Molecular determinants of μ-conotoxin KIIIA interaction with the human voltage-gated sodium channel NaV1.7

Abstract

The voltage-gated sodium (NaV) channel subtype NaV1.7 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 NaV1.7 channel (hNaV1.7). We developed a structural model of hNaV1.7 using Rosetta computational modeling and performed in silico docking of KIIIA using RosettaDock to predict residues forming specific pairwise contacts between KIIIA and hNaV1.7. We experimentally validated these contacts using mutant cycle analysis. Comparison between our KIIIA-hNaV1.7 model and the cryo-EM structure of KIIIA-hNaV1.2 revealed key similarities and differences between NaV 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 NaV channels.

Voltage-Gated Sodium Channel Inhibition by µ-Conotoxins

“…As not all these interactions were consistent with the predicted models, it may suggest that different µ-conotoxins possess different binding modes, compared to KIIIA. Furthermore, Kimball et al used homology modelling and docking simulations to create a structural model of KIIIA in complex with hNa V 1.7 [ 61 ]. Double-mutant cycle analysis identified specific pairwise toxin–channel interactions, including Lys7 and Glu919, as well as His12 and Asp923, consistent with those established in the KIIIA/hNa V 1.2 complex [ 61 ].…”

“…Furthermore, Kimball et al used homology modelling and docking simulations to create a structural model of KIIIA in complex with hNa V 1.7 [ 61 ]. Double-mutant cycle analysis identified specific pairwise toxin–channel interactions, including Lys7 and Glu919, as well as His12 and Asp923, consistent with those established in the KIIIA/hNa V 1.2 complex [ 61 ]. Additionally, the Arg10 and Ile1399 interaction unique to hNa V 1.7 was proposed to underlie the structural basis for the KIIIA block at hNa V 1.7 [ 61 ].…”