中文摘要：

紫杉醇（taxol）是从裸子植物红豆杉中提取的具有抗癌作用的天然药物。异戊烯基焦磷酸异构酶（isopentenyl diphosphate isomerase,IPI）是紫杉醇生物合成途径上催化IPP和二甲基烯丙基焦磷酸（DMAPP）之间进行可逆转化的异构酶。本研究从曼地亚红豆杉中首次克隆了编码IPI蛋白的基因序列（Gen Bank登录号为KP970677）,并对其进行详细的生物信息学分析。研究表明,本研究所获得的IPI基因c DNA全长1 232 bp,编码233个氨基酸,包含Nudix保守结构域,与其他物种的IPI具有高度同源性;系统进化分析表明,植物IPI被分为被子植物和裸子植物两大类群,本文所研究的红豆杉IPI属于裸子植物IPI类群,该结果与红豆杉属于裸子植物这一事实相符;Southern杂交结果表明：Tm IPI是紫杉醇等萜类生物合成途径IPI家族成员。功能验证结果表明：在大肠杆菌中过量表达IPI推动代谢流向下游流动,促进β-胡萝卜素的生物合成,说明IPI在紫杉醇等萜类相关产物生物合成中是一个重要的调节因子。

英文摘要：

Taxol is one of the most potent anti-cancer agents, which is extracted from the plants of Taxus species. Isopentenyl diphosphate isomerase （IPI） catalyzes the reversible transformation between IPP and DMAPP, both of which are the general 5-carbon precursors for taxol biosynthesis. In the present study, a new gene encoding IPI was cloned from Taxus media （namely TmIPI with the GenBank Accession Number KP970677） for the first time. The full-length cDNA of TmIPI was 1 232 bps encoding a polypeptide with 233 amino acids, in which the conserved domain Nudix was found. Bioinformatic analysis indicated that the sequence of TmIPI was highly similar to those of other plant IPI proteins, and the phylogenetic analysis showed that there were two clades of plant IPI proteins, including IPIs of angiosperm plants and IPIs of gymnosperm plants. TmlPI belonged to the clade of gymnosperm plant IPIs, and this was consistent with the fact that Taxus media is a plant species of gymnosperm. Southern blotting analysis demonstrated that there was a gene family of IPI in Taxus media. Finally, functional verification was applied to identify the function of TmlPI. The results showed that biosynthesis of β-carotenoid was enhanced by overexpressing TmlPI in the engineered E. coli strain, and this suggested that TmlPI might be a key gene involved in isoprenoid/terpenoid biosynthesis.