The cytochrome b6f complex is not involved in cyanobacterial state transitions

Abstract : Short title: Cyanobacterial state transitions revisited One-sentence summary: Cyanobacterial state transitions, which balance photosystem activities during photosynthesis, depend on the plastoquinone pool redox state but not on cytochrome b6f or phosphorylation reactions. ABSTRACT Photosynthetic organisms must sense and respond to fluctuating environmental conditions in order to perform efficient photosynthesis and to avoid the formation of dangerous reactive oxygen species. The excitation energy arriving at each photosystem permanently changes due to variations in the intensity and spectral properties of the absorbed light. Cyanobacteria, like plants and algae, have developed a mechanism, named state transitions, that balances photosystem activities. Here, we characterize the role of the cytochrome b 6 f complex and phosphorylation reactions in cyanobacterial state transitions using Synechococcus elongatus PCC 7942 and Synechocystis PCC 6803 as model organisms. First, large Photosystem II fluorescence quenching was observed in State II, which does not appear to be related to energy transfer from Photosystem II to Photosystem I (spillover). This membrane-associated process was inhibited by betaine, sucrose and high concentrations of phosphate. Then, using different chemicals affecting the plastoquinone pool redox state and cytochrome b 6 f activity, we demonstrate that this complex is not involved in state transitions in S. elongatus or Plant Cell Advance Publication.
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Pablo Calzadilla, Jiao Zhan, Pierre Sétif, Claire Lemaire, Daniel Solymosi, et al.. The cytochrome b6f complex is not involved in cyanobacterial state transitions. The Plant cell, American Society of Plant Biologists (ASPB), 2019, tpc.00916.2018. ⟨10.1105/tpc.18.00916⟩. ⟨hal-02108309⟩



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