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@#Objective To compare the effects of different signal peptides on the secretion and expression of SARS-CoV-2S1,receptor binding domain(RBD) and RBD dimer proteins in Expisf9 insect cells.Methods The gene sequences of three proteins,SARS-CoV-2 S1(M1-E661),RBD(R319-P545) and RBD dimer(R319-K537 tandem),were selected and divided into 25 groups according to the different N-terminal signal peptide sequences(Endo,honeybee melittin(HBM),GP64,GP67,chitinase(Chi) and HIV-ENV) and C-terminal label sequences.25 recombinant baculoviruses were constructed by Bac-to-Bac system,and 25 groups of tertiary strain banks were prepared.B2 and C4 viruses were inoculated to logarithmic prestage cells(2.8 × 10~6 cells/mL) and logarithmic metaphase cells(1.2 × 10~7 cells/mL),respectively.The viruses of each group were cultured to 100 mL(500 mL shaker) for protein expression,and samples were taken for SDSPAGE electrophoresis,Western-blot and ELISA detection.Two groups with higher expression levels of S1,RBD and RBD dimer proteins were selected for repeated verification.Results When B2 and C4 were inoculated to high cell density,the secretion expression level showed no increase,while there were significant difference between 4 and 5 d after inoculation.The expression level of A7(Endo-S1-tag) was significantly lower than that of A9(HIV-ENV-S1-tag),the expression level of A4(Gp67-S1-tag) was the highest,and the secreted expression level of A1(Endo-Endo-Sl-tag) was significantly lower than that of A7(Endo-S1-tag).The secretion and expression of B6(HIV-ENV-RBD-tag) was signifi-cantly higher than that of B4(Gp67-RBD-tag) and other signal peptide groups,and C4(Gp67-RBD-dimer-tag) expression was significantly higher than that of C3(Gp64-RBD-dimer-tag).Two groups with high expression of each protein were selected separately for repeated verification(A4,A9;B4,B6;C3,C4) and the results showed that A4,B6 and C4 had the highest secretion expression levels.Conclusion The signal peptide for the highest secretion expression of S1 and RBD dimer proteins is the same,which is GP67 signal peptide,while the most suitable signal peptide for RBD protein is HIV-ENV,indicating that the N-terminal sequence can affect protein secretion,signal peptide sequence is universal to a certain extent,but is also related to the target protein sequence to be expressed.
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Pullulanase is a starch debranching enzyme, which is difficult in secretory expression due to its large molecular weight. Vibrio natriegens is a novel expression host with excellent efficiency in protein synthesis. In this study, we achieved secretory expression of the full-length pullulanase PulA and its truncated mutant PulN2 using V. natriegens VnDX strain. Subsequently, we investigated the effects of signal peptide, fermentation temperature, inducer concentration, glycine concentration and fermentation time on the secretory expression. Moreover, the extracellular enzyme activities of the two pullulanases produced in V. natriegens VnDX and E. coli BL21(DE3) were compared. The highest extracellular enzyme activity of PulA and PulN2 in V. natriegens VnDX were 61.6 U/mL and 64.3 U/mL, which were 110% and 62% that of those in E. coli BL21(DE3), respectively. The results indicated that V. natriegens VnDX can be used for secretory expression of the full-length PulA with large molecular weight, which may provide a reference for the secretory expression of other large molecular weight proteins in V. natriegens VnDX.
Subject(s)
Escherichia coli/genetics , Fermentation , Vibrio/geneticsABSTRACT
【Objective】 To construct the secretory expression system of insect cells to express the secretory TSHR A subunit protein in the ovarian cells of Spotoma oryzae (sf9). 【Methods】 A recombinant plasmid containing the target protein was constructed, and then the positive bacmid was screened out by the blue and white spots experiment. The verified bacmid was transfected into SF9 insect cells to obtain recombinant baculovirus. The virus was amplified, and the titer level was detected by virus plaque assay. Finally, Western blotting was used to identify the expression of the recombinant protein and optimize the expression conditions. 【Results】 During the construction of the protein expression system, PCR identification and sequencing results confirmed the correctness of the sequences of the recombinant plasmid and the recombinant bacmid. After the transfection of the bacmid, the signs of virus budding were observed in sf9 cells. The virus was collected and amplified. The titer of P1 generation virus was 2×107 pfu/m according to the plaque assay. The recombinant protein was identified by Western blotting and confirmed to be exogenous into the culture medium. The optimal condition for virus infection and protein expression was 72 h after the infection when the multiplicity of infection (MOI) was 1. 【Conclusion】 We constructed an insect cell expression system secreting TSHR 22-289 (55 ku), and the protein could be successfully glycolyzed. This system provides a preliminary basis for the construction and production of its industrial platform and also provides a useful tool for studies on TSHR protein and prevention of GO in the future.
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N-glycanase is a class of deglycosylation enzymes, widely used in the study of N-glycosylation modification of glycoprotein. In this study, an N-glycanase gene (OsPNGase A, XM_015775832) with high GC content (69.48%) was cloned from rice and then the yeast secretory expression vector pPICZ(α)A-OsPNGase A was constructed for the purpose of transformation to Pichia pastoris. After induction in Pichia pastoris SMD1168H, the target protein was purified by DEAE Sepharose and HisTrap HP chromatography, with a yield of 12.3 mg OsPNGase A from 1 L fermentation medium, showing a specific activity of 258 U/mg. SDS-PAGE revealed that the purified OsPNGase A was a single band and showed consistentcy with the expected molecular weight. OsPNGase A could act on transferrin recombinantly expressed in rice, avidin recombinantly expressed in corn and horseradish peroxidase. Furthermore, OsPNGase A showed higher activity than commercial PNGase F towards avidin. OsPNGase A displayed the highest digestion activity at pH 6.0 and 40 °C, and was also active in the neutral and alkaline environment. Despite the fact that OsPNGase A was inhibited by reducing agents and surfactants, it still maintained partial enzymatic activity in 100 mmol/L β-ME or DTT. Therefore, the successful expression of rice OsPNGase A provides a new tool for the study of plant glycoproteins and the establishment of yeast secretion expression system lays the foundation for the preparation of PNGase A.
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With the sequence of the vasoactive intestinal peptiepeptide (VIP) from humans and according to the condon bias of Pichia pastoris, we designed PCR primers of VIP and obtained the sequence of VIP by SOE-PCR. Then VIP gene was cloned into Pichia pastoris secretory expression vector and the cell secretary system GS115-pPICZαA-vip was constructed. The recombinant strain was induced by methanol for 96 hours, and we collected the supernatant and identified the VIP by mass spectrometry. The molecular weight of VIP was consistent with theoretical molecular weight. The final result showed that the target peptide VIP was successfully expressed. The experimental investigations of agarose gel diffusion revealed that the recombinant expression modified VIP had relatively strong antibacterial activity to E. coli ATCC25922 and S. aureus ATCC25923. The minimal inhibitory concentration (MIC) of VIP to E. coli ATCC25922 and S. aureus ATCC25923 was 8 mmol/L and 16 mmol/L. Further cytotoxicity and hemolytic experiments indicated that recombinant VIP was non-toxic to normal cells NCM460 and IPEC-J2, had little hemolysis activity to SD rat erythrocytes. Meanwhile, by transmission electron microscopy, we found that VIP mainly inhibited bacteria by disrupting the cell membrane. These experiments established a useful system for further studies, application and mass production of antimicrobial peptide VIP.
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Objective To express a recombinant protein TFPR1 ( the functional region of the snake venom proteins from Trimeresurus flavoviridis) in Pichia pastoris expression system. Methods The target gene was codon-optimized and synthesized according to the sequence of the conserved structural do-main of triflin and then cloned into the Pichia pastoris expression vector pPICZαA to construct the recombi-nant expression plasmid pPICZαA-TFPR1. The recombinant plasmid pPICZαA-TFPR1 was electroporated into the yeast strain X33. The transformed strains carrying expression plasmid were screened out with Zeocin and then induced by methanol to express the recombinant protein TFPR1. ELISA was performed for the screening of positive clones. SDS-PAGE and Western blot were used for further identification of the ex-pressed products. Results The recombinant plasmid pPICZαA-TFPR1 was successfully constructed. The recombinant protein TFPR1 was expressed in a secreted form at a molecular weight of 16×103. Conclusion The recombinant protein TFPR1 was successfully expressed in Pichia pastoris expression system, which laid a foundation for further researches on its biological function and application as an adjuvant.
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Objective To construct a eukaryotic expression vector in Pichia pastoris containing human fibrinogen gene, in order to achieve high level secretory expression in extracellular.Methods Expression plasmid,pGAPZαA-FGB-FGG-FGA-AOX1,was constructed by inserting the synthesized sequence encoding human fibrinogen(FGA, FGB,FGG) and then introduced into Pichia pastoris SMD1168H by electroporation.Transformants were availably screened by Zeocin resistance,the expression of recombinant protein was identified by SDS-PAGE and Western blot analysis, the protein yield was tested by ELISA assay.After ultrafiltration and purification, the biological activity of protein was detected.Results The crude yield of human fibrinogen in Pichia pastoris supernatant reached 15 mg/L in flask and the biological aggregation activity was determined.Conclusion The human fibrinogen gene was obtained and successfully expressed in Pichia pastoris and the active products were secreted into the medium.
