1TF7

Crystal Structure of Circadian Clock Protein KaiC

Summary for 1TF7

• Entry DOI: 10.2210/pdb1tf7/pdb
• Descriptor: KaiC, ADENOSINE-5'-TRIPHOSPHATE (3 entities in total)
• Functional Keywords: homohexamer, hexamer, circadian clock protein
• Biological source: Synechococcus sp.
• Total number of polymer chains: 6
• Total formula weight: 359496.18

Authors

Pattanayek, R.,Wang, J.,Mori, T.,Xu, Y.,Johnson, C.H.,Egli, M. (deposition date: 2004-05-26, release date: 2004-08-24, Last modification date: 2024-02-14)

Primary citation

Pattanayek, R.,Wang, J.,Mori, T.,Xu, Y.,Johnson, C.H.,Egli, M.
Visualizing a Circadian Clock Protein; Crystal Structure of KaiC and Functional Insights
Mol.Cell, 15:375-388, 2004

PubMed Abstract: Circadian (daily) biological clocks express characteristics that are difficult to explain by known biochemical mechanisms, and will ultimately require characterizing the structures, functions, and interactions of their molecular components. KaiC is an essential circadian protein in cyanobacteria that forms the core of the KaiABC clock protein complex. We report the crystal structure of the KaiC homohexameric complex at 2.8 A resolution. The structure resembles a double doughnut with a central pore that is partially sealed at one end. The crystal structure reveals ATP binding, inter-subunit organization, a scaffold for Kai-protein complex formation, the location of critical KaiC mutations, and evolutionary relationships to other proteins. A key auto-phosphorylation site on KaiC (T432) is identified from the crystal structure, and mutation of this residue abolishes circadian rhythmicity. The crystal structure of KaiC will be essential for understanding this circadian clockwork and for establishing its links to global gene expression.

PubMed: 15304218
DOI: 10.1016/j.molcel.2004.07.013

Experimental method

X-RAY DIFFRACTION (2.8 Å)