Insights into the effects of glycosylation and the monosaccharide-binding activity of the plant lectin CrataBL

CrataBL is a glycoprotein isolated from Crataeva tapia bark, containing two N-glycosylation sites. It has been identified to present lectin activity with some specificity for binding glucose over galactose. However, to date, no information on the effects of glycosylation or CrataBL monosaccharide-binding sites and monosaccharide specificity has been obtained. Thus, molecular docking and molecular dynamics simulations were employed to characterize the glycosylated CrataBL conformation and dynamics in aqueous solutions, as well as the molecular basis for its binding specificity. The obtained results indicate both local and distant conformational stabilization effects of N-linked glycans over CrataBL protein moiety. Regarding its lectin activity, molecular docking calculations were performed in two possible binding sites, identified through sequence-based, structure-based and evolutionary information, using α- and β-anomeric states of the monosaccharides. The obtained poses were further refined through molecular dynamics simulations, suggesting that positively-charged amino acids dictate the binding preference for glucose over galactose in both sites. In addition, a possible preference for β-monosaccharides was proposed. Such data are expected to contribute to a better comprehension of the lectins monosaccharide-binding activities and carbohydrate-binding site structures.