Plastid protein transport mechanisms and organelle biogenesis

植物是地球上维持生命活动的支柱，如光合作用、淀粉和油的生产以及呼吸作用。这些活动是由动态的细胞过程控制的，需要无数分子参与者的相互作用，并发生在植物细胞内的特定空间。质体就是这样一个空间，质体是一种为植物捕获和产生能量而设计的细胞器。质体也必须在发育和适应不断变化的环境时调整它们的活动。这种调整伴随着被运送到质体中的蛋白质多样性的巨大变化。因此，对于质体来说，保持一个反应灵敏、有效的蛋白质运输过程是很重要的，它可以解决所有的情况。最近的研究结果表明，作为质体蛋白运输机制的一个动态组成部分，共伴侣Tic40可能参与了调节机制，并且Tic40的作用可能受到细胞器菱形蛋白酶活性的影响或调节。因此，本提案概述了旨在阐明Tic40和菱形蛋白酶在质体蛋白运输中的作用的项目。由于菱形蛋白酶属于一组参与信号传导和发育的高度保守蛋白，因此长期目标将是确定tic40 -菱形蛋白酶的联系以及这种关系在质体蛋白传递、细胞器生物发生、细胞结构和发育中的意义。为了实现相关的短期目标，我们将采用现有的和现代的蛋白质组学方法来具体表征：1)Tic40的结构、功能和菱形切割位点；2)植物细胞器菱形蛋白酶的定位、靶向、酶活性等功能特征；3) Tic40的输入与质体菱形蛋白酶的功能关系。这项工作也将有助于功能蛋白质组学、全细胞研究和商业应用的技术和策略的发展。同样重要的是，通过拟议的5年NSERC计划的学生将接受适用于他们职业生涯的发现研究的强化培训（至少3个博士，6个硕士和10个学士学位）。

Plants form the pillars of the Earth's life-supporting activities like photosynthesis, starch and oil production, and respiration. These activities are governed by dynamic cellular processes, requiring interaction of countless molecular participants and take place in specialized spaces inside plant cells. One such space is the plastid, an organelle designed for capturing and producing energy for plants. Plastids must also adjust their activities during development and when adapting to the ever-changing environment. Such adjustments are accompanied by dramatic shifts to the diversity of proteins being transported into plastids. It is thus important for plastids to maintain a responsive and efficient protein transport process that can address all situations. Recent findings indicate that the co-chaperone Tic40, a dynamic component of the plastid protein transport machinery, may be involved in the adjusting mechanisms and that Tic40's role(s) may be influenced or modulated by the activities of organellar rhomboid proteases. This proposal thus outlines projects aimed at elucidating the role of Tic40 and rhomboid proteases in plastid protein transport. Since rhomboid proteases belong to a group of highly conserved proteins involved in signaling and development, the long-term goals will be to define the Tic40-rhomboid protease link and the meaning of this relationship to plastid protein delivery, organelle biogenesis, cell structure, and development. For the related short-term goals, we will employ established and modern proteomic approaches to characterize specifically : 1) Tic40's structure, its capabilities and its rhomboid cleavage site(s); 2) The functional features of plant organellar rhomboid proteases such as location, targeting, and enzymatic activities; and 3) The functional relationship between Tic40's importation and plastid rhomboid proteases. The work will also contribute to the development of techniques and strategies for functional proteomics, whole cell research, and commercial applications. Equally important, students going through the proposed 5-year NSERC program will receive intensive training in discoveries research applicable to their careers (for at least 3 Ph.D., 6 M.Sc., and 10 B.Sc.).