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Crystal structure o...
Crystal structure of the sodium-proton antiporter NhaA dimer and new mechanistic insights
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Lee, Chiara (author)
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Yashiro, Shoko (author)
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Dotson, David L. (author)
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- Uzdavinys, Povilas (author)
- Stockholms universitet,Institutionen för biokemi och biofysik
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Iwata, So (author)
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Sansom, Mark S. P. (author)
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- von Ballmoos, Christoph (author)
- Stockholms universitet,Institutionen för biokemi och biofysik
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Beckstein, Oliver (author)
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- Drew, David (author)
- Stockholms universitet,Institutionen för biokemi och biofysik,Imperial College London, England
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Cameron, Alexander D. (author)
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(creator_code:org_t)
- 2014-11-24
- 2014
- English.
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In: The Journal of General Physiology. - : Rockefeller University Press. - 0022-1295 .- 1540-7748. ; 144:6, s. 529-544
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Abstract
Subject headings
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- Sodium-proton antiporters rapidly exchange protons and sodium ions across the membrane to regulate intracellular pH, cell volume, and sodium concentration. How ion binding and release is coupled to the conformational changes associated with transport is not clear. Here, we report a crystal form of the prototypical sodium-proton antiporter NhaA from Escherichia coli in which the protein is seen as a dimer. In this new structure, we observe a salt bridge between an essential aspartic acid (Asp163) and a conserved lysine (Lys300). An equivalent salt bridge is present in the homologous transporter NapA, but not in the only other known crystal structure of NhaA, which provides the foundation of most existing structural models of electrogenic sodium-proton antiport. Molecular dynamics simulations show that the stability of the salt bridge is weakened by sodium ions binding to Asp164 and the neighboring Asp163. This suggests that the transport mechanism involves Asp163 switching between forming a salt bridge with Lys300 and interacting with the sodium ion. pK(a) calculations suggest that Asp163 is highly unlikely to be protonated when involved in the salt bridge. As it has been previously suggested that Asp163 is one of the two residues through which proton transport occurs, these results have clear implications to the current mechanistic models of sodium-proton antiport in NhaA.
Subject headings
- NATURVETENSKAP -- Biologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences (hsv//eng)
Keyword
- Biochemistry
- biokemi
Publication and Content Type
- ref (subject category)
- art (subject category)
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- By the author/editor
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Lee, Chiara
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Yashiro, Shoko
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Dotson, David L.
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Uzdavinys, Povil ...
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Iwata, So
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Sansom, Mark S. ...
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show more...
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von Ballmoos, Ch ...
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Beckstein, Olive ...
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Drew, David
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Cameron, Alexand ...
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show less...
- About the subject
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Biological Scien ...
- Articles in the publication
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The Journal of G ...
- By the university
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Stockholm University