Research progress on the puerarin derivatization through biocatalysis / 药学学报

Puerarin, also known as daidzein 8-C-glucoside, is a major isoflavone glycoside from Pueraria lobata. Puerarin has been shown to possess a variety of pharmacological activities. It has been widely used for the treatment of cardiovascular and cerebrovascular diseases. However, the further applications are limited due to its low water solubility and poor bioavailability. Structural modification is thus regarded as an efficient approach to improve the solubility and bioavailability of puerarin. Unlike chemical modifications, enzyme-assisted modifications, namely biocatalysis, is a promising alternative for the regioselective synthesis of puerarin derivatives due to its high selectivity. Up to date, acylation, glycosylation and hydroxylation of puerarin had been achieved through enzyme-based biocatalysis. Diverse active puerarin derivatives with improved solubility and bioavailability have been thus developed. Based on modification groups, this paper focused on the progress in the preparation of puerarin derivatives by biocatalysis, in which the whole-cells or pure enzymes were used as the biocatalysts. This article was expected to provide new ideas for the synthesis and development of puerarin drugs.

The enzymatic biosynthesis of acylated steroidal glycosides and their cytotoxic activity

Herein we describe the discovery and functional characterization of a steroidal glycosyltransferase (SGT) from and a steroidal glycoside acyltransferase (SGA) from and their application in the biosynthesis of acylated steroidal glycosides (ASGs). Initially, an gene, designated as OsSGT1, was isolated from . OsSGT1-containing cell free extract was then used as the biocatalyst to react with 49 structurally diverse drug-like compounds. The recombinant OsSGT1 was shown to be active against both 3- and 17-hydroxyl steroids. Unexpectedly, in an effort to identify OsSGT1, we found the bacteria gene in operon actually encoded an SGA, specifically catalyzing the acetylations of sugar moieties of steroid 17-glucosides. Finally, a novel enzymatic two-step synthesis of two ASGs, acetylated testosterone-17-glucosides (AT-17-Gs) and acetylated estradiol-17-glucosides (AE-17-Gs), from the abundantly available free steroids using OsSGT1 and EcSGA1 as the biocatalysts was developed. The two-step process is characterized by EcSGA1-catalyzed regioselective acylations of all hydroxyl groups on the sugar unit of unprotected steroidal glycosides (SGs) in the late stage, thereby significantly streamlining the synthetic route towards ASGs and thus forming four monoacylates. The improved cytotoxic activities of 3'-acetylated testosterone17-glucoside towards seven human tumor cell lines were thus observable.

Steroids hydroxylation catalyzed by the monooxygenase mutantfromBM3

The search of new substrates with pharmaceutical and industrial potential for biocatalysts including cytochrome P450 enzymes is always challenging. Cytochrome P450 BM3 mutant, a versatile biocatalyst, exhibited hydroxylation activities towards fatty acids and alkanes. However, there were limited reports about its hydroxylation activity towards steroids. Herein, an-based whole-cell extract containing the recombinant 139-3 protein was used as the biocatalyst to screen 13 steroids. Results revealed that 139-3 was able to specifically hydroxylate androstenedione () at 1-position, generating a hydroxylated steroid 1-OH-androstenedione (). To investigate whether C-1hydroxylation catalyzed by BM3 mutantcould be industrially used, an optimization of catalyzing conditions was performed. Accordingly, the BM3 mutant 139-3 enzyme was observed to display maximum activity at 37 °C, under pH 7.0 for 4 h, with 37% transformation rate. Moreover, fourvariants were generated by random mutagenesis with the aim of improving its activity and expanding substrate scope. Surprisingly, these mutants, sharing a common mutated site R379S, lost their activities towards androstenedione (). These data clearly indicated that arginine residue located at site 379 played key role in the hydroxylation activities of 139-3. Overall, these new findings broadened the substrate scope of 139-3 enzyme, thereby expanding its potential applications as a biocatalyst on steroids hydroxylation in pharmaceutical industry.

Enzymatic cyclization of peptides using immobilized sortase A / 药学学报

Peptide cyclization, a pivotal approach to modifying linear precursors of proteins and pepticles, has been used to enhance their biological activities and serum stabilities. Recently, sortase A (SrtA) from Staphyloccus aureus becomes a promising new technology for efficiently incorporating site specific modifications into proteins, conjugating the cell surface and cyclizing the linear peptides. In this study, we constructed two recombinant expression systems, one with chitin binding domain and the other with six-histidine tag and chitin binding domain on the N-terminal of SrtA, separately. The results of enzymatic kinetics indicate that the two recombinant tags do not impair the transpeptidase activity of SrtA compared with the standard reaction reported under the same reaction condition. The two synthesized peptides with N-ternimal three glycines and C-terminal penta-amino acid motif, LPETG, were cyclized using immobilized and recycled SrtA. The SrtA-based cyclization promises to represent a simple method for easy and efficient enzymatic synthesis of large cyclic peptides.

