Cloning and catalytic analysis of Isatis indigotica chalcone isomerase in vitro / 中国中药杂志

Chalcone isomerase is a key rate-limiting enzyme in the biosynthesis of flavonoids in higher plants, which determines the production of flavonoids in plants. In this study, RNA was extracted from different parts of Isatis indigotica and reverse-transcribed into cDNA. Specific primers with enzyme restriction sites were designed, and a chalcone isomerase gene was cloned from I. indigotica, named IiCHI. IiCHI was 756 bp in length, containing a complete open reading frame and encoding 251 amino acids. Homology analysis showed that IiCHI was closely related to CHI protein of Arabidopsis thaliana and had typical active sites of chalcone isomerase. Phylogenetic tree analysis showed that IiCHI was classified into type Ⅰ CHI clade. Recombinant prokaryotic expression vector pET28a-IiCHI was constructed and purified to obtain IiCHI recombinant protein. In vitro enzymatic analysis showed that the IiCHI protein could convert naringenin chalcone into naringenin, but could not catalyze the production of liquiritigenin by isoliquiritigenin. The results of real-time quantitative polymerase chain reaction(qPCR) showed that the expression level of IiCHI in the aboveground parts was higher than that in the underground parts and the expression level was the highest in the flowers of the aboveground parts, followed by leaves and stems, and no expression was observed in the roots and rhizomes of the underground parts. This study has confirmed the function of chalcone isomerase in I. indigotica and provided references for the biosynthesis of flavonoid components.

The UGT74L2 of Andrographis paniculata catalyzes phloretin to produce trilobatin and its enzymatic study / 药学学报

The last essential enzyme in the biosynthetic pathway of trilobatin, phloretin-4'-O glycosyltransferase (P4'-OGT), catalyzes the conversion of trilobatin to phloretin in vitro. However, only a few P4'-OGTs have been found in plants. This study used Malus domestica phloretin-4'-O glycosyltransferase (MdPh-4'-OGT) as a query to identify and clone two UDP-glucuronosyltransferase (UGT) genes, designated UGT74L2 and UGT74L3, from the transcriptome of Andrographis paniculata. According to a phylogenetic tree analysis, UGT74L2 and UGT74L3 belonged to the UGT74 family, which has been linked to several activities in other species. The in vitro enzymatic reaction demonstrated that UGT74L2 could particularly catalyze the formation of trilobatin from phloretin, but UGT74L3 had no effects. By using Ni-NTA affinity chromatography to extract the soluble UGT74L2 recombinant protein, the enzymatic kinetics of the activity was investigated using phloretin as the substrate. The results showed that the optimal temperature and pH for UGT74L2 enzymatic reaction were 40 ℃ and 8.0 (Tris-HCl system), respectively. Three metal ions (Ca2+, Mn2+ and Co2+) showed inhibitory effect on the activity of UGT74L2, while Mg2+ could improve the activity of UGT74L2. Other tested metal ions have no significant effect on UGT74L2. The results of enzymatic kinetic parameters that the Km value was 29.84 μmol·L-1, the kcat was 0.02 s-1, and the kcat·Km-1 was 572.6 mol-1·s-1. By homology modeling, molecular docking and mutation experiments, we found that multiple amino acids residues around the substrate binding pocket play quite an important role during catalytic process, In summary, we identified a novel P4'-OGT gene from medicinal plant Andrographis paniculata and provided a new efficient catalyst to synthesize trilobatin. Meanwhile, this study provides a reference for mining new efficient glycosylation modules from plants.

Biopathway construction of plant natural products / 药学学报

Plant natural products (PNPs) are important sources of innovative drugs. They are mainly obtained by isolation or extraction from plants. Low content and with structural analogues in plants result in high production cost, which restricts the research and application of PNPs. While biopathway construction by synthetic biology provides an alternative for production of PNPs. By biosynthetic pathway analysis of PNPs and reconstructing the biopathway in microorganisms, we can produce PNPs in cell factories efficiently. Recently, several predominantly international reports about biosynthesis of PNPs and its synthetic biology production, triggered the researches of PNPs. Abundant traditional Chinese medicine resources and profound cultural heritage of Chinese medicine make biosynthesis pathway analysis of PNPs to be a research hotspot. And some of the studies have achieved significant progress. Here, recent progress in the biosynthesis of plant natural products and its synthetic biology was reviewed. In particular, the application of new methods and technologies in recent years were summarized and discussed. This will provide reference for the biopathway construction of plant natural products.

