Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, United Kingdom.
Syngenta, Jealotts Hill International Research Centre, Bracknell, Berkshire RG42 6EY, United Kingdom.
Pestic Biochem Physiol. 2022 Mar;182:105055. doi: 10.1016/j.pestbp.2022.105055. Epub 2022 Feb 15.
Insect nicotinic acetylcholine receptors (nAChRs) are molecular targets of highly effective insecticides such as neonicotinoids. Functional expression of these receptors provides useful insights into their functional and pharmacological properties. Here, we report that the α5 nAChR subunit of the honey bee, Apis mellifera, functionally expresses in Xenopus laevis oocytes, which is the first time a homomeric insect nAChR has been robustly expressed in a heterologous system without the need for chaperone proteins. Using two-electrode voltage-clamp electrophysiology we show that the α5 receptor has low sensitivity to acetylcholine with an EC of 2.37 mM. However, serotonin acts as an agonist with a considerably lower EC at 119 μM that is also more efficacious than acetylcholine in activating the receptor. Molecular modelling indicates that residues in the complementary binding site may be involved in the selectivity towards serotonin. This is the first report of a ligand-gated ion channel activated by serotonin from an insect and phylogenetic analysis shows that the α5 subunit of A. mellifera and other non-Dipteran insects, including pest species, belong to a distinct subgroup of subunits, which may represent targets for the development of novel classes of insecticides.
昆虫烟碱型乙酰胆碱受体（nAChRs）是高效杀虫剂如新烟碱类的分子靶标。这些受体的功能表达提供了对其功能和药理学特性的有用见解。在这里，我们报告说，蜜蜂（Apis mellifera）的α5 nAChR 亚基在非洲爪蟾卵母细胞中功能性表达，这是首次在无需伴侣蛋白的情况下在异源系统中强表达同型昆虫 nAChR。我们使用双电极电压钳电生理学表明，α5 受体对乙酰胆碱的敏感性低，EC 为 2.37 mM。然而，血清素作为激动剂，其 EC 低至 119 μM，在激活受体方面比乙酰胆碱更有效。分子建模表明，互补结合位点中的残基可能参与了对血清素的选择性。这是首次报道昆虫烟碱型乙酰胆碱受体由血清素激活的报告，并且系统发育分析表明，A. mellifera 和其他非双翅目昆虫（包括害虫物种）的α5 亚基属于一个独特的亚基亚组，这可能代表开发新型杀虫剂的目标。
