Construction of Prokaryotic Expression Plasmid of Fusion Protein Including Porin A and Porin B of Neisseria Gonorrhoeae and Its Expression in E. coli

In order to provide a rational research basis for clinical detection and genetic engineering vaccine, plasmid pET-28a ( ) encoding both Porin gene PIA and PIB of Neisseria gonorrhoeae was constructed and a fusion protein in E. coli DE3 expressed. The fragments of PIA and PIB gene of Neisseria gonorrhoeae were amplified and cloned into prokaryotic expression plasmid pET-28a ( ) with double restriction endonuclease cut to construct recombinant pET-PIB-PIA. The recombinant was verified with restriction endonuclease and sequenced and transformed into E. coli DE3 to express the fusion protein PIB-PIA after induced with IPTG. The results showed PIA-PIB fusion DNA fragment was proved correct through sequencing. A 67 kD (1 kD=0. 992 1 ku) fusion protein had been detected by SDS-PAGE. It was concluded that the fusion protein was successively expressed.     

Construction of Prokaryotic Expression Plasmid of mtrC Protein of Neisseria gonorrhoeae and Its Expression in E. Coli

Summary： In order to provide a rational research basis for detection of resistance of Neisseria gonorrhoeae to antimierobial hydrophobie agents and study on the resistant mechanism of multiple transferable resistance （mtr） efflux system, plasmid pET-28a（＋） encoding mtrC gene was constructed and the related target protein was expressed in Escherichia colt （E. cold DE3. The fragments of mtrC gene of Neisseria gonorrhoeae from the standard strains were amplified and cloned into prokaryotic expression plasmid pET-28a（＋） with restriction endonuelease to construct recombinant pET-mtrC which was verified by restriction endonuelease and DNA sequencing. The recom- binant was transformed into E. coli DE3 to express the protein mtrC induced by IPTG. The results showed mtrC DNA fragment was proved correct through restriction endonuelease and DNA sequencing. hs sequence was 99.5 % homologus to that published on GeneBank （U14993）. A 48.5 kD fusion protein which was induced by IPTG was detected by SDS-PAGE. It was concluded that the construction of prokaryotic expression plasmid of mtrC protein of Neisseria gonorrhoeae was correct and the fusion protein was successively expressed in E. coli.     

Prokaryotic expression of Chinese bovine enterokinase catalytic subunit

Background To express in vitro the bovine enterokinase catalytic subunit (EKL) protein, which could be used in the future for the cleavage and purification of fusion proteins.Methods Bovine enterokinase catalytic subunit cDNA was obtained by RT-PCR from the duodenal mucosa of a bovine obtained at a wholesale market, and then cloned into a pUCmT cloning vector and sequenced. The desired gene fragment was inserted into a pET39b expression plasmid and the recombinant vector pET39b-EKL was transformed into E. coli BL21 (DE3). Protein expression was induced using IPTG. The recombinant DsbA-EKL was purified with His·Tag affinity chromatography, and its bioactivity was analyzed.Results Compared with the sequence deposited in GenBank, the sequence of the EKL gene cloned in the present study is correct. It was also confirmed that the nucleotide sequence of expression plasmid pET39b-EKL was correct at the conjunction site between the recombinant DNA 5’terminal multi-cloning site and the recombinant fragment. SDS-PAGE analysis indicated that the target product was about 65 kDa and represented 28% of total cell protein. Purified recombinant protein was obtained by metal chelating chromatography using a Ni-IDA resin. After desalting and changing the buffer, the crude kinase was incubated at 21℃ overnight and shown to have a high autocatalytic cleavage activity.Conclusion The EKL gene from a Chinese bovine has been cloned successfully and expressed. This investigation has layed the foundation for future enterokinase activity research and for further large-scale application of expression products.     

Purification and immunity analysis of recombinant 6His-HPT protein expressed in E. coli

Objective To obtain HPT protein (Hygromycin B Phosphotmnsferase), a kind of plant selective maker gene product expressed from E.coli and to prepare the polyclonal antibody (pAbs) against it. Methods HPT cDNA fragment was obtained by PCR and was inserted into the prokaryotic expressing vector pBV222. Then the constructed recombinant plasmid pBV222-HPT was transfered into E.coli DH5α for HPT expression. The recombinant expressing system was confirmed by restriction endonuclease digestion, DNA sequencing and protein expression. E.coli cells were lysed by sonication and detergent dissolution. After cell membrane was extracted, the inclusion bodies were denatured by 8 mol/L Urea and purified with metal chelate affinity chromatography on Ni-NTA agarose under denaturing condition. The purified 6His-HPT was characterized by SDS-PAGE, and used to immunize rabbit. The titer and specificity of antisera were detected by ELISA and Western blot respecitively. Results Analysis of DNA sequence and restricted enzymes showed that the sequence of PBV222-HPT plasmid was correct. The amount of recombinant HPT expressed in E.coli accounted for 30% of total cellular proteins. From 1 liter of fermentative bacteria about 22 milligrams of pure recombinant HPT was isolated with purity above 95%. The recombinant HPT protein could produce high titer antiserum in rabbits and show good immunity activity. Western blot showed specific binding reaction between the antiserum to the purified 6His-HPT protein and their expressed products (plants protein and bacterial protein). Conclusion HPT protein can be expressed and purified from E.coli by a relatively simple method, which has high immunity activity.     

