State 1-State 2 transitions in the cyanobacterium Synechococcus 6301 are controlled by the redox state of electron carriers between Photosystems I and II

Abstract

The mechanism by which state 1-state 2 transitions in the cyanobacterium Synechococcus 6301 are controlled was investigated by examining the effects of a variety of chemical and illumination treatments which modify the redox state of the plastoquinone pool. The extent to which these treatments modify excitation energy distribution was determined by 77K fluorescence emission spectroscopy. It was found that treatment which lead to the oxidation of the plastoquinone pool induce a shift towards state 1 whereas treatments which lead to the reduction of the plastoquinone pool induce a shift towards state 2. We therefore propose that state transitions in cyanobacteria are triggered by changes in the redox state of plastoquinone or a closely associated electron carrier. Alternative proposals have included control by the extent of cyclic electron transport around PS I and control by localised electrochemical gradients around PS I and PS II. Neither of these proposals is consistent with the results reported here.

Light Modulates the Biosynthesis and Organization of Cyanobacterial Carbon Fixation Machinery through Photosynthetic Electron Flow

“…The redox state of photosynthetic electron transport chain functions as the key controller of the distribution of respiratory complexes (Liu et al, 2012), photosystem composition (Fujita et al, 1987), photosynthetic state transitions (Mullineaux and Allen, 1990), and the D, No significant changes in the cell length and width of Synechococcus is detected during inhibitor treatments for 24 h (P . 0.05, n = 500).…”

O2-dependent large electron flow functioned as an electron sink, replacing the steady-state electron flux in photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803, but not in the cyanobacterium Synechococcus sp. PCC 7942

“…Especially, during the phase transitions in HC-grown S. The state transition regulates the light-harvesting efficiency of photon energy by PSII and PSI. 30) State I is induced when PSI is photoexcited more than PSII. Fm′ in state I is higher than in state II.…”

Structural organization of an intact phycobilisome and its association with photosystem II

“…PBS can transfer energy to both photosystem II (PSII) and photosystem I (PSI) [2], and energy distribution between PSII and PSI is regulated by a process called state transition [23,24]. Early reports showed that state transitions occurred in a time range of subseconds to seconds [25] and that this process is controlled by the redox state of electron carriers between PSI and PSII [26]. Liu et al [27] recently reported the isolation of a PBS-PSII-PSI mega-complex, and suggested that PBS does not need to change its spatial position during state transitions.…”