Engineered intrinsically fluorescent galectin-8 variants with altered valency, ligand recognition and biological activity

Galectin-8 is a small soluble lectin with two carbohydrate recognition domains (CRDs). N- and C-terminal CRDs of Gal-8 differ in their specificity for glycan ligands. Here, we wanted to find out whether oligomerization of individual CRDs of galectin-8 affects its biological activity. Using green fluorescent protein polygons (GFPp) as an oligomerization scaffold, we generated intrinsically fluorescent CRDs with altered valency. We show that oligomers of C-CRD are characterized by significant cell surface affinity. Furthermore, the multivalency of the resulting variants has an impact on cellular activities such as cell signaling, heparin binding and proliferation. Our data indicates that tunable valence is a useful tool for modifying the biological activity of CRDs of galectins.