10种药用植物萜类合酶(DXS)生物信息学分析

为研究药用植物DXS酶的性质及其结构功能，利用生物信息学方法对GenBank中青蒿、砂仁、铁皮石斛等10种药用植物DXS编码氨基酸序列的理化特性、系统发育进化、亲/疏水性、亚细胞定位、磷酸化位点、二级结构、信号肽、跨膜结构、功能域等进行分析和预测。结果表明：不同植物DXS酶氨基酸序列的理化性质基本一致；在进化关系上可划分为2类；DXS酶蛋白主要表现为亲水性蛋白；大多数定位于叶绿体，少数定位于线粒体；丝氨酸磷酸化位点占据主导地位；α-螺旋是DXS多肽链中大量的结构元件，散布于整个肽链中；除了铁皮石斛具有1个信号肽，其余DXS氨基酸序列不具有信号肽，可推测出DXS可能不是分泌性蛋白；没有跨膜结构域；具有3个功能域分别为TPP_superfamily、Transket_pyr_ superfamily和Transketolase_C superfamily。研究结果将为DXS的酶学特性及萜类生物合成的分子机理研究提供理论参考。

Bioinformatics Analysis of DXS in Ten Medicinal Plants

In order to study the properties and structure function of DXS enzyme of medicinal plants, the amino acid sequences of 1-deoxy-D-xylulose 5-phosphate synthase (DXS) from Artemisia annua, Amomum villosum, Dendrobium officinale and so on, which were registered in GenBank, were analyzed and predicted by the tools of bioinformatics in the following aspects: physical and chemical characteristics of amino acid sequences, molecular phylogenetic evolution, hyophobicity or hydrophilicity, subcellular localization, phosphorylation site, signal peptide, secondary structure of protein, transmembrane topological structures, function domain, and so on. The results showed that DXS did not have signal peptide, transmembrane topological structures; the most abundant amino acids include Gly, Ala, Leu, Ser, Val. The dominant was the serine phosphorylation sites; mainly located in the chloroplast, the minor part located in mitochondria. The main was a hydrophilic protein, α-helix and random coil were the major motifs of predicted secondary structure of DXS; with three function domains for TPP_superfamily, Transket_pyr_ superfamily and Transketolase_C superfamily. The result provided theoretical reference for studies on both the enzymatic characteristics of DXS and the biosynthesis pathway of terpenoid.