Environment of the gating charges in the Kv1.2 Shaker potassium channel.
Recently, the structure of the Shaker channel Kv1.2 has been determined at a 2.9-angstroms resolution. This opens new possibilities in deciphering the mechanism underlying the function of voltage-gated potassium (Kv) channels. Molecular dynamics simulations of the channel, embedded in a membrane environment show that the channel is in its open state and that the gating charges carried by S4 are exposed to the solvent. The hydrated environment of S4 favors a local collapse of the electrostatic potential, which generates high electric-field gradients around the arginine gating charges. Comparison to experiments suggests furthermore that activation of the channel requires mainly a lateral displacement of S4. Overall, the results agree with the transporter model devised for Kv channels from electrophysiology experiments, and provide a possible pathway for the mechanistic response to membrane depolarization.
Treptow
Werner
W
Equipe de Dynamique des Assemblages Membranaires, Unité Mixte de Recherche CNRS/UHP 7565 Université Henri-Poincaré, 54506 Vandoeuvre-lès-Nancy, France.
Tarek
Mounir
M
D003198:Computer Simulation; D015640:Ion Channel Gating / Q000502:physiology*; D051663:Kv1.2 Potassium Channel / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D051637:Shaker Superfamily of Potassium Channels / Q000737:chemistry*; D055672:Static Electricity; D013816:Thermodynamics
D051663:Kv1.2 Potassium Channel; C076413:Shaker B potassium channel polypeptide; D051637:Shaker Superfamily of Potassium Channels