Structure and molecular mechanism of an anion-selective mechanosensitive channel of small conductance

Xiaozhe Zhang, Jingjing Wang, Yue Feng, Jingpeng Ge, Wenfei Li, Wending Sun, Irene Iscla, Jie Yu, Paul Blount, Yang Li, Maojun Yang

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Mechanosensitive (MS) channels are universal cellular membrane pores. Bacterial MS channels, as typified by MS channel of small conductance (MscS) from Escherichia coli (EcMscS), release osmolytes under hypoosmotic conditions. MS channels are known to be ion selective to different extents, but the underlying mechanism remains poorly understood. Here we identify an anion-selective MscS channel from Thermoanaerobacter tengcongensis (TtMscS). The structure of TtMscS closely resembles that of EcMscS, but it lacks the large cytoplasmic equatorial portals found in EcMscS. In contrast, the cytoplasmic pore formed by the C-terminal β-barrel of TtMscS is larger than that of EcMscS and has a strikingly different pattern of electrostatic surface potential. Swapping the β-barrel region between TtMscS and EcMscS partially switches the ion selectivity. Our study defines the role of the β-barrel in the ion selection of an anion-selective MscS channel and provides a structural basis for understanding the ion selectivity of MscS channels.

Original languageEnglish (US)
Pages (from-to)18180-18185
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number44
DOIs
StatePublished - Oct 30 2012

Keywords

  • Anion selection
  • Crystal structure
  • Cytoplasmic region
  • Electrophysiology
  • Single channel recording

ASJC Scopus subject areas

  • General

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