| 日時: |
2007-02-01 13:30 - 14:30 |
| 場所: |
PF研究棟2階会議室 |
| 会議名: |
放射光セミナー「Crystallographic Studies of the Purple Bacterial Photosynthetic Unit」 |
| 講演者: |
Dr. Aleksander W. Roszak (Glasgow Biomedical Research Centre, University of Glasgow) |
| 講演言語: |
英語 |
| URL: |
http://pfwww.kek.jp/pf-seminar/ |
| アブストラクト: |
Photosynthesis is one of the most important biological reactions on Earth. It provides all of the oxygen we breathe and, ultimately, all the food we eat. Purple photosynthetic bacteria have proved to be excellent model systems in which to study the light reactions of photosynthesis. Their light reactions usually begin with the absorption of a photon by the light harvesting (LH) or antenna system. This absorbed energy is then rapidly and efficiently transferred to the reaction center (RC), where it is used to initiate cyclic electron transport between the RC, cytochrome b/c1, and cytochrome c, producing a proton gradient that drives adenosine triphosphate (ATP) synthase and ultimately converts solar energy into useful chemical energy. These reactions take place in the photosynthetic unit, the PSU, located in the photosynthetic membrane, where the RC is surrounded by two types of antenna complexes, called LH1 and LH2. The LH1 antenna forms a stoichiometric complex with the RC, called the RC-LH1 core complex, while the LH2 antennas are located around the core.
Our crystallographic studies of the PSU of the purple non-sulphur bacteria include determinations of LH2 structure from Rhodopseudomonas (Rps.) acidophila and the structure of RC-LH1 core complex from Rps. palustris. We have also determined structures of several mutants of RC from Rhodobacter (Rb.) sphaeroides to study properties of electron transfer, and structures of the carotenoidless mutant R26.1 of RC either without carotenoid or reconstituted with either natural carotenoid spheroidene or synthetic 3,4-dihydrospheroidene. Most recently we have determined several structures of RC cocrystallised with brominated lipids or detergents in order to study lipid binding sites on the hydrophobic surface of RC. Some of the above structures will be presented in my talk in detail. (For further information, please contact S. Adachi.) |
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