Characterization and structure of a novel thermostable glucoamylase from Talaromyces leycettanus JCM12802 / 生物工程学报

Glucoamylase is a critical ingredient for saccharification in the starch decomposition, and widely used in food, pharmaceutical and fermentation industries. Glucoamylases are usually thermostable and have peak activities at high temperature, as required for the industrial process of glucose production. In this study, a glucoamylase gene belonging to the glycoside hydrolase (GH) family 15, Tlga15A, was cloned from Talaromyces leycettanus JCM12802, and successfully expressed in Pichia pastoris GS115. Recombinant glucoamylase TlGA showed optimal activities at pH 4.5 and 75 °C. The result of thermostability analysis showed that TlGA retained above 70% activity after incubating for 1 h at 65 °C, and 43% residual activity after 30 min at 70 °C. Moreover, TlGA had high resistance to most metal ions and chemical reagents tested. Various starch substrates could be hydrolyzed by TlGA, including soluble starch (255.6±15.3) U/mg, amylopectin (342.3±24.7) U/mg, glycogen (185.4±12.5) U/mg, dextrin (423.3±29.3) U/mg and pullulan (65.7±8.1) U/mg. The primary, secondary and tertiary structures of glucoamylase were further analyzed. The low ratio of Gly in the primary structure and low exposed nonpolarity solvent accessible surface in the tertiary structure may be the main reasons for TlGA's thermostability. These results show that TlGA is great promising for potential use in the commercial production of glucose syrups. Moreover, this research will provide knowledge and innovating ideas for the improvement of glucoamylase thermostability.

Expression and characterization of a multicopper oxidase from Lactobacillus fermentum / 生物工程学报

Biogenic amines (BAs) are low molecular weight organic compounds that present in fermented foods. Large amount of ingested biogenic amines can cause allergy or significant symptoms. Reduction of BAs by enzymatic reaction in fermented foods is one of the most efficient methods for removal of biohazard compounds and assurance food safety. In this study, the multicopper oxidase (MCO) gene in the genome of Lactobacillus fermentum was successfully cloned in Escherichia coli BL21 and expressed at 484 U/L. The recombinant MCO was purified by the immobilized metal affinity chromatography method. The optimal reaction temperature and pH for this enzyme was detected to be 50 °C and 3.5. The Km and Vmax values of the recombinant MCO was determined to be 1.30 mmol/L and 7.67×10⁻² mmol/(L·min). Moreover, this MCO dramatically degrades histamine and tyramine by 51.6% and 40.9%, and can degrade other BAs including tryptamine, phenylethylamine, putrescine, cadaverine and spermidine, and was found to be tolerant to 18% (W/V) NaCl. The recombinant MCO is also capable of degrading BAs in soy sauce. The degradation rate of total BAs in soy sauce reaches 10.6% though a relatively low level of enzyme (500 U/L) is used. Multicopper oxidase has the potential to degrade biogenic amines in fermented foods, which lays a foundation for the further application of this kind of food enzymes.

Production optimization, purification, expression, and characterization of a novel α-L-arabinofuranosidase from Paenibacillus polymyxa

Background: α-L-Arabinofuranosidase (EC 3.2.1.55) catalyzes the hydrolysis of terminal α-L-1,2-, -1,3-, and -1,5- arabinofuranosyl residues in arabinose-containing polymers, and hence, it plays an important role in hemicellulose degradation. Herein, the bacterium Paenibacillus polymyxa, which secretes arabinofuranosidase with high activity, was selected for enzyme production, purification, and characterization. Results: Medium components and cultural conditions were optimized by the response surface method using shake flask cultures. Arabinofuranosidase production reached 25.2 U/mL under optimized conditions, which were pH 7.5, 28°C, and a basic medium supplemented with 1.5 g/L mannitol and 3.5 g/L soymeal. Furthermore, the arabinofuranosidase secreted by P. polymyxa, named as PpAFase-1, was partially purified from the supernatant using a DEAE Sepharose Fast Flow column and a hydroxyapatite column. The approximate molecular mass of the purified PpAFase-1 was determined as 56.8 kDa by SDS-PAGE. Protein identification by mass spectrometry analysis showed that the deduced amino acid sequence had significant similarity to the glycosyl hydrolase family 51. The deduced gene of 1515 bp was cloned and expressed in Escherichia coli BL21 (DE3) cells. Purified recombinant PpAFase-1 was active toward p-nitrophenyl-α-L-arabinofuranoside (pNPAraf). The Km and kcat values toward pNPAraf were 0.81 mM and 53.2 s−1 , respectively. When wheat arabinoxylan and oat spelt xylan were used as substrates, PpAFase-1 showed poor efficiency. However, a synergistic effect was observed when PpAFase-1 was combined with xylanase from Thermomyces lanuginosus. Conclusion: A novel GH51 enzyme PpAFase-1 was cloned from the genome of P. polymyxa and expressed in E. coli. This enzyme may be suitable for hemicellulose degradation on an industrial scale.

