1Y6W

Trapped intermediate of calmodulin


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.220 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structure of a Trapped Intermediate of Calmodulin: Calcium Regulation of EF-hand Proteins from a New Perspective.

Grabarek, Z.

(2005) J.Mol.Biol. 346: 1351-1366

  • DOI: 10.1016/j.jmb.2005.01.004

  • PubMed Abstract: 
  • Calmodulin (CaM) is a multifunctional Ca2+-binding protein that regulates the activity of many enzymes in response to changes in the intracellular Ca2+ concentration. There are two globular domains in CaM, each containing a pair of helix-loop-helix C ...

    Calmodulin (CaM) is a multifunctional Ca2+-binding protein that regulates the activity of many enzymes in response to changes in the intracellular Ca2+ concentration. There are two globular domains in CaM, each containing a pair of helix-loop-helix Ca2+-binding motifs called EF-hands. Ca2+-binding induces the opening of both domains thereby exposing hydrophobic pockets that provide binding sites for the target enzymes. Here, I present a 2.4 A resolution structure of a calmodulin mutant (CaM41/75) in which the N-terminal domain is locked in the closed conformation by a disulfide bond. CaM41/75 crystallized in a tetragonal lattice with the Ca2+ bound in all four EF-hands. In the closed N-terminal domain Ca ions are coordinated by the four protein ligands in positions 1, 3, 5 and 7 of the loop, and by two solvent ligands. The glutamate side-chain in the 12th position of the loop (Glu31 in site I and Glu67 in site II), which in the wild-type protein provides a bidentate Ca2+ ligand, remains in a distal position. Based on a comparison of CaM41/75 with other CaM and troponin C structures a detailed two-step mechanism of the Ca2+-binding process is proposed. Initially, the Ca2+ binds to the N-terminal part of the loop, thus generating a rigid link between the incoming helix (helix A, or helix C) and the central beta structure involving the residues in the sixth, seventh and eighth position of the loop. Then, the exiting helix (helix B or helix D) rotates causing the glutamate ligand in the 12th position to move into the vicinity of the immobilized Ca2+. An adjustment of the phi, psi backbone dihedral angles of the Ile residue in the eighth position is necessary and sufficient for the helix rotation and functions as a hinge. The model allows for a significant independence of the Ca2+-binding sites in a two-EF-hand domain.


    Organizational Affiliation

    Boston Biomedical Research Institute, Watertown, MA 02472, USA. grabarek@bbri.org




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Calmodulin
A
148Homo sapiensGene Names: CALM1 (CALM, CAM, CAM1)
Find proteins for P0DP23 (Homo sapiens)
Go to Gene View: CALM1
Go to UniProtKB:  P0DP23
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download SDF File 
Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
MPD
Query on MPD

Download SDF File 
Download CCD File 
A
(4S)-2-METHYL-2,4-PENTANEDIOL
C6 H14 O2
SVTBMSDMJJWYQN-YFKPBYRVSA-N
 Ligand Interaction
TBU
Query on TBU

Download SDF File 
Download CCD File 
A
TERTIARY-BUTYL ALCOHOL
2-METHYL-2-PROPANOL
C4 H10 O
DKGAVHZHDRPRBM-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
MSE
Query on MSE
A
L-PEPTIDE LINKINGC5 H11 N O2 SeMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.220 
  • Space Group: P 43 21 2
Unit Cell:
Length (Å)Angle (°)
a = 109.875α = 90.00
b = 109.875β = 90.00
c = 42.640γ = 90.00
Software Package:
Software NamePurpose
SHARPphasing
DENZOdata reduction
SCALEPACKdata scaling
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2004-12-07 
  • Released Date: 2005-03-01 
  • Deposition Author(s): Grabarek, Z.

Revision History 

  • Version 1.0: 2005-03-01
    Type: Initial release
  • Version 1.1: 2007-10-16
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance