Docking, synthesis, and NMR studies of mannosyl trisaccharide ligands for DC-SIGN lectin

Abstract

DC-SIGN, a lectin, which presents at the surface of immature dendritic cells, constitutes nowadays a promising target for the design of new antiviral drugs. This lectin recognizes highly glycosylated proteins present at the surface of several pathogens such as HIV, Ebola virus, Candida albicans, Mycobacterium tuberculosis, etc. Understanding the binding mode of this lectin is a topic of tremendous interest and will permit a rational design of new and more selective ligands. Here, we present computational and experimental tools to study the interaction of di- and trisaccharides with DC-SIGN. Docking analysis of complexes involving mannosyl di- and trisaccharides and the carbohydrate recognition domain (CRD) of DC-SIGN have been performed. Trisaccharides Manalpha1,2[Manalpha1,6]Man 1 and Manalpha1,3[Manalpha1,6]Man 2 were synthesized from an orthogonally protected mannose as a common intermediate. Using these ligands and the soluble extracellular domain (ECD) of DC-SIGN, NMR experiments based on STD and transfer-NOE were performed providing additional information. Conformational analysis of the mannosyl ligands in the free and bound states was done. These studies have demonstrated that terminal mannoses at positions 2 or 3 in the trisaccharides are the most important moiety and present the strongest contact with the binding site of the lectin. Multiple binding modes could be proposed and therefore should be considered in the design of new ligands.

Role of Phosphatidylinositol Mannosides in the Interaction between Mycobacteria and DC-SIGN

“…1). Previous studies have shown that DC-SIGN recognizes ␣(132)-linked dimannosyl and trimannosyl structures, with the affinity increasing with length (20,42,61). Furthermore, PIMs are present in the outermost layer of the mycobacterial cell envelope (54), where they function as adhesins for mycobacterial binding to both macrophages and nonphagocytic cells (36,47,71).…”

NMR studies on carbohydrate interactions with DC-SIGN towards a quantitative STD analysis

“…The NMR study was performed recording NOESY experiments in the absence and presence of DC-SIGN EDC (ensuring that DC-SIGN is a tetrameric aggregate), as well as STD NMR experiments for epitope mapping ( Fig. 1) [37].…”

The use of glycoinformatics in glycochemistry

“…One of the major problems of docking algorithms in general is the identification of the correct conformation among the potential binding modes [100]. Therefore, computational docking approaches are frequently combined with wet-lab experiments, such as saturation transfer difference NMR (STD NMR) or transferred nuclear Overhauser effect (trNOE) spectroscopy [75,114–116], to reliably assign the correct conformation of the ligand on the protein surface. Such combinations of experimental and theoretical approaches are also useful to determine the conformations of natural carbohydrates or their synthetic glycan mimetics [117–119].…”