Centre for Plant Biotechnology and Genomics (UPM-INIA), Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain.
Department of Biotechnology-Plant Biology, ETSIAAB, Technical University of Madrid, Madrid, Spain.
Plant Mol Biol. 2017 May;94(1-2):33-44. doi: 10.1007/s11103-017-0590-z. Epub 2017 Mar 15.
Pru p 3, a peach LTP, is located in pollinated flower styles and secreting downy hairs, transporting a derivative of camptothecin bound to phytosphingosine. Pru p 3 may inhibit a second pollination and may keep away herbivores until seed maturation. The allergen Pru p 3, a peach lipid transfer protein, has been well studied. However, its physiological function remains to be elucidated. Our results showed that Pru p 3 usually carries a lipid ligand that play an essential role in its function in plants. Using ESI-qToF, we observed that the ligand was a derivative of camptothecin binding to phytosphingosine, wich that is inserted into the hydrophobic tunnel of the protein. In addition, the described ligand displayed topoisomerase I activity inhibition and self-fluorescence, both recognized as camptothecin properties. During flower development, the highest expression of Pru p 3 was detected in the styles of pollinated flowers, in contrast to its non-expression in unpollinated pistils, where expression decreased after anthesis. During ripening, the expression of Pru p 3 were observed mainly in peel but not in pulp. In this sense, Pru p 3 protein was also localized in trichomes covering the fruit epidermis.
Pru p 3 是一种桃类 LTP，位于授粉花的花柱和分泌的绒毛中，运输与植物鞘氨醇结合的喜树碱衍生物。Pru p 3 可能会抑制第二次授粉，并在种子成熟前阻止食草动物靠近。过敏原 Pru p 3 是一种桃类脂质转移蛋白，已得到充分研究。然而，其生理功能仍有待阐明。我们的研究结果表明，Pru p 3 通常携带一种脂质配体，这种配体在其植物功能中起着至关重要的作用。通过 ESI-qToF，我们观察到配体是喜树碱与植物鞘氨醇结合的衍生物，插入到蛋白质的疏水性隧道中。此外，所述配体显示拓扑异构酶 I 活性抑制和自荧光，这两者都被认为是喜树碱的特性。在花发育过程中，Pru p 3 在授粉花的花柱中表达量最高，而在未授粉的雌蕊中不表达，授粉后表达量下降。在果实成熟过程中，Pru p 3 的表达主要在果皮中，而不在果肉中。从这个意义上说，Pru p 3 蛋白也定位于覆盖果实表皮的毛状体中。
