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Publication Abstract from PubMed

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.

Structural basis for ion selectivity revealed by high-resolution crystal structure of Mg(2+) channel MgtE.,Takeda H, Hattori M, Nishizawa T, Yamashita K, Shah ST, Caffrey M, Maturana AD, Ishitani R, Nureki O Nat Commun. 2014 Nov 4;5:5374. doi: 10.1038/ncomms6374. PMID:25367295^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.