Abstract
Transporters of the Nramp (Natural resistance-associated macrophage protein) family import divalent transition metal ions into cells of most organisms. By supporting metal homeostasis, Nramps prevent diseases and disorders related to metal insufficiency or overload. Previous studies revealed that Nramps take on a LeuT fold and identified the metal-binding site. We present high-resolution structures of Deinococcus radiodurans (Dra)Nramp in three stable conformations of the transport cycle revealing that global conformational changes are supported by distinct coordination geometries of its physiological substrate, Mn2+, across conformations, and by conserved networks of polar residues lining the inner and outer gates. In addition, a high-resolution Cd2+-bound structure highlights differences in how Cd2+ and Mn2+ are coordinated by DraNramp. Complementary metal binding studies using isothermal titration calorimetry with a series of mutated DraNramp proteins indicate that the thermodynamic landscape for binding and transporting physiological metals like Mn2+ is different and more robust to perturbation than for transporting the toxic Cd2+ metal. Overall, the affinity measurements and high-resolution structural information on metal substrate binding provide a foundation for understanding the substrate selectivity of essential metal ion transporters like Nramps.
Original language | English (US) |
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Article number | e84006 |
Journal | eLife |
Volume | 12 |
DOIs | |
State | Published - Apr 2023 |
Externally published | Yes |
ASJC Scopus subject areas
- General Neuroscience
- General Biochemistry, Genetics and Molecular Biology
- General Immunology and Microbiology
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Dive into the research topics of 'High-resolution structures with bound Mn2+ and Cd2+ map the metal import pathway in an Nramp transporter'. Together they form a unique fingerprint.Datasets
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X-ray structure of the Deinococcus radiodurans Nramp/MntH divalent transition metal transporter WT in an occluded, manganese-bound state
Ray, S. (Contributor), Berry, S. P. (Contributor), Wilson, E. A. (Contributor), Zhang, C. H. (Contributor), Shekhar, M. (Contributor), Singharoy, A. (Contributor) & Gaudet, R. (Contributor), Protein Data Bank (PDB), May 3 2023
DOI: 10.2210/pdb8E60, https://www.wwpdb.org/pdb?id=pdb_00008e60
Dataset
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X-ray structure of the Deinococcus radiodurans Nramp/MntH divalent transition metal transporter M230A mutant in an inward-open, manganese-bound state
Ray, S. (Contributor), Berry, S. P. (Contributor), Wilson, E. A. (Contributor), Zhang, C. H. (Contributor), Shekhar, M. (Contributor), Singharoy, A. (Contributor) & Gaudet, R. (Contributor), Protein Data Bank (PDB), May 3 2023
DOI: 10.2210/pdb8E6I, https://www.wwpdb.org/pdb?id=pdb_00008e6i
Dataset
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X-ray structure of the Deinococcus radiodurans Nramp/MntH divalent transition metal transporter WTsoak in an occluded state
Ray, S. (Contributor), Berry, S. P. (Contributor), Wilson, E. A. (Contributor), Zhang, C. H. (Contributor), Shekhar, M. (Contributor), Singharoy, A. (Contributor) & Gaudet, R. (Contributor), Protein Data Bank (PDB), May 3 2023
DOI: 10.2210/pdb8E5V, https://www.wwpdb.org/pdb?id=pdb_00008e5v
Dataset