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-Structure paper
Title | Structure and transport mechanism of the sodium/proton antiporter MjNhaP1. |
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Journal, issue, pages | Elife, Vol. 3, Page e03583, Year 2014 |
Publish date | Nov 26, 2014 |
Authors | Cristina Paulino / David Wöhlert / Ekaterina Kapotova / Özkan Yildiz / Werner Kühlbrandt / |
PubMed Abstract | Sodium/proton antiporters are essential for sodium and pH homeostasis and play a major role in human health and disease. We determined the structures of the archaeal sodium/proton antiporter MjNhaP1 ...Sodium/proton antiporters are essential for sodium and pH homeostasis and play a major role in human health and disease. We determined the structures of the archaeal sodium/proton antiporter MjNhaP1 in two complementary states. The inward-open state was obtained by x-ray crystallography in the presence of sodium at pH 8, where the transporter is highly active. The outward-open state was obtained by electron crystallography without sodium at pH 4, where MjNhaP1 is inactive. Comparison of both structures reveals a 7° tilt of the 6 helix bundle. (22)Na(+) uptake measurements indicate non-cooperative transport with an activity maximum at pH 7.5. We conclude that binding of a Na(+) ion from the outside induces helix movements that close the extracellular cavity, open the cytoplasmic funnel, and result in a ∼5 Å vertical relocation of the ion binding site to release the substrate ion into the cytoplasm. |
External links | Elife / PubMed:25426803 / PubMed Central |
Methods | EM (electron crystallography) / X-ray diffraction |
Resolution | 3.5 - 6.0 Å |
Structure data | EMDB-2636, PDB-4d0a: PDB-4czb: |
Chemicals | ChemComp-K: ChemComp-TAM: |
Source |
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Keywords | MEMBRANE PROTEIN / ANTIPORTER / TRANSPORTER / EXCHANGER / CPA / TRANSPORT PROTEIN |