Gene clone and functional identification of sterol glycosyltransferases from Paris polyphylla var. yunnanensis / 中国中药杂志

In this study, the authors cloned a glycosyltransferase gene PpUGT2 from Paris polyphylla var. yunnanensis with the ORF length of 1 773 bp and encoding 590 amino acids. The phylogenetic tree revealed that PpUGT2 belonged to the UGT80A subfamily and was named as UGT80A49 by the UDP-glycosyltransferase(UGT) Nomenclature Committee. The expression vector pET28a-PpUGT2 was constructed, and enzyme catalytic reaction in vitro was conducted via inducing protein expression and extraction. With UDP-glucose as sugar donor and diosgenin and pennogenin as substrates, the protein was found with the ability to catalyze the C-3 hydroxyl β-glycosylation of diosgenin and pennogenin. To further explore its catalytic characteristic, 15 substrates including steroids and triterpenes were selected and PpUGT2 showed its activity towards the C-17 position of sterol testosterone with UDP-glucose as sugar donor. Homology modelling and molecule docking of PpUGT2 with substrates predicted the key residues interacting with ligands. The re-levant residues of PpUGT2-ligand binding model were scanned to calculate the corresponding mutants, and the optimized mutants were obtained according to the changes in binding affinity of the ligand with protein and the surrounding residues within 5.0 Å of ligands, which had reference value for design of the mutants. This study laid a foundation for further exploring the biosynthetic pathway of polyphyllin as well as the structure of sterol glycosyltransferases.

Cloning and Prokaryotic Expression of Glycosyltransferase Genes from Paris polyphylla var. yunnanensis / 中国实验方剂学杂志

Objective:To clone the full-length glycosyltransferase genes （<italic>PpUGT</italic>1，<italic>PpUGT</italic>7） related to saponins biosynthesis in <italic>Paris polyphylla</italic> var. <italic>yunnanensis</italic>，and perform bioinformatics analysis，relative expression analysis and prokaryotic expression analysis. Method:Total RNA was isolated from <italic>P. polyphylla </italic>var. <italic>yunnanensis </italic>with use of the Eastep^® Super Total RNA Extraction Kit and converted to cDNA. Specific primers were designed according to the transcriptome data to clone the full-length gene. Relevant software was then used for bioinformatic analysis of the protein sequences. The relative gene expression levels were detected by real-time fluorescent quantitative polymerase chain reaction （Real-time PCR） and the prokaryotic expression vectors were built to heterologously express recombinant protein in <italic>Escherichia coli.</italic> Result:The open reading frame （ORF） of <italic>PpUGT</italic>1 was 1 827 bp，encoding 608 amino acids，and was predicted as a steroid glycosyltransferase；the ORF of <italic>PpUGT</italic>7 was 1 380 bp，encoding 459 amino acids，and was predicted as a triterpenoid glycosyltransferase. The calculated relative molecular mass of two proteins were 67.6 kDa and 51.3 kDa respectively，and both of them were hydrophilic proteins，no transmembrane domain，no signal peptides，both showing high similarity and conservativeness with homologous sequences. The results of Real-time PCR showed that the expression level of <italic>PpUGT</italic>1 was root>leaf>flower>stem；the expression level of <italic>PpUGT</italic>7 was stem>leaf>flower>root. In addition，PpUGTs proteins were expressed in <italic>E. coli</italic>. in a soluble form. Conclusion:The genes of <italic>PpUGT</italic>1 and <italic>PpUGT</italic>7 were cloned successfully. Real-time PCR showed the genes were expressed differently in different plant organs， and their recombinant proteins were successfully expressed in <italic>Escherichia coli</italic>. This study lays a foundation for functional characterization of PpUGTs and analysis of the biosynthesis pathway of saponins in <italic>Paris polyphylla </italic>var. <italic>yunnanensis</italic>.

Cloning and characterization of a monoterpene synthase gene from Tripterygium wilfordii / 中国中药杂志

Tripterygium wilfordii is a medicinal plant commonly used in the treatment of rheumatoid arthritis,and with pharmacological activities in anti-tumor and obesity treatment. The known active ingredients in T. wilfordii are mainly terpenoids,but with very low content. Therefore,the analysis of the biosynthesis pathway of terpenoids in T. wilfordii has become a research hotspot to solve the problem of its resources. Terpenoid synthase( TPS) is a key enzyme that catalyzes the formation of a wide variety of terpenoid skeletons. In this study,a gene fragment with an ORF of 1 785 bp was cloned from T. wilfordii. Bioinformatics analysis was performed using NCBI's BLASTP,ProtParam and Interpro online tools and MEGA 6.0 software. The response of this gene to methyl jasmonate was also detected by real-time fluorescent quantitative PCR,and its catalytic function was verified by prokaryotic expression and in vitro enzymatic assay. Bioinformatics analysis indicated that the amino acid sequence encoded by this gene had both N-terminal domain and C-terminal domain of TPS,as well as the DDxx D conserved domain of the class I of TPS family. And Tw MTS gathered together with TPS-b subfamily in the Neighbor-Joining Tree constructed with known homologous TPSs. The results of RT-PCR showed that 50 μmol·L-1 MeJA 12 h could increase the expression of Tw MTS to 735 times in the control group at 12 h,and 1 644 times at 24 h. In addition,in vitro enzymatic reaction results showed that Tw MTS can catalyze the production of β-citronellol with GPP as substrate,indicating that Tw MTS was a monoterpene synthase. The above results provided a new element for the synthetic biology database of T. wilfordii terpenoids,and laid the foundation for future biosynthesis research.

Anticoagulant property of a semi-synthesized sodium beta-1,4-glucan sulfate / 药学学报

<p><b>AIM</b>To investigate the anticoagulant efficacy and mechanism of a semi-synthesized sodium beta-1,4-glucan sulfate (Na-MCS).</p><p><b>METHODS</b>Anticoagulant activity was evaluated by means of coagulation assays in comparison with heparin. The anticoagulant mechanism of Na-MCS was disclosed by inhibitory analysis of the activities of coagulation factors using chromogenic substrates.</p><p><b>RESULTS</b>0.6 microg x mL(-1) Na-MCS could significantly prolong APTT and TT, but has less effect on PT at an even higher concentration. The dosage of Na-MCS required to double APTT of normal human plasma was 0.7 microg x mL(-1), lower than that of heparin with the activity of 150 u x mg(-1).</p><p><b>CONCLUSION</b>Na-MCS represented a potent anticoagulation activity in vitro, which matched the efficacy of heparin in a certain range of concentrations. Na-MCS exhibited anticoagulant activity due to inhibition of the coagulation factors IIa and Xa by the mediation of anti-thrombin AT-III.</p>

Effect of Static Magnetic Fields on the Survival Probability of Bacteria / 微生物学通报

Bacteria are regarded as the main hazard in food industry, and b acteria can be affected by a static magnetic field (SMF) with high intensity. S o the SMF would be useful for controlling the bacteria’s hazard to food. The e ffect of magnetic induction, treatment time on bacteria, and the survival probab ility of bacteria under SMF were studied for investigating their action regulari ty, and the DNA fingerprint of strains after magnetic treatment was compared wit h that of control. The research results would lay the basis of SMF application in food industry on theory and practice.