Identification of sodium channel toxins from marine cone snails of the subgenera Textilia and Afonsoconus

Voltage-gated sodium (Na(V)) channels are transmembrane proteins that play a critical role in electrical signaling in the nervous system and other excitable tissues. µ-Conotoxins are peptide toxins from the venoms of marine cone snails (genus Conus) that block Na(V) channels with nanomolar potency. Most species of the subgenera Textilia and Afonsoconus are difficult to acquire; therefore, their venoms have yet to be comprehensively interrogated for µ-conotoxins. The goal of this study was to find new µ-conotoxins from species of the subgenera Textilia and Afonsoconus and investigate their selectivity at human Na(V) channels. Using RNA-seq of the venom gland of Conus (Textilia) bullatus, we identified 12 µ-conotoxin (or µ-conotoxin-like) sequences. Based on these sequences we designed primers which we used to identify additional µ-conotoxin sequences from DNA extracted from historical specimens of species from Textilia and Afonsoconus. We synthesized six of these µ-conotoxins and tested their activity on human Na(V)1.1–Na(V)1.8. Five of the six synthetic peptides were potent blockers of human Na(V) channels. Of these, two peptides (BuIIIB and BuIIIE) were potent blockers of hNa(V)1.3. Three of the peptides (BuIIIB, BuIIIE and AdIIIA) had submicromolar activity at hNa(V)1.7. This study serves as an example of the identification of new peptide toxins from historical DNA and provides new insights into structure–activity relationships of µ-conotoxins with activity at hNa(V)1.3 and hNa(V)1.7. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00018-023-04935-0.