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

Hayashi, Fumio; Suzuki, Hirofumi; Iwase, Ryo; Uzumaki, Tatsuya; Miyake, A.; Shen, Jian Ren; Imada, Katsumi; Furukawa, Yoshiko; Yonekura, Koji; Namba, Keiichi; Ishiura, Masahiro

doi:10.1046/j.1365-2443.2003.00633.x

Cited by 129 publications

(159 citation statements)

References 30 publications

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“…In the presence of ATP, KaiC forms a hexamer (Hayashi et al 2003). We examined the potential for KaiC monomer exchange between two KaiC hexamers using FLAGtagged KaiC.…”

Section: A Sequential Program Of Kaic Phosphorylationmentioning

confidence: 99%

A Cyanobacterial Circadian Clock Based on the Kai Oscillator

Kondo¹

2007

Cold Spring Harbor Symposia on Quantitative Biology

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“…In the presence of ATP, KaiC forms a hexamer (Hayashi et al 2003). We examined the potential for KaiC monomer exchange between two KaiC hexamers using FLAGtagged KaiC.…”

Section: A Sequential Program Of Kaic Phosphorylationmentioning

confidence: 99%

A Cyanobacterial Circadian Clock Based on the Kai Oscillator

Kondo¹

2007

Cold Spring Harbor Symposia on Quantitative Biology

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“…We determined the three-dimensional structure of KaiC by single particle analysis of cryoelectron microscopic images and demonstrated that the hexamer has a hexagonal, pot-shaped structure composed of six identical dumbbell-shaped subunits (6). The two spherical regions of the dumbbell-shaped structure probably correspond to the two domains of KaiC (6).…”

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confidence: 99%

“…To elucidate the mechanism of Kai protein-based generation of circadian oscillations in cyanobacteria, we analyzed the proteins derived from the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 by biochemical (5-7), structural (6,7), and biophysical techniques (7). T. elongatus cells grow at over 50°C, and their stable heat-tolerant proteins are suitable for analyses.…”

mentioning

confidence: 99%

“…KaiC has a duplicative structure (2,6), and each half has a set of ATPase motifs (Walker motifs A and B and a pair of deduced catalytic carboxylate Glu residues (named CatEs)) (2,6). We determined the three-dimensional structure of KaiC by single particle analysis of cryoelectron microscopic images and demonstrated that the hexamer has a hexagonal, pot-shaped structure composed of six identical dumbbell-shaped subunits (6).…”

mentioning

confidence: 99%

“…The two spherical regions of the dumbbell-shaped structure probably correspond to the two domains of KaiC (6). The hexamerization of KaiC depends on ATP, probably on its binding to each KaiC subunit (6). The hexamerization does not require ATP hydrolysis, because AMPPNP, 1 an unhydrolyzable analog of ATP, as well as ATP, can induce the hexamerization (6).…”

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Roles of Two ATPase-Motif-containing Domains in Cyanobacterial Circadian Clock Protein KaiC

Hayashi

Itoh

Uzumaki

et al. 2004

Journal of Biological Chemistry

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Cyanobacterial clock protein KaiC has a hexagonal, pot-shaped structure composed of six identical dumbbell-shaped subunits. Each subunit has duplicated domains, and each domain has a set of ATPase motifs. The two spherical regions of the dumbbell are likely to correspond to two domains. We examined the role of the two sets of ATPase motifs by analyzing the in vitro activity of ATP␥S binding, AMPPNP-induced hexamerization, thermostability, and phosphorylation of KaiC and by in vivo rhythm assays both in wild type KaiC (KaiC WT ) and KaiCs carrying mutations in either Walker motif A or deduced catalytic Glu residues. We demonstrated that 1) the KaiC subunit had two types of ATPbinding sites, a high affinity site in N-terminal ATPase motifs and a low affinity site in C-terminal ATPase motifs, 2) the N-terminal motifs were responsible for hexamerization, and 3) the C-terminal motifs were responsible for both stabilization and phosphorylation of the KaiC hexamer. We proposed the following reaction mechanism. ATP preferentially binds to the N-terminal high affinity site, inducing the hexamerization of KaiC. Additional ATP then binds to the C-terminal low affinity site, stabilizing and phosphorylating the hexamer. We discussed the effect of these KaiC mutations on circadian bioluminescence rhythm in cells of cyanobacteria.Circadian rhythms, 24-h biological oscillations of metabolic and behavioral activities observed ubiquitously in prokaryotes and eukaryotes, are endogenously regulated by circadian clocks. Several clock and clock-related genes from Drosophila, Neurospora, Arabidopsis, mice, and cyanobacteria have been cloned and analyzed (1).Cyanobacteria are the simplest organisms that exhibit circadian rhythms. We previously cloned and analyzed the kaiABC circadian clock gene cluster in the cyanobacterium Synechococcus sp. strain PCC 7942 (hereafter called Synechococcus) that is essential for the generation of circadian rhythms in cyanobacteria. The gene cluster consists of two

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Phosphorylation at Thr432 induces structural destabilization of the CII ring in the circadian oscillator KaiC

et al. 2017

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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 KaiC , 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.

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

Abstract: ATP-induced KaiC hexamerization is necessary for the clock function of KaiC.

Cited by 129 publications

References 30 publications

A Cyanobacterial Circadian Clock Based on the Kai Oscillator

A Cyanobacterial Circadian Clock Based on the Kai Oscillator

Roles of Two ATPase-Motif-containing Domains in Cyanobacterial Circadian Clock Protein KaiC

Phosphorylation at Thr432 induces structural destabilization of the CII ring in the circadian oscillator KaiC

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