Identification of the OBP gene family and PoOBP83a cloning analysis in Phortica okadai antenna

The objective of this research was to explore the diversity, evolutionary relationships, functional characteristics and potential roles of the antennae odorant binding proteins (OBPs) in the olfactory function of Phortica okadai. This study conducted bioinformatics analysis based on the antennal transcriptome sequencing data of P. okadai including identification and sequence analysis of OBP family genes in the transcriptome. Special emphasis was placed on the cloning of PoOBP83a gene from this family, along with investigations of its protein physicochemical properties, gene expression profiling, and molecular docking simulations. The result showed there were 15 PoOBPs genes with OBP conserved domains in the antenna transcriptome, with the majority of PoOBP proteins exhibiting hydrophilic. These 15 PoOBPs were classified into five subfamilies based on their evolutionary relationships, which was shown in phylogenetic analysis of PoOBPs families. Protein structure predictions indicated that all PoOBP proteins possessed a PBP-GOBP domain. The coding region of the PoOBP83a gene was found to be 501 bp in length, encoding a protein of 166 amino acids, with an approximate protein molecular weight of 19 kDa and a pI of 6.15. The amino acid sequence of PoOBP83a contained six conserved cysteine sites, categorizing it within the Classic-C OBP family. Expression analysis demonstrated that PoOBP83a was present at all developmental stages, with the highest relative expression observed in antennae of male and female adults, followed by wings, mouthparts, and heads, while the lowest expression levels were recorded in legs, abdomen, and thorax. Molecular docking studies indicated that PoOBP83a exhibited strong binding affinities with linalool, ethyl benzoate, ethyl laurate, phenylethyl alcohol, and indole. The results of this investigation provide a theoretical foundation for further research into the olfactory functions of P. okadai.