The application of the cloning and expression of SMCY gender-specific fusion antigens with the corresponding polyclonal antibodies / 中国法医学杂志

Objective with the advantages of rapidity in detection protein, We selected the gender-specific amino acid sequence based on human SMCY and SMCX, cloned and expressed SMCY gender-specific fusion antigens. The rabbits were immunized with purified antigens to obtain the polyclonal antibodies. A new method was established for rapidly sex identification of forensic evidence samples by detecting SMCY antigens with the corresponding polyclonal antibodies. Methods We found three differential fragments by analyzing the sequence of human SMCY and SMCX. Then we cloned this three fragments and ligated as a new recombinant.This SMCY gender-specific fusion antigen gene was sub-cloned into pET-28a and expressed in Escherichia coli. The fusion antigen was purified by Ni-NTA column. The rabbits were immunized with purified antigen to produce the specific polyclonal antibodies.The reactivity of the polyclonal antibody was evaluated by ELISA and Western blotting. We developed a colloidal gold test strip for detecting the gender of human samples. Results We successfully selected gender-specific amino acid sequence, the SMCY gender-specific fusion antigen was expressed by prokaryotic expression and the polyclonal antibody was prepared by immunizing rabbit. The results of colloidal gold strip tests showed that there is a significant difference between male and female serums. Conclusion The results showed that the SMCY gender-specific fusion antigen could be recognized by the polyclonal antibody.The colloidal gold strip tests made by SMCY gender-specific fusion antigens and the corresponding polyclonal antibodies could be used for rapidly determining the gender of forensic evidence samples.

Cloning and expression of zot gene of Vibrio cholerae and its biological activity / 中国人兽共患病学报

The aim of this study is to construct the expression vector of zot gene of Vibrio cholerae and to realize the expression of zot gene of Vibrio cholerae in E.coli and study the biological activity of its recombinant expression product.In order to express zot protein in E.coli,the full-length open reading frame of zot was amplified by PCR from the standard strains of Vibrio cholerae MO45 genome DNA.The PCR product was cloned into prokaryotic expression vector pET-32a(+) with restriction enaymes Bam H I and XhoI.The recombinant vector pET-32a(+)-zot was transformed into E.coli BL21 (DE3) and expressed by IPTG induction.The zot fusion protein was detected by SDS-PAGE and Western blotting and purified by Ni-NTA affinity chromatography.After expression and purification,the recombinant expression protein played as a target for human small intestinal epithelial cells.Restriction endonuclease digestion,PCR and DNA sequencing analysis showed that the zot gene of 1 200 bp was amplified from Vibrio cholerae DNA,and the recombinant plasmid pET-32a(+)-zot was constructed and detected its expression in prokaryotic cell successfully with SDS-PAGE and Western blot techniques.The zot recombinant protein was successfully expressed and purified.The purified zot recombinant protein can cause human intestinal epithelial cells apoptosis.