Research progress of P450 in the biosynthesis of bioactive compound of medicinal plants / 药学学报

Most of the active ingredients of herbs are secondary metabolites of plants. Cytochrome P450s (P450s) are hemoglobin-containing monooxygenases encoded by a super-gene family, which play important roles in the metabolic network of plants. This review focuses on the role of P450s on biosynthesis of secondary metabolites such as terpenoids, alkaloids, flavonoids and phenylpropanoids. This will provide references for biosynthesis and regulation of secondary metabolites in medicinal plants.

Real-time toxicity prediction of stewing system using extractive electrospray ionization mass spectrometry

Due to numerous obstacles such as complex matrices, real-time monitoring of complex reaction systems (, medicinal herb stewing system) has always been a challenge though great values for safe and rational use of drugs. Herein, facilitated by the potential ability on the tolerance of complex matrices of extractive electrospray ionization mass spectrometry, a device was established to realize continuous sampling and real-time quantitative analysis of herb stewing system for the first time. A complete analytical strategy, including data acquisition, data mining, and data evaluation was proposed and implemented with overcoming the usual difficulties in real-time mass spectrometry quantification. The complex Fuzi (the lateral root of )-meat stewing systems were real-timely monitored in 150 min by qualitative and quantitative analysis of the nine key alkaloids accurately. The results showed that the strategy worked perfectly and the toxicity of the systems were evaluated and predicated accordingly. Stewing with trotters effectively accelerated the detoxification of Fuzi soup and reduced the overall toxicity to 68%, which was recommended to be used practically for treating rheumatic arthritis and enhancing immunity. The established strategy was versatile, simple, and accurate, which would have a wide application prospect in real-time analysis and evaluation of various complex reaction systems.

Full-length Cloning and Protein Expression Analysis of Glycosyltransferases Gene SaUGT1/SaUGT2 in Sorbus aucuparia / 中国实验方剂学杂志

Objective: To obtain the glycosyltransferase gene involved in modification reaction of phytoalexin from Sorbus pohuashanensis suspension cell,and conduct sequence analysis and prokaryotic expression analysis. Method: Based on the transcriptome data,specific primers were designed to obtain 2 cDNA sequences of SaUGTs genes,construct prokaryotic expression vector HIS-MBP-pET28a-SaUGTs and induce the expression of recombinant SaUGTs protein. Result: SaUGT1 and SaUGT2 sequences were cloned and obtained from glycosyltransferases,then bioinformatic analysis of the sequence and prokaryotic expression analysis were conducted. SaUGT1 gene contained 1 458 bp open reading frame (ORF),encoding a polypeptide of 485 amino acids,with a relative molecular weight of 54.27 kDa and theoretical isoelectric point (pI) of 5.50.SaUGT2 gene contained 1 431 bp ORF,encoding a polypeptide of 476 amino acids,with a relative molecular weight of 53.49 kDa and theoretical pI of 5.63. Bioinformatics analysis indicated that SaUGT1 and SaUGT2 protein had no signal peptide,and the conserved domains of glycosyltransferase family were detected. Phylogenetic results showed that SaUGT1 and SaUGT2 proteins had the closest relationship with the UGT85 family of A. thaliana. Differential expression analysis revealed that the relative expression levels of SaUGT1 and SaUGT2 were increased significantly after being induced by yeast extract (YE), with the highest expression level found at 24 h and 12 h. The recombinant SaUGT1 and SaUGT2 proteins were successfully expressed in Escherichia coli DE3 cells and finally,the recombinant SaUGT1 and SaUGT2 proteins were purified through Ni2+ affinity chromatography. Conclusion: The glycosyltransferase gene was cloned from the S. aucuparia for the first time,and the prokaryotic expression vector was successfully constructed,laying foundation for further study of the function of this gene.

