期刊
ELIFE
卷 3, 期 -, 页码 -出版社
ELIFE SCIENCES PUBLICATIONS LTD
DOI: 10.7554/eLife.03583
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资金
- Max Planck Society
- Frankfurt Cluster of Excellence Macromolecular Complexes
- Frankfurt International Max Planck Research School
- Transport and communication across biological membranes [SFB 807]
- FCT (Portugal) [SFRH/BD/62643/2009]
- Fundação para a Ciência e a Tecnologia [SFRH/BD/62643/2009] Funding Source: FCT
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 pH8, where the transporter is highly active. The outward-open state was obtained by electron crystallography without sodium at pH4, where MjNhaP1 is inactive. Comparison of both structures reveals a 7 degrees tilt of the 6-helix bundle. Na-22(+) uptake measurements indicate non-cooperative transport with an activity maximum at pH7.5. 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 similar to 5 angstrom vertical relocation of the ion binding site to release the substrate ion into the cytoplasm.
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