A structurally stable snail egg carotenoprotein provides antinutritive defenses against predation

M.Y. PASQUEVICH; M.S. DREON; H. HERAS

Mar del Plata

Congreso; LI Reunion Anual - Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

Eggs of the freshwater snail Pomacea maculata have virtually no reported predators. Its major protein is the oligomeric carotenoprotein PmPV1, which provides egg coloration and would protect embryos against environmental factors. In this study we evaluated the structure-function relationships of PmPV1 and its role in the egg defense system. PmPV1 showed a globular and anisometric shape and a remarkable stability under a wide range of temperatures (25-85°C) and pH (2.0?12.0), as revealed by SAXS, fluorescence and absorption spectroscopy. High GndHCl concentration (4 M) is needed to completely unfold PmPV1. Also, resistance to SDS denaturation was observed. This high stability was consistent with the capacity to withstand proteolytic digestion, evaluated by in vitro treatment with gastrointestinal and fungal proteases. In vivo capacity to withstand the gastrointestinal tract was assayed by oral administration of PmPV1 to mice and feces protein analysis. PmPV1 was able to pass unchanged through the gut and was recovered in feces in its native conformation. As a whole the structural stability and the antinutritive role described for PmPV1 would explain, at least in part, the near absence snail eggs predators. The selective pressure of the harsh gastrointestinal environment would have resulted in the modulation of PmPV1 conformational stability to enhance its resistance to degradation.