AtPTR1 and AtPTR5 transport dipeptides in planta
AtPTR1 and AtPTR5 transport dipeptides in planta
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DOI：
10.1104/pp.108.123844
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发表时间：
2008-10-01
期刊：
影响因子：
7.4
通讯作者：
Rentsch, Doris
中科院分区：
文献类型：
--
作者：
Komarova, Nataliya Y.;Thor, Kathrin;Rentsch, Doris
二肽和三肽转运蛋白属于大型且特征较差的 PTR/NRT1（肽转运蛋白/硝酸盐转运蛋白 1）家族。该基因家族的一个新成员AtPTR5是从拟南芥（Arabidopsis thaliana）中分离出来的。分析了 AtPTR5 的表达，并将其与密切相关的 AtPTR1 的组织特异性进行比较，以辨别它们在植物中的作用。两种转运蛋白均以高亲和力促进二肽的转运，并位于质膜上。将突变体、双突变体和过表达系暴露于多种二肽（包括有毒肽），以分析修饰的转运蛋白表达如何影响花粉萌发、花粉管、根和芽的生长。对 atptr5 突变体和 AtPTR5 过表达株系的分析表明，AtPTR5 促进肽转运到发芽花粉中，并可能转运到成熟花粉、胚珠和种子中。相比之下，AtPTR1 在根吸收肽方面发挥着重要作用，这可以通过降低氮 (N) 水平和减少 atptr1 突变体在以二肽作为唯一氮源的培养基上的生长来表明。此外，AtPTR5 的过度表达导致芽生长增强和氮含量增加。有毒肽进一步证实了肽摄取的功能，有毒肽抑制生长。结果表明，PTR/NRT1家族密切相关的成员在植物中具有不同的功能。这项研究还提供了证据，表明有机氮的使用不仅限于氨基酸，二肽也应被视为植物中的氮源和运输形式。
Transporters for di- and tripeptides belong to the large and poorly characterized PTR/NRT1 (peptide transporter/nitrate transporter 1) family. A new member of this gene family, AtPTR5, was isolated from Arabidopsis (Arabidopsis thaliana). Expression of AtPTR5 was analyzed and compared with tissue specificity of the closely related AtPTR1 to discern their roles in planta. Both transporters facilitate transport of dipeptides with high affinity and are localized at the plasma membrane. Mutants, double mutants, and overexpressing lines were exposed to several dipeptides, including toxic peptides, to analyze how the modified transporter expression affects pollen germination, growth of pollen tubes, root, and shoot. Analysis of atptr5 mutants and AtPTR5-overexpressing lines showed that AtPTR5 facilitates peptide transport into germinating pollen and possibly into maturating pollen, ovules, and seeds. In contrast, AtPTR1 plays a role in uptake of peptides by roots indicated by reduced nitrogen (N) levels and reduced growth of atptr1 mutants on medium with dipeptides as the sole N source. Furthermore, overexpression of AtPTR5 resulted in enhanced shoot growth and increased N content. The function in peptide uptake was further confirmed with toxic peptides, which inhibited growth. The results show that closely related members of the PTR/NRT1 family have different functions in planta. This study also provides evidence that the use of organic N is not restricted to amino acids, but that dipeptides should be considered as a N source and transport form in plants.