2PQ3

N-Terminal Calmodulin Zn-Trapped Intermediate


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.30 Å
  • R-Value Free: 0.192 
  • R-Value Work: 0.143 
  • R-Value Observed: 0.143 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

A 1.3-A structure of zinc-bound N-terminal domain of calmodulin elucidates potential early ion-binding step.

Warren, J.T.Guo, Q.Tang, W.J.

(2007) J Mol Biol 374: 517-527

  • DOI: 10.1016/j.jmb.2007.09.048
  • Primary Citation of Related Structures:  
    2PQ3

  • PubMed Abstract: 
  • Calmodulin (CaM) is a 16.8-kDa calcium-binding protein involved in calcium-signal transduction. It is the canonical member of the EF-hand family of proteins, which are characterized by a helix-loop-helix calcium-binding motif. CaM is composed of N- and C-terminal globular domains (N-CaM and C-CaM), and within each domain there are two EF-hand motifs ...

    Calmodulin (CaM) is a 16.8-kDa calcium-binding protein involved in calcium-signal transduction. It is the canonical member of the EF-hand family of proteins, which are characterized by a helix-loop-helix calcium-binding motif. CaM is composed of N- and C-terminal globular domains (N-CaM and C-CaM), and within each domain there are two EF-hand motifs. Upon binding calcium, CaM undergoes a significant, global conformational change involving reorientation of the four helix bundles in each of its two domains. This conformational change upon ion binding is a key component of the signal transduction and regulatory roles of CaM, yet the precise nature of this transition is still unclear. Here, we present a 1.3-A structure of zinc-bound N-terminal calmodulin (N-CaM) solved by single-wavelength anomalous diffraction phasing of a selenomethionyl N-CaM. Our zinc-bound N-CaM structure differs from previously reported CaM structures and resembles calcium-free apo-calmodulin (apo-CaM), despite the zinc binding to both EF-hand motifs. Structural comparison with calcium-free apo-CaM, calcium-loaded CaM, and a cross-linked calcium-loaded CaM suggests that our zinc-bound N-CaM reveals an intermediate step in the initiation of metal ion binding at the first EF-hand motif. Our data also suggest that metal ion coordination by two key residues in the first metal-binding site represents an initial step in the conformational transition induced by metal binding. This is followed by reordering of the N-terminal region of the helix exiting from this first binding loop. This conformational switch should be incorporated into models of either stepwise conformational transition or flexible, dynamic energetic state sampling-based transition.


    Organizational Affiliation

    Biological Sciences Collegial Division, The University of Chicago, Chicago, IL 60637, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
CalmodulinA76Rattus norvegicusMutation(s): 0 
Gene Names: Calm1CalmCamCam1CaMI
Find proteins for P0DP29 (Rattus norvegicus)
Explore P0DP29 
Go to UniProtKB:  P0DP29
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CAC
Query on CAC

Download Ideal Coordinates CCD File 
B [auth A]CACODYLATE ION
C2 H6 As O2
OGGXGZAMXPVRFZ-UHFFFAOYSA-M
 Ligand Interaction
ZN
Query on ZN

Download Ideal Coordinates CCD File 
C [auth A], D [auth A]ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.30 Å
  • R-Value Free: 0.192 
  • R-Value Work: 0.143 
  • R-Value Observed: 0.143 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 35.211α = 90
b = 35.211β = 90
c = 143.294γ = 90
Software Package:
Software NamePurpose
SOLVEphasing
SHELXrefinement
PDB_EXTRACTdata extraction
HKL-2000data collection
HKL-2000data reduction
SCALEPACKdata scaling
CNSphasing
SHELXL-97refinement

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-10-16
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Derived calculations, Version format compliance