Clock-Dependent Phosphorylation of CikA Regulates Its Activity.

ABSTRACT: In the cyanobacterial circadian clock, a core oscillator comprising the proteins KaiA, KaiB, and KaiC keeps time based on a rhythmic phosphorylation of KaiC, and histidine protein kinases relay temporal information from the KaiABC complex to regulate gene expression. The kinases SasA and CikA engage directly with the oscillator and are responsible for modulating the phosphorylation and dephosphorylation throughout the circadian day of the response-regulator transcription factor RpaA; the phosphorylation state of RpaA in turn determines circadian gene expression. We recently showed that either CikA or SasA can drive rhythmic phosphorylation and DNA binding of RpaA in an in vitro system. However, when SasA is absent in vivo, a bioluminescence reporter gene shows a very low expression and amp

SUBMITTER: Sancar C 

PROVIDER: S-EPMC12353112 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature