Electro-Mechanical Uncoupling of KV7.1 Voltage Sensor and Pore by 1,4-Benzodiazepines Is Modulated by Decoration of Position 1.

The voltage-gated potassium channel KV7.1 (KCNQ1) is essential for cardiac repolarization. Loss-of-function mutations prolong the action potential and cause long QT syndrome 1, predisposing to malignant arrhythmias. Pharmacological activators of KV7.1 are therefore of therapeutic interest. Among them, the 1,4-benzodiazepine derivative (R)-L3 is a potent activator that not only increases current amplitude but also slows activation and deactivation kinetics and abolishes inactivation by uncoupling the voltage sensor from the pore. To explore the structure-activity relationships (SAR) of (R)-L3, we synthesized and functionally characterized a series of novel 1,4-benzodiazepine derivatives and examined their effects on KV7.1 gating. Human KV7.1 channels were heterologously expressed in Xenopus laevis oocytes. Two-electrode voltage clamp recordings were performed to assess current amplitude and kinetic parameters of activation, deactivation, and inactivation. 1,4-Benzodiazepines modified at 1-position reproduced the canonical effects of (R)-L3, including increased current amplitude and suppression of inactivation to varying degrees. Some derivatives displayed completely altered profiles: Modulation of activation, altered (de-)activation kinetics or exerting attenuated effects on inactivation could be uncoupled. These differences suggest that modifications of the 1,4-benzodiazepine scaffold at 1-position shift the interaction between pore binding and voltage sensor-pore uncoupling to isolate kinetic effects. Our data demonstrates that (R)-L3 analogues can differentially modulate KV7.1 gating. By identifying structural determinants of efficacy, this study provides a framework for rational design of next-generation KV7.1 activators. Such compounds may serve as pharmacological tools for dissecting electromechanical coupling in KV7.1 and hold promise as candidates for antiarrhythmic therapy in long QT syndrome.