Yamamoto Kohji, Ichinose Hirofumi, Aso Yoichi, Banno Yutaka, Kimura Makoto, Nakashima Takashi
Faculty of Agriculture, Kyushu University Graduate School, Higashi-ku, Fukuoka, Japan.
Biochim Biophys Acta. 2011 Apr;1810(4):420-6. doi: 10.1016/j.bbagen.2011.01.003. Epub 2011 Jan 13.
The glutathione transferase (GST) superfamily is involved in the detoxification of various xenobiotics. We have identified a GST mRNA that was induced in the fat bodies of a silkworm strain exhibiting diazinon resistance and have investigated the enzyme properties of this GST.
A soluble recombinant protein was overexpressed in Escherichia coli. Amino acid residues of interest were changed to alanine by site-directed mutagenesis.
Phylogenetic analysis of the deduced amino acid sequence indicates that this GST belongs to an unclassified group previously reported in mosquitoes. This enzyme, named bmGSTu, has highly conserved amino acid residues, including Tyr7, Ser12 and Asn50. A recombinant bmGSTu was able to catalyze the biotranslation of glutathione with 1-chloro-2,4-dinitrobenzene, a synthetic substrate of GST. Kinetic analysis of bmGSTu mutants indicated that Tyr7, Ser12 and Asn50 are involved in enzyme function.
These results support the hypothesis that bmGSTu may play a role in insecticide resistance in Bombyx mori.
谷胱甘肽转移酶（GST）超家族参与多种外源性物质的解毒过程。我们在表现出对二嗪农抗性的家蚕品系的脂肪体中鉴定出一种GST mRNA，并对该GST的酶学性质进行了研究。
一种可溶性重组蛋白在大肠杆菌中过表达。通过定点诱变将感兴趣的氨基酸残基替换为丙氨酸。
对推导的氨基酸序列进行系统发育分析表明，这种GST属于先前在蚊子中报道的一个未分类的组。这种酶被命名为bmGSTu，具有高度保守的氨基酸残基，包括Tyr7、Ser12和Asn50。重组bmGSTu能够催化谷胱甘肽与1-氯-2,4-二硝基苯（一种GST的合成底物）的生物转化。对bmGSTu突变体的动力学分析表明，Tyr7、Ser12和Asn50参与酶的功能。
这些结果支持bmGSTu可能在家蚕抗杀虫剂中发挥作用这一假说。
