Molecular determinants of μ-conotoxin KIIIA interaction with the human voltage-gated sodium channel Na(V)1.7

The voltage-gated sodium (Na(V)) channel subtype Na(V)1.7 plays a critical role in pain signaling, making it an important drug target. Here we studied the molecular interactions between μ-Conotoxin KIIIA (KIIIA) and the human Na(V)1.7 channel (hNa(V)1.7). We developed a structural model of hNa(V)1.7 using Rosetta computational modeling and performed in silico docking of KIIIA using RosettaDock to predict residues forming specific pairwise contacts between KIIIA and hNa(V)1.7. We experimentally validated these contacts using mutant cycle analysis. Comparison between our KIIIA-hNa(V)1.7 model and the cryo-EM structure of KIIIA-hNa(V)1.2 revealed key similarities and differences between Na(V) channel subtypes with potential implications for the molecular mechanism of toxin block. The accuracy of our integrative approach, combining structural data with computational modeling, experimental validation, and molecular dynamics simulations, suggests that Rosetta structural predictions will be useful for rational design of novel biologics targeting specific Na(V) channels.