Hydrophobic gating of mechanosensitive channel of large conductance evidenced by single-subunit resolution

J.P. Birkner, B. Poolman, A. Koçer

Research output: Contribution to journalArticleAcademicpeer-review

52 Citations (Scopus)

Abstract

Mechanosensitive (MS) ion channels are membrane proteins that detect and respond to membrane tension in all branches of life. In bacteria, MS channels prevent cells from lysing upon sudden hypoosmotic shock by opening and releasing solutes and water. Despite the importance of MS channels and ongoing efforts to explain their functioning, the molecular mechanism of MS channel gating remains elusive and controversial. Here we report a method that allows single-subunit resolution for manipulating and monitoring “mechanosensitive channel of large conductance” from Escherichia coli. We gradually changed the hydrophobicity of the pore constriction in this homopentameric protein by modifying a critical pore residue one subunit at a time. Our experimental results suggest that both channel opening and closing are initiated by the transmembrane 1 helix of a single subunit and that the participation of each of the five identical subunits in the structural transitions between the closed and open states is asymmetrical. Such a minimal change in the pore environment seems ideal for a fast and energy-efficient response to changes in the membrane tension.
Original languageEnglish
Pages (from-to)12944-12949
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number32
DOIs
Publication statusPublished - 2012
Externally publishedYes

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