Premium
Phosphorylation at Thr432 induces structural destabilization of the CII ring in the circadian oscillator KaiC
Author(s) -
Oyama Katsuaki,
Azai Chihiro,
Matsuyama Jun,
Terauchi Kazuki
Publication year - 2018
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.12945
Subject(s) - random hexamer , phosphorylation , circadian clock , ring (chemistry) , microbiology and biotechnology , biophysics , chemistry , circadian rhythm , biology , biochemistry , neuroscience , organic chemistry
KaiC is the central oscillator protein in the cyanobacterial circadian clock. KaiC oscillates autonomously between phosphorylated and dephosphorylated states on a 24‐h cycle in vitro by mixing with KaiA and KaiB in the presence of ATP . KaiC forms a C 6 ‐symmetrical hexamer, which is a double ring structure of homologous N‐terminal and C‐terminal domains termed CI and CII , respectively. Here, through the characterization of an isolated CII domain protein, CII K aiC , we show that phosphorylation of KaiC Thr432 destabilizes the hexameric state of the CII ring to a monomeric state. The results suggest that the stable hexameric CI ring acts as a molecular bundle to hold the CII ring, which undergoes dynamic structural changes upon phosphorylation.