Reconstitution of Circadian Oscillation of Cyanobacterial KaiC Phosphorylation in Vitro

  title={Reconstitution of Circadian Oscillation of Cyanobacterial KaiC Phosphorylation in Vitro},
  author={Masato Nakajima and Keiko Imai and Hiroshi Ito and Taeko Nishiwaki and Yoriko Murayama and Hideo Iwasaki and Tokitaka Oyama and Takao Kondo},
  pages={414 - 415}
Kai proteins globally regulate circadian gene expression of cyanobacteria. The KaiC phosphorylation cycle, which persists even without transcription or translation, is assumed to be a basic timing process of the circadian clock. We have reconstituted the self-sustainable oscillation of KaiC phosphorylation in vitro by incubating KaiC with KaiA, KaiB, and adenosine triphosphate. The period of the in vitro oscillation was stable despite temperature change (temperature compensation), and the… 

Autonomous synchronization of the circadian KaiC phosphorylation rhythm

The cyanobacterial circadian oscillator can be reconstituted in vitro by mixing three purified clock proteins, KaiA, KaiB and KaiC, with ATP and it is demonstrated that synchronization is tightly linked with KaiC dephosphorylation and is mediated by monomer exchange between KaiC hexamers during the early deph phosphorylation phase.

Evolution Analysis of the Circadian Clock Protein KaiB

Here, the evolution of the KaiB protein is studied to help understand the development of the circadian clock system in cyanobacteria.

A Molecular Dynamics Study of the Cyanobacterial Clock Protein KaiA

The dynamics of the KaiA protein of Thermosynechococcus elongatus is studied in order to understand the function of KaiA and its binding with KaiC and to study the circadian system in cyanobacteria.

Expression and Purification of Cyanobacterial Circadian Clock Protein KaiC and Determination of Its Auto-phosphatase Activity.

Circadian clocks of cyanobacteria are the simplest and one of the best studied models and can be used for in vitro reconstitution experiments and determination of the auto-phosphatase activity of KaiC as described in this protocol.

A model for circadian rhythm of cyanobacteria , which maintains oscillation without gene expression

Results of the present paper suggest that KaiA and KaiB strengthen the nonlinearity of KaiC phosphorylation, thereby promote the circadian rhythm in cyanobacteria.

A cyanobacterial circadian clock based on the Kai oscillator.

  • T. Kondo
  • Biology
    Cold Spring Harbor symposia on quantitative biology
  • 2007
It is demonstrated that the oscillation of KaiC phosphorylation is the primary pacemaker of the cyanobacterial circadian clock and a novel function of proteins as timing devices that govern cellular metabolism is revealed.



KaiA-stimulated KaiC phosphorylation in circadian timing loops in cyanobacteria

It is shown that activation of kaiBC expression by kaiA requires KaiC, suggesting a positive feedback control in the cyanobacterial clockwork, and proposed that KaiA-stimulated circadian KaiC phosphorylation is important for circadian timing.

KaiB functions as an attenuator of KaiC phosphorylation in the cyanobacterial circadian clock system

A novel role for KaiB is proposed in a regulatory link among subcellular localization, protein–protein interactions and post‐translational modification of Kai proteins in the cyanobacterial clock system.

No Transcription-Translation Feedback in Circadian Rhythm of KaiC Phosphorylation

Temperature-compensated, robust circadian cycling of KaiC phosphorylation even without kaiBC messenger RNA accumulation under continuous dark conditions is demonstrated, and the cyanobacterial clock can keep time independent of de novo transcription and translation processes.

Expression of a gene cluster kaiABC as a circadian feedback process in cyanobacteria.

A negative feedback control of kaiC expression by KaiC generates a circadian oscillation in cyanobacteria, and KaiA sustains the oscillation by enhancing kaiA expression.

Cyanobacterial circadian clockwork: roles of KaiA, KaiB and the kaiBC promoter in regulating KaiC

It is concluded that the circadian period in cyanobacteria is determined by the phosphorylation status of KaiC and also by the degradation rate of Kai C, which is integrated into a model proposing rhythmic changes in chromosomal status.

Role of KaiC phosphorylation in the circadian clock system of Synechococcus elongatus PCC 7942.

The results suggest that KaiC phosphorylation regulates its transcriptional repression activity by controlling its binding affinity for other clock proteins.

Identification of key phosphorylation sites in the circadian clock protein KaiC by crystallographic and mutagenetic analyses.

Daily modulations of KaiC activity by phosphorylation at T432 and S431/T426 seem to be key components of the circadian clockwork in cyanobacteria.

The Neurospora Circadian System

Overall, the FRQ/white collar complex feedback loop appears to coordinate the circadian system through its activity to regulate downstream-target clock-controlled genes, either directly or via regulation of driven FLOs.

ATP‐induced hexameric ring structure of the cyanobacterial circadian clock protein KaiC

Background: KaiA, KaiB and KaiC are cyanobacterial circadian clock proteins. KaiC contains two ATP/GTP‐binding Walker's motif As, and mutations in these regions affect the clock oscillations.

Circadian rhythms in prokaryotes: luciferase as a reporter of circadian gene expression in cyanobacteria.

The behavior of this prokaryote disproves the dogma that circadian mechanisms must be based on eukaryotic cellular organization and provides an efficient experimental system for molecular analysis of the circadian clock.