The Sweet Love between Marine Sponge Cells

Abstract

229Trends Glycosci. Glycotechnol. Vol. 20 No. 115 (2008) AbstractTheˆrst step in the marine sponge cell recognition and adhesion operates via a Ca 2＋ -dependent carbohydrate-carbohydrate interaction. For the species Microciona prolifera the 200 kDa N-glycan (g-200) involved in the self-recognition is part of a proteoglycan-like macromolecular complex, the aggregation factor, with a molecular mass of 2×10 4 kDa. The complex has a sunburst-like shape. One of the carbohydrate epitopes involved in the self-interaction is a sulfated disaccharide fragment, b-D-GlcpNAc3S-(1ª3)-a-L-Fucp. In an attempt to mimick the polyvalent g-200 glycan-g-200 glycan self-recognition on the disaccharide level, the disaccharide epitope was synthesized and conjugated with bovine serum albumin, gold nanoparticles, and gold layers. The protein conjugates were used in UV and SPR experiments, the gold glyconanoparticles in TEM experiments, and the gold glycolayers in AFM experiments. It turned out that in the presence of 10 mM CaCl 2 the various disaccharide results match completely those obtained on the polymer level for M. prolifera cells and aggregation-factor-coated beads. A. IntroductionIn biological recognition and adhesion processes, protein-protein, carbohydrate-protein, and carbohydrate-carbohydrate interactions play key roles. The strength of the interactions, whereby carbohydrates are involved is a few orders of magnitude lower than those observed for protein-protein interactions, with carbohydrate-carbohydrate interactions weaker than carbohydrate-protein interactions.For a long time, direct carbohydrate-carbohydrate interactions between glycan chains of glycoproteins, glycolipids, and proteoglycans have been underestimated, if not ignored. However, nowadays the number of reports