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Nucleases is an important enzyme widely used in biotechnology. A codon optimized nuclease gene (SNU) from Northern Shrimps was inserted into pPICZα A vector, and expressed extracellularly in strain SMD1168H. On the basis of multi-copy recombinant strain, we further optimized the expression condition and characterized SNU. SNU was highly expressed and stable after 1% methanol induction for 72 h, yield reached 1.4×10⁵ U/mL. SDS-PAGE electrophoresis demonstrated that this is a N-linked glycoprotein of 50 kDa. It was purified by one step DEAE Sephadex chromatography to the purity of about 15 mg/L with a specific activity of 6.291×10⁶ U/mg. Functional analysis on the nuclease activity indicated that it was stimulated by bivalent iron, such as Ca²⁺, Mn²⁺, Co²⁺ and Mg²⁺, but inhibited by Zn²⁺, Cu²⁺ and high salt. Meanwhile, it was irreversibly inactivated at 70 ℃ for 10 min.
Subject(s)
Animals , Codon , Electrophoresis, Polyacrylamide Gel , Endonucleases , Glycoproteins , Hot Temperature , Penaeidae , Pichia , Metabolism , Recombinant ProteinsABSTRACT
This study employed a Bac-to-Bac/Bombyx mori bioreactor to mass-produce immunogenic urease subunit B (UreB) from Helicobacter pylori. The signal peptide bombyxin from B. mori was used to promote secretory expression to improve expression levels and was designed and integrated into the UreB gene to generate the Bacmid/BmNPV/(signal peptide)-UreB baculovirus expression system. To determine whether the bombyxin signal peptide resulted in secretory expression of recombinant UreB (rUreB) and to determine the secretory efficiency, we tested the secretory expression level of rUreB in Bm5 cells using ELISA. To further investigate whether secretory expression affected cell viability, cells were evaluated using 0.4% trypan blue staining, and Bacmid/BmNPV/UreB without the signal peptide served as a control. The above recombinant bacmid constructs were injected to silkworm larvae, and the secretory expression level of rUreB was detected using SDS-PAGE and semi-quantitative western blot analysis. The results indicated that the bombyxin signal peptide directed the secretory expression of rUreB and that this expression improved the viability of Bm5 cells. Moreover, the results showed that the expression level of rUreB was 1.5 times higher with the Bacmid/BmNPV constructs containing the bombyxin signal sequence than those without the signal sequence. These results demonstrate that secretory expression can enhance rUreB expression levels and is likely to aid in the large-scale expression and yield of rUreB in silkworm larvae.
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Objective To construct the secretory expression vector of recombinant human C-reactive protein(rhCRP) for its se-cretory expression in Pichia pastoris ,rhCRP was expressed as a secretory protein and purified ,and the immunity reactivity of the purified protein was identified .Methods The DNA fragment of rhCRP which was designed and synthesized was cloned into pPICZαA vector .Recombinant plasmid pPICZαA/rhCRP was linearized by SacⅠand transformed into Pichia pastoris X-33 by elec-trotransformation .The rhCRP was secreted into the medium under the methanol induction .RhCRP was purified by Histamine affin-ity chromatography .The purified rhCRP was identified by SDS-PAGE and Western blotting ,and its immunity reactivity and stabili-ty was identified by indirect ELISA .Results The pPICZαA/rhCRP expression vector was successfully constructed .The rhCRP of 23 × 103 was inducted and successfully expressed as a secretory protein by the recombinant Pichia pastoris strains .The rhCRP was purified by one step up to 90 .42% purity ,and it was showed good immunity and stability by indirect ELISA .Conclusion The rh-CRP with higher purity and immunoreactivity was successfully obtained by using the Pichia pastoris expression system ,which pro-vided an important experimental basis for producing anti-human CRP antibodies and developing testing CRP reagent .
