3GIN

Crystal structure of E454K-CBD1

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.193 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history. 

Literature

Structure and functional analysis of a Ca2+ sensor mutant of the na+/ca2+ exchanger

Chaptal, V., Ottolia, M., Mercado-Besserer, G., Nicoll, D.A., Philipson, K.D., Abramson, J.

(2009) J.Biol.Chem. 284: 14688-14692

  • DOI: 10.1074/jbc.C900037200

  • PubMed Abstract: 

    • The mammalian Na(+)/Ca(2+) exchanger, NCX1.1, serves as the main mechanism for Ca(2+) efflux across the sarcolemma following cardiac contraction. In addition to transporting Ca(2+), NCX1.1 activity is also strongly regulated by Ca(2+) binding to two ...

    The mammalian Na(+)/Ca(2+) exchanger, NCX1.1, serves as the main mechanism for Ca(2+) efflux across the sarcolemma following cardiac contraction. In addition to transporting Ca(2+), NCX1.1 activity is also strongly regulated by Ca(2+) binding to two intracellular regulatory domains, CBD1 and CBD2. The structures of both of these domains have been solved by NMR spectroscopy and x-ray crystallography, greatly enhancing our understanding of Ca(2+) regulation. Nevertheless, the mechanisms by which Ca(2+) regulates the exchanger remain incompletely understood. The initial NMR study showed that the first regulatory domain, CBD1, unfolds in the absence of regulatory Ca(2+). It was further demonstrated that a mutation of an acidic residue involved in Ca(2+) binding, E454K, prevents this structural unfolding. A contradictory result was recently obtained in a second NMR study in which Ca(2+) removal merely triggered local rearrangements of CBD1. To address this issue, we solved the crystal structure of the E454K-CBD1 mutant and performed electrophysiological analyses of the full-length exchanger with mutations at position 454. We show that the lysine substitution replaces the Ca(2+) ion at position 1 of the CBD1 Ca(2+) binding site and participates in a charge compensation mechanism. Electrophysiological analyses show that mutations of residue Glu-454 have no impact on Ca(2+) regulation of NCX1.1. Together, structural and mutational analyses indicate that only two of the four Ca(2+) ions that bind to CBD1 are important for regulating exchanger activity.

    Organizational Affiliation: 

    Department of Physiology and Cardiovascular Research Laboratories, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Sodium/calcium exchanger 1
A, B
160Canis lupus familiarisMutation(s): 1 
Gene Names: SLC8A1 (NCX1)
Find proteins for P23685 (Canis lupus familiaris)
Go to Gene View: SLC8A1
Go to UniProtKB:  P23685
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA
Download SDF File 
Download CCD File 
A, B
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.4 Å
  • R-Value Free: 0.259 
  • R-Value Work: 0.193 
  • Space Group: P 41 21 2
Unit Cell:
Length (Å)Angle (°)
a = 91.858α = 90.00
b = 91.858β = 90.00
c = 65.590γ = 90.00
Software Package:
Software NamePurpose
BOSdata collection
SCALEPACKdata scaling
PHASERphasing
REFMACrefinement
HKL-2000data reduction

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-04-21
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Advisory, Version format compliance