MATSUURA Katsumi Tokyo Metropol.Univ.Dept.Biol.Assoc.Prof., 大学院・理学研究科, 助教授 (30181689)
IKEUCHI Masahiko Univ.Tokyo, Dept.Biol., Assoc.Prof., 大学院・総合文化研究科, 助教授 (20159601)
PLUMLEY F.G. アラスカ州立大学, 海洋学部, 助教授
BLANKENSHIP アアリゾナ州立大学, 生化学部, 教授
GANTT E. メリーランド州立大学, 微生物学部, 教授
TANAKA Ayumi Hokkaido Univ.Low temp.Research Inst., Prof., 低温科学研究所, 教授 (10197402)
|Budget Amount *help
¥8,300,000 (Direct Cost : ¥8,300,000)
Fiscal Year 1999 : ¥2,700,000 (Direct Cost : ¥2,700,000)
Fiscal Year 1998 : ¥2,600,000 (Direct Cost : ¥2,600,000)
Fiscal Year 1997 : ¥3,000,000 (Direct Cost : ¥3,000,000)
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
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.