黄独微型块茎鲨烯合酶的基因克隆与序列分析

Cloning and Sequence Analysis of Squalene Synthase(SQS)Gene from Dioscorea bulbifera L.Microtuber

通过黄独微型块茎转录组数据库筛选到SQS基因的核心片段,利用RT-PCR技术获得SQS基因保守片段,采用RACE技术获得SQS基因的3′及5′末端序列,并采用生物信息学方法进行序列分析。结果表明,黄独微型块茎SQS基因编码序列长1548 bp,编码415 bp的氨基酸序列,理论分子量为46786.38 D,等电点(pI)为5.97。SQS蛋白为疏水性蛋白,无信号肽,含有SQS所必需的功能结构域,属于Isoprenoid_Biosym_C1 superfami⁃ly。黄独SQS蛋白与其他植物的SQS蛋白同源性较高,其中与盾叶薯蓣的SQS蛋白氨基酸相似性为96.4%。本试验结果从黄独微型块茎中首次获得SQS基因cDNA全长序列,该基因具有SQS同源基因的典型特征,为进一步研究黄独微型块茎SQS基因结构、基因表达和基因突变提供了基础,并为薯蓣属植物三萜合成通路关键酶SQS的正选择位点与功能的关联性分析提供了数据支持。

The core fragment of SQS gene was screened from the transcriptome database of Dioscorea bulbifera L.microtuber,the conservative fragment of SQS gene was obtained by RT-PCR,and the 3'and 5'terminal sequences of SQS gene were obtained by race technique,and the sequence was analyzed by bioinformatics.The SQS gene of D.bulbifera L.microtuber was 1548 bp long and 415 bp amino acid sequence,with a theoretical molecular weight of 46786.38 D and an isoelectric point of 5.97.SQS protein is a hydrophobic protein without signal peptide.It contains the functional domain necessary for SQS belonging to Isoprenoid_Biosym_C1 superfamily.The homology of SQS protein between D.bulbifera and other plants is high,and the amino acid similarity of SQS protein between D.bulbifera and D.zingiberensis is 96.4%.The full-length sequence of SQS gene was obtained for the first time from D.bulbifera L.microtuber,which has the typical characteristics of SQS homologous gene.It provides the basis for further study on SQS gene structure,gene expression and gene mutation of D.bulbifera microtuber,and provides data support for the correlation analysis of positive selection site and function of SQS,a key enzyme of triterpene synthesis pathway in Dioscorea.