Fluorinated Man9 as a High Mannose Mimetic to Unravel Its Recognition by DC-SIGN Using NMR

TL;DR

This paper describes how fluorinated Man9 was used with NMR to study how DC-SIGN recognizes high mannose sugars.

Contribution

A fluorinated Man9 ligand was developed to overcome NMR signal overlap and identify the binding epitope for DC-SIGN.

Findings

Fluorinated Man9 enabled accurate NMR analysis of the Man9/DC-SIGN interaction.

The binding epitope was unequivocally identified using 1H,19F STD-TOCSYreF NMR experiments.

Fluorine tags improved the resolution of complex oligosaccharide interactions in solution.

Abstract

Lectins are capable of reading out the structural information
contained
in carbohydrates through specific recognition processes. Determining
the binding epitope of the sugar is fundamental to understanding this
recognition event. Nuclear magnetic resonance (NMR) is a powerful
tool to obtain this structural information in solution; however, when
the sugar involved is a complex oligosaccharide, such as high mannose,
the signal overlap found in the NMR spectra precludes an accurate
analysis of the interaction. The introduction of tags into these complex
oligosaccharides could overcome these problems and facilitate NMR
studies. Here, we show the preparation of the Man9 of high
mannose with some fluorine tags and the study of the interaction with
its receptor, dendritic cell-specific intercellular adhesion molecule-3-grabbing
nonintegrin (DC-SIGN). This fluorinated ligand has allowed us to apply
heteronuclear two-dimensional (2D) 1H,19F STD-TOCSYreF
NMR experiments, using the initial slope approach, which has facilitated
the analysis of the Man9/DC-SIGN interaction, unequivocally
providing the binding epitope.

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