Download Mendeley3D Em Map of the Sodium Proton Antiporter Mjnhap1 from Methanocaldococcus Jannaschii
Paulino, C., Woehlert, D., Yildiz, O., Kuhlbrandt, W.(2014) Elife 3
- PubMed: 25426803
- DOI: https://doi.org/10.7554/eLife.03583
- Primary Citation of Related Structures:
4CZB, 4D0A - 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 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.
Organizational Affiliation:
Department of Structural Biology, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
