Alanine Mutagenesis Identifies Specific Amino Acids of Nemertide Alpha‑1 Activity and Its Binding to Target Receptors

TL;DR

Scientists identified key amino acids in a marine worm toxin that affect its ability to target invertebrate sodium channels, which could help develop selective biopesticides.

Contribution

The study identifies specific amino acid residues critical for the activity and selectivity of nemertide alpha-1 against invertebrate sodium channels.

Findings

Key residues S12, T17, N19, W22, and F24 significantly influence nemertide alpha-1's activity on sodium channels.

The S12A mutant shows high selectivity for invertebrate Nav channels.

Findings suggest interactions at site 3 of domain IV on Nav channels are important for binding.

Abstract

We recently discovered and characterized a novel family
of peptide
toxins, the alpha-nemertides, from the marine ribbon worm Lineus longissimus. These 31-residue peptides show potent
neurotoxicity against invertebrate voltage-gated sodium (Nav) channels, making them promising candidates for biopesticide development.
To explore structure–activity relationships, we synthesized
20 nemertide alpha-1 mutants (17 alanine, 3 lysine substitutions)
to identify residues critical for activity and selectivity. Key positions,
including S12, T17, N19, W22, and F24, were found to influence activity
on Nav channels significantly. Notably, the S12A mutant
showed high selectivity for invertebrate Navs, suggesting
its potential as a selective tool or lead scaffold. Our findings highlight
critical interaction points likely to be involved in binding to site
3 of domain IV on Nav channels and demonstrate how targeted
modifications can sharpen selectivity. These insights support the
rational design of more selective peptides and identify S12A as a
promising candidate for further development as a biopesticide.

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