21ENGBIO - Converting a cellular dustbin into a protein storing organelle

21ENGBIO - 将细胞垃圾箱转变为蛋白质储存细胞器

• 批准号: BB/W012162/1
• 负责人: Lorenzo Frigerio
• 金额: $ 12.71万
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FW012162%2F1
• 关键词: 21ENGBIO; Converting; cellular; dustbin; into

Plants feed the world. Most proteins eaten by humans and animals come (either directly or indirectly) from plants, in particular seeds. Plant seed proteins are synthesised in the secretory pathway - a system of cellular membranes that comprises the endoplasmic reticulum, the Golgi complex, endosomal compartments, and the vacuole. Plant seed cells store proteins in the endoplasmic reticulum, the vacuole, or both. The protein storage vacuole (PSV) is the preferred storage site in dicotyledonous plants such as legumes and is the main nutritional repository underpinning seed consumption. Plants are also increasingly used as hosts to produce high value pharmaceutical proteins, including, recently, a vaccine against COVID-19. The main challenge is to ensure that plant-produced proteins are accumulated and stored stably. In non-seed cells, the vacuole normally provides a harsh environment, serving a degradative (lytic) function in most plant tissues (akin to the lysosome in animal cells). Early attempts to express individual seed proteins, or high-value proteins such as antibodies, into the vacuoles of transgenic leaf cells led to the proteins to be degraded over time. In this project we propose to test a starteg to turn lytic vacuoles into protein storage vacuoles. In the last 5 years we have studied how PSV are formed during seed maturation: in seed embryo cells, there is a single lytic vacuole, which during maturation becomes filled with storage proteins and then divides to form multiple, protein-laden PSV. Very recently we have discovered that the seed storage proteins form a separate liquid phase inside the vacuole, which creates dense droplets; these droplets interact with the membrane of the vacuole and cause it to bend, forming buds; the buds eventually separate to form many PSV. We therefore hypothesise that this physical process of protein droplet formation, called liquid-liquid phase separation (LLPS), is the key driver of the transition from a lytic vacuole to a storage vacuole. This is very exciting: if our hypothesis is correct, we will be able to induce this process to convert lytic vacuoles, both in plant non-seed tissues (such as leaves), and in non-plant organisms, such as yeast, into protein-storing organelles. In this project we will test our hypothesis by expressing a panel of seed storage proteins, and other proteins which are known to undergo LLPS, in plant leaves and in yeast. We will therefore be able to establish which proteins are the most suitable for triggering the lytic-to-storage vacuole conversions. Therefore we will provide both the proof of principle and the blueprint for re-purposing cellular 'dustbins' into protein-storing compartments for high value protein contents.

植物养活了世界。人类和动物食用的大部分蛋白质(直接或间接)来自植物，特别是种子。植物种子蛋白质是在分泌途径中合成的，分泌途径是由内质网、高尔基复合体、内体隔室和液泡组成的细胞膜系统。植物种子细胞将蛋白质储存在内质网、液泡或两者都有。蛋白质储藏液泡(PSV)是豆科等双子叶植物的首选储藏场所，也是支撑种子消费的主要营养库。植物也越来越多地被用作宿主，以生产高价值的药用蛋白，包括最近研制的新冠肺炎疫苗。主要的挑战是确保植物产生的蛋白质被稳定地积累和储存。在非种子细胞中，液泡通常提供恶劣的环境，在大多数植物组织中提供降解(裂解)功能(类似于动物细胞中的溶酶体)。早期试图将单个种子蛋白或高价值蛋白(如抗体)表达到转基因叶细胞的液泡中，导致这些蛋白质随着时间的推移而降解。在这个项目中，我们建议测试一种将裂解的空泡转变为蛋白质储存空泡的启动方法。在过去的5年里，我们研究了PSV是如何在种子成熟过程中形成的：在种子胚胎细胞中，只有一个裂解的液泡，在成熟过程中充满了贮藏蛋白，然后分裂形成多个富含蛋白质的PSV。最近，我们发现种子储存蛋白在液泡内形成一个单独的液体相，从而产生致密的液滴；这些液滴与液泡的膜相互作用，使其弯曲，形成芽；芽最终分离，形成许多PSV。因此，我们假设，这种蛋白质液滴形成的物理过程，称为液-液相分离(LLP)，是从裂解液泡向储存液泡转变的关键驱动因素。这是非常令人兴奋的：如果我们的假设是正确的，我们将能够诱导这一过程，将植物非种子组织(如叶子)和非植物生物(如酵母)中的裂解液泡转化为储存蛋白质的细胞器。在这个项目中，我们将通过在植物叶片和酵母中表达一组种子储存蛋白和其他已知经历LLP的蛋白来验证我们的假设。因此，我们将能够确定哪些蛋白质最适合触发裂解液泡向储藏液泡的转化。因此，我们将提供原理证明和蓝图，将细胞‘垃圾桶’重新用于蛋白质储存隔间，以获得高价值的蛋白质含量。