A sequential program of dual phosphorylation of KaiC as a basis for circadian rhythm in cyanobacteria
Open Access
- 23 August 2007
- journal article
- research article
- Published by Springer Nature in The EMBO Journal
- Vol. 26 (17) , 4029-4037
- https://doi.org/10.1038/sj.emboj.7601832
Abstract
The circadian phosphorylation cycle of the cyanobacterial clock protein KaiC has been reconstituted in vitro . The phosphorylation profiles of two phosphorylation sites in KaiC, serine 431 (S431) and threonine 432 (T432), revealed that the phosphorylation cycle contained four steps: (i) T432 phosphorylation; (ii) S431 phosphorylation to generate the double‐phosphorylated form of KaiC; (iii) T432 dephosphorylation; and (iv) S431 dephosphorylation. We then examined the effects of mutations introduced at one KaiC phosphorylation site on the intact phosphorylation site. We found that the product of each step in the phosphorylation cycle regulated the reaction in the next step, and that double phosphorylation converted KaiC from an autokinase to an autophosphatase, whereas complete dephosphorylation had the opposite effect. These mechanisms serve as the basis for cyanobacterial circadian rhythm generation. We also found that associations among KaiA, KaiB, and KaiC result from S431 phosphorylation, and these interactions would maintain the amplitude of the rhythm.Keywords
This publication has 18 references indexed in Scilit:
- Identification of key phosphorylation sites in the circadian clock protein KaiC by crystallographic and mutagenetic analysesProceedings of the National Academy of Sciences, 2004
- Role of KaiC phosphorylation in the circadian clock system of Synechococcus elongatus PCC 7942Proceedings of the National Academy of Sciences, 2004
- Visualizing a Circadian Clock ProteinMolecular Cell, 2004
- KaiB functions as an attenuator of KaiC phosphorylation in the cyanobacterial circadian clock systemThe EMBO Journal, 2003
- Cyanobacterial circadian clockwork: roles of KaiA, KaiB and the kaiBC promoter in regulating KaiCThe EMBO Journal, 2003
- Structure and function from the circadian clock protein KaiA of Synechococcus elongatus : A potential clock input mechanismProceedings of the National Academy of Sciences, 2002
- KaiA-stimulated KaiC phosphorylation in circadian timing loops in cyanobacteriaProceedings of the National Academy of Sciences, 2002
- Nucleotide binding and autophosphorylation of the clock protein KaiC as a circadian timing process of cyanobacteriaProceedings of the National Academy of Sciences, 2000
- Temporal Organization: Reflections of a Darwinian Clock-WatcherAnnual Review of Physiology, 1993
- The structure of the E. coli recA protein monomer and polymerNature, 1992