7DYE image
Entry Detail
PDB ID:
7DYE
Keywords:
Title:
Crystal Structure of Cyanobacterial Circadian Clock Protein KaiC
Biological Source:
PDB Version:
Deposition Date:
2021-01-21
Release Date:
2022-05-18
Method Details:
Experimental Method:
Resolution:
2.60 Å
R-Value Free:
0.33
R-Value Work:
0.27
R-Value Observed:
0.28
Space Group:
H 3
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Circadian clock protein kinase KaiC
Mutations:S431A, T432A
Chain IDs:A, B
Chain Length:519
Number of Molecules:2
Biological Source:Synechococcus elongatus (strain PCC 7942 / FACHB-805)
Primary Citation
Regulation mechanisms of the dual ATPase in KaiC.
Proc.Natl.Acad.Sci.USA 119 e2119627119 e2119627119 (2022)
PMID: 35507871 DOI: 10.1073/pnas.2119627119

Abstact

KaiC is a dual adenosine triphosphatase (ATPase), with one active site in its N-terminal domain and another in its C-terminal domain, that drives the circadian clock system of cyanobacteria through sophisticated coordination of the two sites. To elucidate the coordination mechanism, we studied the contribution of the dual-ATPase activities in the ring-shaped KaiC hexamer and these structural bases for activation and inactivation. At the N-terminal active site, a lytic water molecule is sequestered between the N-terminal domains, and its reactivity to adenosine triphosphate (ATP) is controlled by the quaternary structure of the N-terminal ring. The C-terminal ATPase activity is regulated mostly by water-incorporating voids between the C-terminal domains, and the size of these voids is sensitive to phosphoryl modification of S431. The up-regulatory effect on the N-terminal ATPase activity inversely correlates with the affinity of KaiC for KaiB, a clock protein constitutes the circadian oscillator together with KaiC and KaiA, and the complete dissociation of KaiB from KaiC requires KaiA-assisted activation of the dual ATPase. Delicate interactions between the N-terminal and C-terminal rings make it possible for the components of the dual ATPase to work together, thereby driving the assembly and disassembly cycle of KaiA and KaiB.

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