PROSITE documentation PDOC51146KaiC domain profile
The kaiC domain is a ~240 residue domain of the cyanobacterial circadian (daily) clock protein kaiC and related prokaryotic proteins. The domain is named after Synechococcus sp. kaiC, a regulator of the kai genes and circadian oscillations in cyanobacteria ('kai' means cycle in Japanese). The kaiC protein is composed of two kaiC domains. Besides the typical double-domain kaiC, several single-kaiC-domain proteins occur, also in archaea and proteobacteria, and whereof only certain subfamilies perform circadian functions [1,2]. The domain has a recA/dnaB-like sequence and structure (see <PDOC00131>). The kaiC domain includes an ATP/GTP-binding Walker A and B motif (see <PDOC00017>) and a conserved Glu with potential catalytic function. The phosphorylation of kaiC is essential for the rhythmic pattern of gene expression [3,4,5].
The crystal structure of the cyanobacterial kaiC homohexamer shows that the two kaiC domains fold similarly (see <PDB:1U9I>), but differences occur in their ATP binding pockets [4].
Some proteins known to contain a kaiC domain:
- Cyanobacterial kaiC, a principal circadian clock protein, present in the kaiABC complex. It represses the expression of the kaiBC operon and other global genes.
- Archaeal UPF0273 protein, a hypothetical protein with a single kaiC domain.
The profile we developed covers the entire kaiC domain.
Last update:September 2005 / First entry.
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PROSITE method (with tools and information) covered by this documentation:
| 1 | Authors | Dvornyk V. Vinogradova O. Nevo E. |
| Title | Origin and evolution of circadian clock genes in prokaryotes. | |
| Source | Proc. Natl. Acad. Sci. U.S.A. 100:2495-2500(2003). | |
| PubMed ID | 12604787 | |
| DOI | 10.1073/pnas.0130099100 |
| 2 | Authors | Dvornyk V. Knudsen B. |
| Title | Functional divergence of the circadian clock proteins in prokaryotes. | |
| Source | Genetica 124:247-254(2005). | |
| PubMed ID | 16134337 |
| 3 | Authors | Iwasaki H. Taniguchi Y. Ishiura M. Kondo T. |
| Title | Physical interactions among circadian clock proteins KaiA, KaiB and KaiC in cyanobacteria. | |
| Source | EMBO J. 18:1137-1145(1999). | |
| PubMed ID | 10064581 | |
| DOI | 10.1093/emboj/18.5.1137 |
| 4 | Authors | Pattanayek R. Wang J. Mori T. Xu Y. Johnson C.H. Egli M. |
| Title | Visualizing a circadian clock protein: crystal structure of KaiC and functional insights. | |
| Source | Mol. Cell 15:375-388(2004). | |
| PubMed ID | 15304218 | |
| DOI | 10.1016/j.molcel.2004.07.013 |
| 5 | Authors | Hayashi F. Itoh N. Uzumaki T. Iwase R. Tsuchiya Y. Yamakawa H. Morishita M. Onai K. Itoh S. Ishiura M. |
| Title | Roles of two ATPase-motif-containing domains in cyanobacterial circadian clock protein KaiC. | |
| Source | J. Biol. Chem. 279:52331-52337(2004). | |
| PubMed ID | 15377674 | |
| DOI | 10.1074/jbc.M406604200 |
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