Nuclear accumulation of the phytochrome A photoreceptor requires FHY1
Nuclear accumulation of the phytochrome A photoreceptor requires FHY1
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DOI：
10.1016/j.cub.2005.10.042
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发表时间：
2005-12-06
期刊：
影响因子：
9.2
通讯作者：
Schäfer, E
中科院分区：
文献类型：
--
作者：
Hiltbrunner, A;Viczián, A;Schäfer, E
红光/远红光（R/FR）响应的光敏色素家族在植物的整个生命周期中起着关键作用[1 - 3]。拟南芥有五种光敏色素，phyA - phyE，其中phyA和phyB起着最主要的作用[1 - 3]。光敏色素受光调节的核积累是该途径的一个重要调控步骤，但到目前为止，尚未确定该过程所特需的因子[4]。在所有phyA信号传导突变体中，fhy1和fhy3（远红光下下胚轴伸长1和3）具有最严重的低敏感表型，表明它们起着特别重要的作用[5 - 7]。FHY1是一种功能未知的植物特异性小蛋白，定位于细胞核和细胞质[5, 6]。在此我们表明，FHY1是phyA而非phyB受光调节的核积累所特需的。此外，phyA的积累在fhy3中仅受到轻微影响，这表明在fhy1幼苗中观察到的phyA核积累减少并非仅仅是phyA信号传导降低的一般结果。通过体外下拉和酵母双杂交分析，我们证明FHY1与phyA发生物理相互作用，且优先与它的活性Pfr形式相互作用。此外，FHY1和phyA在植物体内共定位。因此，我们确定了受光调节的光敏色素核积累所需的第一个组分。
The phytochrome family of red/far-red (R/FR)-responsive photoreceptors plays a key role throughout the life cycle of plants [1-3]. Arabidopsis has five phytochromes, phyA-phyE, among which phyA and phyB play the most predominant functions [1-3]. Light-regulated nuclear accumulation of the phytochromes is an important regulatory step of this pathway, but to this date no factor specifically required for this event has been identified [4]. Among all phyA signaling mutants, fhy1 and fhy3 (far-red elongated hypocotyl 1 and 3) have the most severe hyposensitive phenotype, indicating that they play particularly important roles [5-7]. FHY1 is a small plant-specific protein of unknown function localized both in the nucleus and the cytoplasm [5, 6]. Here we show that FHY1 is specifically required for the light-regulated nuclear accumulation of phyA but not phyB. Moreover, phyA accumulation is only slightly affected in fhy3, indicating that the diminished nuclear accumulation of phyA observed in fhy1 seedlings is not simply a general consequence of reduced phyA signaling. By in vitro pull-down and yeast two-hybrid analyses, we demonstrate that FHY1 physically interacts with phyA, preferentially in its active Pfr form. Furthermore, FHY1 and phyA colocalize in planta. We therefore identify the first component required for light-regulated phytochrome nuclear accumulation.