Protein‐mediated electroporation: Pore formation in a calcium voltage‐sensing domain induced by positive and negative <scp>nanosecond pulsed electric fields</scp>

In this work, we investigate the conformational changes induced by a positive and negative nanosecond pulsed electric field (nsPEF) on the voltage-sensing domain (VSD) of a voltage-gated calcium channel. These conformational changes play a critical role in the formation of VSD pores. To formalize this phenomenon, we previously introduced the term protein-mediated electroporation. To explore this process, we conducted multiple Molecular Dynamics simulations using two electric field strengths: <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mo>∣</mml:mo> <mml:mover><mml:mi>E</mml:mi> <mml:mo>→</mml:mo></mml:mover> <mml:mo>∣</mml:mo> <mml:mspace></mml:mspace> <mml:mo>=</mml:mo> <mml:mn>0.145</mml:mn></mml:mrow> <mml:annotation>$$ \mid \overrightarrow{E}\mid \kern0.5em =0.145 $$</mml:annotation></mml:semantics> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mo>∣</mml:mo> <mml:mover><mml:mi>E</mml:mi> <mml:mo>→</mml:mo></mml:mover> <mml:mo>∣</mml:mo> <mml:mspace></mml:mspace> <mml:mo>=</mml:mo> <mml:mo>-</mml:mo> <mml:mn>0.18</mml:mn></mml:mrow> <mml:annotation>$$ \mid \overrightarrow{E}\mid \kern0.5em =-0.18 $$</mml:annotation></mml:semantics> </mml:math> V/nm. Due to the inherent variability of simulated system trajectories under identical conditions, multiple replicas were performed to effectively sample the conformational configurational space of the VSD. We clusterized the conformation ensembles and obtained the most representative structures. The analysis revealed three distinct clusters for both electric field strengths. Although the representative VSD structures within each cluster exhibit minimal differences, the conformational changes observed were sufficient to facilitate the formation of robust pores. Expected upward displacement of positive charges when a depolarizing field is applied was observed. For an expected displacement, we speculate that membrane rearrangement may play a key role in modulating VSD conformational changes under these conditions.