G3'M-TMD3 in the insect GABA receptor subunit, RDL, confers resistance to broflanilide and fluralaner

文献类型： 外文期刊

第一作者： Zhang, Yichi

作者： Zhang, Yichi;Huang, Qiutang;Sheng, Chengwang;Zhang, Kexin;Jia, Zhongqiang;Mao, Xin;Han, Zhaojun;Zhao, Chunqing;Liu, Genyan;Tang, Tao;Jones, Andrew K.;Sheng, Chengwang

作者机构：

期刊名称：PLOS GENETICS （ 影响因子：4.5； 五年影响因子：5.5 ）

ISSN： 1553-7404

年卷期： 2023 年 19 卷 6 期

页码：

收录情况： SCI

摘要： Meta-diamides (e.g. broflanilide) and isoxazolines (e.g. fluralaner) are novel insecticides that target the resistant to dieldrin (RDL) subunit of insect & gamma;-aminobutyric acid receptors (GABARs). In this study, we used in silico analysis to identify residues that are critical for the interaction between RDL and these insecticides. Substitution of glycine at the third position (G3') in the third transmembrane domain (TMD3) with methionine (G3'M (TMD3)), which is present in vertebrate GABARs, had the strongest effect on fluralaner binding. This was confirmed by expression of RDL from the rice stem borer, Chilo suppressalis (CsRDL) in oocytes of the African clawed frog, Xenopus laevis, where the G3'M-TMD3 mutation almost abolished the antagonistic action of fluralaner. Subsequently, G3'M-TMD3 was introduced into the Rdl gene of the fruit fly, Drosophila melanogaster, using the CRISPR/Cas9 system. Larvae of heterozygous lines bearing G3'M-TMD3 did not show significant resistance to avermectin, fipronil, broflanilide, and fluralaner. However, larvae homozygous for G3'M-TMD3 were highly resistant to broflanilide and fluralaner whilst still being sensitive to fipronil and avermectin. Also, homozygous lines showed severely impaired locomotivity and did not survive to the pupal stage, indicating a significant fitness cost associated with the G3'M-TMD3. Moreover, the M3'G(TMD3) in the mouse Mus musculus & alpha;1 & beta;2 GABAR increased sensitivity to fluralaner. Taken together, these results provide convincing in vitro and in vivo evidence for both broflanilide and fluralaner acting on the same amino acid site, as well as insights into potential mechanisms leading to target-site resistance to these insecticides. In addition, our findings could guide further modification of isoxazolines to achieve higher selectivity for the control of insect pests with minimal effects on mammals. Author summaryMeta-diamides (e.g. broflanilide) and isoxazolines (e.g. fluralaner) are members of group 30 of compounds according to the Insecticide Resistance Action Committee, and are defined as & gamma;-aminobutyric acid (GABA)-gated chloride channel allosteric modulators. However, their mode of action on the GABAR remains to be fully elucidated. In the current study, we provide in silico, in vitro and in vivo evidence that G3'(TMD3), the glycine residue at the third position (G3') in the third transmembrane domain (TMD3) of the insect GABAR subunit, resistant to dieldrin (RDL), is critical for the action of these insecticides. Furthermore, the homozygous but not heterozygous lines of the fruit fly Drosophila melanogaster bearing G3'M-TMD3 showed high resistance to broflanilide and fluralaner but were unable to survive to the pupal stage. These findings enhance our understanding of resistance-related and homozygous-lethal gene mutations, and may prove useful for the future synthesis of related insecticides to gain long-term effectiveness and higher selectivity.

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