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The reaction mechanisms of the oxygenic photosynthesis. - Analyses based on the phylogeny of chloroplast proteins

产氧光合作用的反应机理。

基本信息

批准号：
09044241
负责人：
MIMURO Mamoru
金额：
$ 5.31万
依托单位：
YAMAGUCHI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

项目摘要

Reaction mechanisms in photosynthesis will be well understood by introducing the idea of evolution, as shown by the continuity of reaction center complexes from photosynthetic bacteria to oxygenic photosynthetic organisms. There remain many large gaps in the reaction mechanisms in oxygenic photosynthesis, for example, an origin of oxygenic photosynthetic organisms, an origin of water oxidation machinery, evolution of Ch1 a/c algae by the secondary endosymbiosis, and so on. To approach to these large gaps, it is a good idea to compare reaction properties among several groups of oxygenic organisms. We attempted to understand the reaction mechanisms of several critical points by experimental approach and by group discussion.(1) Localization of cytochrome c550, an essential protein for oxygen evolution in cyancibacteria and red algae, and its stoichiometry per reaction center II was investigated. In the red alga Porphyridium cruentum, its localization was not necessarily clear, because of … More its low content. On the other hand, in cyanobacteium Synechocystis sp. PCC6803, there are plural genes related to this cytochrome, however function of individual components were not necessarily clear.(2) A group discussion was realized by a mini-symposium held in the University of Alaska, Fairbanks, in the summer of 1999. Based on the results obtained by the members of this research, we commonly understood the following points. (I) In the course of evolution of photosynthetic bacteria, Chloroflexus aurantiacus, which was postulated to be the oldest ancestor of bacteria, might not be the case based on the gene structure of pigment biosynthetic pathways. (ii) Oxygenic photosynthetic prokaryote probably acquired several genes for pigment synthesis in the early stage of evolution. (iii) A gene structure of dinoflagellates was unique ; one-gene is composed of one-circle. This is completely unexpected property, but its biological significance was not yet clear.Based on the above results and discussion, all the members agreed to continue this kind of co-operative research for the next chance. Less

通过引入进化的思想，光合作用中的反应机制将得到很好的理解，如从光合细菌到产氧光合生物的反应中心复合体的连续性所示。在光合作用的反应机制方面，如光合生物的起源、水体氧化机制的起源、Ch 1 a/c藻类的次生内共生演化等方面，还存在着许多空白，通过比较几类光合生物的反应特性，可以对这些空白进行探讨。我们试图通过实验方法和小组讨论来理解几个临界点的反应机理。(1)研究了蓝藻和红藻细胞色素c550的定位及其在反应中心II的化学计量。在红色的紫球藻中，其定位不一定清楚，因为 ...更多信息低含量。另一方面，在蓝细菌集胞藻PCC 6803中，存在与该细胞色素相关的多个基因，然而单个组分的功能不一定清楚。(2)1999年夏天，在费尔班克斯的阿拉斯加大学举行了一次小型研讨会，实现了小组讨论。根据本研究成员获得的结果，我们共同理解了以下几点。(I)在光合细菌的进化过程中，从色素合成途径的基因结构来看，被认为是细菌最古老祖先的橙黄绿挠曲菌可能并非如此。(ii)在进化的早期阶段，能进行光合作用的原核生物可能获得了几个色素合成基因。(iii)甲藻基因结构独特，一个基因由一个环组成。这是一个完全出乎意料的性质，但其生物学意义尚不清楚。基于上述结果和讨论，所有成员都同意在下次有机会时继续这种合作研究。少