State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, Hubei, China.
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, Hubei, China.
Biochem Biophys Res Commun. 2019 Feb 12;509(3):822-827. doi: 10.1016/j.bbrc.2019.01.010. Epub 2019 Jan 9.
Dioscorea zingiberensis is a perennial medicinal herb rich in a variety of pharmaceutical steroidal saponins. Squalene epoxidase (SE) is the key enzyme in the biosynthesis pathways of triterpenoids and sterols, and catalyzes the epoxidation of squalene in coordination with NADPH-cytochrome P450 reductase (CPR). In this study, we cloned DzSE and DzCPR gene sequences from D. zingiberensis leaves, encoding proteins with 514 and 692 amino acids, respectively. Recombinant proteins were successfully expressed in vitro, and enzymatic analysis indicated that, when SE and CPR were incubated with the substrates squalene and NADPH, 2,3-oxidosqualene was formed as the product. Subcellular localization revealed that both the DzSE and DzCPR proteins are localized to the endoplasmic reticulum. The changes in transcription of DzSE and DzCPR were similar in several tissues. DzSE expression was enhanced in a time-dependent manner after methyl jasmonate (MeJA) treatments, while DzCPR expression was not inducible.
盾叶薯蓣是一种多年生药用植物，富含多种药用甾体皂素。鲨烯环氧酶（SE）是三萜类化合物和甾醇生物合成途径中的关键酶，与 NADPH-细胞色素 P450 还原酶（CPR）协同催化鲨烯的环氧化。在这项研究中，我们从盾叶薯蓣叶片中克隆了 DzSE 和 DzCPR 基因序列，分别编码 514 和 692 个氨基酸的蛋白质。体外成功表达了重组蛋白，酶分析表明，当 SE 和 CPR 与底物鲨烯和 NADPH 孵育时，形成 2,3-氧化鲨烯作为产物。亚细胞定位表明，DzSE 和 DzCPR 蛋白均定位于内质网。几种组织中 DzSE 和 DzCPR 的转录变化相似。茉莉酸甲酯（MeJA）处理后，DzSE 的转录表达呈时间依赖性增强，而 DzCPR 的转录表达没有可诱导性。