A cyclotide against influenza A H1N1 virus from Viola yedoensis / 药学学报

Three cyclotides were isolated from the whole plant of Viola yedoensis in this study. The two, vary peptide E and cycloviolacin Y5, were previously reported, and a novel cycloviolacin VY1 was characterized according to the interpretation of MS/MS fragmentation of peptides which were produced from the reduced and alkylated parent peptide with the digestion of Endo Lys-C, trypsin and chymotrypsin, separately. The stability of remarkable resistance to proteolytic degradation by trypsin and chymotrypsin, and that of thermal denaturation was confirmed again. Besides, the IC50 value of cycloviolacin VY1 against influenza A H1N1 virus was (2.27 +/- 0.20) microg x mL(-1). It is the first cyclotide reported with anti-influenza A H1N1 virus activity in vitro assay.

The advance in synthetic biology: towards a microbe-derived paclitaxel intermediates / 药学学报

The synthetic biology matures to promote the heterologous biosynthesis of the well-known drug paclitaxel that is one of the most important and active chemotherapeutic agents for the first-line clinical treatment of cancer. This review focuses on the construction and regulation of the biosynthetic pathway of paclitaxel intermediates in both Escherichia coli and Saccharomyces cerevisiae. In particular, the review also features the early efforts to design and overproduce taxadiene and the bottleneck of scale fermentation for producing the intermediates.

Research progresses in synthetic biology of artemisinin / 药学学报

Abstract: The first-line drug artemisinin is widely used against malaria. Commercially available artemisinin is extracted from plants. However, the lack of sufficient raw material, artemisinin and the cost associated with the drug's manufacture have limited the supply of ACT to most malaria sufferers in the Developing World. As such, it is important to develop a low cost, fine to environment and high-quality method to supply sufficient and reliable quantities of artemisinin in the future. The field of synthetic biology, which utilizes cell factories to manipulate microbial metabolism to enhance the production of artemisinin and its intermediates, has a particularly strong impact by providing new platforms for chemical production. After a brief introduction of the artemisinin biosynthetic pathway, the present review focuses on the introduction of artemisinin biosynthetic genes, such as the genes encoding amorpha-4, 11-diene monooxygenase, NADPH: cytochrome P450 oxidoreductase, artemisinic aldehyde delta 11(13) reductase and aldehyde dehydrogenase. The review also addresses general considerations for potential contributions of synthetic biology to artemisinin production, with an emphasis on factors influencing interest compounds production in chassis cells.

Construction and preliminary applications of a Saccharomyces cerevisiae detection plasmid using for screening promoter elements / 药学学报

Synthetic biology of natural products is the design and construction of new biological systems by transferring a metabolic pathway of interest products into a chassis. Large-scale production of natural products is achieved by coordinate expression of multiple genes involved in genetic pathway of desired products. Promoters are cis-elements and play important roles in the balance of the metabolic pathways controlled by multiple genes by regulating gene expression. A detection plasmid of Saccharomyces cerevisiae was constructed based on DsRed-Monomer gene encoding for a red fluorescent protein. This plasmid was used for screening the efficient promoters applying for multiple gene-controlled pathways. First of all, eight pairs of primers specific to DsRed-Monomer gene were synthesized. The rapid cloning of DsRed-Monomer gene was performed based on step-by-step extension of a short region of the gene through a series of PCR reactions. All cloned sequences were confirmed by DNA sequencing. A vector named pEASYDs-M containing full-length DsRed-Monomer gene was constructed and was used as the template for the construction of S. cerevisiae expression vector named for pYeDP60-Ds-M. pYeDP60-Ds-M was then transformed into S. cerevisiae for heterologous expression of DsRed-Monomer gene. SDS-PAGE, Western blot and fluorescence microscopy results showed that the recombinant DsRed-Monomer protein was expressed successfully in S. cerevisiae. The well-characterized DsRed-Monomer gene was then cloned into a yeast expression vector pGBT9 to obtain a promoter detection plasmid pGBT9Red. For determination efficacy of pGBT9Red, six promoters (including four inducible promoters and two constitutive promoters) were cloned by PCR from the S. cerevisiae genome, and cloned into pGBT9Red by placing upstream of DsRed-Monomer gene, separately. The fluorescence microscopy results indicated that the six promoters (GAL1, GAL2, GAL7, GAL10, TEF2 and PGK1) can regulate the expression of DsRed-Monomer gene. The successful construction of pGBT9Red lays the foundation for further analysis of promoter activity and screening of promoter element libraries.

