Role of the KcsA channel cytoplasmic domain in pH-dependent gating

Minako Hirano, Yukiko Onishi, Toshio Yanagida, Toru Ide

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

The KcsA channel is a representative potassium channel that is activated by changes in pH. Previous studies suggested that the region that senses pH is entirely within its transmembrane segments. However, we recently revealed that the cytoplasmic domain also has an important role, because its conformation was observed to change dramatically in response to pH changes. Here, to investigate the effects of the cytoplasmic domain on pH-dependent gating, we made a chimera mutant channel consisting of the cytoplasmic domain of the KcsA channel and the transmembrane region of the MthK channel. The chimera showed a pH dependency similar to that of KcsA, indicating that the cytoplasmic domain can act as a pH sensor. To identify how this region detects pH, we substituted certain cytoplasmic domain amino acids that are normally negatively charged at pH 7 for neutral ones in the KcsA channels. These mutants opened independently of pH, suggesting that electrostatic charges have a major role in the cytoplasmic domain's ability to sense and respond to pH.

Original languageEnglish
Pages (from-to)2157-2162
Number of pages6
JournalBiophysical Journal
Volume101
Issue number9
DOIs
Publication statusPublished - 2011

ASJC Scopus subject areas

  • Biophysics

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