The endogenous redox rhythm is controlled by a central circadian oscillator in cyanobacterium Synechococcus elongatus PCC7942

Tanaka, Kenya; Ishikawa, Masahito; Kaneko, Masahiro; Kamiya, Kazuhide; Kato, Souichiro; Nakanishi, Shuji

doi:10.1007/s11120-019-00667-0

Cited by 6 publications

(4 citation statements)

References 29 publications

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“…Furthermore, the redox rhythm disappeared when the transcription/translation of the clock gene was lost, indicating that the transcription/ translation controlled by the KaiABC oscillator sustains the circadian redox rhythm. [152] Figure 12. a) Schematic illustration of the proposed electron transfer pathway via pMBVi. NR, nitrate reductase.…”

Section: Online Detection Of Circadian Redox Rhythmmentioning

confidence: 99%

Redox‐Active Polymers Connecting Living Microbial Cells to an Extracellular Electrical Circuit

Kaneko

Ishihara

Nakanishi

2020

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Microbial electrochemical systems in which metabolic electrons in living microbes have been extracted to or injected from an extracellular electrical circuit have attracted considerable attention as environmentally‐friendly energy conversion systems. Since general microbes cannot exchange electrons with extracellular solids, electron mediators are needed to connect living cells to an extracellular electrode. Although hydrophobic small molecules that can penetrate cell membranes are commonly used as electron mediators, they cannot be dissolved at high concentrations in aqueous media. The use of hydrophobic mediators in combination with small hydrophilic redox molecules can substantially increase the efficiency of the extracellular electron transfer process, but this method has side effects, in some cases, such as cytotoxicity and environmental pollution. In this Review, recently‐developed redox‐active polymers are highlighted as a new type of electron mediator that has less cytotoxicity than many conventional electron mediators. Owing to the design flexibility of polymer structures, important parameters that affect electron transport properties, such as redox potential, the balance of hydrophobicity and hydrophilicity, and electron conductivity, can be systematically regulated.

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Section: Online Detection Of Circadian Redox Rhythmmentioning

confidence: 99%

Redox‐Active Polymers Connecting Living Microbial Cells to an Extracellular Electrical Circuit

Kaneko

Ishihara

Nakanishi

2020

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“…Although these results suggest that KaiABC controls ROS stress tolerance of a cell, there is a possibility that circadian rhythms in CFU can be induced by rhythmical change in the amount of ROS generated by the MV/light treatment. However, electron flux in PETC where ROS is generated is known to be constant in the LL condition in S. elongatus (22,23). Further, as shown above, PETC itself was shown to not be damaged by the MV/light treatment.…”

Section: Effect Of the Circadian Clock Onmentioning

confidence: 72%

“…Therefore, contribution of diurnal variation of expression level of antioxidant enzymes to ROS stress tolerance rhythms may be limited. In contrast, a clear circadian rhythm in reducing power has been demonstrated; for example, in electrochemically demonstrated intracellular redox rhythms (23,30). Further, as mentioned earlier, NADPH production was shown to be activated at night based on glycogen accumulated in the subjective dusk (25).…”

Section: Discussionmentioning

confidence: 87%

Time-of-day-dependent responses of cyanobacterial cellular viability against oxidative stress

Tanaka

Shimakawa

Nakanishi

2019

Preprint

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As an adaptation to periodic fluctuations of environmental light, photosynthetic organisms have evolved a circadian clock. The gene expression of ROS scavenging enzymes is regulated by circadian clock genes, which has been considered to help deal with the diurnal photogeneration of reactive oxygen species (ROS). Although a series of recent discoveries have suggested the correlation between circadian clock control and ROS scavenging mechanisms, circadian rhythms of ROS stress tolerance have not been experimentally demonstrated to date. In the present work, we constructed a novel assay using methyl viologen (MV) which generates ROS under light irradiation and experimentally verified the circadian rhythms of ROS stress tolerance in photosynthetic cells of cyanobacterium Synechococcus elongatus PCC7942, a standard model species for the investigation of circadian clock. Here, we report that ROS generated by MV treatment causes damage to stroma components and not to the photosynthetic electron transportation chain, leading to reduced cell viability. The degree of decrease in cell viability was dependent on the subjective time at which ROS stress was applied. Thus, ROS stress tolerance was shown to exhibit circadian rhythms. Notably, rhythms of ROS stress tolerance disappeared in mutant cells lacking the essential clock genes.Further, ROS stress tolerance showed irregular behaviors under irregular light/dark cycles that mismatched the subjective time. These results clearly show that the antioxidant ability in the stroma varies periodically under the control of clock genes. This is the first demonstration of ROS stress tolerance in cyanobacterial cells at a phenotypic level showing circadian oscillation. Significance statementReactive oxygen species (ROS) in photosynthetic organisms are the molecular basis of oxidative stress and are photogenerated in synchrony with the daily light cycles. Recent studies have revealed crosstalk between ROS scavenging systems and circadian clocks in organisms, but their mutual influence on physiological activities in a cell has not been fully elucidated. Here, we demonstrate for the first time that cellular viability against the ROS stress (i.e., ROS stress tolerance) exhibits circadian rhythms that are under the control of a clock system for cyanobacterium Synechococcus elongatus PCC7942, a standard model species for the investigation of the circadian clock.

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“…The occurrence of the PRDX redox rhythms in cyanobacteria does not require the kaiA gene [202,203]. While the evolution of TTFL has been divergent in different organisms, PRDX oscillations are phylogenetically conserved across all domains of life, serving as a potential universal timekeeping system [202].…”

Section: Why Has Evolution Decided To Start Measuring Time?mentioning

confidence: 99%

Studying the Human Microbiota: Advances in Understanding the Fundamentals, Origin, and Evolution of Biological Timekeeping

Siebieszuk,

Sejbuk,

Witkowska

2023

IJMS

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The recently observed circadian oscillations of the intestinal microbiota underscore the profound nature of the human–microbiome relationship and its importance for health. Together with the discovery of circadian clocks in non-photosynthetic gut bacteria and circadian rhythms in anucleated cells, these findings have indicated the possibility that virtually all microorganisms may possess functional biological clocks. However, they have also raised many essential questions concerning the fundamentals of biological timekeeping, its evolution, and its origin. This narrative review provides a comprehensive overview of the recent literature in molecular chronobiology, aiming to bring together the latest evidence on the structure and mechanisms driving microbial biological clocks while pointing to potential applications of this knowledge in medicine. Moreover, it discusses the latest hypotheses regarding the evolution of timing mechanisms and describes the functions of peroxiredoxins in cells and their contribution to the cellular clockwork. The diversity of biological clocks among various human-associated microorganisms and the role of transcriptional and post-translational timekeeping mechanisms are also addressed. Finally, recent evidence on metabolic oscillators and host–microbiome communication is presented.

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The endogenous redox rhythm is controlled by a central circadian oscillator in cyanobacterium Synechococcus elongatus PCC7942

Cited by 6 publications

References 29 publications

Redox‐Active Polymers Connecting Living Microbial Cells to an Extracellular Electrical Circuit

Redox‐Active Polymers Connecting Living Microbial Cells to an Extracellular Electrical Circuit

Time-of-day-dependent responses of cyanobacterial cellular viability against oxidative stress

Studying the Human Microbiota: Advances in Understanding the Fundamentals, Origin, and Evolution of Biological Timekeeping

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