Rapid cloning and functional characterization of hypericin synthase gene / 药学学报

Hypericin, a red-colored naphtodianthrone, is a natural product synthesized in the medicinal plant Hypericum perforatum, commonly known as St. John's wort. Hypericin has attracted a growing attention of the pharmaceutical industry because of its potential application to various therapies, including the treatment of depression and remarkable antiviral and photodynamic activities, hyp-1 gene encodes for phenolic coupling protein which catalyzes in vitro direct and specific conversion of emodin to hypericin which, however, has not formed common opinion so far. Six pairs of primers specific to hyp-1 gene were synthesized. The rapid cloning of hyp-1 gene was performed based on step-by-step extension of a short region of the gene through a series of PCR reactions. All cloned sequences were confirmed by DNA sequencing. A vector named pET32ahyp containing hyp-1 gene was constructed and was transformed into E. coli to induce heterologous expression. SDS-PAGE and Western blot results showed the recombinant Hyp-1 protein was expressed successfully in E. coli. The soluble fraction was used to test the function of the recombinant Hyp-1. Hypericin was detected by LC-MS/MS with emodin as a substrate under in vitro conditions. The above results corroborated the Hyp-1 function, a confusing question, which lay a material foundation for the synthesis of hypericin by synthetic biotechnology.

Advances in functional studies of nonstructural proteins and development of antiviral agents for enterovirus 71 / 药学学报

Human enterovirus 71 (EV71) is one of the major etiological agents for the hand, foot, and month disease (HFMD) and is causing frequent, widespread occurrence in the mainland of China. The single positive-stranded RNA genome of EV71 is translated into a single polyprotein which is autocleavaged into structural and nonstructural proteins. The functions of many nonstructural proteins characterized in the life cycle of virus are potential targets for blocking viral replication. This article reviews the studies of the structures and functions of nonstructural proteins of EV71 and the anti-enterovirus 71 drugs targeting on these nonstructural proteins.

Elucidating the structure of two cyclotides of Viola tianshanica maxim by MALDI TOF/TOF MS analysis / 药学学报

The cyclotides are a family of cyclic "mini" proteins that occur in Violaceae, Rubiaceae and Cucurbitaceae plant families and contain a head-to-tail cyclic backbone and a cystine knot arranged by three disulfide bonds. To study the natural cyclotides of V tianshanica, dried herb was extracted with 50% ethanol, and the concentrated aqueous extract was subjected to a solvent-solvent partitioning between water and hexane, ethyl acetate and n-butanol, separately. The n-butanol extract containing cyclotides was subjected to column chromatography over Sephadex LH-20, eluted with 30% methanol. The subfractions were directly reduced by DTT and analyzed by reverse-phase HPLC. The peaks with different retention times were shown on the profile of RP-HPLC and collected. The cyclotides were speculated based on masses range from 3 000 to 3 500 Da. The purified cyclotides were reduced with DTT, alkylated with iodoacetamide, and then were cleaved with endoproteinase Glu-C, endoproteinase Lys-C and Trypsin, separately. The digested peptides were purified on RP-HPLC and analyzed on MALDI TOF/TOF analyzer. A new cyclotide, cycloviolacin T1 and a reported cyclotide varv E were systemically determined using MALDI TOF/TOF system. So the method for the isolation and characterization of cyclotides was quickly built up in succession.

Development of a yeast two-hybrid screen for selection of A/H1N1 influenza NS1 non-structural protein and human CPSF30 protein interaction inhibitors / 药学学报

Influenza A/H1N1 virus-encoded nonstructural, or NS1, protein inhibits the 3'-end processing of cellular pre-mRNAs by binding the cellular protein: the 30-kDa subunit of CPSF (cleavage and polyadenylation specificity factor, CPSF30). CPSF30 binding site of the NS1 protein is a potential target for the development of drugs against influenza A/H1N1 virus. A yeast two-hybrid screening system was constructed and used for screening Chinese medicines that inhibit the interaction of the A/H1N1 flu NS1 protein and human CPSF30 protein. The NS1 gene of A/H1N1 virus was amplified by consecutive polymerase chain reaction (PCR), and the human CPSF30 gene of HeLa cell cloned by reverse transcriptase-polymerase chain reaction (RT-PCR). Then the two gene fragments confirmed by sequencing were subcloned into the yeast expression vectors pGBKT7 and pGADT7, respectively. The two constructs, bait vector pGBKNS1 and prey vector pGADCPSF, were co-transformed into yeast AH109. The eight individual yeast colonies were picked and subjected to verification by PCR/gel electrophoresis. The inhibition of the NS1-CPSF30 interaction was allowed the identification of selective inhibitors. The four of more than thirty identified Chinese medicines, including 'Shuanghuanglian oral liquid', showed the strong inhibition of the NS1-CPSF30 interaction.

