Liew Yvonne Jing Mei, Lee Yean Kee, Khalid Norzulaani, Rahman Noorsaadah Abd, Tan Boon Chin
Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.
Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.
PeerJ. 2020 May 1;8:e9094. doi: 10.7717/peerj.9094. eCollection 2020.
Flavonoids and prenylated flavonoids are active components in medicinal plant extracts which exhibit beneficial effects on human health. Prenylated flavonoids consist of a flavonoid core with a prenyl group attached to it. This prenylation process is catalyzed by prenyltranferases (PTs). At present, only a few flavonoid-related genes have been identified. In this study, we aimed to investigate the roles of in flavonoid production. We isolated a putative gene (designated as ) from a medicinal ginger, . The deduced protein sequence shared highest gene sequence homology (81%) with the predicted homogentisate phytyltransferase 2 chloroplastic isoform X1 from subsp. . We then cloned the into pRI vector and expressed in cell suspension cultures via -mediated transformation. The -expressing cells were fed with substrate, pinostrobin chalcone, and their products were analyzed by liquid chromatography mass spectrometry. We found that the amount of flavonoids, namely alpinetin, pinostrobin, naringenin and pinocembrin, in -expressing cells was higher than those obtained from the wild type cells. However, we were unable to detect any targeted prenylated flavonoids. Further in-vitro assay revealed that the reaction containing the BrPT2 protein produced the highest accumulation of pinostrobin from the substrate pinostrobin chalcone compared to the reaction without BrPT2 protein, suggesting that BrPT2 was able to accelerate the enzymatic reaction. The finding of this study implied that the isolated may not be involved in the prenylation of pinostrobin chalcone but resulted in high yield and production of other flavonoids, which is likely related to enzyme promiscuous activities.
黄酮类化合物和异戊烯基黄酮类化合物是药用植物提取物中的活性成分，对人体健康具有有益作用。异戊烯基黄酮类化合物由一个连接有异戊烯基的黄酮类核心组成。这种异戊烯基化过程由异戊烯基转移酶（PTs）催化。目前，仅鉴定出少数与黄酮类相关的基因。在本研究中，我们旨在探究[具体基因名称]在黄酮类化合物生成中的作用。我们从药用姜[植物名称]中分离出一个假定的[基因名称]基因（命名为BrPT2）。推导的蛋白质序列与来自[植物亚种名称]亚种的预测尿黑酸植基转移酶2叶绿体异构体X1的基因序列具有最高的同源性（81%）。然后我们将BrPT2克隆到pRI载体中，并通过农杆菌介导的转化在[植物名称]细胞悬浮培养物中进行表达。用底物松柏苷查耳酮处理表达BrPT2的细胞，并通过液相色谱质谱法分析其产物。我们发现，表达BrPT2的细胞中黄酮类化合物，即高山黄芩素、松柏苷、柚皮素和松属素的含量高于野生型细胞。然而，我们未能检测到任何目标异戊烯基黄酮类化合物。进一步的体外试验表明，与不含BrPT2蛋白的反应相比，含有BrPT2蛋白的反应从底物松柏苷查耳酮中产生的松柏苷积累量最高，这表明BrPT2能够加速酶促反应。本研究结果表明，分离出的BrPT2可能不参与松柏苷查耳酮的异戊烯基化，但能导致其他黄酮类化合物的高产和生成，这可能与酶的混杂活性有关。
