Cross-Linking Effects Dictate the Preference of Galectins to Bind LacNAc-Decorated HPMA Copolymers

Abstract

The interaction of multi-LacNAc (Galβ1-4GlcNAc)-containing N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers with human galectin-1 (Gal-1) and the carbohydrate recognition domain (CRD) of human galectin-3 (Gal-3) was analyzed using NMR methods in addition to cryo-electron-microscopy and dynamic light scattering (DLS) experiments. The interaction with individual LacNAc-containing components of the polymer was studied for comparison purposes. For Gal-3 CRD, the NMR data suggest a canonical interaction of the individual small-molecule bi- and trivalent ligands with the lectin binding site and better affinity for the trivalent arrangement due to statistical effects. For the glycopolymers, the interaction was stronger, although no evidence for forming a large supramolecule was obtained. In contrast, for Gal-1, the results indicate the formation of large cross-linked supramolecules in the presence of multivalent LacNAc entities for both the individual building blocks and the polymers. Interestingly, the bivalent and trivalent presentation of LacNAc in the polymer did not produce such an increase, indicating that the multivalency provided by the polymer is sufficient for triggering an efficient binding between the glycopolymer and Gal-1. This hypothesis was further demonstrated by electron microscopy and DLS methods.

Multivalent glycosystems for human lectins

“…Cryo-EM and DLS experiments further supported that the presence of cross-linked systems was more pronounced in the case of Gal-1. 253…”

“…Cryo-EM and DLS experiments further supported that the presence of cross-linked systems was more pronounced in the case of Gal-1. 253 Multivalent architectures composed of thiodigalactosides (TDGs) have been previously reported as effective Gal-3 binders. 254 In this context, Vrbata et al 255 have recently extended the use of TDGs to prepare HPMA-based glycopolymers.…”

Exploring multivalent carbohydrate–protein interactions by NMR

“…Dynamic light scattering and cryo-electron microscopy experiments allowed deducing the existence of supramolecular and cross-linked entities, further supporting the NMR results. 76 The interaction of natural ligands versus galectins has also been studied by NMR. Typical multivalent presentations can be found in polysaccharides, multiantennae N-glycans, or poly-LacNAc chains.…”

“…Herein, we should mention that Gal-1 is a non-covalent homodimer 74 while the CRD of Gal-3 is a monomer. 75 The phenomenon has also been investigated by NMR, 76 from both the ligand and receptor's perspectives. STD-NMR experiments highlighted that the recognized epitope for the monomer presentations of di- and tri-LacNAc moieties is that of the LacNAc (ligand 1) moiety.…”

Synthesis, Self-Assembly, and Cell Responses of Aromatic IKVAV Peptide Amphiphiles

“…It is speculated that simple and versatile molecular self-assembly systems can provide us with new perspectives to view some complex and unknown biological developments [6,7]. Among the self-assembled materials, self-assembling peptides have gained much attention owing to their biocompatibility, design flexibility, and functionality [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Self-assembling peptides with amphipathic structures are considered significant materials for building self-assembled nanostructures.…”