Do mosquitoes acquire organophosphate resistance by functional changes in carboxylesterases?
Do mosquitoes acquire organophosphate resistance by functional changes in carboxylesterases?
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DOI：
10.1096/fj.07-8237com
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发表时间：
2007-11-01
期刊：
影响因子：
4.8
通讯作者：
Qiao, Chuan-Ling
中科院分区：
文献类型：
--
作者：
Cui, Feng;Qu, Hong;Qiao, Chuan-Ling
昆虫对有机磷（OPs）的羧酸酯酶代谢抗性已被证明源于酯酶编码序列的突变或酯酶基因的扩增。本研究旨在验证蚊子通过羧酸酯酶的功能改变获得OP抗性的假设。采用定点诱变的方法，对库蚊酯酶B1的110和224位点进行了突变。3个单突变体（G110D、W224L和W224S）和2个双突变体（G110D /W224L和G110D/W224S）得到了表达和纯化。所有五个突变体都失去了原生羧酸酯酶活性。突变W224L将酯酶B1转化为OP水解酶，并增加了其马拉硫磷羧酸酯酶活性。G110D和W224S均未观察到OP的明显水解。我们的数据有力地支持了我们的假设，并表明突变W224L可能发生在蚊子的自然种群中。序列比较表明，224位点在各种昆虫羧酸酯酶中具有高度保守性。这导致了另一种假设：在杀虫剂的选择压力下，224位点在昆虫羧酸酯酶从其天然生理功能转向其他功能生态位的过程中起着关键作用。
Carboxylesterase-based metabolic resistance to organophosphates (OPs) in insects has been shown to originate either from mutations in esterase-encoding sequences or from amplification of esterase genes. This study aimed to test the hypothesis that mosquitoes can acquire OP resistance by functional changes in carboxylesterases. Mutations were introduced into the esterase B1 of mosquito Culex pipiens by site-directed mutagenesis at positions 110 and 224. Three single mutants (G110D, W224L, and W224S) and two double mutants ( G110D/W224L and G110D/W224S) were expressed and purified. All five mutants lost native carboxylesterase activity. Mutation W224L converted esterase B1 to an OP hydrolase and increased its malathion carboxylesterase activity. No obvious OP hydrolysis was observed by G110D or W224S. Our data strongly support our hypothesis and suggest that mutation W224L might occur in natural populations of mosquitoes. Sequence comparison shows that the site 224 is especially highly conserved among various insect carboxylesterases. This leads to another hypothesis: that the position 224 plays a key role in insect carboxylesterases' switching from their native physiological functions to other functional niches under selection pressure exerted by insecticides.