4AQR

Crystal structure of calmodulin in complex with the regulatory domain of a plasma-membrane Ca2+-ATPase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.216 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

A Bimodular Mechanism of Calcium Control in Eukaryotes

Tidow, H.Poulsen, L.R.Andreeva, A.Knudsen, M.Hein, K.L.Wiuf, C.Palmgren, M.G.Nissen, P.

(2012) Nature 491: 468

  • DOI: 10.1038/nature11539

  • PubMed Abstract: 
  • Calcium ions (Ca(2+)) have an important role as secondary messengers in numerous signal transduction processes, and cells invest much energy in controlling and maintaining a steep gradient between intracellular (∼0.1-micromolar) and extracellular (∼2 ...

    Calcium ions (Ca(2+)) have an important role as secondary messengers in numerous signal transduction processes, and cells invest much energy in controlling and maintaining a steep gradient between intracellular (∼0.1-micromolar) and extracellular (∼2-millimolar) Ca(2+) concentrations. Calmodulin-stimulated calcium pumps, which include the plasma-membrane Ca(2+)-ATPases (PMCAs), are key regulators of intracellular Ca(2+) in eukaryotes. They contain a unique amino- or carboxy-terminal regulatory domain responsible for autoinhibition, and binding of calcium-loaded calmodulin to this domain releases autoinhibition and activates the pump. However, the structural basis for the activation mechanism is unknown and a key remaining question is how calmodulin-mediated PMCA regulation can cover both basal Ca(2+) levels in the nanomolar range as well as micromolar-range Ca(2+) transients generated by cell stimulation. Here we present an integrated study combining the determination of the high-resolution crystal structure of a PMCA regulatory-domain/calmodulin complex with in vivo characterization and biochemical, biophysical and bioinformatics data that provide mechanistic insights into a two-step PMCA activation mechanism mediated by calcium-loaded calmodulin. The structure shows the entire PMCA regulatory domain and reveals an unexpected 2:1 stoichiometry with two calcium-loaded calmodulin molecules binding to different sites on a long helix. A multifaceted characterization of the role of both sites leads to a general structural model for calmodulin-mediated regulation of PMCAs that allows stringent, highly responsive control of intracellular calcium in eukaryotes, making it possible to maintain a stable, basal level at a threshold Ca(2+) concentration, where steep activation occurs.


    Organizational Affiliation

    Centre for Membrane Pumps in Cells and Disease - PUMPKIN, Aarhus University, Gustav Wieds Vej 10c, DK-8000 Aarhus C, Denmark.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CALMODULIN-7
A, B
149Arabidopsis thalianaMutation(s): 0 
Gene Names: CAM7
Find proteins for P59220 (Arabidopsis thaliana)
Go to UniProtKB:  P59220
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
CALCIUM-TRANSPORTING ATPASE 8, PLASMA MEMBRANE-TYPE
D
57Arabidopsis thalianaMutation(s): 0 
Gene Names: ACA8
EC: 7.2.2.10
Find proteins for Q9LF79 (Arabidopsis thaliana)
Go to UniProtKB:  Q9LF79
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download SDF File 
Download CCD File 
A, B
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.216 
  • Space Group: P 41 21 2
Unit Cell:
Length (Å)Angle (°)
a = 71.251α = 90.00
b = 71.251β = 90.00
c = 163.279γ = 90.00
Software Package:
Software NamePurpose
PHASERphasing
XDSdata reduction
PHENIXrefinement
XDSdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-10-17
    Type: Initial release
  • Version 1.1: 2012-11-07
    Type: Database references
  • Version 1.2: 2012-11-21
    Type: Database references