蓝光受体蛋白隐花素激活与调控的分子机理研究

Photoreceptor proteins transfer light signals to downstream proteins through protein interaction, thus regulating biological clocks, rhythmic changes, and even growth and development. The photoreceptors in plants play an important role in plant development, photomorphogenesis and other physiological processes. Many studies have been done on the physiological functions and signal transduction proteins of plant photoreceptor proteins. However, the mechanism of the activation and regulation of photoreceptor proteins and the molecular mechanism of interaction with many downstream proteins are still not clear. This project uses Arabidopsis blue light receptor cryptochrome (AtCry) as the research object. In this study, we will use structural biology methods to determine the structure of AtCry protein monomer and homodimer, the structure of AtCry and inhibitory protein AtBIC and the structure of AtCry with different downstream signaling proteins. Biophysical methods, such as molecular interaction analysis and conformation analysis will be used to study the structural basis for protein complex interaction and conformation regulation, and we will use plant physiology experiments to characterize the physiological functions of these mechanisms. These research results will eventually answer the key scientific problems such as how the Cry protein activated by dimerization, how Cry protein activity is inhibited, how Cry protein and downstream proteins transfer different signals through protein-protein interactions. Our research resilts will provide a solid foundation for further researches in plant photomorphogenesis.

光受体蛋白通过蛋白互作将光信号传递给下游蛋白，调控了生物钟、节律变化、乃至生长发育等过程。植物中的光受体在植物发育、光形态建成等生理过程中发挥着作用。人们对植物光受体蛋白的生理功能和信号转导蛋白的鉴定方面展开了许多研究，然而光受体蛋白的活化与调控机制、以及与众多下游蛋白互作传递信号的分子机理仍不清楚。本项目以拟南芥中的蓝光受体蛋白—隐花色素(AtCry)为研究对象，利用结构生物学手段，解析AtCry蛋白单体和二聚体的结构、AtCry与抑制蛋白BIC及不同下游信号蛋白复合体的三维结构，通过分子互作、构象分析等生物物理学方法研究蛋白复合体互作和构像变化调控的结构基础，并利用植物生理学实验进行生理功能的表征。研究将最终回答Cry蛋白如何通过二聚化激活，Cry蛋白的活性如何被抑制，Cry蛋白如何与下游蛋白因子发生互作传递不同信号等关键科学问题，为植物光形态建成的进一步研究提供坚实的理论基础。

本项研究主要围绕植物Cry蛋白受蓝光激活的结构与分子机理展开。项目实施四年来，完成了既定的研究任务，达到了既定的目标。取得的研究成果包括：（1）对拟南芥Cry蛋白进行了蛋白纯化、蛋白活性测定、蛋白状态筛选、得到了一个处于稳定二聚体状态的拟南芥AtCRY2W374A突变体并解析了其二聚体和四聚体状态下的结构（2）通过筛选得到了玉米ZmCry1cW368A二聚体并通过冷冻电镜解析了处于二聚体状态和四聚体状态下的ZmCry1cW368A结构（3）通过结构分析，发现了参与形成Cry复合体的关键PHR结构域，揭示了两个Cry蛋白的PHR结构域通过INT1接触面互作形成二聚体，鉴定到了参与复合体形成的关键氨基酸；研究工作发表在Nature Structure and Molecular Biology(2020)上