家蚕微粒体 GST 的鉴定与序列分析

微粒体 GSTs(microsomal glutathione S-transferases,mGSTs)是广泛分布于动物、植物、细菌等生物体中的多功能酶类,具有对药物解毒和抗氧化等功能。作为一类膜蛋白,在研究手段上难于胞质型 GSTs(cytosolic GSTs),迄今为止在昆虫中较少展开功能研究。本研究在基因组水平对家蚕 mGSTs 进行了分析,共鉴定出 BmmGST1和 BmmGST2两个基因,它们位于家蚕15号染色体,呈串联排列,无内含子插入。BmmGST1和 BmmGST2编码的蛋白分别含有151和150个氨基酸残基,分子量为16.9 kD 和16.7 kD。进化分析表明,家蚕 mGSTs 可能是由于世系特异扩增而产生的两个拷贝。分析表达序列标签证实 BmmGST1在5龄3 d 幼虫的翅原基、丝腺和卵巢组织表达。基于组织和发育时期芯片,BmmGST2在各组织和发育期均有表达信号。家蚕与其他昆虫、大鼠的 mGSTs 序列高度保守,是否也有类似于哺乳动物中的功能值得进一步研究。

Identification and sequence analysis of the microsomal GSTs in the silkworm

Microsomal GSTs (mGSTs)are a family of multifunctional enzymes found in animals, plants and bacteria,which contain the activity of detoxification and glutathione peroxidase. As one of the membrane proteins,it is difficult to study compared with cytosolic GSTs in in-sects.In present study,we analyzed putative mGSTs in the silkworm genome,and identified BmmGST 1 and BmmGST2.They were tandemly located on chromosome 15 and encoded 15 1 and 150 amino acids,respectively.Molecular weights of them are 1 6.9 kD and 1 6.7 kD. Phylogenetic analysis suggested that two BmmGSTs were the two copies from linage-spe-cific duplication.The putative coding sequence of silkworm mGSTs was used to do Blastn search in the silkworm expressed sequence tags (ESTs)database.BmmGST 1 expressed in the wing disc,silkgland and ovary on day 3 of fifth instar larvae.Based on the microarray datasets,BmmGST2 was found to express in all tissues on day 3 of fifth instar larvae and all the developmental stages.Silkworm mGSTs were highly conserved with the other insect and Rattus norvegicus microsomal GSTs.It is worth to study whether the silkworm mGSTs con-tain the similar functions in mammals.