Structure of the ILT Mutant Shaker K+ Channel and the Mechanism of Voltage Activation

To understand the process of voltage activation in Kv channels, we determined the cryo-EM structure of the Shaker channel ILT mutant (V369I, I372L, S376T), known to partially decouple the gating charge movement of the voltage sensing domain (VSD) and the opening of the pore domain (PD). The structure captures a previously unobserved intermediate state in which the VSD is only partially activated while the PD remains closed. Combined with computational modeling based on AlphaFold2 predictions and molecular dynamics simulations, it is shown that VSD activation does not mechanically pull the gate open, but instead induces a dynamic shift in the population equilibrium of the VSD-PD linker, providing the basis for electromechanical coupling between the two domains.