Detection and quantitative analysis of two independent binding modes of a small ligand responsible for DC-SIGN clustering

Org Biomol Chem. 2016 Jan 7;14(1):335-44. doi: 10.1039/c5ob02025e. Epub 2015 Nov 27.

Abstract

DC-SIGN (dendritic cell-specific ICAM-3 grabbing non-integrin) is a C-type lectin receptor (CLR) present, mainly in dendritic cells (DCs), as one of the major pattern recognition receptors (PRRs). This receptor has a relevant role in viral infection processes. Recent approaches aiming to block DC-SIGN have been presented as attractive anti-HIV strategies. DC-SIGN binds mannose or fucose-containing carbohydrates from viral proteins such as the HIV envelope glycoprotein gp120. We have previously demonstrated that multivalent dendrons bearing multiple copies of glycomimetic ligands were able to inhibit DC-SIGN-dependent HIV infection in cervical explant models. Optimization of glycomimetic ligands requires detailed characterization and analysis of their binding modes because they notably influence binding affinities. In a previous study we characterized the binding mode of DC-SIGN with ligand 1, which shows a single binding mode as demonstrated by NMR and X-ray crystallography. In this work we report the binding studies of DC-SIGN with pseudotrisaccharide 2, which has a larger affinity. Their binding was analysed by TR-NOESY and STD NMR experiments, combined with the CORCEMA-ST protocol and molecular modelling. These studies demonstrate that in solution the complex cannot be explained by a single binding mode. We describe the ensemble of ligand bound modes that best fit the experimental data and explain the higher inhibition values found for ligand 2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites / drug effects
  • Cell Adhesion Molecules / chemistry*
  • Cell Adhesion Molecules / metabolism
  • Crystallography, X-Ray
  • Dendritic Cells
  • Humans
  • Lectins, C-Type / chemistry*
  • Lectins, C-Type / metabolism
  • Ligands
  • Models, Molecular
  • Molecular Structure
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Binding / drug effects
  • Receptors, Cell Surface / chemistry*
  • Receptors, Cell Surface / metabolism
  • Structure-Activity Relationship
  • Trisaccharides / chemical synthesis
  • Trisaccharides / chemistry
  • Trisaccharides / pharmacology*

Substances

  • Cell Adhesion Molecules
  • DC-specific ICAM-3 grabbing nonintegrin
  • Lectins, C-Type
  • Ligands
  • Receptors, Cell Surface
  • Trisaccharides