Damped Oscillating Phosphoryl Transfer Reaction in the Cyanobacterial Circadian Clock

Hye In Jang, Pyonghwa Kim, Yong Ick Kim

Research output: Contribution to journalArticlepeer-review


Most organisms have circadian clocks to ensure the metabolic cycle to resonate with the rhythmic environmental changes without “damping,” or losing robustness. Cyanobacteria is the oldest and simplest form of life that is known to harbor this biological intricacy. Its KaiABC-based central oscillator proteins can be reconstituted inside a test tube, and the post-translational modification cycle occurs with 24 h periodicity. KaiC’s two major phosphorylation sites, Ser-431 and Thr-432, become phosphorylated and dephosphorylated by interacting with KaiA and KaiB, respectively. Here, we mutate Thr-432 into Ser to find the oscillatory phosphoryl transfer reaction damps. Previously, this mutant KaiC was reported to be arrhythmic in vivo. However, we found that the mutant KaiC gradually loses the ability to run in an autonomous manner and stays constitutively phosphorylated after 3 cycles in vitro.

Original languageEnglish (US)
Pages (from-to)10784-10788
Number of pages5
JournalACS Omega
Issue number12
StatePublished - Mar 28 2023

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering


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