4EEB

CorA coiled-coil mutant under Mg2+ absence


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.80 Å
  • R-Value Free: 0.343 
  • R-Value Work: 0.299 
  • R-Value Observed: 0.301 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Structural asymmetry in the magnesium channel CorA points to sequential allosteric regulation.

Pfoh, R.Li, A.Chakrabarti, N.Payandeh, J.Pomes, R.Pai, E.F.

(2012) Proc Natl Acad Sci U S A 109: 18809-18814

  • DOI: 10.1073/pnas.1209018109
  • Primary Citation of Related Structures:  
    4EED, 4EEB

  • PubMed Abstract: 
  • Magnesium ions (Mg(2+)) are essential for life, but the mechanisms regulating their transport into and out of cells remain poorly understood. The CorA-Mrs2-Alr1 superfamily of Mg(2+) channels represents the most prevalent group of proteins enabling Mg(2+) ions to cross membranes ...

    Magnesium ions (Mg(2+)) are essential for life, but the mechanisms regulating their transport into and out of cells remain poorly understood. The CorA-Mrs2-Alr1 superfamily of Mg(2+) channels represents the most prevalent group of proteins enabling Mg(2+) ions to cross membranes. Thermotoga maritima CorA (TmCorA) is the only member of this protein family whose complete 3D fold is known. Here, we report the crystal structure of a mutant in the presence and absence of divalent ions and compare it with previous divalent ion-bound TmCorA structures. With Mg(2+) present, this structure shows binding of a hydrated Mg(2+) ion to the periplasmic Gly-Met-Asn (GMN) motif, revealing clues of ion selectivity in this unique channel family. In the absence of Mg(2+), TmCorA displays an unexpected asymmetric conformation caused by radial and lateral tilts of protomers that leads to bending of the central, pore-lining helix. Molecular dynamics simulations support these movements, including a bell-like deflection. Mass spectrometric analysis confirms that major proteolytic cleavage occurs within a region that is selectively exposed by such a bell-like bending motion. Our results point to a sequential allosteric model of regulation, where intracellular Mg(2+) binding locks TmCorA in a symmetric, transport-incompetent conformation and loss of intracellular Mg(2+) causes an asymmetric, potentially influx-competent conformation of the channel.


    Organizational Affiliation

    Department of Biochemistry, University of Toronto, Toronto, ON, Canada, M5G 1L7.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Magnesium transport protein CorA ABCDE330Thermotoga maritimaMutation(s): 2 
Gene Names: corATM_0561
Membrane protein
Mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
CorA Superfamily Ion Transporters
Protein: 
CorA Mg2+ Transporter, coiled-coil mutant in the absence of Mg2+
Find proteins for Q9WZ31 (Thermotoga maritima (strain ATCC 43589 / MSB8 / DSM 3109 / JCM 10099))
Explore Q9WZ31 
Go to UniProtKB:  Q9WZ31
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.80 Å
  • R-Value Free: 0.343 
  • R-Value Work: 0.299 
  • R-Value Observed: 0.301 
  • Space Group: P 21 21 2
  • Diffraction Data DOI: 10.15785/SBGRID/127 SBGrid
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 125.6α = 90
b = 221.9β = 90
c = 106.8γ = 90
Software Package:
Software NamePurpose
PHASERphasing
REFMACrefinement
PDB_EXTRACTdata extraction
MxDCdata collection
XDSdata reduction
XSCALEdata scaling

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

  • Deposited Date: 2012-03-28 
  • Released Date: 2012-11-14 
  • Deposition Author(s): Pfoh, R., Pai, E.F.

Revision History  (Full details and data files)

  • Version 1.0: 2012-11-14
    Type: Initial release
  • Version 1.1: 2012-12-12
    Changes: Database references