Zheng Han, Jing Li, Yao Na, Yang Qing-shan, Peng Hua-sheng, Shen Ye, Huang Lu-qi
Yao Xue Xue Bao. 2016 Sep;51(9):1494-501.
1-Deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) is the second rate-limiting enzyme of terpenoid biosynthesis in the methylerythritol-4-phosphate pathway. According to the transcriptome database of Cinnamomum camphora, the DXR cDNA was cloned by rapid amplification of cDNA ends (RACE) from C. camphora, and was named CcDXR1(GenBank number: KU886266). The ORF of CcDXR1 is composed of 1 413 bp, and it encodes 470 amino acids. The bioinformatics analysis suggests that the molecular weight of the encoded protein is 51.1 kD and the theoretically isoelectric point is 6.62, and there is no signal peptide and transmembrane structure in putative protein. The analysis of sequence alignment and phylogenetic tree showed that the CcDXR1 belonged to the DXR family. The results of the realtime PCR indicated that expression level of CcDXR1 in mature leaves was higher than tender leaves, which in roots was similar to leaves and the lowest in branches. The camphor is divided into five chemotypes, according to the main chemical compounds in C. camphora. It also showed that the expression level of CcDXR1 in borneol C. camphora was highest than that in cineol, iso-nerolidol, camphor and linalool. Our results revealed that the expression level of CcDXR1 exhibits diversity among plant tissues, growth periods and five chemical types, and the research provides foundation for further study of the terpenoids biosynthetic pathway in C. camphora.
1-脱氧-D-木酮糖-5-磷酸还原异构酶（DXR）是甲基赤藓糖醇-4-磷酸途径中萜类生物合成的第二个限速酶。根据樟树转录组数据库，通过cDNA末端快速扩增（RACE）技术从樟树中克隆了DXR cDNA，并将其命名为CcDXR1（GenBank登录号：KU886266）。CcDXR1的开放阅读框由1413个碱基对组成，编码470个氨基酸。生物信息学分析表明，编码蛋白的分子量为51.1 kD，理论等电点为6.62，推测蛋白中无信号肽和跨膜结构。序列比对和系统发育树分析表明，CcDXR1属于DXR家族。实时荧光定量PCR结果表明，CcDXR1在成熟叶中的表达水平高于嫩叶，在根中的表达水平与叶相似，在枝条中最低。根据樟树中主要化学物质的不同，樟树可分为五种化学型。研究还表明，CcDXR1在龙脑樟中的表达水平高于桉叶油樟、异橙花叔醇樟、樟脑樟和芳樟醇樟。我们的研究结果表明，CcDXR1的表达水平在植物组织、生长时期和五种化学型之间存在差异，该研究为进一步研究樟树萜类生物合成途径提供了基础。
