UMR INRA/UHP 1136 Interactions Arbres-Microorganismes, IFR 110 Ecosystèmes Forestiers, Agroressources, Bioprocédés et Alimentation, Nancy University, Faculté des Sciences et Techniques, BP 70239, F-54506 Vandoeuvre-les-Nancy Cedex, France.
J Exp Bot. 2010 Jun;61(6):1671-82. doi: 10.1093/jxb/erq036. Epub 2010 Feb 26.
Amino acids are the currency of nitrogen exchange between source and sink tissues in plants and constitute a major source of the components used for cellular growth and differentiation. The characterization of a new amino acid transporter belonging to the amino acid permease (AAP) family, AAP11, expressed in the perennial species Populus trichocarpa is reported here. PtAAP11 expression analysis was performed by semi-quantitative RT-PCR and GUS activity after poplar transformation. PtAAP11 function was studied in detail by heterologous expression in yeast. The poplar genome contains 14 putative AAPs which is quite similar to other species analysed except Arabidopsis. PtAAP11 was mostly expressed in differentiating xylem cells in different organs. Functional characterization demonstrated that PtAAP11 was a high affinity amino acid transporter, more particularly for proline. Compared with other plant amino acid transporters, PtAAP11 represents a novel high-affinity system for proline. Thus, the functional characterization and expression studies suggest that PtAAP11 may play a major role in xylogenesis by providing proline required for xylem cell wall proteins. The present study provides important information highlighting the role of a specific amino acid transporter in xylogenesis in poplar.
氨基酸是植物源和汇组织之间氮交换的货币，构成了用于细胞生长和分化的成分的主要来源。本文报道了属于氨基酸通透酶（AAP）家族的新氨基酸转运蛋白 AAP11 的特性，该蛋白在多年生物种毛白杨中表达。通过半定量 RT-PCR 和杨树转化后的 GUS 活性分析进行了 PtAAP11 表达分析。通过在酵母中的异源表达详细研究了 PtAAP11 的功能。杨树基因组包含 14 个假定的 AAP，与其他分析的物种（除拟南芥外）非常相似。PtAAP11 在不同器官的分化木质部细胞中表达最多。功能特征表明，PtAAP11 是一种高亲和力的氨基酸转运蛋白，特别是对脯氨酸。与其他植物氨基酸转运蛋白相比，PtAAP11 代表了脯氨酸的新型高亲和力系统。因此，功能特征和表达研究表明，PtAAP11 可能通过提供木质部细胞壁蛋白所需的脯氨酸在木质部形成中发挥主要作用。本研究提供了重要信息，突出了特定氨基酸转运蛋白在杨树木质部形成中的作用。
