Molecular determinants of the modulation of the VSD-PD coupling mechanism of the K_V7.1 channel by the KCNE1 ancillary subunits

Abstract

The IKS current is diffused through the plasma membranes of cardiomyocytes during the last phase of the cardiac action potential. This repolarization current is conducted by a tetrameric protein complex derived from the co-expression of four voltage-gated potassium channel KV7.1 α-subunits and KCNE1 ancillary subunits from KCNQ1 and KCNE1 genes, respectively. We studied here the conformational space of KV7.1 in presence and absence of KCNE1, by building transmembrane models of their known Resting, Intermediate, and Activated states. We conducted Molecular Dynamics simulations of these models in lipid bilayers including the phosphatidyl-inositol-4,5-bisphosphate (PIP2) lipids. The comparative analysis of MD trajectories obtained for the KV7.1 and IKS models reveals how KCNE1 shifts the coupling mechanism between the activation state of the Voltage Sensor Domain of the channel and the conformation (open or closed) of its Pore Domain.