Mutations in the house fly Vssc1 sodium channel gene associated with super-kdr resistance abolish the pyrethroid sensitivity of Vssc1/tipE sodium channels expressed in Xenopus oocytes
Mutations in the house fly Vssc1 sodium channel gene associated with super-kdr resistance abolish the pyrethroid sensitivity of Vssc1/tipE sodium channels expressed in Xenopus oocytes
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DOI：
10.1016/s0965-1748(98)00122-2
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发表时间：
1999-02-01
影响因子：
3.8
通讯作者：
Soderlund, DM
中科院分区：
文献类型：
--
作者：
Lee, SH;Smith, TJ;Soderlund, DM
家蝇的超级kdr杀虫剂抗性特性通过降低Ay神经系统的敏感性而赋予对拟除虫菊酯和滴滴涕的抗性。超级kdr基因位点与Vssc 1基因紧密连锁，Vssc 1基因编码电压敏感性钠通道ct亚基，该亚基是拟除虫菊酯作用的主要位点。从几个独立的super-kdr果蝇品系的Vssc 1等位基因的DNA序列分析确定了与super-kdr性状相关的两个氨基酸取代：在位置1014处的亮氨酸被苯丙氨酸取代（L1014 F），这已被证明会导致该物种的kdr抗性性状，以及在位置918处的蛋氨酸被苏氨酸取代（M918 T）。我们研究了这些突变的功能意义，通过表达家蝇钠通道含有它们在非洲爪蟾卵母细胞和表征的生物物理特性和拟除虫菊酯敏感性的表达通道，使用双电极电压钳。通过定点诱变特异性修饰以含有M918 T/L1014 F双突变的家蝇钠通道保存降低了卵母细胞中钠电流表达水平，但在其他方面表现出与野生型通道和含有L1014 F取代的通道相似的功能特性。然而，M918 T/L1014 F通道对高浓度的拟除虫菊酯顺式菊酯和氯氰菊酯完全不敏感。家蝇钠通道专门修改包含M918 T单突变，这是不知道存在于自然界中，除了与L1014 F突变，在卵母细胞中的钠电流非常小。在高浓度的顺式菊酯的存在下，这些电流的测定表明，这种突变本身就足以消除家蝇钠通道的拟除虫菊酯敏感性。这些结果定义了与家蝇的超级kdr性状相关的Vssc 1突变的功能意义，并且与超级kdr性状是由第二位点突变（M918 T）的选择引起的假设一致，该突变赋予果蝇比含有L1014 F突变的X-dr等位基因更大的抗性。(C)1999爱思唯尔科技有限公司。保留所有权利。
The super-kdr insecticide resistance trait of the house fly confers resistance to pyrethroids and DDT by reducing the sensitivity of the Ay nervous system. The super-kdr genetic locus is tightly linked to the Vssc1 gene, which encodes a voltage-sensitive sodium channel ct subunit that is the principal site of pyrethroid action. DNA sequence analyses of Vssc1 alleles from several independent super-kdr fly strains identified two amino acid substitutions associated with the super-kdr trait: replacement of leucine at position 1014 with phenylalanine (L1014F), which has been shown to cause the kdr resistance trait in this species, and replacement of methionine at position 918 with threonine (M918T). We examined the functional significance of these mutations by expressing house fly sodium channels containing them in Xenopus laevis oocytes and by characterizing the biophysical properties and pyrethroid sensitivities of the expressed channels using two-electrode voltage clamp. House fly sodium channels that were specifically modified by site-directed mutagenesis to contain the M918T/L1014F double mutation Save reduced levels of sodium current expression in oocytes but otherwise exhibited functional properties similar to those of wildtype channels and channels containing the L1014F substitution. However, M918T/L1014F channels were completely insensitive to high concentrations of the pyrethroids cismethrin and cypermethrin. House fly sodium channels specifically modified to contain the M918T single mutation, which is not known to exist in nature except in association with the L1014F mutation, gave very small sodium currents in oocytes. Assays of these currents in the presence of high concentrations of cismethrin suggest that this mutation alone is sufficient to abolish the pyrethroid sensitivity of house fly sodium channels. These results define the functional significance of the Vssc1 mutations associated with the super-kdr trait of the house fly and are consistent with the hypothesis that the super-kdr trait arose by selection of a second-site mutation (M918T) that confers to flies possessing it even greater resistance than the X-dr allele containing the L1014F mutation. (C) 1999 Elsevier Science Ltd. All rights reserved.