Molecular cloning and expression of OspC protein of a Chinese Borrelia afzelli FP1 strain and pre-liminary study on the immune protectivity of the rOspC protein / 中华微生物学和免疫学杂志

Objective To clone and express the outer surface protein C ( OspC) from a Chinese Borrelia afzelli FP1 strain and to evaluate the immune protectivity of the recombinant OspC protein ( rOspC) . Methods The gene encoding OspC protein of Borrelia afzelli FP1 strain was amplified by polymerase chain reaction (PCR) and then inserted into pET-30a plasmid to construct the recombinant expression plasmid pET-30a-OspC. The transformed E. coli BL21 strains carrying pET-30a-OspC plasmid were induced by IPTG to express OspC protein. The expressed proteins were purified by Ni-IDA resin chromatography and analyzed by SDS-PAGE and Western blot assay. Indirect immunofluorescence assay ( IFA) was performed to detect anti-rOspC protein antibodies in serum samples from rabbits immunized with rOspC protein. In vitro neutral-ization test was performed for evaluation the immune protectivity of rOspC protein. Results The recombi-nant expression plasmid pET-30a-OspC was successfully constructed and highly expressed in E. coli BL21. A strong antigen-antibody reaction between the rOspC protein and polyclonal antibody against Borrelia afzelli FP1 strain was detected by Western blot assay. The titers of IgG in serum samples from rabbits immunized with rOspC protein were significantly elevated. The in vitro neutralization test indicated that 106/ml of Borre-lia afzelli FP1 strains were neutralized by every anti-OspC protein serum sample from the experiment group. Conclusion The rOspC protein showed a strong immune protectivity against Borrelia afzelli, which could be used in the development of polyvalent subunit vaccine against lyme disease.

Immunogenicity analysis of a recombinant protein CPSIT_p7 and its expression in HeLa cells during persistent Chlamydophila psittaci infection / 中华微生物学和免疫学杂志

Objective To construct a prokaryotic expression plasmid for CPSIT_p7 gene from Chlamydophila psittaci ( Cps) 6BC strain and to evaluate immunogenicity of the recombinant protein His-CPSIT_p7 and detect its dynamic expression at mRNA and protein levels in HeLa cells during persistent Cps infection.Methods The fusion protein His-CPSIT_p7 was expressed in E.coli BL21 and purified by Ni-NTA affinity chromatography .BALB/c mice were immunized with the recombinant protein to prepare polyclonal antibody for evaluation of the immunogenicity of His-CPSIT_p7 by ELISA.Penicillin sodium was used to establish a model of Cps persistence infection .RT-PCR and Western blot assay were performed to de-tect the expression of CPSIT_p7 at mRNA and protein levels during Cps persistent infection .Results The fusion protein His-CPSIT_p7 was successfully expressed with the use of constructed recombinant expression plasmid pET30 a-CPSIT_p7 and purified .ELISA result showed that the specific antibody titer against CPSIT_p7 reached 1 ∶1 000 000 on the 40th days after immunization .The expression of CPSIT_p7 at mRNA and protein levels were increased in a time-dependent manner in Cps-infected HeLa cells .The peak of mRNA level was reached at the time point of 36 hours after infection , followed by a time-dependent decrease during Cps acute infection .However , the expression of CPSIT_p7 at mRNA and protein levels were not decreased until 60 hours after infection during Cps persistent infection .Conclusion His-CPSIT_p7 protein was suc-cessfully expressed in the prokaryotic expression system and purified , showing an advantage of good immuno-genicity.Highly expressed CPSIT_p7 at mRNA and protein levels were detected during Cps persistent infection.

Cloning and expression of rotavirus nonstructural protein 4 and its interference effect on intrancellu-lar calcium homeostasis / 中华微生物学和免疫学杂志

