scholarly journals Reduction-Induced Suppression of Electron Flow (RISE) in the Photosynthetic Electron Transport System ofSynechococcus elongatusPCC 7942

2015 ◽  
pp. pcv198 ◽  
Author(s):  
Keiichiro Shaku ◽  
Ginga Shimakawa ◽  
Masaki Hashiguchi ◽  
Chikahiro Miyake
Keyword(s):  
Electron Transport ◽  
Transport System ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Electron Transport System

scholarly journals Molecular Mechanism of Oxidation of P700 and Suppression of ROS Production in Photosystem I in Response to Electron-Sink Limitations in C3 Plants

Antioxidants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 230 ◽  
Author(s):  
Chikahiro Miyake
Keyword(s):  
Electron Transport ◽  
Molecular Mechanism ◽  
Transport System ◽  
Photosystem I ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Electron Transport System ◽  
C3 Plants ◽  
Ros Production ◽  
Acceptor Side

Photosynthesis fixes CO2 and converts it to sugar, using chemical-energy compounds of both NADPH and ATP, which are produced in the photosynthetic electron transport system. The photosynthetic electron transport system absorbs photon energy to drive electron flow from Photosystem II (PSII) to Photosystem I (PSI). That is, both PSII and PSI are full of electrons. O2 is easily reduced to a superoxide radical (O2−) at the reducing side, i.e., the acceptor side, of PSI, which is the main production site of reactive oxygen species (ROS) in photosynthetic organisms. ROS-dependent inactivation of PSI in vivo has been reported, where the electrons are accumulated at the acceptor side of PSI by artificial treatments: exposure to low temperature and repetitive short-pulse (rSP) illumination treatment, and the accumulated electrons flow to O2, producing ROS. Recently, my group found that the redox state of the reaction center of chlorophyll P700 in PSI regulates the production of ROS: P700 oxidation suppresses the production of O2− and prevents PSI inactivation. This is why P700 in PSI is oxidized upon the exposure of photosynthesis organisms to higher light intensity and/or low CO2 conditions, where photosynthesis efficiency decreases. In this study, I introduce a new molecular mechanism for the oxidation of P700 in PSI and suppression of ROS production from the robust relationship between the light and dark reactions of photosynthesis. The accumulated protons in the lumenal space of the thylakoid membrane and the accumulated electrons in the plastoquinone (PQ) pool drive the rate-determining step of the P700 photo-oxidation reduction cycle in PSI from the photo-excited P700 oxidation to the reduction of the oxidized P700, thereby enhancing P700 oxidation.

Responses of the photosynthetic electron transport system to excess light energy caused by water deficit in wild watermelon

2011 ◽  
Vol 142 (3) ◽  
pp. 247-264 ◽  
Author(s):  
Satoko Sanda ◽  
Kazuo Yoshida ◽  
Masayoshi Kuwano ◽  
Tadayuki Kawamura ◽  
Yuri Nakajima Munekage ◽  
...  
Keyword(s):  
Electron Transport ◽  
Water Deficit ◽  
Transport System ◽  
Photosynthetic Electron Transport ◽  
Light Energy ◽  
Electron Transport System ◽  
Excess Light
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