Production of amorpha-4,11-diene in engineered yeasts / 药学学报

Plasmid-carrying Saccharomyces cerevisia (W303-1B[pYeDP60/G/ADS]) and genome-transformed S. cerevisia (W303-1B[rDNA:ADS]), both harboring amorpha-4,11-diene synthase (ADS) gene were constructed to investigate the production of amorpha-4,11-diene. The recombinant plasmid pYeDP60/G/ADS that harbors the ADS gene was transformed into S. cerevisiae W303-1B, resulting in the engineered yeast W303-1B[pYeDP60/G/ADS], which contains multi-copies of the plasmid. The ADS gene expression cassette was obtained by PCR amplification of the pYeDP60/G/ADS template, and then introduced into S. cerevisiae W303-1B to obtain the engineered yeast W303-1B[rDNA:ADS], in which the ADS gene was integrated into the rDNA locus of the yeast genome through the homologous recombination. GC-MS analysis confirmed that both of the engineered yeasts could produce amorpha-4,11-diene. Moreover, the amorpha-4,11-diene yield of W303-1B[pYeDP60/G/ADS] was higher than that of W303-1B[rDNA:ADS]. Southern blot analysis showed that there is only one copy of ADS gene in the genome of W303-1B[rDNA:ADS]. It implied that the amorpha-4,11-diene yield can be improved by increasing the ADS gene copies.

Recent advances in the study of amorpha-4,11-diene synthase and its metabolic engineering / 药学学报

Amorpha-4,11-diene synthase (ADS) can convert farnesyl pyrophosphate (FPP) to amorpha-4, 11-diene, a precursor of artemisinin. ADS plays an important role in the biosynthesis of artemisinin. This review summarizes the molecular biology and metabolic engineering study of ADS in recent years. The genomic DNA and its cDNA sequences of amorpha-4, 11-diene synthase were cloned from Artemisia annua L. The cDNA encoding amorpha-4, 11-diene synthase contains a 1 641 bp open reading frame coding for 546 amino acids. ADS shows a broad pH optimum and an absolute requirement for divalent metal ions as cofactors. The specificity of ADS to the substrates and products is not high and the formation of amorpha-4, 11-diene by ADS from FPP is achieved by an initial 1, 6-closure with subsequent 1, 10-closure. The ADS cDNA cloned from Artemisia annua L, or totally synthesized by PCR, was introduced into different hosts including E. coli, S. cerevisiae, Nicotiana tabacum L. Arabidopsis thaliana and A. nidulans resulting in varied engineering microorganisms and cells producing amorpha-4, 11-diene. The way to improve the production of amorpha-4, 11-diene was investigated by two strategies such as improving the supply of substrate and directing FPP flux to amorpha-4, 11-diene production from competing pathways.

Expression, purification and antibody preparation of recombinat SARS-CoV X5 protein / 药学学报

X5 protein is one of the putative unknown proteins of SARS-CoV. The recombinant protein has been successfully expressed in E. coli in the form of insoluble inclusion body. The inclusion body was dissolved in high concentration of urea. Affinity Chromatography was preformed to purify the denatured protein, and then the product was refolded in a series of gradient solutions of urea. The purified protein was obtained with the purity of > 95% and the yield of 93.3 mg x L(-1). Polyclonal antibody of this protein was obtained, and Western blotting assay indicated that the X5 protein has the strong property of antigen. Sixty-eight percent of the recombinant protein sequence was confirmed by LC-ESI-MS/MS analysis.

Optimizing expression and purification of recombinant Salvia miltiorrhiza copalyl diphosphate synthase protein in E. coli and preparation of rabbit antiserum against SmCPS / 药学学报

The expression plasmid pET32CPS harboring SmCPS gene was transformed into E. coli BL21 trxB (DE3) resulting in recombinant strain E. coli [pET32CPS]. The induction of E. coli [pET32CPS] in different temperatures, induction time, IPTG concentrations and A600 values of E. coli were performed. The optimal expression conditions of SmCPS were characterized according to the orthogonal analysis, and the ratio of the interest protein to total proteins reached to 35.6%. The recombinant SmCPS protein purified by Ni2+ affinity chromatography column was identified by SDS-PAGE and Western blotting, and then used for rabbit immunization. The titer of the rabbit antiserum against SmCPS was about 1:24 300 after the third immunization, and could specifically recognize the antigen of SmCPS protein by Western blotting analysis. The successful preparation of polyclonal antibody against SmCPS laid a foundation for further correlative study between expression of SmCPS and the production of tanshinones in protein level.

