Related Experiment Video
Updated: Jul 20, 2026

Monitoring Cell-autonomous Circadian Clock Rhythms of Gene Expression Using Luciferase Bioluminescence Reporters
Published on: September 27, 2012
Expression of a gene cluster kaiABC as a circadian feedback process in cyanobacteria
1Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan. ishiura@bio.nagoya-u.ac.jp
Abstract:
Cyanobacteria are the simplest organisms known to have a circadian clock. A circadian clock gene cluster kaiABC was cloned from the cyanobacterium Synechococcus. Nineteen clock mutations were mapped to the three kai genes. Promoter activities upstream of the kaiA and kaiB genes showed circadian rhythms of expression, and both kaiA and kaiBC messenger RNAs displayed circadian cycling. Inactivation of any single kai gene abolished these rhythms and reduced kaiBC-promoter activity. Continuous kaiC overexpression repressed the kaiBC promoter, whereas kaiA overexpression enhanced it. Temporal kaiC overexpression reset the phase of the rhythms. Thus, a negative feedback control of kaiC expression by KaiC generates a circadian oscillation in cyanobacteria, and KaiA sustains the oscillation by enhancing kaiC expression.
Related Concept Videos
Biological Clocks and Seasonal Responses
Prokaryotic Transcriptional Activators and Repressors
Transcription of prokaryotic...
Circadian Rhythms and Gene Regulation
Circadian Rhythms and Gene Regulation
Coordination of Gene Expression Processes in Bacteria
Global Regulatory Systems

