Expression and identification of recombinant human interferon λ1 in HEK-293F cells / 中国生物制品学杂志

@#Objective To express recombinant human interferon λ1(rhIFNλ1)by transient transfection in HEK-293F cells and identify it. Methods Two signal peptides[T cell receptor(TCR)and nature signal peptide(NSP)],three vectors[pcDNA3.4,ubiquitous chromatin opening element(UCOE)and PFR]and the target gene rhIFNλ1 were used to construct recombinant plasmids of six signal peptide-vector combinations. Using HEK-293F as host cells,the recombinant plasmids were transfected transiently to express rhIFNλ1 on a shake flask scale. The recombinant plasmid UCOE-Q46-λ with low glycosylation rhIFNλ1 was constructed by using NSP and vector UCOE,and transfected transiently into HEK-293F cells. The expressed product was purified by cation exchange chromatography(HiTrap SP FF),blue gel chromatography(HiTrap Blue HP)and gel filtration chromatography(Sephacryl S-100 HR),which was then analyzed by Western blot and reversed-phase HPLC,and determined for its molecular mass and N-terminal amino acid sequence by mass spectrometry. Results Six recombinant plasmids were constructed correctly as identified by double enzyme digestion and sequencing. With the extension of transfection time,the expression levels of the six expressed products increased gradually,and reached the highest level of10 ～ 20 mg/L at the 6th day of transfection. Double enzyme digestion and sequencing identification proved that the recombinant plasmid UCOE-Q46-λ with low glycosylation rhIFNλ1 was constructed correctly. The recombinant plasmid UCOE-Q46-λwas transfected into HEK-293F cells for 6 d. The purified product of cell culture supernatant showed a relative molecular mass of about 27 800 and a purity of 97. 372%,which showed specific binding to mouse anti-human IL-29/IFNλ1 monoclonal antibody;Two peaks were detected by reversed-phase HPLC,and the peak was showed at 15. 6 min and 20. 0 min respectively;The mass spectrometry molecular mass was about 24 000;The N-terminal five amino acids were G-P-V-P-T.Conclusion The rhIFNλ1 expressed by HEK-293F cells has high purity,which lays a foundation of further study of the protein.

Extracellular expression in Bacillus subtilis of a thermostable Geobacillus stearothermophilus lipase

BACKGROUND The extracellular expression of enzymes in a secretion host such as Bacillus subtilis is a useful strategy in reducing the cost of downstream processing of industrial enzymes. Here, we present the first report of the successful extracellular expression in Bacillus subtilis WB800 of Geobacillus stearothermophilus lipase (T1.2RQ), a novel industriallydesirable thermostable lipolytic enzyme which has an excellent hydrolytic and transesterification activity. Signal peptides of a-amylase, extracellular protease, and lipase A, as well as two different promoters, were used in the secretion and expression of lipase T1.2RQ. RESULTS Lipase activity assay using p-nitrophenyl laurate showed that all three signal peptides directed the secretion of lipase T1.2RQ into the extracellular medium. The signal peptide of lipase A, resulted in the highest extracellular yield of 5.6 U/ml, which corresponds to a 6-fold increase over the parent Bacillus subtilis WB800 strain. SDS-PAGE and zymogram analysis confirmed that lipase T1.2RQ was correctly processed and secreted in its original size of 44 kDa. A comparison of the expression levels of lipase T1.2RQ in rich medium and minimal media showed that the enzyme was better expressed in rich media, with up to an 8-fold higher yield over minimal media. An attempt to further increase the lipase expression level by promoter optimization showed that, contrary to expectation, the optimized promoter exhibited similar expression levels as the original one, suggesting the need for the optimization of downstream factors. CONCLUSIONS The successful extracellular secretion of lipase T1.2RQ in Bacillus subtilis represents a remarkable feat in the industrial-scale production of this enzyme

Expression and production optimization of sucrose isomerase from Pantoea dispersa in Escherichia coli / 生物工程学报

To improve the yield of sucrose isomerase from Pantoea dispersa UQ68J, we studied the effect of different signal peptides and fermentation conditions on sucrose isomerase expression in Escherichia coli. The gene of sucrose isomerase was optimized and expressed in E. coli BL21 (DE3) with native signal peptide which was named as ORI strain. The total and extracellular enzyme activity was 85 and 65 U/mL in the flask, respectively. The mature protein, which started from the 22th amino acid, was connected with the PelB and OmpA signal peptide to construct P22 and O22 strain, respectively. The total activity of P22 reached 138 U/mL, which was 1.6 times of ORI strain. The total activity of O22 strain was similar to that of ORI strain. Induced by 3.0 g/L lactose, the total activity of P22 strain increased to 168 U/mL. In 3 L fermentor, the effects of glycine concentration and induction time were studied. Induction when the DCW reached 18 g/L (OD₆₀₀=30), with 0.5% glycine, the extracellular enzyme activity reached 1 981 U/mL, and the total enzyme activity reached 2 640 U/mL, which is the highest activity of sucrose isomerase that was expressed in recombinant E. coli.

Genetic Modification of Baculovirus Expression Vectors / 中国病毒学·英文版

As a protein expression vector,the baculovirus demonstrates many advantages over other vectors.With the development of biotechnology,baculoviral vectors have been genetically modified to facilitate high level expression of heterologous proteins in both insect and mammalian cells.These modifications include utilization of different promoters and signal peptides,deletion or replacement of viral genes for increasing protein secretion,integration of polycistronic expression cassette for producing protein complexes,and baculovirus pseudotyping,promoter accommodation or surface display for enhancing mammalian cell targeting gene delivery.This review summarizes the development and the current state of art of the baculovirus expression system.Further development of baculovirus expression systems will make them even more feasible and accessible for advanced applications.

Caveolae-caveolin and associated signaling molecules / 中国病理生理杂志

Caveolae, specialized vesicular invaginations of the plasma membrane ,have attracted increasing attentions to those who are studing siginal transduction .Many proteins involved in signal transduction have been found enriched in these microdomains.Caveolins,as marker proteins of caveolae,form a scaffold onto which many classes of signaling molecules can assemble at steady state or after ligand-induced activiton .In addition to concentrating these signal transducers within a distinct region of the plasma membrane ,caveolin binding may functionally regulate the activation state of caveolae-associated signaling molecules.Thus,an emerging notion is that caveolae are signaling processing centers which orchestrate signaling events at the cell surface that influence cell function .