Wang Yechun, Qiu Chengxiang, Zhang Fei, Guo Binhui, Miao Zhiqi, Sun Xiaofen, Tang Kexuan
Plant Biotechnology Research Center, Fudan-SJTU-Nottingham Plant Biotechnology R&D Center, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.
Biosci Rep. 2009 Apr;29(2):111-9. doi: 10.1042/BSR20070052.
Gossypol, a type of plant defence sesquiterpenoid phytoalexin, is synthesized from the MEP (2C-methyl-D-erythritol 4-phosphate) and MVA (mevalonate) pathway in the isoprenoid biosynthetic system. The key step is the isomerization of IPP (isopentenyl diphosphate) to DMAPP (dimethylallyl diphosphate), which is catalysed by IPI (IPP isomerase; EC 5.3.3.2). A full-length cDNA encoding IPI (designated GbIPI) was cloned from Gossypium barbadense by RACE (rapid amplification of cDNA ends). The full-length cDNA of GbIPI was 1205 bp and contained a 906 bp ORF (open reading frame) encoding a protein of 302 amino acids, with a predicted molecular mass of 34.39 kDa and an isoelectric point of 6.07. Amino acid sequence analysis revealed that the GbIPI has a high level of similarity to other IPIs. Southern-blot analysis revealed that GbIPI belongs to a small gene family. Expression analysis indicated that GbIPI expression is highest in stems, followed by leaves, and is lowest in roots, and that the expression of GbIPI could be induced by Verticillium dahliae Kleb, MeJA (methyl jasmonate) and SA (salicylic acid). The functional colour assay indicated that GbIPI could accelerate the accumulation of beta-carotene in Escherichia coli transformants. The cloning and functional analysis of GbIPI will be useful in increasing understanding of the role of IPI in isoprenoid biosynthesis at the molecular level.
棉酚是一种植物防御性倍半萜类植保素，在类异戊二烯生物合成系统中由MEP（2-C-甲基-D-赤藓糖醇-4-磷酸）和MVA（甲羟戊酸）途径合成。关键步骤是异戊烯基二磷酸（IPP）异构化为二甲基烯丙基二磷酸（DMAPP），这一过程由IPP异构酶（EC 5.3.3.2）催化。通过RACE（cDNA末端快速扩增）技术从海岛棉中克隆到一个编码IPP异构酶的全长cDNA（命名为GbIPI）。GbIPI的全长cDNA为1205 bp，包含一个906 bp的开放阅读框（ORF），编码一个302个氨基酸的蛋白质，预测分子量为34.39 kDa，等电点为6.07。氨基酸序列分析表明，GbIPI与其他IPP异构酶具有高度相似性。Southern杂交分析表明，GbIPI属于一个小基因家族。表达分析表明，GbIPI在茎中表达最高，其次是叶，在根中表达最低，并且GbIPI的表达可被大丽轮枝菌、茉莉酸甲酯（MeJA）和水杨酸（SA）诱导。功能显色分析表明，GbIPI可以加速大肠杆菌转化体中β-胡萝卜素的积累。GbIPI的克隆和功能分析将有助于在分子水平上加深对IPP异构酶在类异戊二烯生物合成中作用的理解。
