Galectins and ToxinsCopyright: L. & F. Biomaterialien
Galectins belong to a lectin subgroup which specifically recognizes β-galactoside providing glycans such as N-acetyllactosamine (LacNAc). Galectins comprise at least one globular folded carbohydrate recognition domain (CRD). The most relevant representatives are galectin‑1 (Gal‑1) and galectin‑3 (Gal‑3). Prototype Gal‑1 comprises two identical CRDs, whereas Gal‑3 is capable of forming polyvalent aggregates (up to pentamers) via its large N-terminal non-lectin domain. Both, Gal‑1 and Gal‑3 fulfill important functions in cell-cell and cell-matrix interactions and thus influencing cell adhesion, migration but also trigger immune response and inflammation events.
Clostridium difficile is a hospital germ, which secretes an enterotoxin A (TcdA). TcdA adheres to gastrointestinal epithelial cells, is internalized via endocytosis and inhibits an intracellular signal cascade. It finally leads to lesions in the colon epithelia (diarrhea). The cell adhesion is mediated by a lectin-glycan interaction. Aqueous microgels and neo-glycoproteins are utilized for deciphering the specificity and binding behavior of TcdA.