Download MendeleyCryo-EM structures of human magnesium channel MRS2 reveal gating and regulatory mechanisms.
Lai, L.T.F., Balaraman, J., Zhou, F., Matthies, D.(2023) Nat Commun 14: 7207-7207
- PubMed: 37938562
- DOI: https://doi.org/10.1038/s41467-023-42599-3
- Primary Citation of Related Structures:
8TUL, 8TUP - PubMed Abstract:
Magnesium ions (Mg 2+ ) play an essential role in cellular physiology. In mitochondria, protein and ATP synthesis and various metabolic pathways are directly regulated by Mg 2+ . MRS2, a magnesium channel located in the inner mitochondrial membrane, mediates the influx of Mg 2+ into the mitochondrial matrix and regulates Mg 2+ homeostasis. Knockdown of MRS2 in human cells leads to reduced uptake of Mg 2+ into mitochondria and disruption of the mitochondrial metabolism. Despite the importance of MRS2, the Mg 2+ translocation and regulation mechanisms of MRS2 are still unclear. Here, using cryo-EM we report the structures of human MRS2 in the presence and absence of Mg 2+ at 2.8 Å and 3.3 Å, respectively. From the homo-pentameric structures, we identify R332 and M336 as major gating residues, which are then tested using mutagenesis and two cellular divalent ion uptake assays. A network of hydrogen bonds is found connecting the gating residue R332 to the soluble domain, potentially regulating the gate. Two Mg 2+ -binding sites are identified in the MRS2 soluble domain, distinct from the two sites previously reported in CorA, a homolog of MRS2 in prokaryotes. Altogether, this study provides the molecular basis for understanding the Mg 2+ translocation and regulatory mechanisms of MRS2.
Organizational Affiliation:
Unit on Structural Biology, Division of Basic and Translational Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA.
