Analysis of KaiA–KaiC protein interactions in the cyano-bacterial circadian clock using hybrid structural methods
| Autor: | Tetsuya Mori, Dewight Williams, Yao Xu, Phoebe L. Stewart, Carl Hirschie Johnson, Rekha Pattanayek, Sabuj Pattanayek, Martin Egli |
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| Rok vydání: | 2006 |
| Předmět: |
Models
Molecular Period (gene) Molecular Sequence Data Circadian clock macromolecular substances Random hexamer Biology Crystallography X-Ray Article General Biochemistry Genetics and Molecular Biology Protein–protein interaction Dephosphorylation Bacterial Proteins Biological Clocks KaiC Protein Interaction Mapping KaiA Amino Acid Sequence Phosphorylation Molecular Biology Sequence Deletion Synechococcus General Immunology and Microbiology Circadian Rhythm Signaling Peptides and Proteins General Neuroscience Circadian Rhythm Microscopy Electron Biochemistry Mutation Biophysics |
| Zdroj: | The EMBO Journal. 25:2017-2028 |
| ISSN: | 1460-2075 0261-4189 |
| DOI: | 10.1038/sj.emboj.7601086 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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