Binding Affinity Characterization of Four Antennae-Enriched Odorant-Binding Proteins From Harmonia axyridis (Coleoptera: Coccinellidae)

Abstract

Harmonia axyridis is an important natural enemy that consumes many agricultural and forestry pests. It relies on a sensitive olfactory system to find prey and mates. Odorant-binding proteins (OBPs) as the first-step of recognizing volatiles, transport odors through sensillum lymph to odorant receptors (ORs). However, little is known about the molecular mechanisms of H. axyridis olfaction. In this study, four H. axyridis antenna specific OBP genes, HaxyOBP3, 5, 12, and 15, were bacterially expressed and the binding features of the four recombinant proteins to 40 substances were investigated using fluorescence competitive binding assays. Three-dimensional structure modeling and molecular docking analysis predicted the binding sites between HaxyOBPs and candidate volatiles. Developmental expression analyses showed that the four HaxyOBP genes displayed a variety of expression patterns at different development stages. The expression levels of HaxyOBP3 and HaxyOBP15 were higher in the adult stage than in the other developmental stages, and HaxyOBP15 was significantly transcriptionally enriched in adult stage. Ligand-binding analysis demonstrated that HaxyOBP3 and HaxyOBP12 only combined with two compounds, β-ionone and p-anisaldehyde. HaxyOBP5 protein displayed binding affinities with methyl salicylate, β-ionone, and p-anisaldehyde (Ki = 18.15, 11.71, and 13.45 μM). HaxyOBP15 protein had a broad binding profile with (E)-β-farnesene, β-ionone, α-ionone, geranyl acetate, nonyl aldehyde, dihydro-β-ionone, and linalyl acetate (Ki = 4.33–31.01 μM), and hydrophobic interactions played a key role in the binding of HaxyOBP15 to these substances according to molecular docking. Taken together, HaxyOBP15 exhibited a broader ligand-binding spectrum and a higher expression in adult stage than HaxyOBP3, 5, and 12, indicating HaxyOBP15 may play a greater role in binding volatiles than other three HaxyOBPs. The results will increase our understanding of the molecular mechanism of H. axyridis olfaction and may also result in new management strategies (attractants/repellents) that increase the biological control efficacy of H. axyridis.

Functional analysis of odorant-binding proteins for the parasitic host location to implicate convergent evolution between the grain aphid and its parasitoid Aphidius gifuensis

“…Values indicated at the nodes are bootstrap values based on 1000 replicates presented with a 95 % cutoff. The orthologous protein sequences from the genomes and transcriptomes of the following species were used in the analysis: M. persicae [63], S. miscanthi [64], A. gossypii [65], A. pisum [66], A. glycines [33], M. viciae [34], R. padi [35], LeryOBP3 (AJO61166), LeryOBP7 (AJO61167)) and the OBP protein sequences from parasitoid A. gifuensis [20,49]; the predators H. axyridis [44], C. pallens [67], Episyrphus balteatus [68] and E. corollae [68,69]. The amino acids of the sequences used are listed in Supplementary file 1.…”

“…During predation and parasitism, natural enemies utilize herbivoreinduced plant volatiles (HIPVs), green leaf volatiles (GLVs), or volatiles from aphids to locate their hosts [14,[39][40][41][42][43][44][45]. The recognition mechanism of EBF in natural enemies of aphids also has been investigated within the olfactory system.…”

“…For instance, CpalOBP10 showed affinities for EBF and green leaf volatiles in Chrysopa pallens [43]. HaxyOBP15 displayed a broad binding profile with EBF as well as multiple other odor ligands in ladybeetle Harmonia axyridis [44]. Furthermore, one EBF olfactory receptor, EcorOR3, as well as a EBF binding protein EcorOBP15, has been identified to be involved in EBF perception in the hoverfly Eupeodes corollae [42].…”

Rational Design of Peptides Derived from Odorant-Binding Proteins for SARS-CoV-2-Related Volatile Organic Compounds Recognition

“…Insect odorant-binding proteins (OBPs) have an outstanding ability to recognize various kinds of VOCs [11][12][13][14][15]. Although expressed at high levels in insects, these OBPs have not been fully characterized and developed as biosensors owing to difficulties in their structural identification and high-cost synthesis.…”

D-limonene binds the target gene odorant-binding protein 3 to control Bemisia tabaci

“…where is the free concentration of 1-NPN, and K 1 − NPN is the dissociation constant of the protein/1-NPN(Qu et al 2022). …”