Role of protein phosphorylation in the maintenance of photosystem two in plants

蛋白质磷酸化在维持植物光系统二中的作用

• 批准号: BB/N016807/1
• 负责人: Peter Nixon
• 金额: $ 49.07万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FN016807%2F1
• 关键词: Role; protein; phosphorylation; maintenance; photosystem

The photosystem two (PSII) protein complex is widely considered to be one of the most remarkable molecular machines on Earth. PSII is found in plants, algae and cyanobacteria and performs the complex task of using sunlight to extract electrons from highly stable water molecules to allow oxygenic photosynthetic organisms to grow. At the same time PSII also produces the oxygen that we breathe. Unfortunately PSII is not a perfect machine; it sometimes breaks down, especially when the sunlight is very bright, and has to be repaired. Without this special repair mechanism PSII would be quickly inactivated in the light and plant growth and oxygen evolution would be inhibited. Despite the physiological importance of PSII repair, the details of the repair process are still unknown. A detailed understanding of PSII repair at the molecular level will provide us with important knowledge to help in the global effort to enhance photosynthesis in crop plants so that we can increase growth to help satisfy the ever increasing demand for more food and more biomass. In the case of land plants, we know that active PSII is located within the thylakoid membrane system of green chloroplasts found in leaves, but is segregated within the characteristic stacked regions of the membrane known as grana. For repair, the damaged PSII complex migrates outwards to the unstacked regions of the thylakoid system where the repair machinery is located. Here damaged PSII subunits can be degraded, newly synthesised subunits inserted and the PSII complex reactivated. How damaged PSII is specifically shuttled to the repair apparatus and how damaged subunits are specifically recognised for replacement is currently unknown. Over the years evidence has accumulated to suggest that the presence of negatively charged phosphate groups on four PSII core subunits might play a role in the repair process and in reshaping the membrane system in bright light to enhance repair. These previous studies have relied on the analysis of mutants that lack the kinase enzymes that phosphorylate PSII. However, it is now clear that these kinase mutants have effects outside PSII so it is still uncertain whether the specific lack of PSII phosphorylation is responsible for all the effects seen in the kinase mutants. In addition the kinase mutants block all PSII phosphorylation which has prevented analysis of the specific role of single subunit phosphorylation. In this application we propose to use a new approach to examine the role of protein phosphorylation in maintaining PSII activity in land plants. Rather than study kinase mutants, we will use chloroplast transformation technology to make tobacco plants that lack the amino-acid residue in each subunit that is normally phosphorylated. The kinase enzyme will still be active in these plants and so the effect of removing just one specific phosphate group from PSII can now be studied in isolation. In background work we have shown that this is a feasible strategy as we have already made tobacco plants unable to phosphorylate the D1 protein. Effects on the damage to PSII, its disassembly, its migration within the thylakoid membrane, the proteolytic degradation of damaged proteins, the reassembly of PSII and the impact on the structure of grana and plant growth under various illumination conditions will be performed use state-of-the-art approaches by a team of researchers with proven expertise in this area. We will study the maintenance of PSII in mutant plants lacking each of the four phosphorylation sites and also in engineered plants in which we remove increasing numbers of the phosphorylation sites to test for overlap of function. Overall our research will provide important new information on how the oxygen-evolving complex of photosynthesis is maintained in land plants and how the structure of the thylakoid membrane system is regulated.

