青天葵1-脱氧-D-木酮糖-5-磷酸合成酶基因片段的鉴定和分析

Identification and Analysis of DXS Gene Fragment in Nervilia fordii

1-脱氧-D-木酮糖-5-磷酸合成酶(1-deoxy-D-xylulose-5-phosphate synthase,DXS)是植物萜类MEP生物合成途径的第一个限速关键酶,提高其编码基因的表达可提高植物萜类化合物的含量。该研究在青天葵全转录组测序数据中获取青天葵DXS基因片段序列,利用生物信息学方法对其系统发育进化、保守功能域、理化性质、亲/疏水性、跨膜结构域、信号肽等进行分析和预测,并采用RPKM法分析其在青天葵叶片和球茎的表达量,为后期利用DXS基因调控青天葵萜类成分的生物合成提供理论依据。结果表明:NfDXS基因片段序列长度为2 154bp,编码含有718个氨基酸、分子量约为77.45kDa的亲水性蛋白,与其它DXS同源性可达80%。NfDXS具有1-脱氧-D-木酮糖-5-磷酸合成酶功能域,没有信号肽和跨膜结构域,二级结构表现为混合型结构蛋白质。NfDXS基因在青天葵中的表达趋势为:叶片>球茎。

1-deoxy-D-xylulose-5-phosphate synthase is the first rate-limiting key enzyme of plant MEP terpenoids biosynthesis pathway.Enhancing the expression of DXSgene can promote the biosynthesis of terpenoids in plants.Here,one DXSgene fragment was identified from the transcriptome data of Nervilia fordii（Hance）Schltr.and named as NfDXSusing bioinformatics.NfDXSencoded 718 amino acids and the coding protein was hydrophilic protein with a molecular weight at 77.45 kDa.NfDXS protein contained a 1-deoxy-D-xylulose-5-phosphate synthase functional domain and none signal peptide and transmembrane region.Secondary structure prediction revealed NfDXS was a hybrid protein.The expression level of NfDXSgene in leaf was higher than in corm.The study would provide a firm foundation for regulating the synthesis of effective terpenoids by gene manipulation of DXSin N.fordii.