Ion transport mechanism in ClC-type channel protein under complex electrostatic potential

In order to illustrate the ion transport mechanism of chloride channel (ClC) protein, a type of ClC protein, ClC-ec1, from Escherichia coli is embedded into an explicit membranewater system by using software VMD. Then a parallel molecular dynamics (MD) simulation is employed to equilibrate the ClC-ec1 structure for 27.5 ns at temperature 298.15 K. Based on this equilibrated structure, we compute the channel geometric size variation and electrostatic potential distribution along the channel. Meanwhile, Cl^- transport process is simulated using oriented random walk method under variable external potential. The simulation result shows that Cl^- transport velocity depends on the width of the narrowest channel region. Mutation of negative glutamate E148 can produce positive potential, which is beneficial for Cl^- transport, around external Cl^- binding region in the channel. The simulated current-voltage curves about Cl^- transporting in ClC-ec1 protein agree with Jayaram’s experimental results.