Functional equilibrium of the KcsA structure revealed by NMR

Shunsuke Imai, Masanori Osawa, Kenichiro Mita, Shou Toyonaga, Asako Machiyama, Takumi Ueda, Koh Takeuchi, Shigetoshi Oiki, Ichio Shimada

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


KcsA is a tetramericK+ channel that is activated by acidic pH. Under open conditions of the helix bundle crossing, the selectivity filter undergoes an equilibrium between permeable and impermeable conformations. Here we report that the population of the permeable conformation (pperm) positively correlates with the tetrameric stability and that the population in reconstituted high density lipoprotein, where KcsA is surrounded by the lipid bilayer, is lower than that in detergent micelles, indicating that dynamic properties of KcsA are different in these two media. Perturbation of the membrane environment by the addition of 1-3% 2,2,2-trifluoroethanol increases pperm and the open probability, revealed by NMR and single-channel recording analyses. These results demonstrate that KcsA inactivation is determined not only by the protein itself but also by the surrounding membrane environments.

Original languageEnglish
Pages (from-to)39634-39641
Number of pages8
JournalJournal of Biological Chemistry
Issue number47
Publication statusPublished - 2012 Nov 16
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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