The priming phosphorylation of KaiC is activated by the release of its autokinase autoinhibition.

ABSTRACT: KaiC, a cyanobacterial circadian clock protein with autokinase activity, catalyzes the dual phosphorylation of its own S431 and T432 residues in a circadian manner in the presence of KaiA and KaiB. Priming phosphorylation at T432 is a key step that promotes secondary phosphorylation at S431. Although KaiA binding is considered essential for KaiC phosphorylation, the mechanisms underlying the activation and inactivation of priming phosphorylation remain elusive. We found that although the priming phosphorylation is autoinhibited within KaiC, it actually proceeds at a rate constant of 0.019 h^-1 even in the absence of KaiA. The autoinhibition of KaiC and the mechanism underlying the release from autoinhibition by KaiA were examined by KaiC structural analysis and by classical molec

SUBMITTER: Furuike Y 

PROVIDER: S-EPMC12065004 | biostudies-literature | 2025 May

REPOSITORIES: biostudies-literature