Potassium transporter TRH1 subunits assemble regulating root-hair elongation autonomously from the cell fate determination pathway
Potassium transporter TRH1 subunits assemble regulating root-hair elongation autonomously from the cell fate determination pathway
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DOI：
10.1016/j.plantsci.2014.11.017
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发表时间：
2015-02-01
期刊：
影响因子：
5.2
通讯作者：
Hatzopoulos, Polydefkis
中科院分区：
文献类型：
--
作者：
Daras, Gerasimos;Rigas, Stamatis;Hatzopoulos, Polydefkis
Trh1植物的毛发母细胞形成根毛起始点，不能进行顶端生长，导致微小的根毛表型。TRH1属于拟南芥KT/KUP/HAK钾转运蛋白家族，控制根毛生长和向重力性。影响细胞命运或根毛起始的trh1和根毛突变体之间的双突变组合表现出相加的表型，这表明TRH1在根毛起始下游独立地发挥作用。当TRH1-YFPC和TRH1-YFPN共转化烟草表皮细胞时，双分子荧光互补(BIFC)导致了TRH1亚基均一二聚化的荧光发射。酵母双杂交分析揭示了两种类型的相互作用。从Q105残基延伸到T141残基的第二和第三跨膜结构域之间的亲水性片段适合于相对较弱的相互作用，而C末端最后一个跨膜结构域之外的区域(从氨基酸R565到A729)具有较强的自相互作用。这些结构域可能有助于TRH1亚单位在细胞膜结构内形成一个活跃的K+转运系统。这些结果支持TRH1作为发育的根毛途径和环境/激素信号途径的汇合点，以保持生长素的动态平衡，确保植物对变化的环境的适应。(C)2014爱思唯尔爱尔兰有限公司。保留所有权利。
Trichoblasts of trh1 plants form root-hair initiation sites that fail to undergo tip growth resulting in a tiny root-hair phenotype. TRH1 belongs to Arabidopsis KT/KUP/HAK potassium transporter family controlling root-hair growth and gravitropism. Double mutant combinations between trh1 and root-hair mutants affecting cell fate or root-hair initiation exhibited additive phenotypes, suggesting that TRH1 acts independently and developmentally downstream of root-hair initiation. Bimolecular Fluorescence Complementation (BiFC), upon TRH1-YFPC and TRH1-YFPN co-transformation into tobacco epidermal cells, led to fluorescence emission indicative of TRH1 subunit homodimerization. Yeast two-hybrid analysis revealed two types of interactions. The hydrophilic segment between the second and the third transmembrane domain extending from residues Q105 to T141 is competent for a relatively weak interaction, whereas the region at the C-terminal beyond the last transmembrane domain, extending from amino acids R565 to A729, strongly self-interacts. These domains likely facilitate the co-assembly of TRH1 subunits forming an active K+ transport system within cellular membrane structures. The results support the role of TRH1 acting as a convergence point between the developmental root-hair pathway and the environmental/hormonal signaling pathway to preserve auxin homeostasis ensuring plant adaptation in changing environments. (C) 2014 Elsevier Ireland Ltd. All rights reserved.