2L1R

The structure of the calcium-sensitizer, dfbp-o, in complex with the N-domain of troponin C and the switch region of troponin I


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the least restraint violations 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

A structural and functional perspective into the mechanism of Ca(2+)-sensitizers that target the cardiac troponin complex.

Robertson, I.M.Sun, Y.B.Li, M.X.Sykes, B.D.

(2010) J Mol Cell Cardiol 49: 1031-1041

  • DOI: 10.1016/j.yjmcc.2010.08.019
  • Primary Citation of Related Structures:  
    2L1R

  • PubMed Abstract: 
  • The Ca(2+) dependent interaction between troponin I (cTnI) and troponin C (cTnC) triggers contraction in heart muscle. Heart failure is characterized by a decrease in cardiac output, and compounds that increase the sensitivity of cardiac muscle to Ca(2+) have therapeutic potential ...

    The Ca(2+) dependent interaction between troponin I (cTnI) and troponin C (cTnC) triggers contraction in heart muscle. Heart failure is characterized by a decrease in cardiac output, and compounds that increase the sensitivity of cardiac muscle to Ca(2+) have therapeutic potential. The Ca(2+)-sensitizer, levosimendan, targets cTnC; however, detailed understanding of its mechanism has been obscured by its instability. In order to understand how this class of positive inotropes function, we investigated the mode of action of two fluorine containing novel analogs of levosimendan; 2',4'-difluoro(1,1'-biphenyl)-4-yloxy acetic acid (dfbp-o) and 2',4'-difluoro(1,1'-biphenyl)-4-yl acetic acid (dfbp). The affinities of dfbp and dfbp-o for the regulatory domain of cTnC were measured in the absence and presence of cTnI by NMR spectroscopy, and dfbp-o was found to bind more strongly than dfbp. Dfbp-o also increased the affinity of cTnI for cTnC. Dfbp-o increased the Ca(2+)-sensitivity of demembranated cardiac trabeculae in a manner similar to levosimendan. The high resolution NMR solution structure of the cTnC-cTnI-dfbp-o ternary complex showed that dfbp-o bound at the hydrophobic interface formed by cTnC and cTnI making critical interactions with residues such as Arg147 of cTnI. In the absence of cTnI, docking localized dfbp-o to the same position in the hydrophobic groove of cTnC. The structural and functional data reveal that the levosimendan class of Ca(2+)-sensitizers work by binding to the regulatory domain of cTnC and stabilizing the pivotal cTnC-cTnI regulatory unit via a network of hydrophobic and electrostatic interactions, in contrast to the destabilizing effects of antagonists such as W7 at the same interface.


    Organizational Affiliation

    Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Troponin CA89Homo sapiensMutation(s): 0 
Gene Names: TNNC1TNNC
UniProt & NIH Common Fund Data Resources
Find proteins for P63316 (Homo sapiens)
Explore P63316 
Go to UniProtKB:  P63316
PHAROS:  P63316
Protein Feature View
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  • Reference Sequence
  • Find similar proteins by:  Sequence   |   Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Troponin IB20Homo sapiensMutation(s): 0 
Gene Names: TNNI3TNNC1
UniProt & NIH Common Fund Data Resources
Find proteins for P19429 (Homo sapiens)
Explore P19429 
Go to UniProtKB:  P19429
PHAROS:  P19429
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SXK (Subject of Investigation/LOI)
Query on SXK

Download Ideal Coordinates CCD File 
D [auth A][(2',4'-difluorobiphenyl-4-yl)oxy]acetic acid
C14 H10 F2 O3
OIXUCWSQNBIMBL-UHFFFAOYSA-N
 Ligand Interaction
CA
Query on CA

Download Ideal Coordinates CCD File 
C [auth A]CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Binding Affinity Annotations 
IDSourceBinding Affinity
SXK PDBBind:  2L1R Kd: 2.70e+5 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the least restraint violations 
  • OLDERADO: 2L1R Olderado

Structure Validation

View Full Validation Report




Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-08-18
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance