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Adaptation of photosynthesis to oxidative environment

光合作用对氧化环境的适应

基本信息

批准号：
09044231
负责人：
MATSUMURA Katsumi
金额：
$ 3.2万
依托单位：
TOKYO METROPOLITAN UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09044231/
关键词：
Photosynthesis Light Energy Photosynthetic Bacteria Energy Transfer Electron Transfer Quinone Cytochrome

项目摘要

Photosynthesis has been evalved under anaerobic environment, and thereafter adapted to oxidative environment. In this study, we have tried to clarify the effect of oxigen molecules in the environment on the excited energy transfer and the photosynthetic electron transfer in the absolute anaerobic green sulfur bacteria, Chlorobium, and the facultatively anaerobic green filamentous bacteria, Chloroflexus, as well as the facultatively anaerobic purple bacteria. Research was done as an international collaborative project among scientists of Japan, Denmark, France and Italy. Followings are main results we obtained.(1)In the light-harvesting appratus of green sulfur bacteria, called chlorosomes, it was known the fluorescence from the photosynthetic pigments is changed by a factor of more than ten depending on the presence or absence of oxygen molecules in the environment. To clarify if this fluoresence changes really affect the efficiency of the photosynthetic electron transfer, we measured … More the light intensity dependence of the photosynthetic electron transfer by changing the redox potential in the environment. It was shown that oxygen regulates the efficiency of electron transfer by affecting the excitation energy transfer.(2)In the green filamentous bacteria, such a regulation was not present. However, when artificial quinone was added to the chlororsomes or whole cells, a similar regulation was observed, indicating that quinone is responsible for the regulation.(3)Such quinones were suggested to be interacted with bacteriochlorophyll c molecules.(4)To clarify the adaptation of purple photosynthetic bacteria to the changes of redox conditions in the environment, cytochrome subunit bound to the photosynthetic reactio center was characterized in various species. We found in a species, Rhodovulum sulfidophilum, which well adapted to oxidative and reductive environment, only three hemes are bound to the subunit instead of the four hemes in the other many species. It was suggested the oxidative environment may have reduced the heme in the subunit evolutionary. Less

光合作用是在厌氧环境下进行的，此后又适应了氧化环境。在本研究中，我们试图阐明环境中的氧分子对绝对厌氧绿硫细菌Chlorobium、兼性厌氧绿丝状细菌Chlorofleus以及兼性厌氧紫色细菌的激发能量传递和光合电子传递的影响。这项研究是作为日本、丹麦、法国和意大利科学家的国际合作项目进行的。主要研究结果如下：(1)在绿色硫磺细菌的捕光器中，我们知道光合色素的荧光随环境中氧分子的存在而变化十倍以上。为了弄清这种荧光变化是否真的影响光合作用电子传递的效率，我们测量了…通过改变环境中的氧化还原电势，更多地依赖于光合作用电子传递的光强。结果表明，氧通过影响激发能传递来调节电子传递的效率。(2)在绿丝状菌中不存在这种调节。然而，当人工醌加入到叶绿体或整个细胞中时，也观察到了类似的调节，表明这种调节是由醌负责的。(3)这种醌被认为是与细菌叶绿素c分子相互作用的。(4)为了阐明紫色光合作用细菌对环境氧化还原条件变化的适应，我们对不同物种的光合作用反应中心结合的细胞色素亚基进行了表征。我们发现，在一个对氧化和还原环境适应性很强的物种--硫化红假单胞菌中，只有三个血红素结合到亚基上，而不是其他许多物种中的四个血红素。有人认为，氧化环境可能减少了亚基进化中的血红素。较少