光系统二 (PSII) 蛋白质复合物被广泛认为是地球上最引人注目的分子机器之一。 PSII 存在于植物、藻类和蓝藻中，执行利用阳光从高度稳定的水分子中提取电子以允许含氧光合生物生长的复杂任务。同时 PSII 还产生我们呼吸的氧气。不幸的是 PSII 并不是一台完美的机器。它有时会发生故障，尤其是在阳光非常明亮的情况下，必须进行修复。如果没有这种特殊的修复机制，PSII 将在光照下迅速失活，植物生长和氧气释放将受到抑制。尽管 PSII 修复具有生理重要性，但修复过程的细节仍然未知。在分子水平上对 PSII 修复的详细了解将为我们提供重要的知识，以帮助全球努力增强作物的光合作用，从而促进生长，帮助满足对更多食物和更多生物量不断增长的需求。就陆地植物而言，我们知道活性 PSII 位于叶子中绿色叶绿体的类囊体膜系统内，但被隔离在称为基粒的膜的特征性堆叠区域内。为了修复，受损的 PSII 复合体向外迁移到修复机器所在的类囊体系统的未堆叠区域。在这里，受损的 PSII 亚基可以被降解，新合成的亚基可以被插入，PSII 复合物可以被重新激活。受损的 PSII 如何被专门运送到修复装置以及受损的子单元如何被专门识别以进行替换目前尚不清楚。多年来积累的证据表明，四个 PSII 核心亚基上存在的带负电荷的磷酸基团可能在修复过程以及在强光下重塑膜系统以增强修复方面发挥作用。先前的这些研究依赖于对缺乏磷酸化 PSII 激酶的突变体的分析。然而，现在已经清楚这些激酶突变体在 PSII 之外具有影响，因此仍不确定 PSII 磷酸化的特定缺乏是否是激酶突变体中所见的所有影响的原因。此外，激酶突变体阻断所有 PSII 磷酸化，这阻碍了对单亚基磷酸化的具体作用的分析。在此应用中，我们建议使用一种新方法来检查蛋白质磷酸化在维持陆地植物 PSII 活性中的作用。我们不会研究激酶突变体，而是使用叶绿体转化技术来制造烟草植物，使其每个亚基中缺乏通常磷酸化的氨基酸残基。激酶在这些植物中仍然具有活性，因此现在可以单独研究从 PSII 中仅去除一个特定磷酸基团的效果。在背景工作中，我们已经证明这是一种可行的策略，因为我们已经使烟草植物无法磷酸化 D1 蛋白。将使用状态来研究不同光照条件下对 PSII 的损伤、其分解、其在类囊体膜内的迁移、受损蛋白质的蛋白水解降解、PSII 的重新组装以及对基粒结构和植物生长的影响。 -由在该领域拥有成熟专业知识的研究人员团队采用的最先进方法。我们将研究缺乏四个磷酸化位点的突变植物中 PSII 的维持，以及在工程植物中的 PSII 维持，其中我们去除了越来越多的磷酸化位点以测试功能重叠。总的来说，我们的研究将为陆地植物如何维持光合作用的放氧复合体以及类囊体膜系统的结构如何调节提供重要的新信息。

项目成果

Engineering a-carboxysomes into plant chloroplasts to support autotrophic photosynthesis.

将α-羧基体工程化到植物叶绿体中以支持自养光合作用。

• DOI: http://dx.10.1038/s41467-023-37490-0
• 发表时间: 2023
• 期刊: Nature communications
• 影响因子: 16.6
• 作者: Chen T

Contrasting Responses to Stress Displayed by Tobacco Overexpressing an Algal Plastid Terminal Oxidase in the Chloroplast.

叶绿体中过度表达藻质体末端氧化酶的烟草对应激的反应对比。

• DOI: http://dx.10.3389/fpls.2020.00501
• 发表时间: 2020
• 期刊: Frontiers in plant science
• 作者: Ahmad N

Recent Advances in Understanding the Structural and Functional Evolution of FtsH Proteases.

了解 FtsH 蛋白酶结构和功能进化的最新进展。

• DOI: http://dx.10.3389/fpls.2022.837528
• 发表时间: 2022
• 期刊: Frontiers in plant science
• 作者: Yi L

Early emergence of the FtsH proteases involved in photosystem II repair

参与光系统 II 修复的 FtsH 蛋白酶的早期出现

• DOI: http://dx.10.1007/s11099-018-0769-9
• 发表时间: 2018
• 期刊: Photosynthetica
• 影响因子: 2.7
• 作者: Shao S

Challenges and perspectives in commercializing plastid transformation technology.

质体转化技术商业化的挑战和前景。

• DOI: http://dx.10.1093/jxb/erw360
• 发表时间: 2016
• 期刊: Journal of experimental botany
• 影响因子: 6.9
• 作者: Ahmad N