Objective To construct prokaryotic expression systems of genes of intact rotavirus non -structural protein 4 (NSP4) and 86 to 175 amino acid peptide of NSP4 (NSP486-175) and to identify the bio-activities of the recombinant expression products .Methods Colloidal gold assay was used to screen group A rotavirus antibody-positive stools , from which the viral RNA was extracted and transcribed into cDNA .Then NSP4 gene and NSP486-175 gene were amplified by PCR and inserted into pET-28a(+) vector to construct the prokaryotic expression plasmids of pET-28a(+)-NSP4 and pET-28a(+)-NSP486-175 , which were transformed into E.coli BL21( DE3) and inducted by IPTG .The expressed NSP486-175 protein was purified by Ni-NTA af-finity chromatography and examined by Western blot .Fluo-3 AM ester was used to label intracellular free Ca2+( [ Ca2+] i) in Caco-2 cells and laser scanning confocal microscopy was performed to detect the effect of NSP486-175 protein on [Ca2+]i.Results DNA sequencing indicated that NSP4 gene and NSP486-175 gene were consistent with the corresponding sequences in NCBI .The intact NSP4 had difficulty in expressing in E.coli. NSP486-175 protein mainly existed in soluble form with a relative molecular weight of 10×103 .Fluorescence in-tensity and distribution were changed by exogenous addition of NSP 486-175 to cultured Caco-2 cells.Conclu-sion The expression vectors of pET-28a(+)-NSP4 and pET-28a(+)-NSP486-175 were successfully construc-ted and the target protein could induce [Ca2+]i imbalance.This phenomenon preliminarily indicates that the prokaryotic expressed NSP486-175 protein has biological activity and can be further used to elucidate rotavirus pathogenic mechanisms and perform vaccine research .

Fosfoproteômica e proteômica quantitativa de células mesenquimais durante a diferenciação osteoblástica mediada por BMP2, expressão e purificação de diferentes tipos de proteínas morfogenéticas ósseas / Quantitative phosphoproteomics and proteomics of mesenchymal stem cells during BMP2-mediated osteoblastic differentiation, expression and purification of different types of bone morphogenetic proteins

As fraturas e perdas ósseas representam altos riscos para o Sistema público de Saúde (SUS), além de afetar a qualidade de vida do paciente, portanto é necessário o entendimento das bases moleculares que envolvem os mecanismos de reparo ósseo. Citocinas secretadas por células do sistema imune presentes no local da inflamação, como as IL-6, IL-10 e TNFα atuam como fatores quimiotáticos para células mesenquimais, que proliferam e se diferenciam em osteoblastos pela ação autócrina e parácrina de Proteínas Morfogenéticas Ósseas (BMPs), principalmente a BMP2. Embora seja conhecido que a ação de BMP2 ocorra através de sua ligação nos receptores ActRI/BMPR, que ativam proteínas SMADS 1/5/8 efetoras, pouco se sabe sobre os mecanismos intracelulares que participam do processo de diferenciação osteoblástico. Neste estudo propôs-se analisar as diferenças no conteúdo de proteínas totais e de proteínas fosforiladas em células mesenquimais de pele induzidas à osteogênese pelo tratamento com BMP2 por diferentes períodos de tempo, utilizando-se de Isótopos Estáveis de Dimetila acoplado ao LC/MS. A partir de 150µg de material inicial, foi possível identificar 2.264 proteínas, as quais foram quantificadas nos diferentes pontos de indução, sendo que 235 são fosforiladas. Análise de motivos de quinases mostrou que diversos substratos possuem sítios fosforilados correspondentes àqueles dos motivos de fosforilação das quinases Casein Kinase, p38, CDK e JNK. A análise da ontologia gênica mostrou um aumento de processos biológicos relacionados com sinalização e diferenciação após a primeira hora de indução com rhBMP2. Além disso, proteínas envolvidas com o rearranjo do citoesqueleto e com vias de sinalização Wnt e Ras foram encontradas como tendo fosforilação diferencial durante todos os períodos estudados. Os dados revelaram novos substratos intracelulares que são fosforilados nos primeiros momentos do comprometimento com a diferenciação osteoblástica mediada pelo tratamento com rhBMP2 em células mesenquimais derivadas da pele. Além disso, clones celulares que superexpressam as proteínas recombinantes humanas BMP2 e BMP4 foram gerados, e sua atividade verificada in vitro. Paralelamente, a rhBMP7, obtida anteriormente, foi purificada por cromatografia de afinidade utilizando-se uma coluna de Heparina-Sepharose, que foi posteriormente utilizada para ensaios in vitro e in vivo, nos quais se mostrou capaz de gerar osteoblastos e tecido ósseo, respectivamente, o que abre novas possibilidades para o uso destas proteínas como biofármacos no Brasil

