Crystal structure of magnesium transporter MgtE cytosolic domain, Mg2+ bound form

Experimental Data Snapshot

  • Resolution: 2.30 Å
  • R-Value Free: 0.286 
  • R-Value Work: 0.256 
  • R-Value Observed: 0.256 

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Crystal structure of the MgtE Mg(2+) transporter

Hattori, M.Tanaka, Y.Fukai, S.Ishitani, R.Nureki, O.

(2007) Nature 448: 1072-1075

  • DOI: https://doi.org/10.1038/nature06093
  • Primary Citation of Related Structures:  
    2YVX, 2YVY, 2YVZ

  • PubMed Abstract: 

    The magnesium ion Mg2+ is a vital element involved in numerous physiological processes. Mg2+ has the largest hydrated radius among all cations, whereas its ionic radius is the smallest. It remains obscure how Mg2+ transporters selectively recognize and dehydrate the large, fully hydrated Mg2+ cation for transport. Recently the crystal structures of the CorA Mg2+ transporter were reported. The MgtE family of Mg2+ transporters is ubiquitously distributed in all phylogenetic domains, and human homologues have been functionally characterized and suggested to be involved in magnesium homeostasis. However, the MgtE transporters have not been thoroughly characterized. Here we determine the crystal structures of the full-length Thermus thermophilus MgtE at 3.5 A resolution, and of the cytosolic domain in the presence and absence of Mg2+ at 2.3 A and 3.9 A resolutions, respectively. The transporter adopts a homodimeric architecture, consisting of the carboxy-terminal five transmembrane domains and the amino-terminal cytosolic domains, which are composed of the superhelical N domain and tandemly repeated cystathionine-beta-synthase domains. A solvent-accessible pore nearly traverses the transmembrane domains, with one potential Mg2+ bound to the conserved Asp 432 within the pore. The transmembrane (TM)5 helices from both subunits close the pore through interactions with the 'connecting helices', which connect the cystathionine-beta-synthase and transmembrane domains. Four putative Mg2+ ions are bound at the interface between the connecting helices and the other domains, and this may lock the closed conformation of the pore. A structural comparison of the two states of the cytosolic domains showed the Mg2+-dependent movement of the connecting helices, which might reorganize the transmembrane helices to open the pore. These findings suggest a homeostasis mechanism, in which Mg2+ bound between cytosolic domains regulates Mg2+ flux by sensing the intracellular Mg2+ concentration. Whether this presumed regulation controls gating of an ion channel or opening of a secondary active transporter remains to be determined.

  • Organizational Affiliation

    Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Mg2+ transporter MgtE278Thermus thermophilus HB8Mutation(s): 0 
Find proteins for Q5SMG8 (Thermus thermophilus (strain ATCC 27634 / DSM 579 / HB8))
Explore Q5SMG8 
Go to UniProtKB:  Q5SMG8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ5SMG8
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.30 Å
  • R-Value Free: 0.286 
  • R-Value Work: 0.256 
  • R-Value Observed: 0.256 
  • Space Group: P 65 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 57.727α = 90
b = 57.727β = 90
c = 317.561γ = 120
Software Package:
Software NamePurpose
ADSCdata collection
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-09-04
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Source and taxonomy, Version format compliance
  • Version 1.2: 2024-03-13
    Changes: Data collection, Database references, Derived calculations