Electrochemical Regulation of the Cyanobacterial Circadian Oscillation

There has been a growing awareness of a close relationship between circadian oscillation and intracellular redox state in diverse species ranging from cyanobacteria to mammals ^[1]. The elucidation of this relationship is of physiological importance since malfunction and disruption of the circadian clock can threaten the wellbeing of living organisms. Here we report that the circadian oscillation of the cyanobacterium Synechococcus elongatus PCC7942, the simplest organism found to exhibit circadian oscillation, can be entrained by periodical modulation of the intracellular redox state via electrochemically controlled-extracellular electron transfer (EC-EET), a process in which intracellular electrons are exchanged with extracellular electrodes ^[2].

In-vivo monitoring of chlorophyll fluorescence revealed that the redox state of plastoquionone pool could be controlled by EC-EET with simply changing the electrode potential in the presence of biocompatible electron mediators. As a result, the endogenous circadian clock of S. elongatuscells was successfully entrained through periodically modulated EC-EET by emulating the natural light-and-dark cycle, even under constant illumination conditions. This represents the first example of regulating the biological oscillation via intracellular redox state by electrochemical technique.

[1] S. Edgar et al., PNAS10.1073. (2012).

[2] Y. Lu et al., Angew. Chem. Int. Ed., 53, 2208-2211 (2014).