Investigating the early steps in the assembly of the oxygen-evolving complex of photosynthesis

研究光合作用放氧复合物组装的早期步骤

• 批准号: BB/L003260/1
• 负责人: Peter Nixon
• 金额: $ 50.61万
• 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: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FL003260%2F1
• 关键词: Investigating; early; steps; assembly; oxygen

The photosystem two (PSII) protein complex is widely considered to be one of the most remarkable and important molecular machines on Earth. It performs the incredibly difficult task of extracting electrons from highly stable water molecules to allow plants, algae and cyanobacteria to grow. PSII also produces the oxygen that we breathe. PSII drives the very demanding water-splitting reaction by capturing solar energy and using it to drive the oxidation of water molecules bound to a highly conserved metal cluster, made up of 1 calcium ion and 4 manganese ions, buried within the PSII complex. The oxygen that is liberated is then fed back into the atmosphere. Dramatic progress has been made in understanding the 3-dimensional structure of the complex so that we now know to a high degree of precision where each atom in the complex is located. We know that active PSII is composed of about 20 individual proteins, bound together in a lipid membrane, and that it contains a large number of specialised pigment molecules to harvest the solar energy, as well as small organic molecules to transport electrons through the complex. Unfortunately PSII is not a perfect machine; it sometimes breaks down, especially when the sunlight is very bright, and has to be repaired. To do this the damaged PSII complex is partially disassembled into a smaller complex, and the damaged protein is replaced by a newly made version. Without this special repair mechanism PSII would be quickly inactivated in the light and plant growth and oxygen evolution would be inhibited. The purpose of our research is to understand how PSII functions to split water, how PSII is assembled from its component parts and how it is repaired efficiently. Understanding these processes might allow us in the future 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. This knowledge might also have applications in the design of new, sustainable herbicides or the design of new man-made catalysts that might act as 'artificial leaves' to provide renewable fuels from solar energy. Together with our collaborators, we have previously shown that PSII is assembled in a stepwise manner from smaller sub-complexes or modules and that these assembly intermediates also bind 'accessory factors' not found in the final active PSII complex. Whilst progress has been made in characterising the larger assembly intermediates, less is known about the early steps in PSII assembly. We propose to find out more about what is happening at this stage of PSII assembly. To do this we will employ a wide range of different experimental techniques and will work with collaborators around the world to maximise the return on the investment in time and money. By using a combination of genetic engineering and protein purification, we will isolate different types of early PSII assembly intermediate: some very early on in assembly when pigment molecules are first inserted into the protein as well as a minimal type of PSII complex, the PSII RC, that assembles later on in the pathway. By analysing the composition of these complexes we hope to identify new proteins that are required for assembly and repair of PSII. We have already identified two accessory proteins, termed Ycf48 and Ycf39, which bind to the PSII RC found in a cyanobacterium. We will employ a combination of mutagenesis, biochemistry and structural biology to find out more about their roles in PSII assembly, their 3D structure and how they interact with PSII. In addition we will use a special type of microscopy to detect the location of the PSII RC in live cyanobacterial cells to see where about this complex is found which will give us clues as to the site of assembly within the cell. Overall our research will provide important new information on how the oxygen-evolving complex of photosynthesis is assembled.

