4U9L: Structure Of A Membrane Protein

Magnesium is the most abundant divalent cation in living cells and is crucial to several biological processes. MgtE is a Mg(2+) channel distributed in all domains of life that contributes to the maintenance of cellular Mg(2+) homeostasis. Here we report the high-resolution crystal structures of the transmembrane domain of MgtE, bound to Mg(2+), Mn(2+) and Ca(2+). The high-resolution Mg(2+)-bound crystal structure clearly visualized the hydrated Mg(2+) ion within its selectivity filter. Based on those structures and biochemical analyses, we propose a cation selectivity mechanism for MgtE in which the geometry of the hydration shell of the fully hydrated Mg(2+) ion is recognized by the side-chain carboxylate groups in the selectivity filter. This is in contrast to the K(+)-selective filter of KcsA, which recognizes a dehydrated K(+) ion. Our results further revealed a cation-binding site on the periplasmic side, which regulate channel opening and prevents conduction of near-cognate cations.
PDB ID: 4U9LDownload
MMDB ID: 125267
PDB Deposition Date: 2014/8/6
Updated in MMDB: 2014/12
Experimental Method:
x-ray diffraction
Resolution: 2.3  Å
Source Organism:
Similar Structures:
Biological Unit for 4U9L: dimeric; determined by author and by software (PISA)
Molecular Components in 4U9L
Label Count Molecule
Proteins (2 molecules)
Magnesium Transporter Mgte(Gene symbol: TTHA1060)
Molecule annotation
Chemicals (6 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB