Novel Mg ²⁺ binding sites in the cytoplasmic domain of the MgtE Mg ²⁺ channels revealed by X-ray crystal structures.

ABSTRACT: MgtE is a Mg ²⁺-selective channel regulated by the intracellular Mg ²⁺ concentration. MgtE family proteins are highly conserved in all domains of life and contribute to cellular Mg ²⁺ homeostasis. In humans, mutations in the SLC41 proteins, the eukaryotic counterparts of the bacterial MgtE, are known to be associated with various diseases. The first MgtE structure from a thermophilic bacterium, Thermus thermophilus, revealed that MgtE forms a homodimer consisting of transmembrane and cytoplasmic domains with a plug helix connecting the two and that the cytoplasmic domain possesses multiple Mg ²⁺ binding sites. Structural and electrophysiological analyses revealed that the dissociation of Mg ²⁺ ions from the cytoplasmic domain induces structural changes in the cytoplasmic domain, leading to channel opening. Thus, previous works showed the importance of MgtE cytoplasmic Mg ²⁺ binding sites. Nevertheless, due to the limited structural information on MgtE from different species, the conservation and diversity of the cytoplasmic Mg ²⁺ binding site in MgtE family proteins remain unclear. Here, we report crystal structures of the Mg ²⁺-bound MgtE cytoplasmic domains from two different bacterial species, Chryseobacterium hispalense and Clostridiales bacterium, and identify multiple Mg ²⁺ binding sites, including ones that were not observed in the previous MgtE structure. These structures reveal the conservation and diversity of the cytoplasmic Mg ²⁺ binding site in the MgtE family proteins.

SUBMITTER: Wang M 

PROVIDER: S-EPMC10200709 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature