Energetics of rotational gating mechanisms of an ion channel induced by membrane deformation

Abstract

We consider the gating mechanisms of an ion channel which has a conical structure for a closed state and a cylindrical or a bottleneck structure for an open state depending on the gating mechanisms. Applying the simplified continuum model of the membrane in the presence of a strong hydrophobic interaction between the channel proteins and the nearby lipid molecules of the membrane, we obtain energy differences between closed and open states for two known and one newly proposed rotational gating mechanism. We compare the energetics of three gating mechanisms and find out the most favorable mechanism under the given biological conditions such as hydrophobic mismatch, spontaneous curvature of a monolayer, and membrane moduli in our approach. Our results show that spontaneous curvature plays more important role in these gating mechanisms than surface tension does. Introducing spontaneous curvature to the inner or outer layer of the membrane affects the gating mechanism. We also discuss an effect of membrane thickness change due to the channel's conformational transition during gating. © 2006 The American Physical Society.