2GBL

Crystal Structure of Full Length Circadian Clock Protein KaiC with Phosphorylation Sites

Summary for 2GBL

• Entry DOI: 10.2210/pdb2gbl/pdb
• Related: 1TF7 1U9I
• Descriptor: Circadian clock protein kinase kaiC, MAGNESIUM ION, ADENOSINE-5'-TRIPHOSPHATE, ... (5 entities in total)
• Functional Keywords: circadian clock protein homohexamer, circadian, kaia, kaib, kaic, hexamer, circadian clock protein, transferase
• Biological source: Synechococcus elongatus; More
• Total number of polymer chains: 6
• Total formula weight: 355468.41

Authors

Pattanayek, R.,Williams, D.R.,Pattanayek, S.,Xu, Y.,Mori, T.,Johnson, C.H.,Stewart, P.L.,Egli, M. (deposition date: 2006-03-10, release date: 2007-01-23, Last modification date: 2024-10-09)

Primary citation

Pattanayek, R.,Williams, D.R.,Pattanayek, S.,Xu, Y.,Mori, T.,Johnson, C.H.,Stewart, P.L.,Egli, M.
Analysis of KaiA-KaiC protein interactions in the cyano-bacterial circadian clock using hybrid structural methods.
Embo J., 25:2017-2028, 2006

PubMed Abstract: The cyanobacterial circadian clock can be reconstituted in vitro by mixing recombinant KaiA, KaiB and KaiC proteins with ATP, producing KaiC phosphorylation and dephosphorylation cycles that have a regular rhythm with a ca. 24-h period and are temperature-compensated. KaiA and KaiB are modulators of KaiC phosphorylation, whereby KaiB antagonizes KaiA's action. Here, we present a complete crystallographic model of the Synechococcus elongatus KaiC hexamer that includes previously unresolved portions of the C-terminal regions, and a negative-stain electron microscopy study of S. elongatus and Thermosynechococcus elongatus BP-1 KaiA-KaiC complexes. Site-directed mutagenesis in combination with EM reveals that KaiA binds exclusively to the CII half of the KaiC hexamer. The EM-based model of the KaiA-KaiC complex reveals protein-protein interactions at two sites: the known interaction of the flexible C-terminal KaiC peptide with KaiA, and a second postulated interaction between the apical region of KaiA and the ATP binding cleft on KaiC. This model brings KaiA mutation sites that alter clock period or abolish rhythmicity into contact with KaiC and suggests how KaiA might regulate KaiC phosphorylation.

PubMed: 16628225
DOI: 10.1038/sj.emboj.7601086

Experimental method

X-RAY DIFFRACTION (2.8 Å)