Ito-Miwa Kumiko, Onoue Yasuhiro, Kondo Takao, Terauchi Kazuki
Graduate School of Science and Institute for Advanced Research, Nagoya University, Nagoya, Japan.
College of Life Sciences, Ritsumeikan University, Shiga, Japan.
Commun Biol. 2025 May 29;8(1):828. doi: 10.1038/s42003-025-08273-8.
The cyanobacterial clock protein KaiC exhibits robust 24-h oscillation of phosphorylation when incubated with KaiA, KaiB, and ATP in vitro. This study shows that the period of the in vitro phosphorylation rhythm of KaiC was correlated with solution pH, varying from 15 h at pH 6.5-36 h at pH 8.5, without affecting the period's temperature compensation. The solution pH altered the autophosphorylation and autodephosphorylation of KaiC and the effect of KaiB on KaiC but had little effect on its ATPase activity. It also modified the surface charge of the interface between two ATPase domains in KaiC, thereby affecting the autophosphorylation and autodephosphorylation activity of this protein via interdomain communication. These findings not only reveal key biochemical properties of the Kai oscillator but also provide insight into its evolutionary adaptation to environmental changes in cyanobacteria.
蓝藻生物钟蛋白KaiC在体外与KaiA、KaiB和ATP一起孵育时，表现出强大的24小时磷酸化振荡。本研究表明，KaiC体外磷酸化节律的周期与溶液pH值相关，在pH 6.5时为15小时，在pH 8.5时为36小时，且不影响周期的温度补偿。溶液pH值改变了KaiC的自磷酸化和自去磷酸化以及KaiB对KaiC的影响，但对其ATP酶活性影响很小。它还改变了KaiC中两个ATP酶结构域之间界面的表面电荷，从而通过结构域间通讯影响该蛋白的自磷酸化和自去磷酸化活性。这些发现不仅揭示了Kai振荡器的关键生化特性，还为其在蓝藻中对环境变化的进化适应提供了见解。
