Defining the scope and components of ubiquitin-dependent chloroplast-associated protein degradation

定义泛素依赖性叶绿体相关蛋白降解的范围和组成部分

• 批准号: BB/V007300/1
• 负责人: Paul Jarvis
• 金额: $ 83.18万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FV007300%2F1
• 关键词: Defining; scope; components; ubiquitin; dependent

The human population is growing rapidly and set to exceed 9bn by 2050. This presents significant challenges to food security, and places ever increasing pressure on natural resources. Thus, the drivers for increased crop yields with resilience to sub-optimal growing conditions are stronger than ever. To meet these demands it will be essential to develop improved crops. Through research on the model plant thale cress, we recently made some significant breakthroughs: We discovered a new regulatory process, named "CHLORAD", that controls vital aspects of plant growth, including plant responses to environmental stresses like drought and salinity. Significantly, modifying CHLORAD activity makes plants more tolerant of such stresses. In this project, we will define the molecular targets and mechanisms of CHLORAD, and in so doing develop a better understanding of how it can be used to deliver novel crop improvement strategies.CHLORAD (which stands for "chloroplast-associated protein degradation") regulates the development and operation of structures inside plant cells called chloroplasts, which are normal cellular constituents (i.e., organelles). They define plants, contain the green pigment chlorophyll, and are responsible for photosynthesis, harnessing sunlight energy to power the activities of the cell and the growth of the plant. As photosynthesis is the only significant mechanism of energy-input into the living world, chloroplasts are of huge importance, not just to plants but to all life on Earth. Chloroplasts also have critical roles in plant responses to stress, and so are ideal targets for engineering resilient crops.Chloroplasts are composed of thousands of different proteins, most of which are encoded by genes in the cell nucleus and so are made outside of the organelle in the cellular matrix known as the cytosol. As chloroplasts are surrounded by a double-membrane "envelope", sophisticated machinery is needed to enable the import of these proteins into the organelle. This comprises molecular machines in both membranes, called TOC (for "Translocon at the Outer membrane of Chloroplasts") and TIC. Each machine is composed of several proteins that work cooperatively.Currently, CHLORAD is known to act on the TOC machinery, breaking up its constituent proteins in order to control which other proteins are imported into the organelle (this in turn influences organelle development and operation). Known components of the CHLORAD machinery are proteins called SP1, SP2 and CDC48. The first, SP1, is a "ubiquitin E3 ligase" that labels-up unwanted proteins to target them for removal. The SP2 protein forms a channel in the chloroplast outer membrane, providing the exit route for removal of proteins labelled by SP1. Lastly, CDC48 is a molecular motor that drives extraction of the unwanted to the cytosol, where they are then broken down.Our unpublished results have revealed that additional proteins (or "cofactors") work together with CDC48 in CHLORAD. We believe that these cofactors are required for the docking of CDC48 onto the unwanted TOC proteins, and for the subsequent release of those proteins from CDC48. Here, we will study these cofactors in detail, to better understand how unwanted chloroplast proteins are removed in CHLORAD. Furthermore, we have additional new results showing that CHLORAD acts on a much larger number of target proteins than previously envisaged (i.e., not just TOC proteins), including proteins of the chloroplast interior. We will systematically identify these novel targets, and seek to understand how they are processed by CHLORAD even when deep inside the organelle. Informed by information on the identity of the targets, we will also explore the broader physiological significance of CHLORAD, for plant growth and development.Overall, the knowledge gained will enhance our understanding of CHLORAD, and will be important for the development of crops with improved chloroplast performance.