Construtcion of Neisseria Gonorrhoeae Porin B Plasmid Recombinant and Its Expression in E. coli

A prokaryotic expression recombinant plasmid pET-PIB to express porin B (PIB) of Neisseria gonorrhoeae in E. coli DE3 was constructed in order to provide a basis of research in detection, prophylactic and therapeutic vaccine against the pathogen infection. The gene encoding PIB was amplified by PCR from Neisseria gonorrhoeae and cloned into prokaryotic expression plasmid pET-28a( ) to construct a pET-PIB recombinant, which was verified by restriction endonuclease and DNA sequencing. Protein PIB was expressed in E. coli DE3 induced with IPTG. The antigenicity of the expressed protein was evaluated by indirect ELISA. Rabbits were immunized with the protein and serum was collected after immunization. To assess the immunogenicity of the protein, the titer of serum to protein PIB was determined by ELISA. DNA sequence analysis showed that the nucleic acid sequence of PIB gene was 99.28 % of homology compared with that (NGPIB18) published in GenBank. A 41 kD fused protein was detected by SDS-PAGE and was proven to have reactivity with anti-PIB polyclonal antibody from mouse. A polyclonal antibody to PIB of 1：4000 titer determined by indirect ELISA was obtained from rabbit immunized with the purified product. Recombinant plasmid encoding PIB of Neisseria gonorrhoeae was constructed. Protein PIB with antigenicity and immunogenicity was successfully expressed.     

The Immunity Induced by Recombinant Spike Proteins of SARS Coronavirus in Balb/c Mice

The immune effect of two recombinant protein fragments of spike protein in severe acute respiratory syndrome coronavirus (SARS CoV) was investigated in Balb/c mice. Two partial spike gene fragments S1 (322-1464 bp) and S2 (2170-2814 bp) of SARS coronavirus were amplified by RT-PCR, and cloned into pET-23a prokaryotic expression vector, then transformed into competent Escherichia E.coli BL21 (DE3)(pLysS) respectively. Recombinant proteins were expressed and puri- fied by Ni2 immobilized metal ion affinity chromatography. The purified proteins mixed with com- plete Freund adjuvant were injected into Balb/c mice three times at a two-week interval. High titer antibody was detected in the serum of immunized Balb/c mice, and mice immunized with S1 protein produced high titer IgG1, IgG2a, IgG2b and IgG3, while those immunized with S2 protein produced high titer IgG1, IgG2a, but lower titer IgG2b and IgG3. Serum IFN-γ concentration was increased significantly but the concentrations of IL-2, IL-4 and IL-10 had no significant change. And a marked increase was observed in the number of spleen CD8 T cells. The results showed that recombinant proteins of SARS coronavirus spike protein induced hormonal and cellular immune response in Balb/c mice.     

凋亡素原核表达载体的构建、表达与抗体制备

目的 构建凋亡素基因的原核表达载体,进行表达并制备表达蛋白的多克隆抗体.方法 构建凋亡素 pGEM-T/Apoptin载体,并将凋亡素基因亚克隆至原核表达载体pET-28a(+)中,将该质粒转化至大肠杆菌E.coli BL21(DE3)受体菌中,以IPTG对其进行诱导表达,聚丙烯酰胺凝胶电泳分析目的蛋白.用表达蛋白常规免疫Balb/c小鼠,间接ELISA检测小鼠血清中抗体的滴度.结果 凋亡素基因被成功的克隆至pET-28a(+),表达产物经SDS-PAGE分析,在相对分子量约17 000的位置出现目的蛋白条带,大小与预期结果一致,Balb/c小鼠经5次免疫后,得到了滴度为1:5×10~5血清抗体.结论 凋亡素原核表达载体的成功构建和多克隆抗体的制备为进一步研究凋亡素的功能和凋亡素的应用研究奠定了基础.

Abstract：

Objective To construct a prokaryotic expression vector for apoptin and prepare polyclonal antibody of apoptin.Methods Apoptin gene amplified from pGEM-T/Apoptin plasmid by PCR was cloned into pET-28a(+).E.coli BL21(DE3) was transformed by the recombinant plasmid,and apoptin protein expression induced by IPTG was analyzed by SDS-PAGE.BALB/c mice were immunized with the protein and the titer of the antibody was determined using indirect enzyme-linked immunosorbent assay(ELISA).Results Apoptin gene was successfully cloned into pET-28a(+),and the expression of a protein with relative molecular mass of about 17 000 was identified by SDA-PAGE.After 5 immunizations of the mice with the protein,the blood antibody titer reached 1:5×10~5.Conclusion The prokaryotic expression vector for apDptin is successfully conslructed and the polyclonal antibody of apoptin is Obtailled.which allows further functional study of apoptin.     

