Abstract
Sirex noctilio, a major forestry quarantine pest, has spread rapidly and caused serious harm. However, existing methods still need to be improved because its olfactory interaction mechanisms are poorly understood. In order to study the role of male-specific protein SnocOBP7 in the protein–ligand interactions, we selected it as the object of computational simulation and analysis. By docking it with 11 ligands and evaluating free binding energy decomposition, the three best binding ligands were found to be female sex pheromones ((Z)-7-heptacosene and (Z)-7-nonacosene) and symbiotic fungal volatiles ((−)-globulol). Binding mode analysis and computational alanine scanning suggested that five residues play key roles in the binding of each female sex pheromone to SnocOBP7, whereas two residues play key roles in (−)-globulol binding. Phe108 and Leu36 may be the crucial sites via which SnocOBP7 binds female sex pheromones, whereas Met40 may regulate the courtship behavior of males, and Leu61 may be related to mating and host finding. Our studies predicted the function of SnocOBP7 and found that the interaction between SnocOBP7 and pheromone is a complex process, and we successfully predicted its binding key amino-acid sites, providing a basis for the development of new prevention and control methods relying on female sex pheromones and symbiotic fungi.
Highlights
As one of the main mechanisms through which insects perceive the external environment, the olfactory system plays a very important role in foraging, defense, mating, reproduction, information exchange, and habitat selection [1]
The results showed that SnocOBP7 contains 131 amino acids with six conserved cysteine residues
In order to find the most suitable template to create the 3D structure of SnocOBP7, we first identified Locusta migratoria OBP1 (PDB ID: 4PTI) (Figure 2b) as the currently available template with the highest homology, and it was used as the initial template for optimization
Summary
As one of the main mechanisms through which insects perceive the external environment, the olfactory system plays a very important role in foraging, defense, mating, reproduction, information exchange, and habitat selection [1]. Studying how odor molecules in the environment act on insect sensilla and induce insects to produce behavioral responses will illuminate the molecular interaction mechanisms underlying insect host identification, interspecific interaction, and intraspecific communication, allowing the formulation of corresponding management and protection strategies with advantages over currently available methods. Signal transduction in the peripheral olfactory system of insects can be summarized as follows: odor molecules enter the antennal sensilla lymph through the stratum corneum, where they bind to odorant-binding proteins (OBPs) or chemosensory proteins (CSPs) [2]. After entering the organism through a series of olfactory proteins, the odor molecules are recognized and degraded, which is regarded as a vital ecological interaction process between organisms and the environment
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