Pectin-derived neoglycolipids: Tools for differentiation of Shiga toxin subtypes and inhibitors of Shiga toxin-mediated cellular injury

Abstract

Gut pathogenic enterohemorrhagic Escherichia coli (EHEC) release Shiga toxins (Stxs) as major virulence factors, which bind to globotriaosylceramide (Gb3Cer, Galα1-4 Galβ1-4Glcβ1-1Cer) on human target cells. The aim of this study was the production of neoglycolipids (neoGLs) using citrus pectin-derived oligosaccharides and their application as potential inhibitors of Stxs. The preparation of neoGLs starts with the reduction of the carboxylic acid group of the pectic poly(α1-4)GalUA core structure to the corresponding alcohol, followed by hydrolytic cleavage of resulting poly(α1-4)Gal into (α1-4)Gal_n oligosaccharides and their linkage to phosphatidylethanolamine (PE). Thin-layer chromatography overlay assays of the produced (α1-4)Gal_n-PE and corresponding Amadori (α1-4)Gal_n=PE neoGLs revealed distinguishable binding patterns for Stx1a, Stx2a, and Stx2e. Furthermore, prepared neoGLs protected Vero cells against the cytotoxic action of Stxs when applied as multivalent glycovesicles. The produced neoGLs are applicable for differentiation of Stx subtypes and represent a promising approach to combat infections of EHEC by blocking their major toxins.

Keywords: Citrus pectin; EHEC; Glycovesicles; Neoglycolipids; STEC; Shiga toxin.