A novel lectin family inside snail eggs?

BROLA, T.R.; HERAS, H; DREON MS,; ITUARTE S,

Buenos Aires

Congreso; 3er Simposio Argentino de Glicobiología: GlycoAR 2019; 2019

Pomacea snails lay their eggs outside the water, exposing them to terrestrial predators. They have evolved an efficient defense system against egg predation. Among these defences, Pomacea scalaris eggs have an abundant carotenoprotein (PsSC) with lectin activity. Previously we showed PsSC withstands gastrointestinal digestion in mice and alters gut morphophysiology. Interestingly, PsSC has no sequence similarity with other known lectins. This prompted us to search for other related lectins. To that aim, we isolated the major egg carotenoprotein of P. diffusa, a closely related species to P. scalaris which we named PdPV1. We sequenced each subunit and analysed them by bioinformatics. PdPV1 global shape was studied by SAXS, lectin activity was characterized by hemagglutination assays and glycan specificity determined by glycan array screening. Finally, in vivo experiments evaluated its resistance to gastrointestinal digestion. PdPV1 is an anisometric oligomer, resistant to in vivo gastrointestinal digestion, characteristics that resemble PsSC. Further, it is composed by 6 subunits with >90% sequence similarity with PsSC. PdPV1 agglutinates erythrocytes and its activity was inhibited by galactosides. Glycan array showed that PdPV1 recognizes the same ganglioside motifs as PsSC. Due to the similarities between PsSC and PdPV1 and the lack of sequence similarity with other lectins, we propose these snail lectins may be part of a new lectin family, not yet described.