Single Molecule FRET Reveals Pore Size and Opening Mechanism of MscL
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{\AA}, 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 {\alpha}-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.
Cite
@article{arxiv.1401.7887,
title = {Single Molecule FRET Reveals Pore Size and Opening Mechanism of MscL},
author = {Yong Wang and Yanxin Liu and Hannah A. DeBerg and Takeshi Nomura and Melinda Tonks Hoffman and Paul R. Rohde and Klaus Schulten and Boris Martinac and Paul R. Selvin},
journal= {arXiv preprint arXiv:1401.7887},
year = {2014}
}