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Science. 2008 Aug 29;321(5893):1210-4. doi: 10.1126/science.1159674.

A structural mechanism for MscS gating in lipid bilayers.

Author information

1
Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22908, USA.

Abstract

The mechanosensitive channel of small conductance (MscS) is a key determinant in the prokaryotic response to osmotic challenges. We determined the structural rearrangements associated with MscS activation in membranes, using functorial measurements, electron paramagnetic resonance spectroscopy, and computational analyses. MscS was trapped in its open conformation after the transbilayer pressure profile was modified through the asymmetric incorporation of lysophospholipids. The transition from the closed to the open state is accompanied by the downward tilting of the transmembrane TM1-TM2 hairpin and by the expansion, tilt, and rotation of the TM3 helices. These movements expand the permeation pathway, leading to an increase in accessibility to water around TM3. Our open MscS model is compatible with single-channel conductance measurements and supports the notion that helix tilting is associated with efficient pore widening in mechanosensitive channels.

PMID:
18755978
PMCID:
PMC2897165
DOI:
10.1126/science.1159674
[Indexed for MEDLINE]
Free PMC Article

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