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Updated: Aug 16, 2026

Monitoring Cell-autonomous Circadian Clock Rhythms of Gene Expression Using Luciferase Bioluminescence Reporters
Published on: September 27, 2012
Physical interactions among circadian clock proteins KaiA, KaiB and KaiC in cyanobacteria
H Iwasaki1, Y Taniguchi, M Ishiura
1Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
Abstract:
The kai gene cluster, which is composed of three genes, kaiA, kaiB and kaiC, is essential for the generation of circadian rhythms in the unicellular cyanobacterium Synechococcus sp. strain PCC 7942. Here we demonstrate the direct association of KaiA, KaiB and KaiC in yeast cells using the two-hybrid system, in vitro and in cyanobacterial cells. KaiC enhanced KaiA-KaiB interaction in vitro and in yeast cells, suggesting that the three Kai proteins were able to form a heteromultimeric complex. We also found that a long period mutation kaiA1 dramatically enhanced KaiA-KaiB interaction in vitro. Thus, direct protein-protein association among the Kai proteins may be a critical process in the generation of circadian rhythms in cyanobacteria.
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