Molecular basis of FtsH function in the cyanobacterium Synechocystis PCC 6803

蓝藻集胞藻 PCC 6803 中 FtsH 功能的分子基础

• 批准号: BB/F021526/1
• 负责人: Jon Nield
• 金额: $ 3.68万
• 依托单位: Queen Mary University of London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FF021526%2F1
• 关键词: Molecular; basis; FtsH; function; cyanobacterium

Cyanobacteria are a diverse group of bacteria that have the ability to carry out plant-like photosynthesis, using solar energy to drive the fixation of carbon dioxide into organic matter and the liberation of oxygen from water. They are found in aquatic environments and make an important contribution to global oxygenic photosynthesis. Their photosynthetic activity is therefore crucial to determining levels of carbon dioxide, a greenhouse gas, in the atmosphere. Cyanobacteria are also closely related to the chloroplasts found in plants and many of the biochemical processes are conserved. Consequently cyanobacteria have been widely used as models to study related processes in chloroplasts, such as how the protein components involved in photosynthesis work. In particular the cyanobacterium Synechocystis 6803 is a widely used experimental system because of the ease of doing genetic engineering experiments in this organism. Recently Peter Nixon and colleagues identified a cyanobacterial protease, termed FtsH2, which was involved in the repair of the oxygen-evolving Photosystem II complex following light damage. Homologues of FtsH2 are also involved in the same process in chloroplasts. Subsequently FtsH2 has been shown to be involved in the successful acclimation of Synechocystis 6803 to a number of other environmental stresses including heat, high salt and reduced availability of inorganic carbon. FtsH2 is therefore an important factor controlling a number of different physiological processes vital for survival of the cyanobacterium. In background work to this proposal we have developed the experimental tools to conduct important fundamental studies on this class of FtsH protease. We have developed techniques to purify the FtsH2 protease and have shown that it forms a complex with the related FtsH3 protease. By using electron microscopy we could show for the first time that this FtsH2/FtsH3 complex is made of six subunits. In this application we describe a series of experiments to assess the structure and function of FtsH2 and the other three members of the FtsH protease family found in Synechocystis 6803. We propose to identify the location of each of the FtsH subunits in the cell, determine the number and composition of the different types of FtsH complex in the cell, identify potential targets for each of the FtsH proteases and determine if the physiological effects displayed by the FtsH2 mutants is as a result of the proteolytic activity of the FtsH complex or the ability of FtsH complexes to help pull or refold cellular targets. Beside improving our understanding of how cyanobacteria respond to various environmental stresses, our results will also be of special significance to plant scientists who are trying to understand the role of FtsH in the chloroplast. Ultimately work on the FtsH proteases might allow the generation of photosynthetic organisms, such as crop plants, that are able to grow more productively under a range of environmental conditions including high light stress.

蓝细菌是一组不同的细菌，它们能够进行类似植物的光合作用，利用太阳能将二氧化碳固定到有机物中，并从水中释放氧气。它们存在于水生环境中，并对全球含氧光合作用做出重要贡献。因此，它们的光合作用活性对于确定大气中二氧化碳（一种温室气体）的水平至关重要。蓝细菌也与植物中的叶绿体密切相关，并且许多生化过程是保守的。因此，蓝细菌已被广泛用作研究叶绿体中相关过程的模型，例如参与光合作用的蛋白质组分如何工作。特别是蓝细菌集胞藻6803是一种广泛使用的实验系统，因为在这种生物体中进行基因工程实验很容易。最近Peter尼克松和他的同事发现了一种蓝藻蛋白酶，称为FtsH 2，它参与了光损伤后光系统II复合体的氧释放修复。FtsH 2的同源物也参与叶绿体中的相同过程。随后，FtsH 2已被证明参与集胞藻6803成功适应许多其他环境胁迫，包括热，高盐和无机碳的可用性降低。因此，FtsH 2是控制许多对蓝细菌生存至关重要的不同生理过程的重要因素。在这项建议的背景工作中，我们已经开发了实验工具来对这类FtsH蛋白酶进行重要的基础研究。我们已经开发了纯化FtsH 2蛋白酶的技术，并已表明它与相关的FtsH 3蛋白酶形成复合物。通过使用电子显微镜，我们可以第一次表明，这种FtsH 2/FtsH 3复合物是由六个亚基。在本申请中，我们描述了一系列的实验，以评估的结构和功能的FtsH 2和其他三个成员的FtsH蛋白酶家族中发现的集胞藻6803。我们建议确定每个FtsH亚基在细胞中的位置，确定细胞中不同类型的FtsH复合物的数量和组成，确定每个FtsH蛋白酶的潜在目标，并确定FtsH 2突变体所显示的生理效应是否是由于FtsH复合物的蛋白水解活性或FtsH复合物帮助拉动或重折叠细胞目标的能力。除了提高我们对蓝藻如何应对各种环境胁迫的理解外，我们的研究结果对试图了解FtsH在叶绿体中的作用的植物科学家也具有特殊意义。最终，对FtsH蛋白酶的研究可能会产生光合生物，如农作物，它们能够在包括高光胁迫在内的一系列环境条件下更高效地生长。