Mechanistic insights into K_v1.6 inhibition by conotoxin Pl14A from molecular dynamics simulation

Conotoxins are peptide toxins that are found in marine cone snails and inhibit ion channels with high affinity and selectivity. Pl14A is a conotoxin belonging to the J-superfamily, and is one of a few conotoxins that can inhibit two types of receptors, the K_v1.6 subtype of voltage-gated potassium channels as well as nicotinic acetylcholine receptors (nAChRs). In this work, we use classical molecular dynamics simulations to examine the mechanism of inhibition and structural interactions between Pl14A and the K_v1.6 channel. Our study reveals that Pl14A binds stably in the extracellular vestibule of K_v1.6, engaging key residues within the selectivity filter and turret region through a combination of electrostatic and hydrophobic contacts. The peptide's basic residues, mainly the arginine residue and putative dyad motif Lys18 and Tyr19, are implicated in its subtype specificity and pore-blocking activity. Structural analysis and free energy calculations provide a quantitative view of the conformational changes in both the peptide and the channel, consistent with a pore blocking mode of inhibition. These findings help us to understand the modulation of the K_v1.6 channel by conotoxin Pl14A and offer insight for designing selective peptide inhibitors with therapeutic potential against K_v1.6 related pathologies.