THE MAJOR EGG PROTEIN OF POMACEA SCALARIS IS A LIPO-GLYCO-CAROTENOPROTEIN WITH CITOTOXIC EFFECT ON CACO2 CELLS

ITUARTE, SANTIAGO; HERAS, HORACIO; DREON, MARCOS S.

La Plata

Congreso; 8th International Conference on Lipid Binding Proteins; 2013

INIBIOLP-CCT La Plata

The reproductive strategy of the snails of the genus Pomacea consists in lay eggs above the water line, exposing them to sunlight, high temperatures, and predators. Pomacea eggs have evolved proteins involved in the adaptation to these harsh environmental conditions. The major egg protein of Pomacea scalaris, PsSC, is a lipo-glyco-carotenoprotein of 380 kDa, composed of several subunits of 24-35 kDa. Besides the usual role as reserve protein, PsSC presents lectin activity associated with a high structural stability against temperature (>65°C) and pH (2.0-10.0). Moreover, it is able to withstand in vitro gastrointestinal digestion. These stability properties are shared with other Pomacea egg proteins studied in our laboratory, namely PcOvo and PcPV2. To better understand the functions these proteins play in the reproductive strategy of Pomacea, we further characterized the lectin activity of PsSC. We determined its oligosaccharide specificity using glycan arrays, evaluated its interaction with Caco2 cells by fluorescence microscopy, analyzed the citotoxicity of PsSC on Caco2 cells by MTT assay and its bactericide effect on Escherichia coli. PsSC showed binding affinity to glycans of the ABO human blood group and gangliosides, the latter well represented on the cell surface of Caco2. In agreement with this, PsSC was able to interact with Caco2 cell membranes, reducing cell viability. Though no bactericide/bacteriostatic effect was detected, PsSC showed the capability to agglutinate E. coli. We could suggest a role of PsSC in protecting eggs from pathogen invasion. However, the resistance to gastrointestinal digestion together with its citotoxicity on Caco2 cells led us to speculate that PsSC could also be involved in embryo defense against predation, though further work is needed to elucidate the role of PsSC in the reproductive strategy of this snail. Finally, our results point out the potential of PsSC as a biotechnologycal tool, particularly in the biomedical field.