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  Conformations of NhaA, the Na+/H+ Exchanger from Escherichia coli, in the pH-Activated and Ion-Translocating States

Appel, M., Hizlan, D., Vinothkumar, K. R., Ziegler, C., & Kühlbrandt, W. (2009). Conformations of NhaA, the Na+/H+ Exchanger from Escherichia coli, in the pH-Activated and Ion-Translocating States. Journal of Molecular Biology, 388(3), 659-672. doi:10.1016/j.jmb.2009.03.010.

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 Creators:
Appel, Matthias1, Author           
Hizlan, Dilem1, Author           
Vinothkumar, Kutti Ragunath1, 2, Author           
Ziegler, Christine1, Author           
Kühlbrandt, Werner1, Author           
Affiliations:
1Department of Structural Biology, Max Planck Institute of Biophysics, Max Planck Society, ou_2068291              
2Structural Studies Division, MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB22QH, UK., ou_persistent22              

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Free keywords: electron microscopy; proton transport; membrane protein structure; sodium–proton antiporter; membrane transport
 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-Å 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.

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Language(s): eng - English
 Dates: 2008-12-112008-09-052008-12-152009-03-212009-05-08
 Publication Status: Published in print
 Pages: 14
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1016/j.jmb.2009.03.010
PMID: 19396973
 Degree: -

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Title: Journal of Molecular Biology
  Other : JMB
  Abbreviation : J. Mol. Biol.
Source Genre: Journal
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Publ. Info: Elsevier
Pages: - Volume / Issue: 388 (3) Sequence Number: - Start / End Page: 659 - 672 Identifier: ISSN: 0022-2836
CoNE: https://pure.mpg.de/cone/journals/resource/0022-2836