Controlled gating of MS channels in bacterial cells in vivo using a mechanical load

The ability to sense mechanical stimuli is an essential characteristic of living systems. In higher organisms mechanotransduction mediates, for example, the senses of touch and hearing. The main molecular transducers of mechanical stimuli into downstream signals are believed to be mechanically activated ion channels. The understanding of the gating mechanism of such channels, however, is far from complete. In-plane lipid membrane tension and attachment to intra- and extracellular structures are the most likely mechanisms. Mechanosensory ion channels (Msc) were first discovered in prokaryotes. E coli expresses seven different types of Mscs in its inner membrane. Their key role is to prevent cell lysis during hypoosmotic shocks. To date, patch clamping of ‘in vitro’ model membranes have been the only way to measure single-channel activity. There is no in vivo data at single channel resolution, and therefore it remains unknown how Mscs function in their complex native environment. We here present a new experimental approach to characterize gating activity of Mscs in bacteria in vivo. We use atomic force microscope cantilevers functionalized with large beads to compress cells. We observe pressure dependent channel gating at single channel resolution