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Multifunctional, Micropipette-based Method for Incorporation And Stimulation of Bacterial Mechanosensitive Ion Channels in Droplet Interface Bilayers
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Structure and molecular mechanism of an anion-selective mechanosensitive channel of small conductance

Xiaozhe Zhang1, Jingjing Wang, Yue Feng

  • 1Key Laboratory for Protein Sciences of Ministry of Education, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.

Proceedings of the National Academy of Sciences of the United States of America
|October 18, 2012
PubMed

Insights

Researchers identified an anion-selective mechanosensitive channel small conductance (MscS) from Thermoanaerobacter tengcongensis. The C-terminal β-barrel region dictates ion selectivity in MscS channels, providing a structural basis for their function.

Area of Science:

  • Membrane biophysics
  • Structural biology
  • Microbial physiology

Background:

  • Mechanosensitive (MS) channels are crucial cellular pores that respond to mechanical stimuli.
  • Bacterial MS channels, like MscS from Escherichia coli (EcMscS), regulate osmolyte release under hypotonic stress.
  • The precise mechanisms governing the ion selectivity of MS channels are not fully understood.

Purpose of the Study:

  • To identify and characterize an anion-selective MscS channel.
  • To elucidate the structural determinants of ion selectivity in bacterial MscS channels.

Main Methods:

  • Protein structure determination
  • Site-directed mutagenesis
  • Ion selectivity assays
  • Comparative structural analysis

Main Results:

  • Anion-selective TtMscS channel identified from Thermoanaerobacter tengcongensis.
  • TtMscS shares structural similarity with EcMscS but lacks large cytoplasmic equatorial portals.
  • The C-terminal β-barrel of TtMscS is larger and exhibits distinct electrostatic properties compared to EcMscS.
  • Swapping β-barrel regions between TtMscS and EcMscS partially altered ion selectivity.

Conclusions:

  • The C-terminal β-barrel region plays a critical role in determining the ion selectivity of MscS channels.
  • This study provides a structural foundation for understanding anion selectivity in MscS channels.

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