Shiga toxins (STXs) are virulence factors of Escherichia coli and Shigella strains that cause disease in humans. Members of the Shiga toxin family are composed of a pentameric array of glycolipid-binding B-subunits and a single enzymatic A subunit that inhibits ribosomal function. Globotriaosylceramide (Gb3) is the most common glycolipid cell surface receptor for Shiga toxin molecules and the presence of the glycolipid in cell membranes allows the toxins to target cells for protein synthesis inhibition. However, the cellular functions of Gb3 beyond serving as a Shiga-toxin receptor have not been well documented. Shiga-toxin amino acid sequences were used in this research to identify additional proteins that may interact with Gb3 as part of their functions. In some cases amino acid substitutions were allowed in Shiga toxin B-subunit sequences used in BLAST searches to identify potential Gb3-binding sites on additional proteins. Cn3D was used to visualize structures of proteins with pdb files so identified, and the potential presence of Shiga toxin-like Gb3-binding sites on these proteins was evaluated.
