Conformational state of the MscS mechanosensitive channel in solution revealed by pulsed electron-electron double resonance (PELDOR) spectroscopy

Christos Pliotas, Richard James Ward, Emma Branigan, Akiko Rasmussen, Gregor Hageluken, Hexian Huang, Susan S. Black, Ian R. Booth, Olav Schiemann, James H Naismith

Research output: Contribution to journalArticlepeer-review

Abstract

The heptameric mechanosensitive channel of small conductance (MscS) provides a critical function in Escherichia coli where it opens in response to increased bilayer tension. Three approaches have defined different closed and open structures of the channel, resulting in mutually incompatible models of gating. We have attached spin labels to cysteine mutants on key secondary structural elements specifically chosen to discriminate between the competing models. The resulting pulsed electron–electron double resonance (PELDOR) spectra matched predicted distance distributions for the open crystal structure of MscS. The fit for the predictions by structural models of MscS derived by other techniques was not convincing. The assignment of MscS as open in detergent by PELDOR was unexpected but is supported by two crystal structures of spin-labeled MscS. PELDOR is therefore shown to be a powerful experimental tool to interrogate the conformation of transmembrane regions of integral membrane proteins.
Original languageEnglish
Pages (from-to)E2675-E2682
Number of pages8
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number40
DOIs
Publication statusPublished - 10 Sept 2012

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