Psathyrella velutina mushroom lectin exhibits high affinity toward sialoglycoproteins possessing terminal N-acetylneuraminic acid α2,3-linked to penultimate galactose residues of trisialyl N-glycans: Comparison with other sialic acid-specific lectins

Abstract

A lectin from the fruiting body of the Psathyrella velutina mushroom (PVL) was found to bind specifically to N-acetylneuraminic acid, as well as to GlcNAc (Ueda, H., Kojima, K., Saitoh, T., and Ogawa, H. (1999) FEBS Lett. 448, 75-80). In this study, the glycan sequences that PVL recognizes with high affinity on sialoglycoproteins were revealed. Among sialic acid-specific lectins only PVL could reveal the sialylated N-acetyllactosamine structure of glycoproteins in blotting studies, based on the dual specificity. The affinity of PVL to fetuin was measured by surface plasmon resonance to be 107 M-1, which is an order of magnitude higher than those of Sambucus nigra agglutinin and Maackia amurensis mitogen, whereas affinity to asialofetuin was ∼0 and to asialoagalactofetuin was 108 M-1, suggesting that PVL exhibits remarkably high affinities toward glycoproteins possessing trisialo- or GlcNAc-exposed glycans. Transferrin was separated into fractions that correspond to the sialylation states on an immobilized PVL column. Transferrin-possessing trisialoglycans containing α2,3-linked N-acetylneuraminic acid on the β1,4-linked GlcNAc branch bound to the PVL column and eluted with GlcNAc; those containing only α2,6-linked sialic acids were retarded, whereas other transferrin fractions passed through the column. These results indicate that PVL is a lectin with potential for separation and detection of sialoglycoproteins because of its dual specificity toward sialoglycans and GlcNAc exposed glycans.