Molecular Cloning and Characteristics of a Lectin from the Bivalve Glycymeris yessoensis

Abstract

C-type lectins (CTLs) are a family of carbohydrate-binding proteins that mediate multiple biological events, including adhesion between cells, the turnover of serum glycoproteins, and innate immune system reactions to prospective invaders. Here, we describe the cDNA cloning of lectin from the bivalve Glycymeris yessoensis (GYL), which encodes 161 amino acids and the C-type carbohydrate recognition domain (CRD) with EPN and WND motifs. The deduced amino acid sequence showed similarity to other CTLs. GYL is a glycoprotein containing two N-glycosylation sites per subunit. N-glycans are made up of xylose, mannose, D-glucosamine, 3-O-methylated galactose, D-quinovoses, and 3-O-methylated 6-deoxy-D-glucose. The potential CRD tertiary structure of the GYL adopted CTL-typical long-form double-loop structure and included three disulfide bridges at the bases of the loops. Additionally, when confirming the GYL sequence, eight isoforms of this lectin were identified. This fact indicates the presence of a multigene family of GYL-like C-type lectins in the bivalve G. yessoensis. Using the glycan microarray approach, natural carbohydrate ligands were established, and the glycotope for GYL was reconstructed as “Galβ1–4GlcNAcβ obligatory containing an additional fragment”, like a sulfate group or a methyl group of fucose or N-acetylgalactosamine residues.

New l-Rhamnose-Binding Lectin from the Bivalve Glycymeris yessoensis: Purification, Partial Structural Characterization and Antibacterial Activity

“…In our previous study, the C-type lectins GYL and GYLman were identified from the hemolymph of mollusk G. yessoensis. They have a wide spectrum of microbial binding, including Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Vibrio proteolyticus) and possibly participate in the immune defense of the G. yessoensis against bacterial attacks [24][25][26]. Considering the large number of bacteria in the aquatic environment, there should be other lectins to protect the mollusk from various pathogens.…”