Protein disorder in crop stress adaptation

全球气候变化导致了干旱和高温等恶劣天气事件。这些环境压力对作物生长和粮食安全造成严重影响，如粮食减少和作物产量减少。研究作物如何应对环境挑战是植物生物学研究的一个基本问题，并将为未来的可持续农业提出战略思考。本文旨在阐明蛋白质紊乱在作物植物胁迫反应中的作用，以及参与潜在生物学过程的大分子的作用机制。内在无序蛋白（IDPs）是一组天然缺乏明确三维结构的蛋白质。无序特征使IDPs具有构象灵活性和对环境压力的快速响应，从而作为调节中心，并根据不同的情况与各种合作伙伴进行互动。文献表明，IDPs可能在植物适应环境挑战中发挥关键作用。例如，非生物抗逆性生物能源作物柳枝稷和抗旱性复活草的蛋白质比例最高，且紊乱程度强烈。此外，缓步动物的无序蛋白质已被证明在干燥中存活起着至关重要的作用。无序脱水剂也被证明在脱水胁迫条件下保护植物。确切的功能和作用机制在很大程度上仍然是未知的。为了解IDPs参与植物胁迫响应的机制，本研究将利用结构工具核磁共振（NMR）波谱来绘制IDPs的构象动力学并描述其机制。水稻和大麦的三种胁迫响应性IDPs将作为案例研究，以提供植物胁迫响应中蛋白质紊乱的结构见解。在此目标下，将开发一种突破性的植物细胞核磁共振技术，使一般植物生物学家能够在时间和空间维度上监测植物体内蛋白质动力学和相互作用，并研究各种发育过程和胁迫反应的分子机制。IDPs是液-液相分离（LLPS）复合物的关键触发物，也被称为生物分子凝聚物，它通过局部浓缩大分子来实现生化反应的时空组织。在本研究中，通过对两种胁迫诱导的IDPs进行近距离标记，然后对LLPS复合物的蛋白质成分进行亲和纯化和鉴定，并通过核磁共振和细胞生物学工具验证它们的相互作用和LLPS特性，将解决LLPS在植物胁迫响应中的功能。由于目前的IDP数据库主要集中在哺乳动物细胞和生物医学相关蛋白，本研究将建立作物胁迫响应IDP数据库，从水稻开始扩展到其他作物，这将有利于从事作物科学和胁迫生物学研究的植物生物学家。由于全球气候变化，炎热和干旱的时间越来越长，了解作物植物用来应对各种压力的策略变得很重要。该研究将为研究植物胁迫响应中的IDPs提供新的方法，为植物胁迫生理学的基础知识和机制的认识提供新的思路，为应对全球气候变化和解决粮食安全问题提供新的思路。

Global climate change has caused severe weather events such as droughts and high temperatures. These environmental stresses have severe impact on crop plant growth and food security such as fewer grains and smaller crop yields. Investigating how crop plants respond to environmental challenges is a fundamental issue in plant biology research and will raise strategic thinking for future sustainable agriculture. This proposal aims at elucidating the role of protein disorder in crop plant stress responses as well as the mechanisms of action of the macromolecules involved in the underlying biological processes.Intrinsically disordered proteins (IDPs) are a group of proteins natively lacking defined three-dimensional structures. The disordered features enable IDPs to have conformational flexibility and quick responsiveness to environmental stresses, thus serve as regulatory hubs and interact with various partners depending on different circumstances. Literatures suggest that IDPs may play critical roles in plant adaptation to environmental challenges. For example, the abiotic stress-tolerant bioenergy crop switchgrass and the desiccation-tolerant resurrection grass have the highest proportion of proteins with intense disorder. Furthermore, tardigrade disordered proteins have been shown to play a crucial role in surviving desiccation. Disordered dehydrins have also been shown to protect plants under dehydration stress conditions. The precise functions and mechanisms of action are still largely unknown.To understand the mechanism of IDPs involved in plant stress responses, the structural tool nuclear magnetic resonance (NMR) spectroscopy will be used in this study to map the conformational dynamics of IDPs and describe the mechanisms. Three stress responsive IDPs from rice and barley will be used as case studies to provide structural insight into protein disorder in plant stress responses. Within this objective, a breakthrough technology in plant cell NMR method will be developed, which will benefit general plant biologists in terms of monitoring of plant protein dynamics and interaction in vivo in both the time and space dimensions and investigation on molecular mechanism of various developmental processes and stress responses.IDPs are key triggers of liquid-liquid phase separation (LLPS) complexes, also known as biomolecular condensates, which allow the spatiotemporal organization of biochemical reactions by concentrating macromolecules locally. In this proposed research, proximity labeling of two stress-induced IDPs followed by affinity purification and identification of the protein components of LLPS complexes and verification of their interactions and LLPS properties via NMR and cell biology tools will address the function of LLPS in plant stress responses.Since the current IDP databases are mainly focused on mammalian cells and biomedically related proteins, this study will establish the database regarding crop stress responsive IDPs, starting from rice and extending to other crops, which will benefit plant biologists who work on crop science and stress biology.Given the increasing periods of heat and drought due to global climate change, it has become important to understand the strategies that crop plants utilize to cope with various stresses. The proposed research will provide new methods to study plant IDPs in stress responses, fundamental knowledge and mechanistic insights into plant stress physiology, and novel ideas for facing global climate change and solving food security problems.