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KaiB functions as an attenuator of KaiC phosphorylation in the cyanobacterial circadian clock system
Author(s) -
Kitayama Yohko,
Iwasaki Hideo,
Nishiwaki Taeko,
Kondo Takao
Publication year - 2003
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdg212
Subject(s) - biology , circadian clock , phosphorylation , bacterial circadian rhythms , circadian rhythm , microbiology and biotechnology , biochemistry , neuroscience
In the cyanobacterium Synechococcus elongatus PCC 7942, the KaiA, KaiB and KaiC proteins are essential for generation of circadian rhythms. We quantitatively analyzed the intracellular dynamics of these proteins and found a circadian rhythm in the membrane/cytosolic localization of KaiB, such that KaiB interacts with a KaiA–KaiC complex during the late subjective night. KaiB–KaiC binding is accompanied by a dramatic reduction in KaiC phosphorylation and followed by dissociation of the clock protein complex(es). KaiB attenuated KaiA‐enhanced phosphorylation both in vitro and in vivo . Based on these results, we propose a novel role for KaiB in a regulatory link among subcellular localization, protein–protein interactions and post‐translational modification of Kai proteins in the cyanobacterial clock system.