The GalNAc/Gal-specific
lectin from the sea mussel Crenomytilus grayanus (CGL) with anticancer activity represents а novel
lectin family with β-trefoil fold. Earlier, the crystal structures of CGL complexes with
globotriose,
galactose and
galactosamine, and mutagenesis studies have revealed that the
lectin contained three
carbohydrate-binding sites. The ability of CGL to recognize
globotriose (Gb3) on the surface of
breast cancer cells and bind
mucin-type
glycoproteins, which are often associated with oncogenic transformation, makes this compound to be perspective as a biosensor for
cancer diagnostics. In this study, we describe results on in silico analysis of binding mechanisms of CGL to
ligands (
galactose,
globotriose and
mucin) and evaluate the individual contribution of the
amino acid residues from
carbohydrate-binding sites to CGL activity by site-directed mutagenesis. The
alanine substitutions of His37, His129, Glu75, Asp127, His85, Asn27 and Asn119 affect the CGL
mucin-binding activity, indicating their importance in the manifestation of
lectin activity. It has been found that CGL affinity to
ligands depends on their structure, which is determined by the number of hydrogen bonds in the CGL-
ligand complexes. The obtained results should be helpful for understanding molecular machinery of CGL functioning and designing a synthetic analog of CGL with enhanced
carbohydrate-binding properties.