V originále
Lectins (from Latin, legere, to select or choose) are multivalent proteins with the ability to recognize and reversibly bind mono- and oligosacharides. The sugar binding sites of lectins, called carbohydrate recognition domain (CRD), promote specific recognition in accordance with the key-lock model. Mutagenesis in CRD may lead to the improvement of binding specificity of lectins, making them markers for carbohydrate structural motifs in nature. Ralstonia solanacearum lectin (RSL) isolated from Ralstonia solanacearum, a phytopathogen causing lethal wilting of agricultural crops, is a trimeric L-fucose specific lectin with the six bladed b-propeller fold. Each monomer presents two fucose specific binding sites, resulting in six symmetrically arranged CRDs. Core fucosylation is the most important core modification in vertebrate N-glycans. It is the addition of fucose via a1-6 linkage to the N-acetylglucosamine adjecent to asparagine in the core. Core fucosylation is involved in many physiological events such as growth and cell differentiation. Recent studies revealed that increasing level of core fucosylation is associated with some diseases (for instance hepatocellular carcinoma). Our work is focused on structural and functional characterization of RSL mutants that might show (based on the results of in silico mutagenesis and docking) higher specificity towards core fucose. Mutagenesis was performed by PCR and the affinity towards different fucose derivatives was measured by isothermal titration calorimetry (ITC) and microscale thermoforesis (MST). Structural changes in CRD after mutagenesis, were determined by protein crystallography.