The Relation Between The Ion Conduction Through The KcsA Potassium Channel And The Water Molecules Inside The Selectivity Filter Of The Channel

KcsA potassium channel has often been utilized to study the properties and functions of potassium channels because it has a simple structure that shares the common features of potassium channels. Here we study the ion conduction process using the KcsA potassium channel as the model system. A special structural feature of the potassium channel is the selectivity filter, which can select and conduct ions. The dehydrated potassium ions can pass through the selectivity filter one by one, but usually intervened by water molecules. Can the ion conduction process be affected by the presence of water molecules inside the selectivity filter or by their different positions inside the filter? In order to know this, we have studied the ion conduction process under the different conditions defined by the different water molecule configurations inside the selectivity filter using the molecular dynamics simulations. We find that the water molecules in the selectivity filter can affect the ion conduction process with dual effects, i.e., they can facilitate or impede the ion movements inside the selectivity filter.