4EED

CorA coiled-coil mutant under Mg2+ presence


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.92 Å
  • R-Value Free: 0.351 
  • R-Value Work: 0.297 

wwPDB Validation 3D Report Full Report


This is version 1.2 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.USA 109: 18809-18814

  • DOI: 10.1073/pnas.1209018109
  • Primary Citation of Related Structures:  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 M ...

    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: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Magnesium transport protein CorA
A, B, C, D, E
330Thermotoga maritima (strain ATCC 43589 / MSB8 / DSM 3109 / JCM 10099)Gene Names: corA
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
CorA Superfamily Ion Transporters
Protein: 
CorA Mg2+ Transporter
Find proteins for Q9WZ31 (Thermotoga maritima (strain ATCC 43589 / MSB8 / DSM 3109 / JCM 10099))
Go to UniProtKB:  Q9WZ31
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MG
Query on MG

Download SDF File 
Download CCD File 
A, B, C, D, E
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

Unit Cell:
Length (Å)Angle (°)
a = 121.700α = 90.00
b = 132.500β = 90.00
c = 179.100γ = 90.00
Software Package:
Software NamePurpose
XSCALEdata scaling
XDSdata reduction
DENZOdata reduction
SCALEPACKdata scaling
REFMACrefinement
MxDCdata collection
PHASERphasing
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

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

Revision History 

  • Version 1.0: 2012-11-14
    Type: Initial release
  • Version 1.1: 2012-12-12
    Type: Database references
  • Version 1.2: 2017-11-15
    Type: Refinement description