Bone fractures and loss represent significant costs for the public health system and often affect the patients quality of life, therefore, understanding the molecular basis for bone regeneration is essential. Cytokines, such as IL-6, IL-10 and TNFα, secreted by inflammatory cells at the lesion site, at the very beginning of the repair process, act as chemotactic factors for mesenchymal stem cells, which proliferate and differentiate into osteoblasts through the autocrine and paracrine action of bone morphogenetic proteins (BMPs), mainly BMP-2. Although it is known that BMP-2 binds to ActRI/BMPR and activates the SMAD 1/5/8 downstream effectors, little is known about the intracellular mechanisms participating in osteoblastic differentiation. We assessed differences in the phosphorylation status of different cellular proteins upon BMP-2 osteogenic induction of isolated human skin mesenchymal stem cells using Triplex Stable Isotope Dimethyl Labeling coupled with LC/MS. From 150 µg of starting material, 2,264 proteins containing two or more peptides were identified and quantified at five different time points, 235 of which are differentially phosphorylated. Kinase motif analysis showed that several substrates display phosphorylation sites for Casein Kinase, p38, CDK and JNK. Gene ontology analysis showed an increase in biological processes related with signaling and differentiation at early time points after BMP2 induction. Moreover, proteins involved in cytoskeleton rearrangement, Wnt and Ras pathways were found to be differentially phosphorylated during all timepoints studied. Taken together, these data, allow new insights on the intracellular substrates which are phosphorylated early on during commitment to BMP2-driven osteoblastic differentiation of skin-derived mesenchymal stem cells. Cell clones overexpressing the human BMP 2 and 4 recombinant proteins were also generated, and their biological activity was confirmed in vitro. In parallel, chromatography-affinity purified rhBMP7, obtained using heparin-Sepharose columns, was used for in vivo and in vitro assays to evaluate the ability of this purified protein to generate osteoblasts and bone tissue, respectively, opening new avenues for the use of these proteins as biopharmaceuticals in Brazil

Recombination expression and immunoprotective effects of the P6 outer membrane protein of nontypeable Haemophilus influenzae / 中华微生物学和免疫学杂志

Objective To clone and express recombinant outer membrane protein P6, determine its optimal expression conditions and to investigate the immunoprotective effects of the P6 protein on mice. Methods The P6 gene of nontypeable Haemophilus influertzae(NTHi) was amplified by PCR from the NTHi genome and cloned into expression vector pET-32a (+) to generate the pET-32a-P6 recombinants. They were confirmed by nuclease digestion and sequence analysis. The verified recombinant was transformed into E. coli BL21 (DE3). Its optimal expression conditions were determined such as engineering strains, the concentration of IPTG, inducing temperature, inducing time, different medium etc. The recombinant protein was purified by Q Sepharose~(TM) XL ion exchange and gel filtration chromatography. The protein was analyzed by SDS-PAGE, Western blot and sequencing. BALB/c mice were immunized with recombinant protein be-fore challenged by NTHi through intraperitoneal injection. Then the mortality rate of different group was com-pared. Results The recombinant P6 of NTHi was successfully constructed and expressed in E. coli at a rel-atively high level. The purity was up to 95% after purification. The relative molecular mass of the protein is 14 145. 848. The recombinant protein was confirmed to show specific reaction on the antiserum through Western blot. The animal experiments showed the mortality rates of immunization groups were significantly lower than that of the control group (P < 0.05). Conclusion The successful expression of the recombinant P6 will be very helpful for the further study on development of vaccine, its purified, immunological activity and antibody preparation.

