Plastid protein transport mechanisms and organelle biogenesis

植物构成了地球生命活动的支柱，如光合作用、淀粉和油的生产以及呼吸作用。这些活动由动态的细胞过程控制，需要无数分子参与者的相互作用，并在植物细胞内的专门空间发生。其中一个空间是叶绿体，这是一种为植物捕捉和产生能量的细胞器。在发育过程中和适应不断变化的环境时，叶绿体也必须调整它们的活动。这样的调整伴随着运输到质体中的蛋白质多样性的戏剧性变化。因此，对叶绿体来说，重要的是保持一个能应对所有情况的响应和有效的蛋白质运输过程。最近的研究表明，胞质蛋白运输机制中的一个动态成分Tic40可能参与了调节机制，Tic40的S作用(S)可能受到细胞器菱形蛋白水解酶活性的影响或调节。因此，该提案概述了旨在阐明Tic40和菱形蛋白水解酶在叶绿体蛋白运输中的作用的项目。由于菱形蛋白水解酶属于一组高度保守的蛋白质，参与信号传递和发育，长期目标将是确定Tic40-菱形蛋白水解酶的联系以及这种联系对叶绿体蛋白运输、细胞器生物发生、细胞结构和发育的意义。对于相关的短期目标，我们将利用成熟的现代蛋白质组学方法来具体表征：1)Tic40‘S的结构、功能及其菱形裂解位点(S)；2)植物细胞器菱形蛋白酶的功能特性，如定位、靶向和酶活性；以及3)Tic40’S导入与叶绿体菱形蛋白酶之间的功能关系。这项工作还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战略的发展。同样重要的是，通过拟议的5年制NSERC计划的学生将接受适用于其职业的发现研究方面的强化培训(至少3个博士学位、6个硕士学位和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.).