# Binding Mechanism of PsauPBP3 to Sex Pheromones in Peridroma saucia: Insights from Computational and Experimental Approaches

## TL;DR

This study identifies key amino acids in PsauPBP3 that bind to sex pheromones in the variegated cutworm, offering a potential strategy for pest control.

## Contribution

The study reveals specific amino acid residues in PsauPBP3 critical for binding to two sex pheromones in Peridroma saucia.

## Key findings

- PsauPBP3 shows high binding affinity for both Z11-16: Ac and Z9-14: Ac pheromones.
- Five amino acid residues (Thr-10, Phe-13, Ile-53, Ile-95, and Phe-119) are key to pheromone binding.
- Phe-13 and Ile-95 are particularly important for binding both pheromones.

## Abstract

Peridroma saucia Hübner is a newly emerged agricultural pest in the Huang-Huai River Basin, China. The female sex pheromones of P. saucia are Z11-16: Ac and Z9-14: Ac. Pheromone-binding proteins (PBPs) serve as a key component in the initial step of sex pheromone recognition. Functional research on PBPs is a major current focus, yet the precise mechanism underlying their binding remains poorly understood. An improved understanding of PBP-mediated sex pheromone binding mechanisms could lead to eco-friendly strategies for insect population control by scrambling mate detection. Herein, we conducted a series of structure–function analyses of pheromone binding protein 3 (PsauPBP3) in sex pheromone recognition of P. saucia. PsauPBP3, which is predominantly expressed in male antennae of P. saucia, exhibited high binding affinities for both Z11-16: Ac and Z9-14: Ac. Further molecular dynamics simulation and molecular docking indicated that five amino acid residues could steadily interact with these two sex pheromones. Finally, computational alanine scanning and site-directed mutagenesis demonstrated that four residues were driving forces for the binding affinities of PsauPBP3, especially Phe-13 and Ile-95, which significantly contribute to the binding for both sex pheromones. These findings may lead to novel approaches for managing this pest by hindering its mating behaviors.

The variegated cutworm Peridroma saucia Hübner, a recently emerged polyphagous pest in China’s Huang-Huai River Basin, uses sex pheromones (Z)-11-hexadecenyl acetate (Z11-16: Ac) and (Z)-9-tetradecenyl acetate (Z9-14: Ac) for mate finding. Insect pheromone-binding proteins (PBPs) serve as the primary filter for detecting specific sex pheromones. Although comprehensive functional analyses of PBPs exist, their binding mechanisms remain poorly characterized. In this study, we elucidated the binding properties and mechanisms of PsauPBP3 in sex pheromone recognition by computational and experimental approaches. PsauPBP3, predominantly expressed in male P. saucia antennae, showed high binding affinity for both Z11-16: Ac and Z9-14: Ac, as demonstrated by binding-free-energy calculations and fluorescence binding assays. Molecular dynamics simulations and docking studies identified five key residues (Thr-10, Phe-13, Ile-53, Ile-95, and Phe-119) that consistently interact with these pheromones, indicating their critical role in ligand binding. Computational alanine scanning further demonstrated that all five residues act as binding determinants, with Phe-13 and Ile-95 making particularly significant contributions to ligand affinity. The results were further validated by site-directed mutagenesis and fluorescence binding assays. This work provides insights into the function and binding mechanisms of PBPs in sex pheromone recognition and supports the development of targeted mating disruption strategies for P. saucia control.