木榄θ型谷胱甘肽转移酶(BgGSTT)cDNA的克隆及其在盐胁迫下的表达分析  

Molecular Cloning and Expression Analysis of θ Class Glutathione S-transferase cDNA in Bruguiera gymnorrhiza under Salt Stress

作　　者：周小群[1] 李谊[1] 胡文军[1] 叶波平[1] 

机构地区：[1]中国药科大学生命科学与技术学院,江苏南京210009

出　　处：《药物生物技术》2012年第2期100-104,共5页Pharmaceutical Biotechnology

基　　金：教育部"新世纪优秀人才支持计划"项目(NCET-05-0496)

摘　　要：谷胱甘肽转移酶(Glutathione S-transferases,GSTs,EC 2.5.1.18)是生物体内重要的一种解毒和抗氧化酶类。为进一步研究该酶在木榄适应盐生环境中的作用,从前期构建的木榄幼叶cDNA文库中克隆到编码theta型GST(BgGSTT)的cDNA全序列,分析和预测了其编码产物的结构特征,探讨了该基因在不同盐度下生长的木榄幼苗叶片及根中的表达变化。结果发现:编码BgGSTT的cDNA全长1111 bp,编码区为753 bp,编码的蛋白由250个氨基酸残基组成,理论相对分子质量为28.1k,pI为9.42。系统发育分析显示BgGSTT与来源于拟南芥和乳浆大戟的GSTT同源性较高(identity分别为72%和65%)。利用荧光实时定量RT-PCR检测了BgGSTT在不同盐度下生长的木榄幼苗叶片及根中的表达变化,结果发现BgGSTT基因在木榄幼苗叶片中表达量较高,并且随着培养盐度的升高其表达逐渐加强,在25‰盐度达到最高,随后稍有下降但仍维持在较高水平。根据上述结果,推测BgGSTT基因可能参与了木榄适应盐胁迫的过程,并且该基因的表达在木榄幼苗叶片和根中具有严格的转录调控机制。Glutathione S-transferases（（GSTs,EC 2.5.1.18） are thought to play very important role in detoxification and oxidative stress response.To make better understanding of their roles in salt-tolerance of halophytes,a full-length cDNA encoding theta class GST（（BgGSTT） was cloned and sequenced from the Bruguiera gymnorrhiza seedling leave cDNA library.The cDNA is 1111 bp in length,and the open reading frame（（ORF） of this cDNA is 753 bp presumed to encode a protein consist of 250 amino acid residues with theoretical molecular weight of 28.1kD and pI of 9.42.The deduced amino acid sequence of BgGSTT shares 72% and 65% identity with those reported in Arabidopsis thaliana and Euphorbia esula respectively.Fluorescent real-time RT-PCR was used to analyze the expression levels of BgGSTT in B.gymnorrhiza seedling leaves and roots.The results showed that the expression levels of BgGSTT in seedling leaves were obviously higher than those in roots under the same salinity conditions,which suggestinged that the expression of BgGSTT was tightly controlled in different tissues.In seedling leaves,the expression of BgGSTT were up-regulated under the increasing salinity with its maximum at 25‰ salinity,then declined slowly and steadily,and maintained at a relative high level between 35‰~50‰ salinity.This showed a positive correlation with salinity.Thus,we presume that BgGSTT gene plays an important role in the adaptation of B.gymnorrhiza under salinity conditions.

关 键 词：木榄 谷胱甘肽转移酶θ亚型 结构与功能 盐胁迫 基因表达 

分 类 号：Q55[生物学—生物化学]