The subunit exchange rate of the cyanobacterial circadian clock component kaic is independent of phosphorylation state

Abstract

The study of the in vitro circadian oscillator of the cyanobacterium Synechococcus elongatus has uncovered a complex interplay of its three protein components. Synchronization of the clock's central oscillatory component, KaiC, has been thought to be achieved through subunit shuffling at specific intervals during the clock’s period. By utilizing an established fluorescence-based analysis on completely phosphorylated and dephosphorylated mutants as well as wild-type KaiC, this study has shown that shuffling rates are largely unaffected by phosphorylation state. These findings conflict with previous reports and hence revise our understanding of this oscillator.