Computational design of binders targeting the VSDIV from NaV1.7 sodium channel

Chronic pain affects about 20% of the US population, but safe treatments are limited. There is an urgent need for effective and non-addictive therapies for chronic pan conditions. Voltage-gated sodium (NaV) channel, NaV1.7, is a key player in pain signaling pathway, making it a promising target for novel pain therapeutics. Achieving high subtype selectivity when targeting NaV channels is of primary importance to avoid impairing vital physiological functions mediated by off-target channels. Efforts to selectively target NaV1.7 have been hindered by the difficulties in targeting NaV1.7 over other NaV channel subtypes. Peptidic gating modifier toxins (GMTs), such as Protoxin-II (ProTx2), are promising scaffolds for novel peptide design targeting ion channels with high potency and subtype selectivity. ProTx2 binds to the second and fourth voltage-sensing domains (VSDII and VSDIV) from NaV1.7 with moderate subtype selectivity and can modulate channel activation and inactivation. In this project, we modeled ProTx2 bound to human NaV1.7 VSDIV in an activated state. We used RoseTTAFold Diffusion and Protein MPNN protein design methods to generate protein binders inspired by ProTx2 binding motif with increased predicted binding affinity for human NaV1.7 VSDIV in an activated state. Additionally, we applied these protein design methods to create de novo binders targeting human NaV1.7 VSDIV in an activated state. We anticipate that trapping the VSDIV in an activated conformation will stabilize an inactivated state of the channel, as activation of VSDIV is coupled with channel fast inactivation. Initial electrophysiological screening of our top in silico binders identified promising candidates that inhibited NaV1.7 in the micromolar range. These binders will undergo further testing and optimization against NaV1.7 to create novel molecular tools to study NaV channel activity and effective and safe therapies for chronic pain.