An investigation of the interactions of E-selectin with fuco-oligosaccharides of the blood group family

Abstract

This investigation is concerned with assignments of Lewisa (Lea) and Lex analogs on linear and branched di- to hexasaccharide backbones as components of the recognition motifs for E-selectin. The influence of the location of fucose residue(s) was investigated using 14 structurally defined and variously fucosylated oligosaccharides in biotinylated form or as neoglycolipids in static binding assays, in microwells, and on thin-layer chromatograms. Results of the two assay systems were in agreement overall and showed that the recognition motifs for E-selectin include 4-fucosyl-lacto (Lea) and 3-fucosyl-neo-lacto (Lex) sequences strictly at capping positions and not Lex at an internal position as a part of VIM-2 antigen sequence. There is greater potency of the Lea over the Lex series. Additional fucose residues α1-2-linked to neighboring galactoses or α1-3-linked to inner N-acetyglucosamines or to reducing-terminal glucose residues of the tetrasaccharide backbone had little or no effect on the selectin binding. E-selectin binding to the Lea or Lex capping motif on a 3-linked branch was equivalent to the binding on the corresponding linear backbone. A lack of E-selectin binding to the Lex motif capping a 6-linked branch and to the Lex trisaccharide linked to biotin via a nine-carbon spacer indicates that the -GlcNAcβ1-3Gal- sequence on the oligosaccharide backbone adjoining the Lex is a part of recognition motif for E-selectin. These findings contribute to understanding the molecular basis of E-selectin recognition and could influence future designs of selectin antagonists as possible therapeutic substances.