2R28

The complex Structure of Calmodulin Bound to a Calcineurin Peptide


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.86 Å
  • R-Value Free: 0.280 
  • R-Value Work: 0.230 
  • R-Value Observed: 0.230 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

The complex structure of calmodulin bound to a calcineurin peptide.

Ye, Q.Wang, H.Zheng, J.Wei, Q.Jia, Z.

(2008) Proteins 73: 19-27

  • DOI: 10.1002/prot.22032
  • Primary Citation of Related Structures:  
    2R28

  • PubMed Abstract: 
  • The activity of the protein phosphatase calcineurin (CN) is regulated by an autoinhibition mechanism wherein several domains from its catalytic A subunit, including the calmodulin binding domain (CaMBD), block access to its active site. Upon binding of C ...

    The activity of the protein phosphatase calcineurin (CN) is regulated by an autoinhibition mechanism wherein several domains from its catalytic A subunit, including the calmodulin binding domain (CaMBD), block access to its active site. Upon binding of Ca2+ and calmodulin (Ca2+/CaM) to CaMBD, the autoinhibitory domains dissociate from the catalytic groove, thus activating the enzyme. To date, the structure of the CN/CaM/Ca2+ complex has not been determined in its entirety. Previously, we determined the structure of a fusion protein consisting of CaM and a 25-residue peptide taken from the CaMBD, joined by a 5-glycine linker. This structure revealed a novel CaM binding motif. However, the presence of the extraneous glycine linker cast doubt on the authenticity of this structure as an accurate representation of CN/CaM binding in vivo. Thus, here, we have determined the crystal structure of CaM complexed with the 25-residue CaMBD peptide without the glycine linker at a resolution of 2.1 A. The structure is essentially identical to the fusion construction which displays CaM bound to the CaMBD peptide as a dimer with an open, elongated conformation. The N-lobe from one molecule and C-lobe from another encompass and bind the CaMBD peptide. Thus, it validates the existence of this novel CaM binding motif. Our experiments suggest that the dimeric CaM/CaMBD complex exists in solution, which is unambiguously validated using a carefully-designed CaM-sepharose pull-down experiment. We discuss structural features that produce this novel binding motif, including the role of the CaMBD peptide residues Arg-408, Val-409, and Phe-410, which work to provide rigidity to the otherwise flexible central CaM helix joining the N- and C-lobes, ultimately keeping these lobes apart and forcing "head-to-tail" dimerization to attain the requisite N- and C-lobe pairing for CaMBD binding.


    Organizational Affiliation

    Department of Biochemistry, Queen's University, Canada.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Calmodulin AB149Homo sapiensMutation(s): 0 
Gene Names: CALM1CALMCAMCAM1
Find proteins for P0DP23 (Homo sapiens)
Explore P0DP23 
Go to UniProtKB:  P0DP23
NIH Common Fund Data Resources
PHAROS:  P0DP23
Protein Feature View
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Serine/threonine-protein phosphatase 2B catalytic subunit alpha isoform CD25Homo sapiensMutation(s): 0 
Gene Names: PPP3CACALNACNA
EC: 3.1.3.16
Find proteins for Q08209 (Homo sapiens)
Explore Q08209 
Go to UniProtKB:  Q08209
NIH Common Fund Data Resources
PHAROS:  Q08209
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.86 Å
  • R-Value Free: 0.280 
  • R-Value Work: 0.230 
  • R-Value Observed: 0.230 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 120.7α = 90
b = 43.2β = 109.9
c = 70.9γ = 90
Software Package:
Software NamePurpose
ADSCdata collection
PHASESphasing
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-07-01
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance