Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Universidad Nacional de La Plata (UNLP) - CONICET CCT-La Plata, La Plata, Argentina.
Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, UNLP, Argentina.
Sci Rep. 2017 Nov 20;7(1):15848. doi: 10.1038/s41598-017-16185-9.
Plants have evolved sophisticated embryo defences by kinetically-stable non-digestible storage proteins that lower the nutritional value of seeds, a strategy that have not been reported in animals. To further understand antinutritive defences in animals, we analysed PmPV1, massively accumulated in the eggs of the gastropod Pomacea maculata, focusing on how its structure and structural stability features affected its capacity to withstand passage through predator guts. The native protein withstands >50 min boiling and resists the denaturing detergent sodium dodecyl sulphate (SDS), indicating an unusually high structural stability (i.e., kinetic stability). PmPV1 is highly resistant to in vitro proteinase digestion and displays structural stability between pH 2.0-12.0 and 25-85 °C. Furthermore, PmPV1 withstands in vitro and mice digestion and is recovered unchanged in faeces, supporting an antinutritive defensive function. Subunit sequence similarities suggest a common origin and tolerance to mutations. This is the first known animal genus that, like plant seeds, lowers the nutritional value of eggs by kinetically-stable non-digestible storage proteins that survive the gut of predators unaffected. The selective pressure of the harsh gastrointestinal environment would have favoured their appearance, extending by convergent evolution the presence of plant-like hyperstable antinutritive proteins to unattended reproductive stages in animals.
植物通过动力学稳定的不可消化储存蛋白来进化出复杂的胚胎防御机制，从而降低种子的营养价值，这种策略在动物中尚未有报道。为了进一步了解动物中的抗营养防御机制，我们分析了大量积累在腹足纲Pomacea maculata 卵中的 PmPV1，重点研究了其结构和结构稳定性特征如何影响其通过捕食者肠道的能力。天然蛋白能承受 >50 分钟的煮沸，并能抵抗变性去污剂十二烷基硫酸钠 (SDS)，这表明其具有异常高的结构稳定性（即动力学稳定性）。PmPV1 对体外蛋白酶消化具有高度抗性，在 pH 2.0-12.0 和 25-85°C 之间显示出结构稳定性。此外，PmPV1 能耐受体外和小鼠消化，并在粪便中以未改变的形式回收，支持其具有抗营养防御功能。亚基序列相似性表明存在共同起源和对突变的耐受性。这是第一个已知的动物属，它像植物种子一样，通过动力学稳定的不可消化储存蛋白降低卵的营养价值，这些蛋白在捕食者的肠道中不受影响而存活下来。恶劣的胃肠道环境的选择压力促进了它们的出现，通过趋同进化将植物样超稳定抗营养蛋白的存在扩展到动物无人照管的生殖阶段。
