Characterization of two kdr mutations at predicted pyrethroid receptor site 2 in the sodium channel of Aedes aegypti and Nilaparvata lugens

Authors: HUAHUA, SUN - Duke University; YOSHIKO, NOMURA - Michigan State University; Du, Yuzhe - Cathy; ZEWEN, LIU - Nanjing Agricultural University; BORIS, ZHOROV - McMaster University; KE, DONG - Duke University

Submitted to: Insect Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2022
Publication Date: 8/3/2022
Citation: Huahua, S., Yoshiko, N., Du, Y., Zewen, L., Boris, Z.S., Ke, D. 2022. Characterization of two kdr mutations at predicted pyrethroid receptor site 2 in the sodium channel of Aedes aegypti and Nilaparvata lugens. Insect Biochemistry and Molecular Biology. https://doi.org/10.1016/j.ibmb.2022.103814.
DOI: https://doi.org/10.1016/j.ibmb.2022.103814

Interpretive Summary: Pyrethroids are widely used as effective insecticides against agriculture pests. However, the development of insect resistance to pyrethroids has markedly curtailed the effective use of pyrethroids in pest control and highlights the urgent need for alternative strategies in the management of insect resistance. Pyrethroids exert their insecticidal action by interfering with the function of voltage-gated sodium channels. They prolong the opening of insect sodium channels by binding to two predicted pyrethroid receptor sites (PyR), PyR1 and PyR2. Naturally occurring mutations in sodium channels confer pyrethroid resistance in various insect pests and disease vectors. While PyR1 possesses most of the functionally confirmed kdr mutations, two new mutations, V253F and T267A, in PyR2 have been recently identified in pyrethroid-resistant populations of Aedes aegypti and Nilaparvata lugens, respectively. Here we report functional characterization of the V253F and T267A mutations in the N. lugens sodium channel NlNav1 and the Ae. aegypti sodium channel AaNav2-1 expressed in Xenopus oocytes. Both mutations reduced channel sensitivity to pyrethroids, including etofenprox. We docked etofenprox in a homology model of the NlNav1 channel based on the crystal structure of a bacterial sodium channel. In the low-energy binding pose etofenprox formed contacts with V253 and T267 within PyR2. Our findings provide new insights into the molecular details of PyR2 and a example for a positive interaction between PyR1 and PyR2 mutations in sodium channel gating while conferring higher level pyrethroid resistance.

Technical Abstract: Pyrethroids exert their insecticidal action by interfering with the function of voltage-gated sodium channels. They prolong the opening of insect sodium channels by binding to two predicted pyrethroid receptor sites (PyR), PyR1 and PyR2. Naturally occurring mutations in sodium channels confer pyrethroid resistance (known as knockdown resistance, kdr) in various insect pests and disease vectors. While PyR1 possesses most of the functionally confirmed kdr mutations, two new mutations, V253F and T267A, in PyR2 have been recently identified in pyrethroid-resistant populations of Aedes aegypti and Nilaparvata lugens, respectively. However, the role of these mutations in pyrethroid resistance has not been functionally examined. Here we report functional characterization of the V253F and T267A mutations in the N. lugens sodium channel NlNav1 and the Ae. aegypti sodium channel AaNav2-1 expressed in Xenopus oocytes. Both mutations reduced channel sensitivity to pyrethroids, including etofenprox. Both mutations alone significantly altered the gating of the sodium channels. Interestingly, V253F- and T267A-induced gating modifications disappeared when they were co-expressed with a PyR1 kdr mutation that was found to co-exist in field resistant populations. We docked etofenprox in a homology model of the NlNav1 channel based on the crystal structure of NavMs, a bacterial sodium channel. In the low-energy binding pose etofenprox formed contacts with V253 and T267 within PyR2. Our findings provide new insights into the molecular details of PyR2 and a first example for a positive interaction between PyR1 and PyR2 mutations in preventing negative tradeoffs in sodium channel gating while conferring higher level pyrethroid resistance.