Structures and gating of the Arabidopsis mechanosensitive ion channel MSL10.

Abstract

Plants encode an array of mechanosensitive ion channels, which can sense and respond to mechanical force, to manage drastically different osmotic environments during growth and development. Here, we report structural and electrophysiological analysis of a MscS-like mechanosensitive channel from Arabidopsis thaliana, AtMSL10, which plays a major role in hypo-osmotic shock adaptation and programmed cell death induction. The cryo-electron microscopy structures reveal unique domain organization of MSL10, suggesting a distinct gating mechanism. Unprecedently, structures of the wild-type channel, in detergent or lipid environment and in the absence of membrane tension, represent an open conformation. In addition, the structure of a non-conductive mutant channel reveals closure of the ion conduction path, which is achieved mainly through reorientation of the bulky hydrophobic side chain of a phenylalanine residue at the gate. Our work provides unique insights into mechanotransduction in ion channels.