3SD6

Crystal structure of the amino-terminal domain of human cardiac troponin C in complex with cadmium at 1.4 resolution.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.37 Å
  • R-Value Free: 0.148 
  • R-Value Work: 0.133 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

The structure of cardiac troponin C regulatory domain with bound Cd(2+) reveals a closed conformation and unique ion coordination.

Zhang, X.L.Tibbits, G.F.Paetzel, M.

(2013) Acta Crystallogr.,Sect.D 69: 722-734

  • DOI: 10.1107/S0907444913001182
  • Primary Citation of Related Structures:  3SWB, 4GJE, 4GJF, 4GJG

  • PubMed Abstract: 
  • The amino-terminal domain of cardiac troponin C (cNTnC) is an essential Ca(2+) sensor found in cardiomyocytes. It undergoes a conformational change upon Ca(2+) binding and transduces the signal to the rest of the troponin complex to initiate cardiac ...

    The amino-terminal domain of cardiac troponin C (cNTnC) is an essential Ca(2+) sensor found in cardiomyocytes. It undergoes a conformational change upon Ca(2+) binding and transduces the signal to the rest of the troponin complex to initiate cardiac muscle contraction. Two classical EF-hand motifs (EF1 and EF2) are present in cNTnC. Under physiological conditions, only EF2 binds Ca(2+); EF1 is a vestigial site that has lost its function in binding Ca(2+) owing to amino-acid sequence changes during evolution. Proteins with EF-hand motifs are capable of binding divalent cations other than calcium. Here, the crystal structure of wild-type (WT) human cNTnC in complex with Cd(2+) is presented. The structure of Cd(2+)-bound cNTnC with the disease-related mutation L29Q, as well as a structure with the residue differences D2N, V28I, L29Q and G30D (NIQD), which have been shown to have functional importance in Ca(2+) sensing at lower temperatures in ectothermic species, have also been determined. The structures resemble the overall conformation of NMR structures of Ca(2+)-bound cNTnC, but differ significantly from a previous crystal structure of Cd(2+)-bound cNTnC in complex with deoxycholic acid. The subtle structural changes observed in the region near the mutations may play a role in the increased Ca(2+) affinity. The 1.4 Å resolution WT cNTnC structure, which is the highest resolution structure yet obtained for cardiac troponin C, reveals a Cd(2+) ion coordinated in the canonical pentagonal bipyramidal geometry in EF2 despite three residues in the loop being disordered. A Cd(2+) ion found in the vestigial ion-binding site of EF1 is coordinated in a noncanonical `distorted' octahedral geometry. A comparison of the ion coordination observed within EF-hand-containing proteins for which structures have been solved in the presence of Cd(2+) is presented. A refolded WT cNTnC structure is also presented.


    Organizational Affiliation

    Department of Molecular Biology and Biochemistry, Simon Fraser University, South Science Building, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Troponin C, slow skeletal and cardiac muscles
A
89Homo sapiensGene Names: TNNC1 (TNNC)
Find proteins for P63316 (Homo sapiens)
Go to Gene View: TNNC1
Go to UniProtKB:  P63316
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ACT
Query on ACT

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Download CCD File 
A
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
 Ligand Interaction
CA
Query on CA

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

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Download CCD File 
A
CADMIUM ION
Cd
WLZRMCYVCSSEQC-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.37 Å
  • R-Value Free: 0.148 
  • R-Value Work: 0.133 
  • Space Group: P 61 2 2
Unit Cell:
Length (Å)Angle (°)
a = 49.576α = 90.00
b = 49.576β = 90.00
c = 116.041γ = 120.00
Software Package:
Software NamePurpose
PHASERphasing
MxDCdata collection
REFMACrefinement
HKL-2000data scaling
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-06-13
    Type: Initial release
  • Version 1.1: 2013-05-15
    Type: Database references
  • Version 1.2: 2017-11-08
    Type: Refinement description