Conformational Dynamics of Shaker-Type Kv1.1 Ion Channel in Open, Closed, and Two Mutated States

摘要

The dynamic properties of shaker-type Kv1.1 ion channel in its open, closed, & two mutated (E325D & V408A) states embedded in DPPC membrane have been investigated using all-atom force field-based MD simulation. Here, we represent the detailed channel stability, gating environment of charge-carrying residues, salt bridge interaction among the voltage-sensing domains (VSDs), movement of S4 helix, and ion conduction of pore. At positive potential, the S4 helix undergoes lateral fluctuations in accordance with their gating motions found in every model. During transition from closed to active state conformation, charged residues of S4 move "up" across the membrane with an average tilt angle difference of 24A degrees, which is more consistent with the paddle model of channel gating. The E325D mutation at C-terminal end of S4-S5 helical linker leads the channel to a rapid activated state by pushing the gating charge residues upward beside the VSDs resulting in more prominent tilt of S4. Similarly in V408A mutant model, disruption of hydrophobic gate at S6 C-terminal end takes place, which causes the violation of channel-active conformation by bringing the C-terminal end of S4 to its corresponding resting state. The ion permeation is observed only in open-state conformation.