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Objective: To clarify whether the signal peptide of human nerve growth factor can mediate secretory expression of beta-endorphin and whether there is difference between the efficiency of signal peptides from human and mouse nerve growth factor. Methods: Two kinds of eukaryotic vectors containing human or mouse signal sequence-mediated secretory expression of beta-endorphin were constructed. The culture supernatant and cells were collected 48 h after NIH3T3 cells were transfected by the two kinds of vectors, and the cover slips with single-layer cells was prepared. The concentration of beta-endorphin in the culture was determined by radio-immunoassay. The total RNA was extracted from cells and mRNA from fusion genes was assayed by RT-PCR. Cells on cover slips were subjected to immunofluorescence staining. Results: RT-PCR showed that the fusion genes were expressed in NIH3T3 cells; the expression of beta-endorphin was mainly in the cytoplasm of NIH3T3 cells. The concentrations of beta-endorphin in the supernatants 48 h after transfection with pcDNA3. 1-hEP and pcDNA3. 1-mEP were (280.33±24.16) pg/ml and (191.04±7.96) pg/ml (P<0.05), respectively, and they were significantly different from that of the blank control group (P<0.01). Conclusion: The signal sequence of human nerve growth factor can mediate the secretory expression of protein and the efficacy of human signal peptide is higher than that of mouse signal peptide.
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The sequence encoding an E2 main antigen glycoprotein of the C strain of classical swine fever virus (CSFV) was highly expressed in the host cell E. coli BL21-CodonPlus (DE3)-RIL using the pGEX-4T-1 expression vector and the soluble recombinant product was purified with Glutathione Sepharose TM<'4B> by centrifugation. The soluble recombinant protein showed good immune reactions and was confirmed by Western blot using anti-CSFV-specific antibodies. Then an indirect ELISA with the purified E2 protein as the coating antigen was established to detect antibody against CSFV. The result revealed that the optimal concentration of coated antigen was 0.6 μg/well and the optimal dilution of serum was 1:80. The positive cut-off value of this ELISA assay was OD<,tested serum>/OD<,negative serum>≥2.1- The E2-ELISA method was evaluated by comparison with the indirect hemagglutination test (IHAT). When a total of 100 field serum samples were tested the sensitivity and specificity were 90.3% and 94.7% respectively. Specificity analysis showed that there were no cross-reactions between BVD serum and the purified E2 protein in the E2-ELISA.
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To construct a secretory-expression vector of antimicrobial peptide Bactenecin 7(Bac7),and identify the secretory-expression product in L.lactis MG1363 and its bioactivity.The splicing primers of regulation elements and Bac7 gene,which designed according to codon usage preferences of L.lactis MG1363,were chemically synthesized,and the overlap-extension PCR method was used to splice the full length of Bac7 gene.Then the Bac7 gene was linked to expression vector pMG36e to construct pMG36e/Bac7 vector,and pMG36e/Bac7 was transformed into L.lactis MG1363 by electrophoration.RT-PCR and Western blot assays were applied to investigate the expression of the Bac7 gene in L.lactis,and bioactivity of Bac7 in culture supernatant of L.lactis was tested with plate-diffusion method.The results showed that the Bac7 gene and its regulation elements was amplified and cloned in the vector pMG36e successfully,The secretory-expressed Bac7 in L.lactis MG1363 harboring pMG36e/Bac7 was identified by Western blot,and it had high bacteriostatic activity against E.coli.These results indicate that the recombinant L.lactis MG1363 could express bioactive Bac7,which lays a foundation for further study of oral administration of a Bac7-secreting L.lactis to treat intestinal bacteria infection.
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Aim To obtain recombinant human IL-24 secretorily expressed in Pichia pastoris,and study the activity of inducing tumor cells apoptosis of this N-glycosylation protein. Methods By the recombinant plasmid ?/pUC18,the confirmed IL-24 gene was inserted between the sites of BamH Ⅰ and EcoR Ⅰ of expression plasmid pPIC9K. The recombinant plasmid IL-24/pPIC9K was transformed into P. pastoris strain GS115. Yeast transformants were induced for expression of recombinant human IL-24 with methanol. The desired protein was identified with Tricine-SDS-PAGE and Western blot.Amount of IL-24 was assayed with ELISA and the glycosylation was analyzed by PNGase F.The activity of inducing tumor cells apoptosis was confirmed by MTT assay and Hoechst assay in vitro.Results Recombinant expression plasmid IL-24/pPIC9K was successfully constructed. 5 transformants were screened with G418 and PCR. Induced with methanol,the expression level of IL-24 was (81.31?14.46) mg?L-1 at flask fermentation,and 70 % IL-24 generated N-glycosylation.Recombinant IL-24 induced apoptosis in MCF-7 cells,but not in NHLF.Conclusion The secretorily expression of the N-glycosylation IL-24 protein in P. pastoris and the study of inducing tumor cells apoptosis lay the foundation for the further study of molecular mechanism of IL-24 on anti-tumors and the potential application.
