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

View Full Validation Report or Ramachandran Plots



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