No Transcription-Translation Feedback in Circadian Rhythm of KaiC Phosphorylation

作者：Jun Tomita, Masato Nakajima, Takao Kondo, Hideo Iwasaki · 发表于：Science · 年份：2004 · DOI：10.1126/science.1102540 · 被引用次数：506 · 研究领域：Light effects on plants、Circadian rhythm and melatonin、Photosynthetic Processes and Mechanisms

An autoregulatory transcription-translation feedback loop is thought to be essential in generating circadian rhythms in any model organism. In the cyanobacterium Synechococcus elongatus, the essential clock protein KaiC is proposed to form this type of transcriptional negative feedback. Nevertheless, we demonstrate here temperature-compensated, robust circadian cycling of KaiC phosphorylation even without kaiBC messenger RNA accumulation under continuous dark conditions. This rhythm persisted in the presence of a transcription or translation inhibitor. Moreover, kinetic profiles in the ratio of KaiC autophosphorylation-dephosphorylation were also temperature compensated in vitro. Thus, the cyanobacterial clock can keep time independent of de novo transcription and translation processes.