The degradation of HFR1, a putative bHLH class transcription factor involved in light signaling, is regulated by phosphorylation and requires COP1
The degradation of HFR1, a putative bHLH class transcription factor involved in light signaling, is regulated by phosphorylation and requires COP1
复制标题
DOI：
10.1016/j.cub.2004.12.026
复制
发表时间：
2004-12-29
期刊：
影响因子：
9.2
通讯作者：
Fankhauser, C
中科院分区：
文献类型：
--
作者：
Duek, PD;Elmer, MV;Fankhauser, C
在植物的整个生命周期中，所有的发育转变都受到光的影响。在拟南芥中，包括UV-A/蓝色感应隐花色素（cry 1 -2）和红色/远红响应光敏色素（phyA-E）在内的多种光感受器监测环境光条件[1，2]。光调节蛋白质的稳定性是光形态建成的主要控制点[3]。泛素E3连接酶COP 1组成型光形态发生1）调节几种光信号组分的稳定性[4-6]。HFR 1（远红光下的长胚轴）是一种假定的转录因子，具有一个作用于phyA和隐花色素下游的bHLH结构域[7-9]。HFR 1与PIF 1、PIF 3和PIF 4（光敏色素相互作用因子1、3和4）密切相关，但与后三者相反，没有证据表明HFR 1与光敏色素之间存在直接相互作用[7，10-12]。在这里，我们表明HFR 1的蛋白质丰度受到光的严格控制。HFR 1是一种不稳定的磷蛋白，特别是在黑暗中。体内需要蛋白酶体和COP 1来降解磷酸化的HFR 1。此外，HFR 1可以与COP 1相互作用，这与COP 1直接介导HFR 1降解的想法一致。我们确定了一个结构域，在参与光信号传导的几种bHLH类蛋白中保守[13，14]，作为HFR 1稳定性的决定因素。我们的生理学实验表明，HFR 1蛋白丰度的控制对于正常的去黄化反应是重要的。
All developmental transitions throughout the life cycle of a plant are influenced by light. In Arabidopsis, multiple photoreceptors including the UV-A/blue-sensing cryptochromes (cry1-2) and the red/far-red responsive phytochromes (phyA-E) monitor the ambient light conditions [1, 2]. Light-regulated protein stability is a major control point of photomorphogenesis [3]. The ubiquitin E3 ligase COP1 constitutively photomorphogenic 1) regulates the stability of several light-signaling components [4-6]. HFR1 (long hypocotyl in far-red light) is a putative transcription factor with a bHLH domain acting downstream of both phyA and the cryptochromes [7-9]. HFR1 is closely related to PIF1, PIF3, and PIF4 (phytochrome interacting factor 1, 3 and 4), but in contrast to the latter three, there is no evidence for a direct interaction between HFR1 and the phytochromes [7, 10-12]. Here, we show that the protein abundance of HFR1 is tightly controlled by light. HFR1 is an unstable phosphoprotein, particularly in the dark. The proteasome and COP1 are required in vivo to degrade phosphorylated HFR1. In addition, HFR1 can interact with COP1, consistent with the idea of COP1 directly mediating HFR1 degradation. We identify a domain, conserved among several bHLH class proteins involved in light signaling [13, 14], as a determinant of HFR1 stability. Our physiological experiments indicate that the control of HFR1 protein abundance is important for a normal de-etiolation response.