1U9I

Crystal Structure of Circadian Clock Protein KaiC with Phosphorylation Sites


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.290 
  • R-Value Work: 0.250 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Identification of key phosphorylation sites in the circadian clock protein KaiC by crystallographic and mutagenetic analyses

Xu, Y.Mori, T.Pattanayek, R.Pattanayek, S.Egli, M.Johnson, C.H.

(2004) PROC.NATL.ACAD.SCI.USA 101: 13933-13938

  • DOI: 10.1073/pnas.0404768101

  • PubMed Abstract: 
  • In cyanobacteria, KaiC is an essential hexameric clock protein that forms the core of a circadian protein complex. KaiC can be phosphorylated, and the ratio of phospho-KaiC to non-phospho-KaiC is correlated with circadian period. Structural analyses ...

    In cyanobacteria, KaiC is an essential hexameric clock protein that forms the core of a circadian protein complex. KaiC can be phosphorylated, and the ratio of phospho-KaiC to non-phospho-KaiC is correlated with circadian period. Structural analyses of KaiC crystals identify three potential phosphorylation sites within a 10-A radius of the ATP binding regions that are at the T432, S431, and T426 residues in the KaiCII domains. When these residues are mutated by alanine substitution singly or in combination, KaiC phosphorylation is altered, and circadian rhythmicity is abolished. These alanine substitutions do not prevent KaiC from hexamerizing. Intriguingly, the ability of KaiC overexpression to repress its own promoter is also not prevented by alanine substitutions at these sites, implying that the capability of KaiC to repress its promoter is not sufficient to allow the clockwork to oscillate. The KaiC structure and the mutational analysis suggest that S431 and T426 may share a phosphate that can shuttle between these two residues. Because the phosphorylation status of KaiC oscillates over the daily cycle, and KaiC phosphorylation is essential for clock function as shown here, daily modulations of KaiC activity by phosphorylation at T432 and S431/T426 seem to be key components of the circadian clockwork in cyanobacteria.


    Organizational Affiliation

    Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
KaiC
A, B, E, F
519Synechococcus elongatus (strain PCC 7942)Gene Names: kaiC
EC: 2.7.11.1
Find proteins for Q79PF4 (Synechococcus elongatus (strain PCC 7942))
Go to UniProtKB:  Q79PF4
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
KaiC
C, D
519Synechococcus elongatus (strain PCC 7942)Gene Names: kaiC
EC: 2.7.11.1
Find proteins for Q79PF4 (Synechococcus elongatus (strain PCC 7942))
Go to UniProtKB:  Q79PF4
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ATP
Query on ATP

Download SDF File 
Download CCD File 
A, B, C, D, E, F
ADENOSINE-5'-TRIPHOSPHATE
C10 H16 N5 O13 P3
ZKHQWZAMYRWXGA-KQYNXXCUSA-N
 Ligand Interaction
MG
Query on MG

Download SDF File 
Download CCD File 
A, B, C, D, E, F
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  2 Unique
IDChainsTypeFormula2D DiagramParent
SEP
Query on SEP
A, B, E, F
L-PEPTIDE LINKINGC3 H8 N O6 PSER
TPO
Query on TPO
A, B, C, D, E, F
L-PEPTIDE LINKINGC4 H10 N O6 PTHR
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.8 Å
  • R-Value Free: 0.290 
  • R-Value Work: 0.250 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 132.873α = 90.00
b = 135.576β = 90.00
c = 204.951γ = 90.00
Software Package:
Software NamePurpose
RAVEphasing
DENZOdata reduction
SCALEPACKdata scaling
CNSrefinement
MLPHAREphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-04-19
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Source and taxonomy, Version format compliance
  • Version 1.3: 2013-03-06
    Type: Other