Institute of Plant Protection, Guangdong Academy of Agricultural Sciences, Key Laboratory of Green Prevention and Control on Fruits and Vegetables in South China Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of High Technology for Plant Protection, Guangzhou, P.R. China.
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, P.R. China.
Insect Mol Biol. 2024 Aug;33(4):405-416. doi: 10.1111/imb.12907. Epub 2024 Mar 13.
Odorant-binding proteins (OBPs) initiate insect olfactory perception and mediate specific binding and selection of odorants via uncertain binding mechanisms. We characterized the binding characteristics of four OBPs from the striped flea beetle Phyllotreta striolata (SFB), a major cruciferous crop pest. Tissue expression analysis revealed that the two ABPII OBPs (PstrOBP12 and PstrOBP19) were highly expressed mainly in the antenna, whereas the two minus-C OBPs (PstrOBP13 and PstrOBP16) showed a broad expression pattern. Competitive binding assays of cruciferous plant volatiles showed that PstrOBP12, PstrOBP16 and PstrOBP19 had very strong binding capacities for only two phthalate esters (K < 20 μM), and PstrOBP13 specifically bound to four aromatic volatiles (K < 11 μM). Fluorescence quenching assays displayed that two phthalate esters bound to three PstrOBPs via different quenching mechanisms. PstrOBP12/PstrOBP16-diisobutyl phthalate and PstrOBP19-bis(6-methylheptyl) phthalate followed static quenching, while PstrOBP12/PstrOBP16-bis(6-methylheptyl) phthalate and PstrOBP19-diisobutyl phthalate followed dynamic quenching. Homology modelling and molecular docking displayed that PstrOBP12-diisobutyl phthalate was driven by H-bonding and van der Waals interactions, while PstrOBP16-diisobutyl phthalate and PstrOBP19-bis(6-methylheptyl) phthalate followed hydrophobic interactions. Finally, behavioural activity analysis demonstrated that phthalate esters exhibited different behavioural activities of SFB at different doses, with low doses attracting and high doses repelling. Overall, we thus revealed the different binding properties of the three PstrOBPs to two phthalate esters, which was beneficial in shedding light on the ligand-binding mechanisms of OBPs.
气味结合蛋白（OBPs）启动昆虫的嗅觉感知，并通过不确定的结合机制介导特定的气味结合和选择。我们对来自十字花科作物主要害虫黄曲条跳甲（Phyllotreta striolata）的 4 种 OBPs 的结合特性进行了表征。组织表达分析显示，两种 ABPII OBPs（PstrOBP12 和 PstrOBP19）主要在触角中高度表达，而两种 minus-C OBPs（PstrOBP13 和 PstrOBP16）表现出广泛的表达模式。对十字花科植物挥发物的竞争性结合分析表明，PstrOBP12、PstrOBP16 和 PstrOBP19 对仅两种邻苯二甲酸酯（K < 20 μM）具有很强的结合能力，而 PstrOBP13 特异性结合四种芳香族挥发物（K < 11 μM）。荧光猝灭分析显示，两种邻苯二甲酸酯通过不同的猝灭机制与三种 PstrOBPs 结合。PstrOBP12/PstrOBP16-邻苯二甲酸二异丁酯和 PstrOBP19-邻苯二甲酸双（6-甲基庚基）酯遵循静态猝灭，而 PstrOBP12/PstrOBP16-邻苯二甲酸双（6-甲基庚基）酯和 PstrOBP19-邻苯二甲酸二异丁酯遵循动态猝灭。同源建模和分子对接显示，PstrOBP12-邻苯二甲酸二异丁酯由氢键和范德华相互作用驱动，而 PstrOBP16-邻苯二甲酸二异丁酯和 PstrOBP19-邻苯二甲酸双（6-甲基庚基）酯遵循疏水相互作用。最后，行为活性分析表明，邻苯二甲酸酯在不同剂量下对黄曲条跳甲表现出不同的行为活性，低剂量吸引，高剂量排斥。总体而言，我们揭示了三种 PstrOBPs 对两种邻苯二甲酸酯的不同结合特性，这有助于阐明 OBPs 的配体结合机制。
