AUTHOR=Dongol Yashad , Wilson David T. , Daly Norelle L. , Cardoso Fernanda C. , Lewis Richard J. 

TITLE=Structure-function and rational design of a spider toxin Ssp1a at human voltage-gated sodium channel subtypes

JOURNAL=Frontiers in Pharmacology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2023.1277143

DOI=10.3389/fphar.2023.1277143

ISSN=1663-9812

ABSTRACT=<p>The structure-function and optimization studies of Na<sub>V</sub>-inhibiting spider toxins have focused on developing selective inhibitors for peripheral pain-sensing Na<sub>V</sub>1.7. With several Na<sub>V</sub> subtypes emerging as potential therapeutic targets, structure-function analysis of Na<sub>V</sub>-inhibiting spider toxins at such subtypes is warranted. Using the recently discovered spider toxin Ssp1a, this study extends the structure-function relationships of Na<sub>V</sub>-inhibiting spider toxins beyond Na<sub>V</sub>1.7 to include the epilepsy target Na<sub>V</sub>1.2 and the pain target Na<sub>V</sub>1.3. Based on these results and docking studies, we designed analogues for improved potency and/or subtype-selectivity, with S7R-E18K-rSsp1a and N14D-P27R-rSsp1a identified as promising leads. S7R-E18K-rSsp1a increased the rSsp1a potency at these three Na<sub>V</sub> subtypes, especially at Na<sub>V</sub>1.3 (∼10-fold), while N14D-P27R-rSsp1a enhanced Na<sub>V</sub>1.2/1.7 selectivity over Na<sub>V</sub>1.3. This study highlights the challenge of developing subtype-selective spider toxin inhibitors across multiple Na<sub>V</sub> subtypes that might offer a more effective therapeutic approach. The findings of this study provide a basis for further rational design of Ssp1a and related NaSpTx1 homologs targeting Na<sub>V</sub>1.2, Na<sub>V</sub>1.3 and/or Na<sub>V</sub>1.7 as research tools and therapeutic leads.</p>