MS channel gating in live bacteria detected in AFM under parallel plate compression

Bacteria avoid lysis under abrupt hypoosmotic shocks by engaging mechanosensitive (MS) channels: membrane proteins that release small solutes in response to mechanical stress in the cytoplasmic membrane. The exact mechanism of channel gating in the native setting, however, has been elusive due to the lack of experimental methods appropriate for the small dimensions of prokaryotes. We here present experimental data on the gating of MS channels of E. coli subjected to compressive force under iso-osmotic conditions. We compress single living cells with micron-sized beads attached to the cantilever of an atomic force microscope (AFM) and monitor the mechanical response of the cell with nanometer/piconewton resolution. We show that mechanosensitive channels gate under compressive forces and quantify turgor pressure changes after gating, the cytoplasmic water volume leaked by gating events, and the timescale of the volume release process. We present and discuss data for different E. coli strains expressing different MS channel combinations.