Identification of the ligand of Pru p 3, a peach LTP
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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.
KeywordsPru p 3 Lipid transfer protein Secondary metabolites Camptothecin Flower development Pollination Fruit development
The authors thank the Centro de Supercomputación y Visualización de Madrid (CeSViMa) and Centre for Metabolomics and Bioanalysis (CEMBIO) for computing resources and technical assistance. The study was supported by the Ministry of Science and Innovation (project BIO2013-041403-R) and FIS-Thematic Networks and Co-operative Research Centres: RIRAAF (RD12/0013/0014). The funders had no role in the study design, data collection and analysis, the decision to publish, or the preparation of the manuscript.
Sample collection: MH; Experimental design and analysis of results: PGM, MH, LFP, AD-P; Experimental development: NCB, CGC, LT; Modelling and molecular dynamics analysis: MGA, LFP; Confocal microscopy: CRC, PGM.
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Conflict of interest
The authors declare that they have no competing interests.
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