A protein fold switch joins the circadian oscillator to clock output in cyanobacteria

作者：Chang Yong Gang; Cohen Susan E; Phong Connie; Myers William K; Kim Yong Ick; Tseng Roger; Lin Jenny; Zhang Li; Boyd Joseph S; Lee Yvonne; Kang Shannon; Lee David; Li Sheng; Britt R David; Rust Michael J; Golden Susan S; LiWang Andy^*

来源：Science, 2015, 349(6245): 324-328.

DOI：10.1126/science.1260031

Organisms are adapted to the relentless cycles of day and night, because they evolved timekeeping systems called circadian clocks, which regulate biological activities with similar to 24-hour rhythms. The clock of cyanobacteria is driven by a three-protein oscillator composed of KaiA, KaiB, and KaiC, which together generate a circadian rhythm of KaiC phosphorylation. We show that KaiB flips between two distinct three-dimensional folds, and its rare transition to an active state provides a time delay that is required to match the timing of the oscillator to that of Earth's rotation. Once KaiB switches folds, it binds phosphorylated KaiC and captures KaiA, which initiates a phase transition of the circadian cycle, and it regulates components of the clock-output pathway, which provides the link that joins the timekeeping and signaling functions of the oscillator.

• 出版日期2015-7-17