posted on 2021-03-22, 16:35authored byMasayuki Iwamoto, Shigetoshi Oiki
Various types of
channels vary their function by membrane tension
changes upon cellular activities, and lipid bilayer methods allow
elucidation of direct interaction between channels and the lipid bilayer.
However, the dynamic responsiveness of the channel to the membrane
tension remains elusive. Here, we established a time-lapse tension
measurement system. A bilayer is formed by docking two monolayer-lined
water bubbles, and tension is evaluated via measuring intrabubble
pressure as low as <100 Pa (Young–Laplace principle). The
prototypical KcsA potassium channel is tension-sensitive, and single-channel
current recordings showed that the activation gate exhibited distinct
tension sensitivity upon stretching and relaxing. The mechanism underlying
the hysteresis is discussed in the mode shift regime, in which the
channel protein bears short “memory” in their conformational
changes.