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- PDB-8db3: Crystal structure of KaiC with truncated C-terminal coiled-coil domain -
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Open data
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Basic information
Entry | Database: PDB / ID: 8db3 | ||||||
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Title | Crystal structure of KaiC with truncated C-terminal coiled-coil domain | ||||||
![]() | (Circadian clock protein KaiC) x 2 | ||||||
![]() | CIRCADIAN CLOCK PROTEIN / autokinase | ||||||
Function / homology | ![]() kinase activity / non-specific serine/threonine protein kinase / ATP hydrolysis activity / ATP binding / metal ion binding Similarity search - Function | ||||||
Biological species | ![]() | ||||||
Method | ![]() ![]() ![]() | ||||||
![]() | Padua, R.A.P. / Grant, T. / Pitsawong, W. / Hoemberger, M.S. / Otten, R. / Bradshaw, N. / Grigorieff, N. / Kern, D. | ||||||
Funding support | ![]()
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![]() | ![]() Title: From primordial clocks to circadian oscillators. Authors: Warintra Pitsawong / Ricardo A P Pádua / Timothy Grant / Marc Hoemberger / Renee Otten / Niels Bradshaw / Nikolaus Grigorieff / Dorothee Kern / ![]() Abstract: Circadian rhythms play an essential part in many biological processes, and only three prokaryotic proteins are required to constitute a true post-translational circadian oscillator. The evolutionary ...Circadian rhythms play an essential part in many biological processes, and only three prokaryotic proteins are required to constitute a true post-translational circadian oscillator. The evolutionary history of the three Kai proteins indicates that KaiC is the oldest member and a central component of the clock. Subsequent additions of KaiB and KaiA regulate the phosphorylation state of KaiC for time synchronization. The canonical KaiABC system in cyanobacteria is well understood, but little is known about more ancient systems that only possess KaiBC. However, there are reports that they might exhibit a basic, hourglass-like timekeeping mechanism. Here we investigate the primordial circadian clock in Rhodobacter sphaeroides, which contains only KaiBC, to elucidate its inner workings despite missing KaiA. Using a combination of X-ray crystallography and cryogenic electron microscopy, we find a new dodecameric fold for KaiC, in which two hexamers are held together by a coiled-coil bundle of 12 helices. This interaction is formed by the carboxy-terminal extension of KaiC and serves as an ancient regulatory moiety that is later superseded by KaiA. A coiled-coil register shift between daytime and night-time conformations is connected to phosphorylation sites through a long-range allosteric network that spans over 140 Å. Our kinetic data identify the difference in the ATP-to-ADP ratio between day and night as the environmental cue that drives the clock. They also unravel mechanistic details that shed light on the evolution of self-sustained oscillators. | ||||||
History |
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Structure visualization
Structure viewer | Molecule: ![]() ![]() |
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Downloads & links
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Download
PDBx/mmCIF format | ![]() | 887.3 KB | Display | ![]() |
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PDB format | ![]() | 620.5 KB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
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-Validation report
Arichive directory | ![]() ![]() | HTTPS FTP |
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-Related structure data
Related structure data | ![]() 8dbaC ![]() 8fwiC ![]() 8fwjC ![]() 1tf7S S: Starting model for refinement C: citing same article ( |
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Similar structure data | Similarity search - Function & homology ![]() |
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Links
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Assembly
Deposited unit | ![]()
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1 | ![]()
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Unit cell |
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Components
#1: Protein | Mass: 53687.105 Da / Num. of mol.: 2 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() ![]() #2: Protein | | Mass: 53767.082 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() ![]() #3: Chemical | ChemComp-ADP / Has ligand of interest | Y | Has protein modification | Y | |
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-Experimental details
-Experiment
Experiment | Method: ![]() |
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Sample preparation
Crystal | Density Matthews: 2.16 Å3/Da / Density % sol: 43.11 % |
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Crystal grow | Temperature: 291 K / Method: vapor diffusion, sitting drop Details: 0.2 M Ammonium acetate, 0.1 M Sodium citrate tribasic dihydrate pH 5.6, 30% w/v Polyethylene glycol 4,000 |
-Data collection
Diffraction | Mean temperature: 100 K / Serial crystal experiment: N |
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Diffraction source | Source: ![]() ![]() ![]() |
Detector | Type: ADSC QUANTUM 315r / Detector: CCD / Date: Nov 3, 2017 |
Radiation | Protocol: SINGLE WAVELENGTH / Monochromatic (M) / Laue (L): M / Scattering type: x-ray |
Radiation wavelength | Wavelength: 0.8855 Å / Relative weight: 1 |
Reflection | Resolution: 2.9→59.75 Å / Num. obs: 31367 / % possible obs: 99.89 % / Redundancy: 7.2 % / Biso Wilson estimate: 49.59 Å2 / CC1/2: 0.976 / Net I/σ(I): 5.54 |
Reflection shell | Resolution: 2.9→3.004 Å / Mean I/σ(I) obs: 1.15 / Num. unique obs: 3103 / CC1/2: 0.343 |
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Processing
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Refinement | Method to determine structure: ![]() Starting model: 1tf7 Resolution: 2.9→59.75 Å / SU ML: 0.4098 / Cross valid method: FREE R-VALUE / σ(F): 1.34 / Phase error: 30.6042 Stereochemistry target values: GeoStd + Monomer Library + CDL v1.2
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Solvent computation | Shrinkage radii: 0.9 Å / VDW probe radii: 1.11 Å / Solvent model: FLAT BULK SOLVENT MODEL | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Displacement parameters | Biso mean: 52.43 Å2 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Refinement step | Cycle: LAST / Resolution: 2.9→59.75 Å
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Refine LS restraints |
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LS refinement shell |
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Refinement TLS params. | Method: refined / Refine-ID: X-RAY DIFFRACTION
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Refinement TLS group | Refine-ID: X-RAY DIFFRACTION
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