人口正在快速增长，预计到 2050 年将超过 90 亿。这对粮食安全提出了重大挑战，并对自然资源造成了越来越大的压力。因此，提高作物产量和抵御次优生长条件的驱动力比以往任何时候都更加强大。为了满足这些需求，开发改良作物至关重要。通过对模型植物拟南芥的研究，我们最近取得了一些重大突破：我们发现了一种名为“CHLORAD”的新调控过程，它控制着植物生长的重要方面，包括植物对干旱和盐度等环境胁迫的反应。值得注意的是，改变 CHLORAD 活性使植物更能耐受此类胁迫。在这个项目中，我们将定义 CHLORAD 的分子靶点和机制，并在此过程中更好地了解它如何用于提供新颖的作物改良策略。CHLORAD（代表“叶绿体相关蛋白降解”）调节植物细胞内称为叶绿体的结构的发育和运作，叶绿体是正常的细胞成分（即细胞器）。它们定义了植物，含有绿色色素叶绿素，负责光合作用，利用阳光能量为细胞活动和植物生长提供动力。由于光合作用是向生命世界输入能量的唯一重要机制，叶绿体不仅对植物而且对地球上的所有生命都非常重要。叶绿体在植物对胁迫的反应中也发挥着关键作用，因此是工程抗逆作物的理想目标。叶绿体由数千种不同的蛋白质组成，其中大部分是由细胞核中的基因编码的，因此是在细胞器外产生的细胞基质称为细胞质。由于叶绿体被双膜“包膜”包围，因此需要复杂的机器才能将这些蛋白质输入细胞器中。这包括两个膜中的分子机器，称为 TOC（“叶绿体外膜的转运蛋白”）和 TIC。每台机器都由几种协同工作的蛋白质组成。目前，CHLORAD 已知作用于 TOC 机器，分解其组成蛋白质，以控制哪些其他蛋白质被输入到细胞器中（这反过来又影响细胞器的发育和运行） 。 CHLORAD 机制的已知组件是称为 SP1、SP2 和 CDC48 的蛋白质。第一个是 SP1，是一种“泛素 E3 连接酶”，可以标记不需要的蛋白质以将其去除。 SP2 蛋白在叶绿体外膜中形成通道，为去除 SP1 标记的蛋白提供退出途径。最后，CDC48 是一种分子马达，可驱动将不需要的物质提取到细胞质中，然后将其分解。我们未发表的结果表明，CHLORAD 中其他蛋白质（或“辅因子”）与 CDC48 一起发挥作用。我们相信这些辅因子是 CDC48 与不需要的 TOC 蛋白对接以及随后从 CDC48 中释放这些蛋白所必需的。在这里，我们将详细研究这些辅助因子，以更好地了解 CHLORAD 中如何去除不需要的叶绿体蛋白。此外，我们还有其他新结果表明，CHLORAD 作用于比以前设想的更多数量的靶蛋白（即不仅仅是 TOC 蛋白），包括叶绿体内部的蛋白。我们将系统地识别这些新靶标，并试图了解 CHLORAD 如何处理它们，即使它们位于细胞器深处。根据目标身份的信息，我们还将探索 CHLORAD 对于植物生长和发育的更广泛的生理意义。总体而言，所获得的知识将增强我们对 CHLORAD 的理解，并且对于改良作物的发育非常重要。叶绿体性能。

项目成果

Mutations in TIC100 impair and repair chloroplast protein import and impact retrograde signalling

TIC100 突变损害和修复叶绿体蛋白输入并影响逆行信号传导

• DOI: 10.1101/2022.01.18.476798
• 发表时间: 2022
• 作者: Loudya N

The chloroplast-associated protein degradation pathway controls chromoplast development and fruit ripening in tomato

• DOI: 10.1038/s41477-021-00916-y
• 发表时间: 2021-05-01
• 期刊: NATURE PLANTS
• 影响因子: 18
• 作者: Ling, Qihua;Sadali, Najiah Mohd;Jarvis, R. Paul
• 通讯作者: Jarvis, R. Paul

Mutations in the chloroplast inner envelope protein TIC100 impair and repair chloroplast protein import and impact retrograde signaling.

• DOI: 10.1093/plcell/koac153
• 发表时间: 2022-07-30
• 期刊: The Plant cell

Ubiquitin-based pathway acts inside chloroplasts to regulate photosynthesis.

• DOI: 10.1126/sciadv.abq7352
• 发表时间: 2022-11-18
• 期刊: SCIENCE ADVANCES
• 影响因子: 13.6
• 作者: Sun, Yi;Yao, Zujie;Ye, Yiting;Fang, Jun;Chen, Honglin;Lyu, Yuping;Broad, William;Fournier, Marjorie;Chen, Genyun;Hu, Yonghong;Mohammed, Shabaz;Ling, Qihua;Jarvis, R. Paul
• 通讯作者: Jarvis, R. Paul

Crosstalk between the chloroplast protein import and SUMO systems revealed through genetic and molecular investigation in Arabidopsis.

• DOI: 10.7554/elife.60960
• 发表时间: 2021-09-02
• 期刊: eLife
• 影响因子: 7.7
• 作者: Watson SJ;Li N;Ye Y;Wu F;Ling Q;Jarvis RP
• 通讯作者: Jarvis RP