4EHQ

Crystal Structure of Calmodulin Binding Domain of Orai1 in Complex with Ca2+/Calmodulin Displays a Unique Binding Mode


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9005 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.179 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystal structure of calmodulin binding domain of orai1 in complex with ca2+*calmodulin displays a unique binding mode.

Liu, Y.Zheng, X.Mueller, G.A.Sobhany, M.Derose, E.F.Zhang, Y.London, R.E.Birnbaumer, L.

(2012) J.Biol.Chem. 287: 43030-43041

  • DOI: 10.1074/jbc.M112.380964

  • PubMed Abstract: 
  • Orai1 is a plasma membrane protein that in its tetrameric form is responsible for calcium influx from the extracellular environment into the cytosol in response to interaction with the Ca(2+)-depletion sensor STIM1. This is followed by a fast Ca(2+)· ...

    Orai1 is a plasma membrane protein that in its tetrameric form is responsible for calcium influx from the extracellular environment into the cytosol in response to interaction with the Ca(2+)-depletion sensor STIM1. This is followed by a fast Ca(2+)·calmodulin (CaM)-dependent inhibition, resulting from CaM binding to an Orai1 region called the calmodulin binding domain (CMBD). The interaction between Orai1 and CaM at the atomic level remains unknown. Here, we report the crystal structure of a CaM·Orai1-CMBD complex showing one CMBD bound to the C-terminal lobe of CaM, differing from other CaM-target protein complexes, in which both N- and C-terminal lobes of CaM (CaM-N and CaM-C) are involved in target binding. Orai1-CMBD binds CaM-C mainly through hydrophobic interactions, primarily involving residue Trp(76) of Orai1-CMBD, which interacts with the hydrophobic pocket of CaM-C. However, NMR data, isothermal titration calorimetry data, and pulldown assays indicated that CaM-N and CaM-C both can bind Orai1-CMBD, with CaM-N having ∼4 times weaker affinity than CaM-C. Pulldown assays of a Orai1-CMBD(W76E) mutant, gel filtration chromatography data, and NOE signals indicated that CaM-N and CaM-C can each bind one Orai1-CMBD. Thus our studies support an unusual, extended 1:2 binding mode of CaM to Orai1-CMBDs, and quantify the affinity of Orai1 for CaM. We propose a two-step mechanism for CaM-dependent Orai1 inactivation initiated by binding of the C-lobe of CaM to the CMBD of one Orai1 followed by the binding of the N-lobe of CaM to the CMBD of a neighboring Orai1.


    Organizational Affiliation

    Laboratory of Neurobiology, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA. liuy3@niehs.nih.gov




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Calmodulin
A
148Rattus norvegicusMutation(s): 0 
Gene Names: Calm1 (Calm, Cam, Cam1, CaMI)
Find proteins for P0DP29 (Rattus norvegicus)
Go to UniProtKB:  P0DP29
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Calcium release-activated calcium channel protein 1
G
20Homo sapiensMutation(s): 0 
Gene Names: ORAI1 (CRACM1, TMEM142A)
Find proteins for Q96D31 (Homo sapiens)
Go to Gene View: ORAI1
Go to UniProtKB:  Q96D31
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

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

Download SDF File 
Download CCD File 
A, G
GAMMA-BUTYROLACTONE
DIHYDROFURAN-2(3H)-ONE
C4 H6 O2
YEJRWHAVMIAJKC-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9005 Å
  • R-Value Free: 0.216 
  • R-Value Work: 0.179 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 100.074α = 90.00
b = 24.709β = 100.10
c = 60.903γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data collection
PHENIXphasing
PHENIXmodel building
SCALEPACKdata scaling
PHENIXrefinement
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-11-07
    Type: Initial release
  • Version 1.1: 2012-11-14
    Type: Database references
  • Version 1.2: 2013-01-02
    Type: Database references