A ShK-like Domain from Steinernema carpocapsae with Bioinsecticidal Potential

Jorge Frias, Duarte Toubarro, Gro Elin Kjæreng Bjerga, Pål Puntervoll, João B. Vicente, Rui L. Reis, Nelson Simões

Research output: Contribution to journalArticlepeer-review


Entomopathogenic nematodes are used as biological control agents against a broad range of insect pests. We ascribed the pathogenicity of these organisms to the excretory/secretory products (ESP) released by the infective nematode. Our group characterized different virulence factors produced by Steinernema carpocapsae that underlie its success as an insect pathogen. A novel ShK-like peptide (ScK1) from this nematode that presents high sequence similarity with the ShK peptide from a sea anemone was successfully produced recombinantly in Escherichia coli. The secondary structure of ScK1 appeared redox-sensitive, exhibiting a far-UV circular dichroism spectrum consistent with an alpha-helical secondary structure. Thermal denaturation of the ScK1 allowed estimating the melting temperature to 59.2 ± 0.1 °C. The results from toxicity assays using Drosophila melanogaster as a model show that injection of this peptide can kill insects in a dose-dependent manner with an LD50 of 16.9 µM per adult within 24 h. Oral administration of the fusion protein significantly reduced the locomotor activity of insects after 48 h (p < 0.05, Tukey’s test). These data show that this nematode expresses insecticidal peptides with potential as next-generation insecticides.

Original languageEnglish
Article number754
Issue number11
Publication statusPublished - Nov 2022


  • disulfide-rich peptide
  • entomopathogenic nematodes
  • excretory/secretory products
  • fruit fly
  • insecticidal toxins
  • locomotor activity
  • ShK
  • toxicity assay


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