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  Electrogenic Cation Binding in the Electroneutral Na+/H+ Antiporter of Pyrococcus abyssi

Călinescu, O., Linder, M., Wöhlert, D., Yildiz, Ö., Kühlbrandt, W., & Fendler, K. (2016). Electrogenic Cation Binding in the Electroneutral Na+/H+ Antiporter of Pyrococcus abyssi. The Journal of Biological Chemistry, 291(52), 26786-26793. doi:10.1074/jbc.M116.761080.

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 Creators:
Călinescu, Octavian1, 2, Author           
Linder, Mark1, 3, 4, Author           
Wöhlert, David3, Author           
Yildiz, Özkan3, Author           
Kühlbrandt, Werner3, Author           
Fendler, Klaus1, Author           
Affiliations:
1Department of Biophysical Chemistry, Max Planck Institute of Biophysics, Max Planck Society, ou_2068289              
2Department of Biophysics, “Carol Davila” University of Medicine and Pharmacy, 050474 Bucharest, Romania, ou_persistent22              
3Department of Structural Biology, Max Planck Institute of Biophysics, Max Planck Society, ou_2068291              
4Central Electron Microscopy Facility, Max Planck Institute of Biophysics, Max Planck Society, ou_3249263              

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Free keywords: archaea; electrophysiology; membrane transport; pH regulation; sodium-proton exchange; PaNhaP; solid supported membrane
 Abstract: Na+H+ antiporters in the CPA1 branch of the cation proton antiporter family drive the electroneutral exchange of H+ against Na+ ions and ensure pH homeostasis in eukaryotic and prokaryotic organisms. Although their transport cycle is overall electroneutral, specific partial reactions are electrogenic. Here, we present an electrophysiological study of the PaNhaP Na+H+ antiporter from Pyrococcus abyssi reconstituted into liposomes. Positive transient currents were recorded upon addition of Na+ to PaNhaP proteoliposomes, indicating a reaction where positive charge is rapidly displaced into the proteoliposomes with a rate constant of k > 200 s-1. We attribute the recorded currents to an electrogenic reaction that includes Na+ binding and possibly occlusion. Subsequently, positive charge is transported out of the cell during H+ binding, so that the overall reaction is electroneutral. We show that the differences in pH profile and Na+ affinity of PaNhaP and the related MjNhaP1 from Methanocaldococcus jannaschii can be attributed to an additional negatively charged glutamate residue in PaNhaP. The results are discussed in the context of the physiological function of PaNhaP and other microbial Na+H+ exchangers. We propose that both, electroneutral and electrogenic Na+H+ antiporters, represent a carefully tuned self-regulatory system, which drives the cytoplasmic pH back to neutral after any deviation.

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Language(s): eng - English
 Dates: 2016-10-042017-11-072016-11-072016-12-23
 Publication Status: Published in print
 Pages: 9
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1074/jbc.M116.761080
 Degree: -

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Title: The Journal of Biological Chemistry
  Other : JBC
Source Genre: Journal
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Publ. Info: Baltimore, etc. : American Society for Biochemistry and Molecular Biology [etc.]
Pages: - Volume / Issue: 291 (52) Sequence Number: - Start / End Page: 26786 - 26793 Identifier: ISSN: 0021-9258
CoNE: https://pure.mpg.de/cone/journals/resource/954925410826_1