The endogenous redox rhythm is controlled by a central circadian oscillator in cyanobacterium Synechococcus elongatus PCC7942
The intracellular redox and the circadian clock in photosynthetic organisms are two major regulators globally affecting various biological functions. Both of the global control systems have evolved as systems to adapt to regularly or irregularly changing light environments. Here, we report that the two global regulators mutually interact in cyanobacterium Synechococcus elongatus PCC7942, a model photosynthetic organism whose clock molecular mechanism is well known. Electrochemical assay using a transmembrane electron mediator revealed that intracellular redox of S. elongatus PCC7942 cell exhibited circadian rhythms under constant light conditions. The redox rhythm disappeared when transcription/translation of clock genes is defunctionalized, indicating that the transcription/translation controlled by a core KaiABC oscillator generates the circadian redox rhythm. Importantly, the amplitude of the redox rhythm at a constant light condition was large enough to affect the KaiABC oscillator. The findings indicated that the intracellular redox state is actively controlled to change in a 24-h cycle under constant light conditions by the circadian clock system.
KeywordsCircadian clock Intracellular redox Cyanobacteria Electrochemistry Photosynthesis
We thank Prof. H. Iwasaki (Waseda University) for kindly providing the mutants used in this work. This work was partially supported by the Advanced Low Carbon Technology Research and Development Program (JPMJAL1402) of the Japan Science and Technology Agency (JST) and JSPS KAKENHI Grant No. 18J20176.
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Conflict of interest
The authors declare that they have no conflict of interest.