Peptides Derived From Reactive Center Loops Inhibit Digestive Trypsin-Like Enzymes in Lepidopteran Pests

Area of Science:

• Agricultural Entomology
• Biochemistry
• Molecular Biology

Background:

• Soybean production is significantly impacted by pest damage, particularly from defoliating insects like Anticarsia gemmatalis (Lepidoptera: Noctuidae).
• There is a critical need for novel, effective bioinsecticides to manage Lepidopteran pests, with protease inhibitors (PIs) showing considerable potential.

Purpose of the Study:

• To design and evaluate novel peptide-based protease inhibitors inspired by BPTI and SKTI.
• To assess the potential of these peptides as competitive inhibitors of trypsin-like proteases in Anticarsia gemmatalis.

Main Methods:

• In silico analysis to predict peptide binding affinity and identify key molecular interactions (e.g., pi-sigma bonds).
• Kinetic analyses to determine the nature of enzyme inhibition (competitive).
• Enzyme inhibition assays using A. gemmatalis trypsin-glen proteases to measure peptide efficacy.

Main Results:

• Four peptides (TGPCK, TGPCR, AVIMK, AVIMR) were designed and tested.
• In silico and kinetic studies revealed specific chemical interactions influencing peptide binding affinity, with AVIMK showing high affinity via pi-sigma bonds.
• All tested peptides functioned as competitive inhibitors of A. gemmatalis trypsin-glen proteases, with TGPCK exhibiting the strongest inhibitory activity.

Conclusions:

• BPTI-derived peptides are effective competitive inhibitors of A. gemmatalis trypsin-like proteases.
• The peptide TGPCK demonstrates significant potential as a lead compound for developing new bioinsecticides against soybean pests.
• Further research is warranted to assess the in-planta efficacy and phytotoxicity of these PIs for practical pest management applications.