The cyanobacterial circadian clock has three relatively independent parts: the input path, the core oscillator, and the output path. The core oscillator is composed of three clock proteins: KaiA, KaiB, and KaiC. The interactions among these three proteins generate a rhythmic signal and convey the input signals to the output signals to maintain the accuracy and stability of the oscillation of downstream signals. Based on the cyanobacterial circadian clock and the structure, function, and interaction of the clock proteins of the core oscillator, combining the recent results from our laboratory, this review summarized the recent progresses of the molecular mechanism of KaiA in regulating KaiC's enzymatic activity, mediating phase reset of the oscillator, and competing with CikA for the binding site of KaiB.
蓝藻生物钟系统主要包括输入途径、核心振荡器和输出途径3 部分，核心振荡器主要由时钟蛋白KaiA、KaiB、KaiC 构成。3 种蛋白之间的相互作用产生节律信号及调控输入、输出信号进而维持生物振荡的精确与稳定。文中围绕蓝藻生物钟核心振荡器及核心振荡器组成蛋白的结构、功能与相互作用特点，结合本实验室近期取得的研究成果，针对时钟蛋白KaiA 调节KaiC 的酶活性、介导核心振荡器的时相重置、与CikA 竞争KaiB 的结合位点等方面近年来的研究进展进行了综述。.
Keywords: circadian clock; clock protein KaiA; core oscillator; cyanobacterium.