Naphthylphthalamic acid associates with and inhibits PIN auxin transporters

第一作者：Lindy Abas

第一单位：奥地利自然资源与生命科学大学

通讯作者：Ulrich Z. Hammes

 Abstract 

背景回顾：N-1-naphthylphthalamic acid (NPA) is a key inhibitor of directional (polar) transport of the hormone auxin in plants. For decades, it has been a pivotal tool in elucidating the unique polar auxin transport-based processes underlying plant growth and development.

存在问题：Its exact mode of action has long been sought after and is still being debated, with prevailing mechanistic schemes describing only indirect connections between NPA and the main transporters responsible for directional transport, namely PIN auxin exporters.

主要发现：Here we present data supporting a model in which NPA associates with PINs in a more direct manner than hitherto postulated.

NPA直接抑制PINs：We show that NPA inhibits PIN activity in a heterologous oocyte system and that expression of NPA-sensitive PINs in plant, yeast, and oocyte membranes leads to specific saturable NPA binding. We thus propose that PINs are a bona fide NPA target.

研究意义：This offers a straightforward molecular basis for NPA inhibition of PIN-dependent auxin transport and a logical parsimonious explanation for the known physiological effects of NPA on plant growth, as well as an alternative hypothesis to interpret past and future results.

方向拓展：We also introduce PIN dimerization and describe an effect of NPA on this, suggesting that NPA binding could be exploited to gain insights into structural aspects of PINs related to their transport mechanism.

 摘  要 

NPA是植物生长素定向（极性）转运的关键抑制剂。数十年来，NPA作为一种重要的试剂用于对基于生长素转运的植物生长和发育调控机制进行研究。长久以来，人们一直在探究NPA作用的确切方式，目前仍然还有争论，现行的理论只能解释NPA与生长素定向运输主要转运体，即生长素外流蛋白PINs之间的间接关联。本文中，作者的研究表明NPA与PINs之间的联系要比迄今为止所认为的更加直接。作者发现，在异源卵母细胞中NPA会抑制PIN的活性，并且在植物、酵母和卵母细胞膜中表达NPA敏感性蛋白会导致特异性的NPA饱和结合。因此，作者认为PINs是NPA的直接靶标。这为NPA抑制PIN依赖型的生长素转运提供了一个直接的分子基础，为NPA对于植物生长已知的生理效应提供了一个逻辑上的解释，同时也为过去和未来的相关研究结果提供了可能的假设。作者进一步引入了PIN二聚化，并描述了NPA对其的影响，表明NPA结合可以被用来深入了解PINs结构方面及其生长素转运的分子机制。

doi: https://doi.org/10.1073/pnas.2020857118

Journal: PNAS

Published date: Jan 05, 2020