Biochemical Mechanism of Regulation of Phytochrome Interacting Factor 1 by Light

PI：Enamul HuqProposal#0822811标题：光调节光敏色素相互作用因子1的生化机制生长和发育在植物生命周期的所有阶段都受到环境光信号的高度调控。植物已经进化出几种光受体，包括光敏色素(PHY)家族，用于监测红光和远红光，隐花色素，趋光蛋白和ZTL/FKF1家族的F-box蛋白，用于监测UV-A和蓝光，以及一个未知的受体，用于监测UV-B光。虽然对这些光感受器的研究已经很多，但它们调节植物生长发育的主要生化机制仍不清楚。近年来，转录因子在黑暗和光照下的降解被证明在光信号通路中起着核心作用。一般来说，有一类光信号因子在黑暗中降解。它们包括HY5、LAF1和HFR1，它们中的大多数都是光形态建成的正调控因子。第二类因子在光照下被降解。这一类包括光敏色素相互作用因子(PIF)，其中大多数负向调节光形态建成。虽然，暗诱导降解的机制已经被很好地研究了，但光诱导的PIF的降解还不是很清楚。本项目致力于利用生化、分子和遗传学方法研究光诱导bHLH转录因子PIF1降解的早期事件。PIF1在红光和远红光条件下都能迅速降解。光诱导的PIF1蛋白水解性去除解除了PIF1的负调控，促进了种子萌发、叶绿素的生物合成和下胚轴的生长抑制。由于PIF1是光敏色素信号转导的主要伙伴，其稳定性由光敏色素通过直接的物理相互作用来调节，本项目的结果将为光敏色素调控发育途径的机制提供基础信息。这项研究将在几个方面产生广泛的影响。首先，了解植物中PIF1调控的生化机制将为农业生物技术提高作物和生物质产量提供基础知识和分子工具。其次，研究结果和研究工具将通过出版物、会议演示文稿和我们实验室的网站直接发布给社区。第三，该项目将有助于培养现代功能基因组学和分子遗传学方面的下一代科学家，包括本科生、研究生和博士后。这一培训将为他们提供对植物生物学和生物技术领域作出重大贡献的独特机会，并为他们今后作为独立研究人员的职业生涯做好准备。

PI: Enamul HuqProposal # 0822811Title: Biochemical Mechanism of Regulation of Phytochrome Interacting Factor 1 by LightGrowth and development are highly regulated by environmental light signals at all phases of a plant's life cycle. Plants have evolved several light receptors including the phytochrome (phy) family of photoreceptors to monitor the red and far-red light, the cryptochromes, the phototropins and the ZTL/FKF1 family of F-box proteins to monitor the UV-A and blue light, and an unidentified receptor to monitor the UV-B light. Although much has been learned on these photoreceptors, the primary biochemical mechanism by which they regulate plant growth and development is still unknown. In recent years, degradation of transcription factors both in the dark and light has been shown to play central roles in the light signaling pathways. In general, one class of light signaling factors are degraded in the dark. They include HY5, LAF1 and HFR1, most of which are positive regulators of photomorphogenesis. The second class factors are degraded in light. This class includes Phytochrome Interacting Factors(PIFs), most of which negatively regulate photomorphogenesis. Although, the mechanisms of dark-induced degradation are well investigated, the light-induced degradation of PIFs is less well understood. This project is focused on investigating the early events in the light-induced degradation of the bHLH transcription factor, PIF1, using biochemical, molecular and genetic approaches. PIF1 is rapidly degraded under both red and far-red light conditions. Light-induced proteolytic removal of PIF1 relieves the negative regulation by PIF1 and promote seed germination, chlorophyll biosynthesis and hypocotyl growth inhibition. Since PIF1 is a primary phytochrome-signaling partner, whose stability is regulated by phytochromes through direct physical interaction, the results from this project will provide fundamental information on the mechanism of phytochrome regulated developmental pathways. This study will have broad implications in several ways. First, understanding the biochemical mechanism of regulation of PIF1 in plants will provide fundamental knowledge and molecular tools applicable in agricultural biotechnology for enhanced crop and biomass production. Second, the results and the research tools will be distributed to the community through publications, conference presentations, and website postings directly from our laboratories. Third, this project will contribute to training the next generation scientists in modern functional genomics and molecular genetics, including undergraduate, graduate and postdoctoral students. This training will provide them with the unique opportunity to make significant contributions to the field of plant biology and biotechnology and will prepare them for future careers as independent researchers.