1994 Fiscal Year Final Research Report Summary
Regulation of photosystem formation : A flexibility of energy-conversion system in thylakoids responding to environments
| Project/Area Number |
04454016
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
植物生理学
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| Research Institution | National Institute for Basic Biology |
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Principal Investigator |
FUJITA Yoshihiko Natl.Inst.Basic Biol.Professor, 基礎生物学研究所, 教授 (40013560)
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| Project Period (FY) |
1992 – 1994
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| Keywords | Chl a synthesis / Light acclimation / Photosynthesis / Photosystem I synthesis / Photosystem stoichiometry / Two-light reaction |
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| Research Abstract |
The study aimed to make clear the characteristics of PSI/PSII variation found with photosynthesis of cyanophytes. The characterization was made in three aspects. The first was analysis of molecular mechanism for requlation of PSI formation. Most effort was paid focusing on identification of the target step (s) in PSI formation. Analysis of steps for apoprotein synthesis revealed that the regulation occurs at translation level ; the translation is suppressed under PSI light and is released from suppression under PSII light. The regulation was found to correlate with Chl a biosynthesis. We suspect that PSI formation is regulated at the step (s) for chl a installation into apoprotein.
In the study of the second aspect, we examined PSI/PSII variation with algal organisms other than cyanophytes. We examined with the red alga Porphyra yezoensis and the green alga Chlamydomonas reinhardtii. Results indicated that PSI/PSII variation occurs in these organisms in a similar manner to that in cyanophytes. PSI/PSII variation in different phyla indicates that the regulatory mechanism of this type is a common ability of oxygenic photosynthesis of green plants.
Our study for the third aspect was made for comparison of PSI/PSII variation induced by chromatic light with the variation induced by environmental stresses other than light regime. CO_2- and Na^+-stresses cause a biassed state of ETS as similar to that caused by light shift from PSI light to PSII light. As expected, the two environmental stresses caused an increase in PSI/PSII ratio, like the light shift. Results clearly indicate that PSI/PSII ratio is regulated in response to the state of ETS and support our previous hypothesis.
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[Publications] Aizawa, K., Shimizu, T., Hiyama, T., Satoh, K., Nakamura, Y.and Fujita, Y.: "Changes in composition or membrane proteins accompanying the regulation of PSI/PSII stoichiometry observed with Synechocystis PCC 6803." Photosyn. Res.32. 131-138 (1992)
Description
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