BACKGROUND Most plant cytochrome P450 (P450) proteins need to be supplied with electrons from a redox partner, e.g. an NADPH-cytochrome P450 reductase (CPR), for the activation of oxygen molecules via heme. CPR is a flavoprotein with an N-terminal transmembrane domain, which transfers electrons from NADPH to the P450 via coenzymes flavin adenine dinucleotide and flavin mononucleotide. RESULTS In this study, a novel CPR (SdCPR) was isolated from a tropical medicinal plant Scoparia dulcis L. The deduced amino acid of SdCPR showed high homology of > 76% with CPR from higher plants and belonged to the class II CPRs of dicots. Recombinant SdCPR protein reduced cytochrome c, ferricyanide (K3Fe(CN)6), and dichlorophenolindophenol in an NADPH-dependent manner. To elucidate the P450 monooxygenase activity of SdCPR, we isolated a cinnamic acid 4-hydroxylase (SdC4H, CYP73A111) gene from S. dulcis. Biochemical characterization of SdCPR/SdC4H demonstrated that SdCPR supports the oxidation step of SdC4H. Real-time qPCR results showed that expression levels of SdCPR and SdC4H were inducible by mechanical wounding treatment and phytohormone elicitation (methyl jasmonate, salicylic acid), which were consistent with the results of promotor analyses. CONCLUSIONS Our results showed that the SdCPR and SdC4H are related to defense reactions, including the biosynthesis of secondary metabolites.

中文翻译：

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Scoparia dulcis L.的NADPH-细胞色素P450还原酶和肉桂酸4-羟化酶编码基因的功能表征

背景技术大多数植物细胞色素P450（P450）蛋白需要由氧化还原伴侣（例如NADPH-细胞色素P450还原酶（CPR））提供电子，以通过血红素激活氧分子。CPR是一种具有N端跨膜结构域的黄素蛋白，可通过辅酶黄素腺嘌呤二核苷酸和黄素单核苷酸将电子从NADPH转移到P450。结果在这项研究中，从热带药用植物Scoparia dulcis L分离出一种新型的CPR（SdCPR）。SdCPR的推导氨基酸与高等植物的CPR表现出高度同源性> 76％，属于双子叶植物的II类CPR。重组SdCPR蛋白以NADPH依赖性方式还原细胞色素c，铁氰化物（K3Fe（CN）6）和二氯苯酚吲哚酚。为了阐明SdCPR的P450单加氧酶活性，我们从S. dulcis中分离了肉桂酸4-羟化酶（SdC4H，CYP73A111）基因。SdCPR / SdC4H的生化表征表明，SdCPR支持SdC4H的氧化步骤。实时qPCR结果显示，通过机械伤口处理和植物激素诱导（茉莉酸甲酯，水杨酸）诱导SdCPR和SdC4H的表达水平，与启动子分析的结果一致。结论我们的结果表明SdCPR和SdC4H与防御反应有关，包括次生代谢产物的生物合成。实时定量PCR结果表明，通过机械伤口处理和植物激素诱导（茉莉酸甲酯，水杨酸）可诱导SdCPR和SdC4H的表达水平，这与启动子分析的结果一致。结论我们的结果表明SdCPR和SdC4H与防御反应有关，包括次生代谢产物的生物合成。实时定量PCR结果表明，通过机械伤口处理和植物激素诱导（茉莉酸甲酯，水杨酸）可诱导SdCPR和SdC4H的表达水平，这与启动子分析的结果一致。结论我们的结果表明SdCPR和SdC4H与防御反应有关，包括次生代谢产物的生物合成。