Lipids tell channel to open wide

Structural studies of a bacterial ion channel in a new article by Eduardo Perozo (University of Virginia, Charlottesville, VA), Boris Martinac (University of Western Australia, Crawley, Australia), and colleagues reveal how the channel senses when to open through interactions with membrane lipids.

Mechanosensitive channels, such as bacterial MscL studied by Perozo, open when the pressure inside a cell increases, thus allowing the passage of ions and other solutes. MscL needs only a lipid environment to respond to pressure, indicating that interactions between lipids and channel proteins are sufficient to regulate channel structure. The new study reveals that a change in intramembrane pressure rather than membrane thinning is the key determinant for channel opening.

As tension grows in the cell, the bilayer thins, possibly exposing hydrophobic amino acids of the channel to the aqueous environment. Perozo et...