Mechanism underlying the ultralow energy-consumption rapid ion dehydration for the high flux of KcsA potassium channels

High-flux and ultralow energy consumption transport of biological and artificial ion channels has been widely reported [1-22]. However, there is a precondition for such transport: Ultralow energy-consumption rapid ion dehydration; its mechanism is a remaining challenge. Here, we demonstrate that a K+ ion can transfer from the hydration water outside KcsA channel to the water bound in the channel without its hydration water accompanying, i.e., a tunneling-like motion, which provides a basis for the ultralow energy-consumption ion dehydration. In our molecular dynamics simulations, a KcsA channel was divided into three regions: Cavity-1, Cavity-2 and filter. As a hydrated K+ ion moves from Cavity-1 to Cavity-2, there occurs a resonant energy transfer to the ion from the filter-confined coherently oscillating ions, leading to a tunneling-like motion of the ion from the Cavity-1 water to Cavity-2 water with no hydration shell accompanying and no influence on the Cavity-2 water. As the hydrated K+ ion further moves from Cavity-2 to KcsA filter, the ion adjusts its hydration-shell water structure to coherence-resonantly couples with the filter-confined ions, leading to another tunneling-like ion motion to reach complete dehydration. Such two processes cause directionally rapid ion dehydration of KcsA channel, as a basis for the high flux of channel. Our findings provide an understanding of the dehydration dynamics in biological channels and its relationship with the high flux of ultralow energy-consumption, potentially promoting the development of artificial membranes design.