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Objective:To construct a gene of ScFv against human HAb18G molecule and secretively express it in E coli Methods:The V H and V L genes cloned from McAb HAb18 hybridoma cell were ligated with a flexible linker(Gly4Ser) 3 to construct ScFv gene Then corresponding restriction endonuclease digestion site was introduced into 5′and 3′ end of ScFv gene Finally, it was cloned into expression vector pCANTAB 5His and expressed in E coli HB2151 Expression proteins were purified by affinity chromatography and detected by SDS PAGE electrophoresis?Western blot and ELISA Results:Restriction endonuclease digestion and DNA sequencing proved that ScFv gene was correctly cloned into expression vector SDS PAGE electrophoresis and Western blot analysis showed that ScFv was successfully expressed in E coli HB2151 The relative molecular mass (Mr) of the expression products was 31 kD, according with its predicted Mr value And ELISA assured that expression products had antigen specific binding activity Conclusion:The successful expression of anti HAb18G ScFv gene in E coli laid a solid foundation for its further application in diagnosis and therapy of human hepatoma.
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Objective To express the short consensus repeat 15-18 (SCR15-18) domain of human complement receptor 1 (CR1) in Pichia pastoris as a secreted protein in order to found a base for large-scale industry fermentation. Methods The gene fragment of CR1-SCR15-18 was amplified by PCR from plasmid pET32a-sCR1-SCR15-18. The obtained sequence was subcloned into Pichia pastoris secretory expression vector pPIC9. After identification the recombinant plasmid pPIC9-CR1-SCR15-18 was electrotransported into the yeast. Positive clones were identified using colony PCR. Positive recombinants were fermented in shake flaskes and induced with methanol. The recombinant proteins were identified with SDS-PAGE and Western blot analysis. After the recombinant protein was purified by Ni-NTA agarose metal chelate affinity chromatography, inhibiting complement hemolysis testing was used to detect the biological activity. Results Recombinant expression plasmid pPIC9-CR1-SCR15-18 was successfully constructed. SDS-PAGE and Western blot analysis revealed that the target gene was successfully expressed in the yeast and the recombinant protein was successful secreted in the culture supernatant. After purification, the protein inhibited complement hemolysis in vitro. Conclusion CR1-SCR15-18 is successful expressed in Pichia Pastoris with high activity of inhibiting complement hemolysis.
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Objective:To express and secrete rBPI m23 bactericidal protein in Pichia pastoris expression system. Methods:pPICZ? synBPI m600 recombinant expression vector was constructed with prepared vectors (pUC18 synBPI 414 and PBV220 BPI m420 ) according to Molecular Cloning Laboratory Manual. The Pichia pastoris GS115 were electroporated with linearized pPICZ? synBPI m600 vectors , positive clones were screened on low salt LB medium with Zeocin , then the positive clones were identified by PCR and Mut phenotype analysis. rBPI m23 was induced to express in BMMY ,purified by SP Sepharose beads , identified by SDS PAGE and Western blot and measured with BCA method. Results:①pPICZ? synBPI m600 expression vector was successfully constructed.②Pichia pastoris GS115 strains integrated with synBPI m600 stably were obtained.③SDS PAGE showed the molecular weight of the recombinant protein was approximate 23 kD,and Western blot confirmed that the protein could bind to the anti BPI antibody specially.④The supernate protein concentration was about 2 9 mg/L.Conclusion:rBPI m23 was expressed and secreted effectively in Pichia pastoris GS115.
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Objective:To clarify whether the signal peptide of human nerve growth factor can mediate secretory expression of beta-endorphin and whether there is difference between the efficiency of signal peptides from human and mouse nerve growth factor.Methods: Two kinds of eukaryotic vectors containing human or mouse signal sequence-mediated secretory expression of beta-endorphin were constructed.The culture supernatant and cells were collected 48 h after NIH3T3 cells were transfected by the two kinds of vectors,and the cover slips with single-layer cells was prepared.The concentration of beta-endorphin in the culture was determined by radio-immunoassay.The total RNA was extracted from cells and mRNA from fusion genes was assayed by RT-PCR.Cells on cover slips were subjected to immunofluorescence staining.Results: RT-PCR showed that the fusion genes were expressed in NIH3T3 cells;the expression of beta-endorphin was mainly in the cytoplasm of NIH3T3 cells.The concentrations of beta-endorphin in the supernatants 48 h after transfection with pcDNA3.1-hEP and pcDNA3.1-mEP were(280.33?24.16) pg/ml and(191.04?7.96) pg/ml(P