Single molecule FRET reveals pore size and opening mechanism of a mechano-sensitive ion channel

Yong Wang, Yanxin Liu, Hannah A. DeBerg, Takeshi Nomura, Melinda Tonks Hoffman, Paul R. Rohde, Klaus Schulten, Boris Martinac, Paul R. Selvin

Research output: Contribution to journalArticlepeer-review

Abstract

The mechanosensitive channel of large conductance, which serves as a model system for mechanosensitive channels, has previously been crystallized in the closed form, but not in the open form. Ensemble measurements and electrophysiological sieving experiments show that the open-diameter of the channel pore is >25 Å, but the exact size and whether the conformational change follows a helix-tilt or barrel-stave model are unclear. Here we report measurements of the distance changes on liposome-reconstituted MscL transmembrane α-helices, using a 'virtual sorting' single-molecule fluorescence energy transfer. We observed directly that the channel opens via the helix-tilt model and the open pore reaches 2.8 nm in diameter. In addition, based on the measurements, we developed a molecular dynamics model of the channel structure in the open state which confirms our direct observations.

Original languageEnglish (US)
Article numbere01834
JournaleLife
Volume2014
Issue number3
DOIs
StatePublished - Feb 18 2014

ASJC Scopus subject areas

  • Neuroscience(all)
  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)

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