Two-stage electro-mechanical coupling of a K V channel in voltage-dependent activation

In voltage-gated potassium (K V ) channels, the voltage-sensing domain (VSD) undergoes sequential activation from the resting state to the intermediate state and activated state to trigger pore opening via electro-mechanical (E-M) coupling. However, the spatial and temporal details underlying E-M coupling remain elusive. Here, we leverage K V 7.1’s unique two open states associated with the VSD adopting the intermediate and activated conformations to report a two-stage E-M coupling mechanism in voltage-dependent gating of K V 7.1 as triggered by VSD activations to the intermediate and then activated state. When the S4 segment transitions to the intermediate state, the hand-like C-terminus of the VSD-pore linker (S4-S5L) interacts with the pore in the same subunit. When S4 then proceeds on to the fully-activated state, the elbow-like hinge between S4 and S4-S5L engages with the pore to activate conductance. This two-stage “hand-and-elbow” gating mechanism elucidates distinct tissue-specific modulations, pharmacology, and disease pathogenesis of K V 7.1, and likely applies to numerous K V channels.