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European Biophysics Journal

, Volume 39, Issue 7, pp 1057–1068 | Cite as

Salt bridges in the miniature viral channel Kcv are important for function

  • Brigitte Hertel
  • Sascha Tayefeh
  • Thomas Kloss
  • Jennifer Hewing
  • Manuela Gebhardt
  • Dirk Baumeister
  • Anna Moroni
  • Gerhard ThielEmail author
  • Stefan M. Kast
Original Paper

Abstract

The viral potassium channel Kcv comprises only 94 amino acids, which represent the pore module of more complex K+ channels. As for Kir-type channels, Kcv also has a short N-terminal helix exposed to the cytoplasm, upstream of the first transmembrane domain. Here we show that this helix is relevant for Kcv function. The presence of charged amino acids, which form dynamic inter- and intra-subunit salt bridges is crucial. Electrophysiological measurements, yeast rescue experiments and molecular dynamics simulations show that mutants in which the critical salt bridge formation is impaired have no or reduced channel activity. We conclude that these salt bridges destabilise the complexation of K+ ions by negative charges on the inner transmembrane domain at the entrance into the cavity. This feature facilitates a continuous and coordinated transfer of ions between the cavity and the cytoplasm for channels without the canonical bundle crossing.

Keywords

Salt bridge Kcv-channel Channel gating K+ channel MD simulation 

List of abbreviations

TM

Transmembrane

GFP

Green fluorescent protein

MD

Molecular dynamic

Notes

Acknowledgments

This work was supported in part by the Deutsche Forschungsgemeinschaft (to G. T. and S. M. K), GrK1114 (to G.T.), Fonds der Chemischen Industrie (to S. M. K.) the Adolf-Messer-Stiftung (to S. M. K.) and the European Drug Initiative on Channels and Transporters (EDICT) project EU FP7 (201924) to A.M. We are grateful to D. Herten and P. Heinlein for help with microscopy (Bioquant, Heidelberg). Computer time was provided on IBM Regatta systems at the Hochschulrechenzentrum Darmstadt and at the Forschungszentrum Jülich. Yeast strains were generously provided by Dr. D. Minor (UCSF).

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Copyright information

© European Biophysical Societies' Association 2009

Authors and Affiliations

  • Brigitte Hertel
    • 1
  • Sascha Tayefeh
    • 1
    • 2
  • Thomas Kloss
    • 2
  • Jennifer Hewing
    • 1
  • Manuela Gebhardt
    • 1
  • Dirk Baumeister
    • 1
  • Anna Moroni
    • 3
  • Gerhard Thiel
    • 1
    Email author
  • Stefan M. Kast
    • 2
  1. 1.Institute for BotanyDarmstadtGermany
  2. 2.Eduard-Zintl-Institut für Anorganische und Physikalische ChemieDarmstadtGermany
  3. 3.Department of General Physiology and BiochemistryUniversità degli Studi di MilanoMilanItaly

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