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Plant Cell：拟南芥磷脂翻转酶ALA3作用于生长素转运蛋白PIN的转运和极性

已有 2620 次阅读 2020-3-21 12:32 |个人分类:每日摘要|系统分类:论文交流

Arabidopsis Flippases Cooperate with ARF GTPase Exchange Factors to Regulate the Trafficking and Polarity of PIN Auxin Transporters

First author: Xixi Zhang; Affiliations: Institute of Science and Technology Austria (奥地利科学技术研究院): Klosterneuburg, Austria

Corresponding author: Jiří Friml

Cell polarity is a fundamental feature of all multicellular organisms. PIN auxin transporters are important cell polarity markers that play crucial roles in a plethora of developmental processes in plants. Here, to identify components involved in cell polarity establishment and maintenance in plants, we carried out a forward genetic screening of PIN2:PIN1-HA;pin2 Arabidopsis thaliana plants, which ectopically express predominantly basally localized PIN1 in root epidermal cells, leading to agravitropic root growth. We identified the regulator of PIN polarity 12 (repp12) mutation, which restored gravitropic root growth and caused a switch in PIN1-HA polarity from the basal to apical side of root epidermal cells. Next Generation Sequencing and complementation experiments established the causative mutation of repp12 as a single amino acid exchange in Aminophospholipid ATPase3 (ALA3), a phospholipid flippase predicted to function in vesicle formation. repp12 and ala3 T-DNA mutants show defects in many auxin-regulated processes, asymmetric auxin distribution, and PIN trafficking. Analysis of quintuple and sextuple mutants confirmed the crucial roles of ALA proteins in regulating plant development as well as PIN trafficking and polarity. Genetic and physical interaction studies revealed that ALA3 functions together with the ARF GTPase exchange factors GNOM and BIG3 in regulating PIN polarity, trafficking, and auxin-mediated development.

细胞极性是所有多细胞生物的基础特性。PIN生长素转运蛋白是重要的细胞极性标记，在植物多个发育进程中扮演着至关重要的作用。本文中，为了鉴定植物中参与细胞极性建立和维持的组分，作者对PIN2:PIN1-HA;pin2转基因拟南芥进行正向遗传学筛选，该突变体会在根表皮细胞中异位表达主要定位于基部的PIN1蛋白，导致根的无向重力生长。作者通过这种方法鉴定到了一个repp12突变体，该突变体能够恢复PIN2:PIN1-HA;pin2转基因拟南芥根的向重力性生长，并且引起根表皮细胞中PIN1-HA的定位从基部到顶部的一个转换。NGS以及互补试验显示该突变体的突变是由于氨基磷脂ATP酶ALA3上的一个氨基酸转变所导致的，而ALA3是一个磷脂翻转酶，作用于植物中泡囊（vesicle）的形成。repp12和ala3 T-DNA突变体植株显示多个生长素相关进程、不对称生长素分布以及PIN转运都存在缺陷。五突和六突的分析显示ALA蛋白在植物发育、PIN转运和极性等方面发挥至关重要的作用。遗传及物理互作研究揭示了ALA3蛋白与ARF GTPase交换因子GNOM和BIG3一起作用于PIN极性、转运以及生长素介导的发育。