The Rapid Mechanically Activated channel transduces increases in plasma membrane tension into transient calcium...

Plants respond to mechanical stimuli by a rapid increase in cytosolic calcium. The intensity and kinetics of the calcium changes define calcium signatures important for biological responses. In this study, we determine the properties of a calcium-permeable force-gated channel localized at the plasma membrane called Rapid Mechanically Activated (RMA). Using patch clamp and pressure clamp, we characterized the kinetics of the Arabidopsis thaliana RMA channel upon stimulation by pressure pulses applied onto the plasma membrane. Combining pressure pulse protocols at different frequencies with modeling, we investigated the channel's capacity to transduce high frequency mechanical stimuli. The RMA channel rapidly activates in response to membrane tension, then it inactivates during prolonged stimulation. Upon repeated stimulations, the RMA current amplitude decreases irreversibly indicating that it undergoes attenuation. The channel kinetics were modeled with four chemical states and the model predicts that it behaves as a pass band filter in the 10 Hz-1 kHz range. In conclusion, due to its activation/inactivation, the RMA channel is a candidate for mediating cytosolic calcium signaling in response to mechanostimulation. Its attenuation and filtering properties suggest its involvement in the transduction of high frequency mechanical stimulation, such as those produced by insects' vibrations.