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The European corn borer (Ostrinia nubilalis) is a major lepidopteran pest, causing annual maize losses of 5.5–8.5 million tons worldwide. Successful mating relies on the male’s ability to detect species-specific, hydrophobic sex pheromones released by females. Pheromone-binding proteins (PBPs), abundantly expressed in male antennae, capture these pheromones and transport them through the sensillar lymph to olfactory receptor neurons. Here, we report the first successful heterologous expression, purification, and functional characterization of O. nubilalis PBP2 (OnubPBP2). Fluorescence binding assays show that recombinant OnubPBP2 is active and binds both E- and Z-isomers of 11-tetradecenyl acetate with nanomolar affinity at pH 6.5. The calculated binding energies based on molecular docking simulation are in good agreement with the binding affinities measured using fluorescence displacement assays. High-resolution NMR titrations reveal a reversible pH-dependent conformational transition, with OnubPBP2 adopting a partially unfolded, molten-globule-like state under acidic conditions. Such conformational flexibility, observed across several Ostrinia PBPs, likely represents an adaptive mechanism that balances structural stability with ligand release efficiency, defining a divergent PBP subclass with unique pH-dependent dynamics likely contributing to enhanced functional versatility. 

Sex pheromones mediate mate recognition in insects through interactions with pheromone-binding proteins (PBPs). Targeting this pathway with pheromone analogs offers a species-specific approach to pest management. Here, we report the design, synthesis, and evaluation of a pheromone analog, (6E,11Z)-heptadeca-6,11-dien-1-yl acetate, as an inhibitor of Antheraea polyphemus PBP1 (ApolPBP1). Molecular docking predicted potential binding orientations and interactions within the pocket. Fluorescence-based binding assays revealed a four-fold higher dissociation constant, and 2D [¹H, ¹⁵N] HSQC NMR titrations confirmed reduced affinity, with ApolPBP1 transitioning to the bound state only at higher analog concentrations. Overall, these findings highlight the sensitivity of PBPs to subtle structural modifications in their ligands and emphasize the importance of preserving key molecular interactions for effective binding. 

Odorant-binding proteins derived from pigs, bovines, and other animals are the next frontier in localized, climate-smart sensing of pesticide spills, greenhouse gas precursors, and more. 

Insects utilize sophisticated olfactory systems to detect chemical cues critical for behaviors such as mating, host selection, and predator avoidance. In lepidopteran moths, sex pheromone communication offers a well-established model where males detect female-emitted signals over long distances. Central to this process are pheromone-binding proteins (PBPs), which solubilize and transport hydrophobic pheromones through the sensillar lymph to olfactory receptors, enabling precise signal detection. Recent advances in molecular biology, structural biochemistry, and gene-editing technologies such as CRISPR/Cas9 have uncovered nuanced mechanisms underlying PBP function, including ligand-binding specificity, pH-dependent conformational dynamics, and molecular interactions. These discoveries have broad implications, extending beyond chemosensory biology to applications in reverse chemical ecology, biosensing, and environmentally conscious pest control. This review synthesizes insights from in vitro, in silico, and in vivo studies, highlighting the structural and functional diversity of PBPs across species and emphasizing their translational utility as molecular targets for sustainable agriculture and biodiversity conservation.