Sequence analysis,cloning expression and immunogenicity analysis of lactate dehydrogenase gene from Taenia solium / 中国人兽共患病学报

The structure and properties about encoding protein of lactate dehydrogenase A from Taenia solium(Ts LDH-A)were analyzed and predicted by bioinformatics in this study.The immunological characteristics of this novel gene were also analyzed by cloning and expressing.The full-length cDNA encoding Ts LDH-A was identified from the cDNA plasmid library by blastx and rpsblast programs provided by NCBI.The physico-chemical properties and structures of Ts LDH-A were analyzed by tools provided by ExPASy.And the B cell epitopes of Ts LDH-A were predicted by the B Cell Epitope Prediction Tools provided by IEDB Analysis Resource.The PCR amplified coding region of Ts LDH-A was cloned into the prokaryotic expression vector pET-28a (+) and expressed in E.coli BL21 with IPTG induction.The immunogenicity of the purified recombinant protein was analyzed by Western Blotting.It was demonstrated that the amino acid sequence of Ts LDH-A had identity with that of LDH-A from other specie and there was a conserved LDH domain in the deduced amino acid sequence.The full-length cDNA sequence encoding Ts LDH-A included a complete open reading frame(ORF)of 1332 bp and coded to a putative protein with 331 amino acids.The molecular weight of Ts LDH-A was predicted to be 35461.1 Da and the coding protein was demonstrated to contain 3 trans-membrane regions and 4 main B cell epitopes.The active site of L-lactate dehydrogenase located at the epitope aa190-199.The 3 key residues in the catalytic site of enzyme were conserved in different species and located near to each other in spatial position.PCR,double enzyme restriction and DNA sequencing were used to identify pET28a (+)-Ts LDH-A.The recombinant protein could react with the rat's sera as well as the sera from the patients and the swine infected Taenia solium.It is clear that the full-length cDNA sequence encoding Ts LDH-A can be screened from the cDNA library of adult Taenia solium by bioinformatics analysis and can be used to investigate the structure and properties about gene and encoding protein of Ts LDH-A as well as the immunological activities of gene expression in the prokaryotic system.

The immunoprotective effects of new gene R049 of uropathogenic Escherichia coli / 中华微生物学和免疫学杂志

Objective To clone and express the new gene R049 of uropathogenic Escherichia coli 132.and to investigate the immunopmtective effects of the R049 recombinant protein on mice.Methods The pmkaryotic expression system of gene R049 was constructed by directed cloning.Thereafter,the R049 recombinant protein Was expressed and purified by Ni affinity chromatography.Polyclonal antibody was pre-pared by immunizing BALB/c mice with R049 recombinant protein.The R049 recombinant protein and whole bacterial proteins of UPEC132 were analyzed by SDS-PAGE and Western blot.BALB/c mice were im-munized with R049 recombinant protein before challenged by UPECl32 through urinary tract.Then the differences of urine and renal colony counts between immunization group and control group were compared.Results The recombinant strain E coli BL21(DE3)/pET32a-R049 ORF was constructed successfully,and the relative molecular mass of the R049 recombinant protein was 66.9×103 and its purity was up to 95% af-ter purification.The titer of polyclonal antibody wag≥1:102 400 analyzed by indirect ELISA.Both of the R049 recombinant protein and whole bacterial proteins of UPECl 32 were confirmed to show specffic reactions on the antiserunl throughh Western blot.The animal experiments showed the urine and renal colony counts of immunization group were significantly lower than that of the control group(P<0.01,P<0.05).Conclu-sion The new gene R049 of uropathogenic E.coli 132 had immunopmtective effects on mice and the defini-tive mechanism would be needed to further study.

Purification and Characterization of ?-AE Protein Expressed in E.coli / 中国生物工程杂志

Many bioactive peptides from neural and endocrine tissue are amidated at C-terminals,which is essential for their activities.The ?-amide comes from post-translational modification that is catalyzed by ?-AE (?-amidating enzyme) or PAM (pepdilylglycine ?-amidating monooxygenase).The gene encoding ?-AE was amplified with PCR and cloned into the plasmid pET-30a.After the recombinant plasmid pET-A was transformed into E.coli BL21,the ?-AE was expressed and purified by the Ni2+affinity chromatography,which has the ability catalyzing Dns-Tyr-Val-Gly to Dns-Tyr-Val-NH2.It identified that the recombinant protein producing by E.coli BL21 is ?-AE,which will benefit for studies of amidation at the C-terminals of peptides.

