A protein fold switch joins the circadian oscillator to clock output in cyanobacteria
Document Type
Article
Publication Date
7-2015
Abstract
Organisms are adapted to the relentless cycles of day and night, because they evolved timekeeping systems called circadian clocks, which regulate biological activities with ~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.
Recommended Citation
Yong-Gang Chang et al., A protein fold switch joins the circadian oscillator to clock output in cyanobacteria. Science 349, 324-328 (2015). DOI:10.1126/science.1260031
Comments
The version of record is available from the publisher at https://www.science.org/doi/epdf/10.1126/science.1260031.
Copyright © 2015, American Association for the Advancement of Science. All rights reserved.