor

Submission

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• Glycoscience
• glycoproteins
• proteoglycans
• glycolipids
• oligosaccharides
• polysaccharides

Type of Paper: Article
Title: Nucleocytoplasmic plant lectins and their interaction with glycan structures
Authors: Elke Fouquaert and Els J.M. Van Damme *
Affiliation Laboratory of Biochemistry and Glycobiology, Department of Molecular Biotechnology, Ghent University, Coupure links 653, 9000 Ghent, Belgium; E-Mail: ElsJM.vanDamme@Ugent.be (E.J.M.V.D.)
Abstract: Plant lectins are a heterogeneous group of proteins, classified together based on their ability to recognize and specifically bind carbohydrate ligands. For a long time plant lectins were regarded as abundant proteins that are located in the vacuolar/extracellular compartment of the plant cell. In recent years evidence has accumulated that plants also synthesize small amounts of well-defined carbohydrate-binding proteins upon exposure to stresses like drought, high salt, wounding, treatment with some plant hormones or pathogen attack. In contrast to the 'classical’ plant lectins, this new class of inducible lectins is located in the cytoplasm and the nucleus. Hitherto, six families of such nucleocytoplasmic lectins have been identified in plants. This review will focus on the carbohydrate-binding properties of some of these inducible lectins. Taking into account that any physiological role of plant lectins most likely relies on their specific carbohydrate-binding activity and specificity, the discovery of these stress-related lectins provides strong evidence for the importance of protein-carbohydrate-interactions in plant cells.

Type of Paper: Article
Title: Hyaluronidases Preferentially Act on Chondroitin 4-sulfate Rather than Hyaluronan
Author: Shuhei Yamada
Affiliation: Laboratory of Proteoglycan Signaling and Therapeutics, Faculty of Advanced Life Science, Graduate School of Life Science, Hokkaido University, Sapporo 001-0021, Japan; E-Mail: tjohej@sci.hokudai.ac.jp
Abstract: Chondroitin sulfate (CS) chains are involved in the regulation of various biological processes. The cellular degradation of CS occurs predominantly in lysosomes. Following the fragmentation of polysaccharides by an endo-type hydrolase, the oligosaccharide products are degraded sequentially from the nonreducing end by exo-type glycosidases and sulfatases to liberate monosaccharide moieties. Hyaluronan (HA)-degrading enzymes, hyaluronidases, are considered to be the enzymes acting at the initial stage of the degradation process, because HA is similar in structure to nonsulfated CS, chondroitin (Chn). Although human hyaluronidase-1 (HYAL1) and testicular hyaluronidase (PH-20) can degrade not only HA but also CS, it has been considered that they digest CS to a limited extent and therefore that their preferred substrate is HA rather than CS. However, the distinct preference of the substrate recognition by hyaluronidases had not been determined. In this study, the hydrolytic activity of HYAL1 and PH-20 toward various substrates was quantitatively analyzed. HYAL1 depolymerized CS-A and HA to a similar extent. PH-20 also exhibited the activity to degrade CS-A, Chn, and HA to similar extents. CS is widely distributed from very primitive organisms to humans, whereas HA has been reported to be present only in vertebrates except for a mollusk. Therefore, the genuine substrate of HYAL1 appears to be CS rather than HA.

Type of Paper: Review
Title: Glycobiology Aspects of the Cell Envelope of the Periodontal Pathogen Tannerella forsythia
Authors: Gerald Posch, Gerhard Sekot, Valentin Friedrich, Zoë Megson, Paul Messner and Christina Schäffer
Affiliation: Department of NanoBiotechnology, NanoGlycobiology unit, University of Natural Resources and Life Sciences, Muthgasse 11, 1190 Vienna, Austria; E-Mails: christina.schaeffer@boku.ac.at (C.S.); paul.messner@boku.ac.at (P.M.)
Abstract: Cell surface glycosylation is an important element in defining the life of the periodontal pathogen Tannerella forsythia. The glycosylated surface (S-) layer of this bacterium is formed by co-assembly of two glycoproteins into a square 2D lattice with a spacing of 10.1±0.7 nm. The S-layer would be anchored to the cell wall by a novel type of rough lipopolysaccharide. The S-layer glycan is a so far unique oligosaccharide with the structure 4-Me-β-ManpNAcCONH₂-(1→3)-[Pse5Am7Gc-(2→4)-]-β-ManpNAcA-(1→4)-[4-Me-α-Galp-(1→2)-]-α-Fucp-(1→4)-[-α-Xylp-(1→3)-]-β-GlcpA-(1→3)-[-β-Digp-(1→2)-]-α-Galp that is O-glycosidically linked to distinct serine and threonine residues within the (D)(S/T)(A/I/L/M/T/V) motif. Also several other Tannerella proteins are modified with that oligosaccharide, most of which are found in the outer membrane. This pinpoints to the presence of a general O-glycosylation system in this bacterium. It obviously impacts the life style of T. forsythia since a defined mutant carrying truncated S-layer glycans favors biofilm formation. While the S-layer has also been shown to delay the bacterium's recognition by the innate immune system, the contribution of glycosylation to this phenomenon is currently being assessed. This review focuses on a general protein O-glycosylation system in T. forsythia that is essential for creating a rich glycoproteome and which has possible relevance for the virulence of this bacterium.