title: Single molecule FRET reveals pore size and opening mechanism of a mechano-sensitive ion channel.
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. DOI: http://dx.doi.org/10.7554/eLife.01834.001.
authors.affiliation: Department of Physics, University of Illinois at Urbana-Champaign, Urbana, United States.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Yanxin
authors.initials: Y
authors.lastname: Liu
authors.forename: Hannah A
authors.initials: HA
authors.lastname: Deberg
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nomura
authors.forename: Melinda Tonks
authors.initials: MT
authors.lastname: Hoffman
authors.forename: Paul R
authors.initials: PR
authors.lastname: Rohde
authors.forename: Klaus
authors.initials: K
authors.lastname: Schulten
authors.forename: Boris
authors.initials: B
authors.lastname: Martinac
authors.forename: Paul R
authors.initials: PR
authors.lastname: Selvin
mesh_terms: D003001:Cloning, Molecular; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000378:metabolism; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008081:Liposomes; D040542:Mechanotransduction, Cellular; D008564:Membrane Potentials; D056004:Molecular Dynamics Simulation; D009154:Mutation; D016062:Porosity; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship
chemical_list: D029968:Escherichia coli Proteins; D005456:Fluorescent Dyes; D007473:Ion Channels; D008081:Liposomes; C086596:MscL protein, E coli
keywords: MscL; barrel-stave model; helix-tilt model