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The mechanism of a photoprotective molecular switch in the photosynthetic light-harvesting complex of plants

植物光合捕光复合体中光保护分子开关的机制

基本信息

批准号：
BB/E009743/1
负责人：
Alexander Ruban
金额：
$ 48.12万
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：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FE009743%2F1
关键词：
mechanism photoprotective molecular switch photosynthetic

项目摘要

The life of our biosphere is entirely dependent upon photosynthesis. Over millions of years oxygen-evolving organisms have been giving all heterotrophic organisms, including us, air to breathe and a source of food, energy and vital materials. The success of oxygenic photosynthesis on this planet is a great biological phenomenon, that relies first of all upon the efficient design and adaptability to the changing environmental conditions of the molecular machinery of the photosynthetic apparatus. The photosynthetic membrane is the most complex of all biological membranes and is the most enriched in various proteins. The latter bind a number of important co-factors: chlorophylls, carotenoids, lipids, ions and water. Protein tunes and co-ordinates the functions of these co-factors. This co-ordination lies at the heart of their biological function. One of the major pigment-lipoprotein complexes of the photosynthetic membrane is the light harvesting complex of photosystem II (LHCII). It collects the most significant part of the light energy received by the photosynthetic membrane and transfers it to the reaction centers, where charge separation occurs to initiate a chain of events leading to a synthesis of the universal biological fuel ATP and NADPH. LHCII was found to play an important regulatory role by controlling the amount of energy delivered to the reaction center. This is being achieved by dissipation of the excess energy into heat. Recently we have discovered that the currently available structure of LHCII does correspond to the structure of this complex in the rather dissipative state. This is an important finding, since it offers us structural insights of how the photosynthetic membrane is sensing and dealing with the excess light, hence how plants can protect themselves against this type of stress and survive it. The current program is built upon the knowledge of LHCII structure and aims to answer a number of important mechanistic questions. We want to find out what factors lead to the switching of LHCII into the dissipative mode, at what level of protein organization does this switch work: domains of the monomer, trimer or more collective, higher oligomer units? What is the nature of the new energetic parameters like fluorescence, combinational scattering (Raman) and absorption features accompanying the dissipative state and what is the nature of the excitation energy dissipation? What is the role of minor ligands, xanthophyll cycle carotenoids, violaxanthin and zeaxanthin in the regulation of the LHCII switch? The project should provide us with the knowledge of the very fundamental features put into the LHCII antenna design, which allow the light harvesting process in nature to be efficient and flexible at the same time, insuring a high level of plant productivity and adaptability to the light environment on our planet.

我们生物圈的生命完全依赖于光合作用。数百万年来，放氧生物为包括我们在内的所有异养生物提供了呼吸的空气和食物、能源和重要物质的来源。在这个星球上，氧合光合作用的成功是一种伟大的生物现象，首先依赖于光合作用装置的分子机械的有效设计和对不断变化的环境条件的适应。光合膜是所有生物膜中最复杂的，也是各种蛋白质中含量最丰富的。后者结合了许多重要的辅助因素：叶绿素、类胡萝卜素、类脂、离子和水。蛋白质调节和协调这些辅助因子的功能。这种协调是它们生物功能的核心。光系统II捕光复合体(LHCII)是光合作用膜上主要的色素-脂蛋白复合体之一。它收集光合膜接收到的最重要的光能部分，并将其转移到反应中心，在那里发生电荷分离，启动一系列事件，导致合成通用生物燃料ATP和NADPH。LHCII被发现通过控制传递到反应中心的能量量起到重要的调节作用。这是通过将多余的能量消散成热量来实现的。最近我们发现，目前可用的LHCII结构确实与该络合物处于相当耗散状态的结构相对应。这是一个重要的发现，因为它为我们提供了光合作用膜如何感知和处理过量光的结构洞察，从而植物如何保护自己免受这种类型的胁迫并生存下来。目前的计划建立在LHCII结构知识的基础上，旨在回答一些重要的机械问题。我们想找出是什么因素导致LHCII转换到耗散模式，这种转换是在什么蛋白质组织水平上工作的：单体、三聚体或更多集体的结构域，更高的低聚单元？伴随耗散态而来的新的能量参数如荧光、组合散射和吸收特征的性质是什么？激发能量耗散的性质是什么？次要配体、叶黄素循环类胡萝卜素、紫黄质和玉米黄质在调节LHCII开关中的作用是什么？该项目应该为我们提供LHCII天线设计中非常基本的功能的知识，这些功能允许自然界中的光收集过程同时高效和灵活，确保高水平的植物生产力和对地球上光环境的适应性。