Cloning, Expression and Characterization of The Cold Active Lipase (Lip3) From Metagenomic DNA of an Antarctic Deep Sea Sediment / 生物化学与生物物理进展

The metagenomic DNA was extracted from the deep sea sediment with the depth of 900m of Prydz Bay, Antarctic. A lipase gene (lip3) with the size of 948bp was cloned from the metagenomic DNA by PCR with the primers designed. The deduced Lip3 protein was composed of 315 amino acids (AA) with a molecular mass of 34.577 ku. The motifs GFGNS(GXGXS)and G-N-S-M-G(GXSXG)in the AA sequences of Lip3 were found to be conserved in other lipase. They were most conserved sequence among the serine hydrolase and were necessary for the activity. A 35 ku of Lip3 was purified by Ni-NTA chelating sepharose column from the extract of recombinant E.coli Top 10F′ cell harboring a pLLP-OmpA plasmid inserted with lip3. The purified Lip3 was most active at 25℃ and kept 22% of activity at 0℃. Only 10% of activity was retained after it was incubated at 35℃ for 60 min. The optimal pH value for the Lip3 activity was 8.0. The Km value of the enzyme towards p-nitrophenyl palmitate increased with the increasing of assayed temperature. These results indicated that Lip3 was a typical alkaline cold active enzyme.

A Method of Construction Polycistron Tandem Gene of Small Peptide / 中国生物工程杂志

Objective: To construct a polycistron tandem repeated Echistatin (Ecs) gene. Methods: Three Ecs genes with independent initiation and termination codon were ligated tandem through restriction enzyme sites after amplified with 3 pairs of primers using pMD18T-Ecs as template. The polycistron Ecs gene was inserted into pET30a and expressed in E.coli BL21(DE3) with IPTG induction. The expression results were identified by 18% SDS-PAGE and Western blot. Results: The expression of Ecs polycistron was accomplished with 18% expression level of total protein determined by SDS-PAGE and Western blot. Conclusion: The successful expression of Ecs polycistron provided a new method for the preparation of low molecular weight protein.

Cloning and expression of Escherichia coli O157∶H7 Stx2B subunit / 医学研究生学报

Objective: To clone,identify and express the Shigalike toxin 2B(Stx2B) subunit gene of EHEC O157∶H7.Methods: A pair of primers were designed based on the Stx2B subunit gene sequence of EHEC O157∶H7.The Stx2B gene was amplified from the EHEC O157∶H7 chromosome by PCR and cloned into the pMD18-T vector.Thereafter,the gene was cut from the pMD18-T vector and cloned into the prokaryotic expression plasmid pET-28a vector.Then the recombinant plasmids were transformed into E. coli BL21(DE3) and the transformed host strain induced by IPTG.The expression protein was detected by SDS-PAGE and Western-blot analyses.Results: The Stx2B gene was successfully cloned into pMD18-T and pET-28a vectors,and the expressed protein identified by SDS-PAGE and Western blot.The molecular mass(Mr) of the expressed product was about 7 500,and the expression rate about 40%. Conclusion: The Stx2B gene was successfully cloned and effectively expressed in the prokaryotic expression system.

Expression of kringle 1-3 domain fragment of human plasmihogen in E.coli and the anti-tumor activity of its product / 中国免疫学杂志

Objective:To study the expression of kringle 1-3 domain fragment of human plasmihogen in E.coli and the anti-tumor activity of its product.Methods:The K1-3 domain fragment was cloned in expression vector pBV220,the resulted recombinant plasmid pBV-K13 was transformed into E.coli DH5? and its product was purified and assayed its bioactivity.Results:K1-3 domain fragment was expressed in(E.coli) DH5?.The results showed the expressed product covered 20% of the total bacterial protein on SDS-PAGE and the Western blot analysis showed that the product had immunological specificity with the antiserum of human plasminogen and inhibits the growth of chorioallantoic membrane(CAM) angiogenesis and mouse B16 melanoma.Conclusion:Human plasminogen K1-3 domain fragment was expressed in E.coli;the expressed product has anti-angiogenesis and anti-tumor activity.

