目的 对建泽泻原萜烷型三萜类成分生物合成关键酶鲨烯合酶（squalene synthase，SS）进行基因全长的克隆和生物信息学分析。方法 以建泽泻总RNA为模板，运用同源克隆法和RACE技术克隆建泽泻SS基因的cDNA全长，并通过DNAMAN软件及ExPASy在线分析等方法对其进行生物信息学研究。结果 获得建泽泻SS基因全长cDNA，GenBank注册号为JX866770，序列分析表明，所克隆的cDNA序列全长为1 577 bp，包含一个长1 230 bp的开放阅读框架，编码409个氨基酸的蛋白，与其他药用植物具有较高的同源性。预测该蛋白的相对分子质量为4.68×10⁴，等电点为5.97，无信号肽，包含2个富含天冬氨酸（DXXDD）的保守功能域。结论 首次克隆获得建泽泻SS基因的全长cDNA，为泽泻原萜烷型三萜类成分生物合成途径阐明与生物工程应用提供科学依据。

Objective To clone the full-length cDNA encoding squalene synthase (SS), a key enzyme of protostane type triterpenes biosynthesis, from Alisma orientalis and to perform bioinformatic analysis. Methods With the total RNA as template, the full-length cDNA of SS in A. orientalis was cloned via homology-based cloning approach and rapid amplification of cDNA ends technique. The bioinformatics of the cloning SS gene was analyzed by DNAMAN and ExPASy online analysis. Results The full-length cDNA (1 577 bp) of SS gene was obtained (GenBank accession number JX866770), with an open reading frame of 1 230 bp, encoding 409 amino acid polypeptides, which had higher homology with the known SS in other medicinal species. The calculated relative molecular mass was 4.68 × 10⁴, the isoelectric point was 5.97, and there was no signal peptide in SS. The deduced protein sequence exhibited two conserved domains rich in Asp (DXXDD). Conclusion The cDNA encoding SS from A. orientalis is cloned and reported for the first time. This work provides a foundation for exploring the biosynthetic pathway of protostane type triterpenes in A. orientalis and their applications in bioengineering.

国家自然科学基金面上项目（81173483）；中国博士后科学基金（2012M521097）；江苏省博士后科研资助计划（1102097C）；江苏省“青蓝工程”资助