Unraveling Sugar Binding Modes to DC-SIGN by Employing Fluorinated Carbohydrates

• Main Authors: J. Daniel Martínez, Pablo Valverde, Sandra Delgado, Cecilia Romanò, Bruno Linclau, Niels C. Reichardt, Stefan Oscarson, Ana Ardá, Jesús Jiménez-Barbero, F. Javier Cañada
• Format: Article
• Language: English
• Published: MDPI AG 2019-06-01
• Series: Molecules
• Subjects: NMR; molecular recognition; lectin; glycomimetics; DC-SIGN; C-type lectins; fluorinated sugars; ¹⁹F-NMR; screening; molecular dynamics
• Online Access: https://www.mdpi.com/1420-3049/24/12/2337

A fluorine nuclear magnetic resonance (¹⁹F-NMR)-based method is employed to assess the binding preferences and interaction details of a library of synthetic fluorinated monosaccharides towards dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (DC-SIGN), a lectin of biomedical interest, which is involved in different viral infections, including HIV and Ebola, and is able to recognize a variety of self- and non-self-glycans. The strategy employed allows not only screening of a mixture of compounds, but also obtaining valuable information on the specific sugar−protein interactions. The analysis of the data demonstrates that monosaccharides Fuc, Man, Glc, and Gal are able to bind DC-SIGN, although with decreasing affinity. Moreover, a new binding mode between Man moieties and DC-SIGN, which might have biological implications, is also detected for the first time. The combination of the ¹⁹F with standard proton saturation transfer difference (¹H-STD-NMR) data, assisted by molecular dynamics (MD) simulations, permits us to successfully define this new binding epitope, where Man coordinates a Ca²⁺ ion of the lectin carbohydrate recognition domain (CRD) through the axial OH-2 and equatorial OH-3 groups, thus mimicking the Fuc/DC-SIGN binding architecture.