Electrochemical Detection of Circadian Redox Rhythm in Cyanobacterial Cells via Extracellular Electron Transfer
Electrochemical Detection of Circadian Redox Rhythm in Cyanobacterial Cells via Extracellular Electron Transfer
复制标题
DOI：
10.1093/pcp/pcv066
复制
发表时间：
2015-06-01
影响因子：
4.9
通讯作者：
Nakanishi, Shuji
中科院分区：
文献类型：
--
作者：
Nishio, Koichi;Pornpitra, Tunanunkul;Nakanishi, Shuji
最近对细胞昼夜节律的研究表明，转录-翻译反馈回路和细胞内氧化还原振荡的耦合对于强大的昼夜节律计时至关重要。为了阐明昼夜节律的分子机制，需要能够动态同时检测活细胞中的转录/翻译和氧化还原振荡的方法。在此，我们报告了蓝藻的昼夜氧化还原节律可以基于细胞外电子转移（EET）电化学检测，这是一个细胞内电子与细胞外电极交换的过程。由于基于eet的方法具有非破坏性，因此利用生物发光报告菌株进行转录/翻译节律同步检测成为可能。通过新合成的具有细胞膜通透性的电子介质，构建了蓝细菌胞内与胞外电极电化学连接的EET通路。在介质存在的情况下，培养基的开路电位表现出约24 h周期性的温度补偿节律。重要的是，在没有电子介质的情况下，没有观察到这种开路电位的昼夜节律，这表明EET过程将有关细胞内氧化还原状态的动态信息传递给细胞外电极。这些发现首次直接证明了蓝藻细胞的细胞内昼夜氧化还原节律。
Recent research on cellular circadian rhythms suggests that the coupling of transcription-translation feedback loops and intracellular redox oscillations is essential for robust circadian timekeeping. For clarification of the molecular mechanism underlying the circadian rhythm, methods that allow for the dynamic and simultaneous detection of transcription/translation and redox oscillations in living cells are needed. Herein, we report that the cyanobacterial circadian redox rhythm can be electrochemically detected based on extracellular electron transfer (EET), a process in which intracellular electrons are exchanged with an extracellular electrode. As the EET-based method is non-destructive, concurrent detection with transcription/translation rhythm using bioluminescent reporter strains becomes possible. An EET pathway that electrochemically connected the intracellular region of cyanobacterial cells with an extracellular electrode was constructed via a newly synthesized electron mediator with cell membrane permeability. In the presence of the mediator, the open circuit potential of the culture medium exhibited temperature-compensated rhythm with approximately 24 h periodicity. Importantly, such circadian rhythm of the open circuit potential was not observed in the absence of the electron mediator, indicating that the EET process conveys the dynamic information regarding the intracellular redox state to the extracellular electrode. These findings represent the first direct demonstration of the intracellular circadian redox rhythm of cyanobacterial cells.