Tunable multivalent Fe(II)-based glycoassemblies as mimetics for native high-mannose glycans

High Mannose Glycans (HMGs) play key roles in eukaryotic biology, regulating processes ranging from protein folding to host pathogen defense. Lectins have evolved to interact with these glycans through multivalent interactions facilitated by the multiple sugars displayed on glycans and via multiple binding sites on each lectin. Using Fe(II) iminopyridine complexes, we generated chemically defined multivalent glycan displays where the valency, arm length, and spatial display of mannose residues can be controlled via subcomponent synthesis. Due to its sensitivity towards the geometric display of mannose residues, monomeric Griffithsin (mGRFT) was utilized as a model lectin. Interactions between the Fe(II) glycan assemblies and mGRFT were characterized using biolayer interferometry (BLI), isothermal titration calorimetry (ITC), and NMR spectroscopy. Our results display a >1000-fold range in K_D for Fe(II) iminopyridine complexes that can be tuned by factors such as saccharide tether length and number of sugars displayed. Through leveraging systematic molecular-level modifications, we demonstrate that tunable Fe(II) glycan assemblies can be used both as mimetics for high mannose glycans as well as competitive inhibitors for native glycan binding.