Cloning and Expression of the Signaling Protein 14-3-3 of Toxoplasma gondii / 中国寄生虫学与寄生虫病杂志

Objective To clone and express the cell signaling protein 14-3-3 gene from Toxoplasma gondii RH strain. Methods Toxoplasma RH strain tachyzoites, which maintained by mouse passage, were harvested from ascites of mice and genomic DNA was prepared. A pair of primers were designed and synthesized based on the sequence of Toxo 14-3-3 cDNA. A specific fragment of Toxo 14-3-3 gene was obtained by RT-PCR amplification from Toxoplasma genomic DNA. The PCR products were ligated to pGEM-T. The EcoRI / Xho I restricted fragments, confirmed by PCR and EcoRI / XhoI digestion, were cloned into expression vector pET28a and the recombinants were transformd into E.coli BL21. Fusion expression was induced by isopropyl-beta-D-thiogalactoside (IPTG) and confirmed by Western blotting with rabbit anti-Toxoplasma sera. Results The molecular size of Toxo 14-3-3 was 803 bp, which is highly homologous to the previous report cloned from the parasites of intestinal epithelial stage in cat. High expression was obtained in pET28a/ Toxo 14-3-3/E.coli BL21 when confirmed by Western blotting. Conclusion The recombinant construction of Toxo 14-3-3 was generated and expression was induced.

Expression of recombined human endothelial monocyte-activating polypeptideⅡand determination of its activity / 中国肿瘤生物治疗杂志

Objective: To chine and express the recombinant human endothelial monocyte-activating polypeptide-Ⅱ(EMAP-Ⅱ)and identify its anti-tumor biological activities.Methods: EMAP-Ⅱ_(147-312)was expressed by the expression vector pMAL-p2x and E.coli BL-21 and the product was purified.The production of tissue factor(TF)in human umbili- cal vein endothelial cell ECV-304 mediated by the recombinant EMAP-Ⅱwas determined by chemiluminescence sub- strate.The promoting effect of recombinant EMAP-Ⅱon TNF?-induced ECV-304 cell.Apoptosis was determined by flow cytometry.Its inhibitory effect on human pancreaic cancer cell SW1990 proliferation was determined by MTT method. Results:DNA sequencing verified that EMAP-Ⅱwas correctly cloned.The molecular mass of the protein identified by SDS-PAGE was consistent with the theoretic value.The productivity of recombinant EMAP-Ⅱwas 500?g per 1 g bacteria (wet mass).The purified product induced expression of tissue factor(TF)in ECV-304 cells;it also enhanced the sensi- tivity of ECV-304 cells to the apoptotic effect of TNF?([16.6?2.5]% vs[25.6?2.3]%,P

Eukaryotic Expression and Primarily Application of Human Smith D1 Antigen in Methylotrophic Yeast Pichia pastoris / 微生物学通报

To clone, express and primarily use human autoantigen Sm D1 in methylotrophic yeast Pichia Pastoris. The gene Sm D1 was cloned by PCR.The PCR product was inserted into the vector pPIC9k. The recombinant plasmid pPIC9k- Sm D1 was transformed into yeast SMD1168 by electroporation. The positive clones were screened in MD plates. The high copy number transformants were rapidly selected by using G418 and were induced by methanol. Supernatants after induction were analyzed by SDS-PAGE and im-munodot. The PCR product was showed about 360 bp in size which was in accordance with predicted. The pPIC9k-Sm D1 showed the same seqencing result with GenBank’s report and restriction enzyme analysis confirmed our prediction. The pPIC9k-Sm D1 positive clone produced an about 16 kD protein which had natural immunogenicity of human autoantigen Sm D1 by SDS-PAGE and immunodot. The sensitivity and specificity of immunodot were 96% and 100%, respectively. The agreement between immunodot and im-munoblot was 98%. Successfully cloning and high-level expression of human autoantigen Sm D1 in methy-lotrophic yeast Pichia pastoris laid a foundation for further research work.