3FI1

NhaA dimer model

Summary for 3FI1

• Entry DOI: 10.2210/pdb3fi1/pdb
• EMDB information: 5037
• Descriptor: Na(+)/H(+) antiporter nhaA (1 entity in total)
• Functional Keywords: membrane protein sodium proton antiporter, antiport, cell inner membrane, cell membrane, ion transport, membrane, sodium transport, transmembrane, transport, membrane protein
• Biological source: Escherichia coli K-12
• Total number of polymer chains: 1
• Total formula weight: 39846.58

Authors

Appel, M.,Hizlan, D.,Vinothkumar, K.R.,Ziegler, C.,Kuehlbrandt, W. (deposition date: 2008-12-10, release date: 2009-01-13, Last modification date: 2024-02-21)

Primary citation

Appel, M.,Hizlan, D.,Vinothkumar, K.R.,Ziegler, C.,Kuhlbrandt, W.
Conformations of NhaA, the Na/H exchanger from Escherichia coli, in the pH-activated and ion-translocating states
J.Mol.Biol., 386:351-365, 2009

PubMed Abstract: NhaA, the main sodium-proton exchanger in the inner membrane of Escherichia coli, regulates the cytosolic concentrations of H and Na. It is inactive at acidic pH, becomes active between pH 6 and pH 7, and reaches maximum activity at pH 8. By cryo-electron microscopy of two-dimensional crystals grown at pH 4 and incubated at higher pH, we identified two sequential conformational changes in the protein in response to pH or substrate ions. The first change is induced by a rise in pH from 6 to 7 and marks the transition from the inactive state to the pH-activated state. pH activation, which precedes the ion-induced conformational change, is accompanied by an overall expansion of the NhaA monomer and a local ordering of the N-terminus. The second conformational change is induced by the substrate ions Na and Li at pH above 7 and involves a 7-A displacement of helix IVp. This movement would cause a charge imbalance at the ion-binding site that may trigger the release of the substrate ion and open a periplasmic exit channel.

PubMed: 19135453
DOI: 10.1016/j.jmb.2008.12.042

Experimental method

ELECTRON CRYSTALLOGRAPHY (7 Å)