光系统2（PSII）蛋白复合物被广泛认为是地球上最显着和最重要的分子机器之一。它完成了从高度稳定的水分子中提取电子的艰巨任务，使植物，藻类和蓝藻生长。PSII还产生我们呼吸的氧气。PSII通过捕获太阳能来驱动非常苛刻的水裂解反应，并利用它来驱动与高度保守的金属簇结合的水分子的氧化，该金属簇由1个钙离子和4个锰离子组成，埋在PSII复合物中。释放出来的氧气又被送回大气中。在理解复合物的三维结构方面已经取得了巨大的进展，因此我们现在可以高度精确地知道复合物中每个原子的位置。我们知道，活性PSII由大约20个单独的蛋白质组成，它们在脂质膜中结合在一起，并且它包含大量专门的色素分子来收集太阳能，以及小的有机分子来通过复合物传输电子。不幸的是，PSII并不是一台完美的机器;它有时会发生故障，特别是当阳光非常明亮时，必须进行修理。为了做到这一点，受损的PSII复合物被部分分解成一个较小的复合物，受损的蛋白质被新的版本所取代。如果没有这种特殊的修复机制，PSII将在光照下迅速失活，植物的生长和放氧将受到抑制。我们研究的目的是了解PSII如何分解水，PSII如何从其组成部分组装以及如何有效地修复。了解这些过程可能使我们在未来能够增强作物的光合作用，以便我们能够增加生长，以帮助满足对更多食物和更多生物质日益增长的需求。这一知识也可能应用于设计新的可持续除草剂或设计新的人造催化剂，这些催化剂可能作为“人造叶子”，从太阳能中提供可再生燃料。与我们的合作者一起，我们以前已经表明，PSII是从较小的子复合物或模块以逐步的方式组装的，并且这些组装中间体还结合了最终活性PSII复合物中未发现的“辅助因子”。虽然在表征较大的组装中间体方面取得了进展，但对PSII组装的早期步骤知之甚少。我们建议更多地了解在PSII组装的这个阶段发生了什么。为此，我们将采用各种不同的实验技术，并与世界各地的合作者合作，以最大限度地提高时间和金钱投资的回报。通过使用基因工程和蛋白质纯化的组合，我们将分离不同类型的早期PSII组装中间体：一些非常早期的组装，当色素分子首次插入蛋白质以及最小类型的PSII复合物，PSII RC，组装后的途径。通过分析这些复合物的组成，我们希望确定PSII组装和修复所需的新蛋白质。我们已经鉴定了两种辅助蛋白，称为Ycf 48和Ycf 39，它们与在蓝藻中发现的PSII RC结合。我们将采用诱变，生物化学和结构生物学的组合，以了解更多关于他们的PSII组装，他们的三维结构，以及他们如何与PSII相互作用的作用。此外，我们将使用一种特殊类型的显微镜来检测PSII RC在活蓝藻细胞中的位置，以了解在哪里发现这种复合物，这将为我们提供细胞内组装位点的线索。总的来说，我们的研究将为光合作用的放氧复合物是如何组装的提供重要的新信息。

项目成果

Structure of Psb29/Thf1 and its association with the FtsH protease complex involved in photosystem II repair in cyanobacteria.

PSB29/THF1的结构及其与蓝细菌中光系统II修复的FTSH蛋白酶复合物的关联。

• DOI: 10.1098/rstb.2016.0394
• 发表时间: 2017-09-26
• 期刊: Philosophical transactions of the Royal Society of London. Series B, Biological sciences
• 作者: Bec Ková M;Yu J;Krynická V;Kozlo A;Shao S;Koník P;Komenda J;Murray JW;Nixon PJ
• 通讯作者: Nixon PJ

Assembly of D1/D2 complexes of photosystem II: Binding of pigments and a network of auxiliary proteins.

• DOI: 10.1093/plphys/kiac045
• 发表时间: 2022-06-01
• 期刊: Plant physiology
• 影响因子: 7.4

The Photosystem II Assembly Factor Ycf48 from the Cyanobacterium Synechocystis sp. PCC 6803 Is Lipidated Using an Atypical Lipobox Sequence.

• DOI: 10.3390/ijms22073733
• 发表时间: 2021-04-02
• 期刊: International journal of molecular sciences
• 影响因子: 5.6
• 作者: Knoppová J;Yu J;Janouškovec J;Halada P;Nixon PJ;Whitelegge JP;Komenda J
• 通讯作者: Komenda J

Supplementary figures from Structure of Psb29/Thf1 and its association with the FtsH protease complex involved in photosystem II repair in cyanobacteria

Psb29/Thf1 结构及其与参与蓝藻光系统 II 修复的 FtsH 蛋白酶复合物的关联的补充图

• DOI: 10.6084/m9.figshare.5171929
• 发表时间: 2017
• 作者: Becková M