Cloning and bioinformatics analysis of P450 cDNA in Artemisia annua / 中国中药杂志

<p><b>OBJECTIVE</b>Cloning and bioinformatics analysis of P450 cDNA in Artemisia annua.</p><p><b>METHOD</b>A P450 cDNA gene was cloned from A. annua by RT-PCR. The bioinformatics analysis of the P450 gene was performed.</p><p><b>RESULT</b>The complete ORF of this P450 cDNA is 1 464 bp and encodes 488 aa. The sequence was reported to GenBank and coded as DQ667171. Bioinformatics analysis of the P450 cDNA showed it encoded an A-type P450 protein with 54. 992 kDa, it's isoelectric point was 8.83 and the possibility of export to mitochondria was 0.893 2.</p><p><b>CONCLUSION</b>The comparable analysis of the P450 with CYP71AV1 revealed that the two proteins probably performed the same function because of the similar character.</p>

Optimization of expression condition of SARS-CoV PUPs genes in E. coli / 药学学报

According to previous studies of SARS-CoV (Severe acute respiratory syndrome coronavirus), a variety of novel accessory genes have been identified in SARS-CoV genome, which were interspersed the structural genes of SARS-CoV and considered to be unique to the SARS-CoV genome. The predicted unknown proteins (PUPs) encoded by the accessory genes might play important roles in the SARS-CoV infection. Three of those genes, called X4, X5 and ORF10, were synthesized and introduced into E. coli to induce expression. SDS-PAGE and Western blotting revealed that the three genes have been expressed in E. coli. The induction of SARS PUPs genes expression in different temperatures, induction times, IPTG concentrations and A values of E. coli cells were performed. The optimal induction condition of SARS-CoV PUPs genes was characterized according to the orthorgonal analysis. The ratio of recombinant proteins of PUPs to total proteins is as follows: X4, 20%; X5, 27.8%; ORF10, 68.5% under the optimum conditions.

Increase of copy number of HMG-CoA reductase and FPP synthase genes improves the amorpha4,11-diene production in engineered yeast / 药学学报

The gene encoding amorpha-4, 11-diene synthase was cloned from Artemisia annua L. Other two genes encoding the FPP synthase (FPPS) and HMG-CoA reductase (HMGR) were cloned from Saccharomyces cerevisiae. The cloned cDNAs were confirmed by DNA sequencing. Two expression vectors were constructed, one is named pGBT9/A/HMG/FPP harboring genes for HMG-CoA reductase and FPP synthase and the other is pYeDP60/G/AS, containing the gene encoding amorpha-4,11-diene synthase. Two kinds of engineered yeast were constructed: the first was named WHT [AS], which contained the plasmid pYeDP60/G/AS; the second was WHT [HMG + FPP + AS], in which the vectors pGBT9/A/ HMG/FPP and pYeDP60/G/AS were introduced by cotransformation mediated with LiOAc and PEG4000. The positive clones were identified for further fermentations. The samples from fermentations were analyzed by GC-MS for amorpha-4,11-diene. The results show that engineered yeasts could produce amorpha-4,11-diene. Moreover, the amorpha-4,11-diene production of WHT[ HMG + FPP + AS] and WHT[ AS] were 23.6 mg x L(-1) and 10 microg x L(-1), respectively. Its concentrations were reported as equivalents of valencene. The results showed the copy number increase of HMGR and FPPS genes can improve the production of amorpha-4, 11-diene in the fermentation of engineered yeasts.

Recent advances in the biosynthesis of Taxol / 药学学报

Taxol is one of the most potent chemotherapeutic agents known, showing excellent activity against a range of cancers. In addition to anticancer, taxol has the effect of preventing graft arteriosclerosis, antiscaring formation and inhibiting angiogenesis. There are five possible routes to industrialize taxol production: isolation from the bark of the yew species, total synthesis, semisynthesis, tissue or cell culture, endophytic fungal fermentation and metabolism engineering. There are at least 14 genes related to the taxol biosynthesis had been cloned from yews and functionally expressed in different hosts. The combinational expression system of taxol makes progress as the clarification of biosynthetic pathway of taxol.