Mitogen-activated protein kinase genes of Artemisia annua and their expression analysis under Cadmium stress / 中国中药杂志

In order to study Artemisia annua under cadmium stress, whether there are corresponding MAPK genes involved in transduction of the cadmium signal. 17 AaMAPK genes, named AaMAPK1-AaMAPK17 repectively, were finally obtained by using Trinity method for de novo assembly of transcripts from SRA database and BLAST search against AtMAPK genes and determing conserved domain using a series of bioinformatics tools. There exist 16 MAPK genes contained T[D/E]Y conserved domains among the obtained genes. The expressions of these genes were analyzed by Real-time PCR under cadmium stress. The results showed that the expressions level of AaMAPK3 and AaMAPK10 were down-regulated and MAPK7, MAPK9 and MAPK12 were up-regulated. These indicated that there exist corresponding MAPK genes involved in transduction of the cadmium signal.

Status and future of natural resource for Chinese materia medica / 中国中药杂志

For thousands of years, the natural resource for Chinese materiamedica has been the foundation of the traditional Chinese medicine industry, which provides abundant medicine for human. In recent years, increasing demands and irrational exploitation led to a lot of problems such as rapid decrease of traditional Chinese herbs reserves, low quality of medicine and dismishing traditional cultures. These restricted the development of the traditional Chinese medicine. To solve these problems, scientists have done much work on investigating traditional Chinese medicine resources, exploring the metabolic pathway of bioactive ingredients, cultivating new varieties, and carrying out synthetic biology. These studies provided a theoretical basis for sustainable utilizationand future developmentof traditional Chinese medicine resources.

Cloning and expression analysis of a hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl transferasegene(IiHCT) from Isatis indigotica / 中国中药杂志

Based on the transcriptome data, we cloned the open reading frame of IiHCT gene from Isatis indigotica, and then performed bioinformatic analysis of the sequence. Further, we detected expression pattern in specific organs and hairy roots treated methyl jasmonate( MeJA) by RT-PCR. The IiHCT gene contains a 1 290 bp open reading frame( ORF) encoding a polypeptide of 430 amino acids. The predicted isoelectric point( pI) was 5.7, a calculated molecular weight was about 47.68 kDa. IiHCT was mainly expressed in stem and undetectable in young root, leaf and flower bud. After the treatment of MeJA, the relative expression level of IiHCT increased rapidly. The expression level of IiHCT was the highest at 4 h and maintained two fold to control during 24 h. In this study, cloning of IiHCT laid the foundation for illustrating the biosynthesis mechanism of phenylpropanoids in I. indigotica.

Stability analysis of reference gene based on real-time PCR in Artemisia annua under cadmium treatment / 中国中药杂志

In this study, Actin, 18S rRNA, PAL, GAPDH and CPR of Artemisia annua were selected as candidate reference genes, and their gene-specific primers for real-time PCR were designed, then geNorm, NormFinder, BestKeeper, Delta CT and RefFinder were used to evaluate their expression stability in the leaves of A. annua under treatment of different concentrations of Cd, with the purpose of finding a reliable reference gene to ensure the reliability of gene-expression analysis. The results showed that there were some significant differences among the candidate reference genes under different treatments and the order of expression stability of candidate reference gene was Actin > 18S rRNA > PAL > GAPDH > CPR. These results suggested that Actin, 18S rRNA and PAL could be used as ideal reference genes of gene expression analysis in A. annua and multiple internal control genes were adopted for results calibration. In addition, differences in expression stability of candidate reference genes in the leaves of A. annua under the same concentrations of Cd were observed, which suggested that the screening of candidate reference genes was needed even under the same treatment. To our best knowledge, this study for the first time provided the ideal reference genes under Cd treatment in the leaves of A. annua and offered reference for the gene expression analysis of A. annua under other conditions.

In silico cloning and bioinformatics analysis of an AP2/EFR family gene from Arnebia euchroma / 中国中药杂志

A cDNA sequence of Arnebia euchroma AP2/ERF named AeAP2/ERF was cloned by in silico cloning in this study, using ACX71873 sequence from Lithospermum erythrorhizon as the probe sequence. Some characters of the AP2/ERF gene and encoded protein sequences were predicted and analyzed by the bioinformatics methods, including general physical and chemical properties, hydrophobieity, signal peptide, secondary structure, localization sites in cells. Results showed that the 876 bp long gene included a 1 077 bp ORF and encoding 205 amino acid. The AeAP2/ERF protein had no signal peptide, it was a hydrophilic proteins located in nucleus. The function of the AP2/ERF protein was mainly involved with metabolism controlling and signal transduction.