4CZB: Structure Of The Sodium Proton Antiporter Mjnhap1 From Methanocaldococcus Jannaschii At Ph 8

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{degree sign} tilt of the 6 helix bundle. 22Na+ 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 ~5 A vertical relocation of the ion binding site to release the substrate ion into the cytoplasm.
PDB ID: 4CZBDownload
MMDB ID: 125361
PDB Deposition Date: 2014/4/16
Updated in MMDB: 2014/12
Experimental Method:
x-ray diffraction
Resolution: 3.5  Å
Source Organism:
Similar Structures:
Biological Unit for 4CZB: dimeric; determined by author and by software (PQS)
Molecular Components in 4CZB
Label Count Molecule
Proteins (2 molecules)
Na(+)/h(+) Antiporter 1(Gene symbol: MJ_RS00290)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB