title: Physicochemical Evidence on Sublethal Neonicotinoid Imidacloprid Interacting with an Odorant-Binding Protein from the Tea Geometrid Moth, Ectropis obliqua.
abstract: Nowadays the excessive usage of neonicotinoid insecticides always results in residues in Chinese tea fields. It is not clear whether the insecticide residue at the sublethal level influences the physiological processes of tea pests. Here, we provide evidence of interaction between the neonicotinoid imidacloprid and a general odorant-binding protein, EoblGOBP2, from the tea geometrid moth, Ectropis obliqua. The interacting process was demonstrated through multiple fluorescence spectra, UV absorption spectra, circular dichroism (CD) spectra, molecular docking, etc. The binding mode was determined to be static (from 300 to 310 K) and dynamic quenching (from 290 to 300 K). The binding distance was calculated to be 6.9 nm on the basis of FRET theory. According to the thermodynamic analysis, the process was mainly driven by enthalpy (ΔH < 0), and hydrogen bond and van der Waals interactions were the main driving forces in the static and dynamic binding cases, respectively. Moreover, synchronous fluorescence spectra and CD spectra analysis showed stretching of the EoblGOBP2 peptide chains with a decreasing α-helix when imidacloprid was added. Molecular docking was applied and predicted that two hydrogen bonds were formed between imidacloprid and Arg110 in the mature peptide of EoblGOBP2. Moreover, when the absolute amounts of EoblGOBP2 in the moth antennae were measured and calculated by using real-time PCR, it was estimated that imidacloprid at sublethal level (about 0.233 and 0.175 ng/male and female moth antennae, respectively) inhibited the binding of a tea volatile, E-2-hexenal, to EoblGOBP2 at about half. This study indicates that neonicotinoid insecticide at sublethal level may still affect the olfactory cognition of the tea geometrid moth to volatile compounds from tea leaves.
authors.affiliation: Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University , Hangzhou 310018, China.
authors.forename: Hongliang
authors.identifier: http://orcid.org/0000-0001-7094-2472
authors.initials: H
authors.lastname: Li
authors.affiliation: Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University , Hangzhou 310018, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University , Hangzhou 310018, China.
authors.forename: Xiaobin
authors.initials: X
authors.lastname: Fu
authors.affiliation: Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University , Hangzhou 310018, China.
authors.forename: Xinmi
authors.initials: X
authors.lastname: Song
authors.affiliation: Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University , Hangzhou 310018, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Wu
authors.affiliation: Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University , Hangzhou 310018, China.
authors.forename: Mingzhu
authors.initials: M
authors.lastname: Tang
authors.affiliation: Tea Research Institute, Hangzhou Academy of Agricultural Sciences , Hangzhou 310024, China.
authors.forename: Hongchun
authors.initials: H
authors.lastname: Cui
authors.affiliation: Tea Research Institute, Hangzhou Academy of Agricultural Sciences , Hangzhou 310024, China.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Yu
mesh_terms: D000818:Animals; D005260:Female; D007093:Imidazoles / Q000737:chemistry / Q000378:metabolism*; D019476:Insect Proteins / Q000737:chemistry / Q000378:metabolism*; D007306:Insecticides / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D015394:Molecular Structure; D009036:Moths / Q000737:chemistry / Q000378:metabolism*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000737:chemistry / Q000378:metabolism*; D018035:Receptors, Odorant / Q000737:chemistry / Q000378:metabolism*
chemical_list: D007093:Imidazoles; D019476:Insect Proteins; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D018035:Receptors, Odorant; C045648:odorant-binding protein; C082359:imidacloprid
keywords: binding interaction; general odorant-binding protein; neonicotinoid imidacloprid; sublethal dose; tea geometrid moth