Regulation of Arabidopsis HFR1 Activity in Light Signaling

拟南芥 HFR1 光信号活性的调节

• 批准号: 0420932
• 负责人: Haiyang Wang
• 金额: --
• 依托单位: Boyce Thompson Institute Plant Research
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0420932&HistoricalAwards=false
• 关键词: Regulation; Arabidopsis; HFR1; Activity; Light

The sessile nature of plants demands a high degree of plasticity in their growth and development in response to the ambient environment, and light is one of the major environmental signals that controls many aspects of plant development. Arabidopsis seedling photomorphogenesis has been used as a model system for molecular genetic studies to dissect the mechanisms regulating light signaling in plants. Two blue/UV-A absorbing cryptochromes (cry1 and cry2) and five red/far-red light absorbing phytochromes (phyA-phyE) are the primary photoreceptors responsible for mediating Arabidopsis seedling photomorphogenesis. HFR1, a bHLH transcription factor, acts as a positive regulator in both phyA-mediated far-red and cry1-mediated blue light signaling. A regulatory mechanism of HFR1 activity was suggested by the observed physical interactions between HFR1 with COP1 and SPA1. COP1 is an E3 ubiquitin ligase targeting a subset of positive regulators of photomorphogenesis for degradation, thus repressing photomorphogenesis. SPA1 is a negative regulator of phyA signaling and is structurally related to COP1. It is hypothesized that COP1 ubiquitinates HFR1 in a process modulated by SPA1, and targets HFR1 for degradation via the 26S proteasome pathway, thus desensitizing light signaling. Experiments are designed to substantiate such a working hypothesis at the genetic, physiological and biochemical levels. The outcome of this research is expected to: 1) provide significant insights into the regulatory mechanisms of HFR1 function in both phyA and cry1 signaling, a better understanding of COP1 and SPA1 function, and the role of regulated proteolysis in regulating plant development in general; 2) provide guidance for genetic engineering to fine-tune light-responsive growth traits (such as height, leaf area, flowering time and sowing density) in crops of agronomic importance; 3) provide excellent training opportunities for scientists at different levels, including postdoctoral fellows, graduate and undergraduate/high school students/high school teachers, with a focus on the inclusion of underrepresented groups.

植物的无根性要求其生长发育具有高度的可塑性，以响应周围环境，而光是控制植物发育许多方面的主要环境信号之一。拟南芥幼苗光形态发生已被用作分子遗传学研究的模型系统，以揭示植物光信号的调节机制。2种蓝色/UV-A吸收隐色素（cry1和cry2）和5种红色/远红光吸收光敏色素（phyA-phyE）是介导拟南芥幼苗光形态发生的主要光感受器。HFR1是一种bHLH转录因子，在phya介导的远红光和cry1介导的蓝光信号传导中都起着积极的调节作用。通过观察到HFR1与COP1和SPA1之间的物理相互作用，提出了HFR1活性的调控机制。COP1是一种E3泛素连接酶，针对光形态形成的正调节因子亚群进行降解，从而抑制光形态形成。SPA1是phyA信号的负调控因子，在结构上与COP1相关。假设COP1在SPA1调节的过程中泛素化HFR1，并通过26S蛋白酶体途径靶向HFR1降解，从而使光信号脱敏。设计实验是为了在遗传、生理和生化水平上证实这种可行的假设。本研究的结果有望：1)对HFR1在phyA和cry1信号中的功能调控机制提供重要见解，更好地了解COP1和SPA1的功能，以及受调节的蛋白水解在调节植物发育中的作用；2)指导基因工程对重要农艺作物的光响应生长性状（如高度、叶面积、开花时间和播种密度）进行微调；3)为不同层次的科学家提供优秀的培训机会，包括博士后、研究生和本科生/高中生/高中教师，重点关注代表性不足的群体。