Yixi Zhang, Liu Zewen, Han Zhaojun, Song Feng, Yao Xiangmei, Shao Ying, Li Jian, Millar Neil S
Key Laboratory of Monitoring and Management of Plant Diseases and Insects, Ministry of Agriculture, College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
J Neurochem. 2009 Sep;110(6):1855-62. doi: 10.1111/j.1471-4159.2009.06280.x. Epub 2009 Jul 14.
Neonicotinoid insecticides, such as imidacloprid, are selective agonists of insect nicotinic acetylcholine receptors (nAChRs) and are used extensively to control a variety of insect pest species. Previously, we have identified a nAChR point mutation (Y151S) associated with insecticide resistance in the brown planthopper Nilaparvata lugens. Although this mutation has been identified in two different N. lugens nAChR subunits (Nlalpha1 and Nlalpha3) because of difficulties in heterologous expression of Nlalpha3; its influence on agonist potency has been examined only in Nlalpha1-containing nAChRs. Here we describe the cloning of a novel nAChR subunit from N. lugens (Nlalpha8), together with evidence for its co-assembly with Nlalpha3 in native and recombinant nAChRs. This has, for the first time, enabled the functional effects of the Nlalpha3(Y151S) mutation to be examined. The Nlalpha3(Y151S) mutation has little effect on agonist potency of acetylcholine but has a dramatic effect on neonicotinoid insecticides (reducing I(max) values and increasing EC(50) values). The apparent affinity of neonicotinoids was higher and the effect of the Y151S mutation on neonicotinoid agonist potency was more profound in Nlalpha3-containing, rather than Nlalpha1-containing nAChR. We conclude that Nlalpha3- and Nlalpha1-containing nAChRs may be representative of two distinct insect nAChR populations.
新烟碱类杀虫剂，如吡虫啉，是昆虫烟碱型乙酰胆碱受体（nAChRs）的选择性激动剂，被广泛用于控制多种害虫物种。此前，我们已经在褐飞虱Nilaparvata lugens中鉴定出一种与杀虫剂抗性相关的nAChR点突变（Y151S）。尽管由于Nlalpha3异源表达困难，该突变已在两种不同的褐飞虱nAChR亚基（Nlalpha1和Nlalpha3）中被鉴定出来；但其对激动剂效力的影响仅在含有Nlalpha1的nAChRs中进行了研究。在这里，我们描述了从褐飞虱中克隆出一种新型nAChR亚基（Nlalpha8），以及其在天然和重组nAChRs中与Nlalpha3共同组装的证据。这首次使得能够研究Nlalpha3（Y151S）突变的功能效应。Nlalpha3（Y151S）突变对乙酰胆碱的激动剂效力影响不大，但对新烟碱类杀虫剂有显著影响（降低I(max)值并增加EC(50)值）。在含有Nlalpha3而非含有Nlalpha1的nAChR中，新烟碱类的表观亲和力更高，且Y151S突变对新烟碱类激动剂效力的影响更为显著。我们得出结论，含有Nlalpha3和含有Nlalpha1的nAChRs可能代表了两种不同的昆虫nAChR群体。