Expression and identification of type 1 diabetes associated autoantigen IA-2

Objectives To obtain prokaryotic expressed IA-2 recombinant protein and to identify its immunological activity.Methods The complimentary DNA (cDNA) coding for the intracytoplasmic part of IA-2 (IA-2ic) was amplified from human fetal brain RNA, and was subcloned into the PinPoint Xa-1 T vector to construct recombinant expression plasmid, and was then expressed in E. coli JM109 cells as a fusion protein with a biotinylated peptide sequence at the aminoterminus. The biotinylated fusion protein was then purified by affinity chromatography and was subsequently dialyzed. Finally, its immunogenicity was evaluated by enzyme linked immunosorbent assay (ELISA).Results The purified IA-2ic fusion protein resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as a single Coomassie brilliant blue stained band with a molecular weight of 59 kDa and its immunogenicity was confirmed by ELISA.Conclusions E. coli expressed IA-2ic fusion protein has immunological activity. It can be used for detection of IA-2 autoantibodies (IA-2A) and for further studies on type 1 diabetes in future,     

Construction of recombinant adeno-associated virus vector co-expressing hVEGF_(165) and hBMP_7 gene

Objective: To construct recombinant adeno-associated virus co-expressing human vascular epithelial growth factor 165(hVEGF165) and bone morphogenetic protein 7(hBMP7),measure the virus titer and verify the recombination. Methods:The AAV helper-free system was used as basis to generate recombinant AAV. The IRES sequence of plasmid pIRES was cut down and subcloned into ITR/MCS containing vector pAAV-MCS to construct recombinant plasmid pAAV-MCSa-IRES-MCSb. The hVEGF165 and hBMP7 gene was amplified by PCR and inserted into upstream MCSa and downstream MCSb respectively. Then,recombinant plasmid pAAV-hVEGF165-IRES-hBMP7,pAAV-RC and pHelper were co-transfected into AAV-293 cells to complete rAAV-hVEGF165-IRES-hBMP7 packaging. The GFP labeled rAAV-IRES-GFP was simultaneously packaged by using the parallel plasmid pAAV-IRES-hrGFP. The efficiency of AAV packaging was monitored under fluorescent microscope and recombinant viral particles were harvested from infected AAV-293 cells. The virus titer was measured by infecting AAV-HT1080 cells,and the recombinant AAV-hVEGF165-IRES-hBMP7 was verified by PCR of the exogenous interest genes. Results:Recombinant pAAV-hVEGF165-IRES-hBMP7 was verified by double digestion. GFP expression in AAV-293 could be observed under fluorescent microscope 72 h after transfection and the system provided a high packing ratio of 95%. The recombinant adeno-associated virus has a high titer of 5.5×1011vp/ml,and AAV-HT 1080 was infected at a ratio of 90%. The recombinant virus was confirmed by PCR of exogenous hBMP7 and hVEGF165 gene. Conclusion:Recombinant rAAV-hVEGF165-IRES-hBMP7 was successfully constructed with a high virus titer,which may offer foundation for in vitro and in vivo experiments of hVEGF165 and hBMP7 co-expression and provide a new method for gene therapy of bone regeneration.     

Expression and purification of recombinant human hemangiopoietin in Escherichia coli

Objective： To express the soluble recombinant hemangiopoietin protein in E. coli BL21 （DE3）. Methods： Using human fetal live cDNA as a template, a partial cDNA fragment of HAPO coding N-terminal region was subcloned into plasmids pTrc99, pQE60 and pET32c to construct different recombinant prokaryotic expression systems. After selecting, the soluble rhHAPO fusion protein was expressed stably in E. coli BL21 （DE3） by vector pET32c-HAPO and further isolated by nickelnitrilotriacetic acid （NTA） affinity chromatography. After cleavage with enterokinase, the rhHAPO protein was applied to Fast Flow SP sepharose column. Results： The rhHAPO protein had a purity of more than 95% and a good bioactivity based on the cell adhesion assay in ECV304 cells. Conclusion： We have established a protein engineering system to produce rhHAPO which may provide the possibility for clinical application     

人Tenascin-Raa454-1069蛋白的原核表达及多克隆抗体制备

目的 表达和纯化带多聚组氨酸（6×His）标签的人Tenascin-R EGFL结构域（Tenascin-Raa454-1069）的融合蛋白,并制备相应的兔源性多克隆抗体（pAb）。方法 利用PCR从PMD18-T-TNR获得Tenascin-Raa454-1069编码序列,将其亚克隆至原核表达载体pET30a(+),构建重组表达质粒pET30a(+)-Tenascin-Raa454-1069;将阳性重组质粒转化大肠杆菌,IPTG诱导表达6×His-Tenascin-Raa454-1069融合蛋白,经Ni-NTA螯合树脂纯化,纯化蛋白免疫新西兰大白兔制备多克隆抗血清, Protein A Sepharose柱纯化获得多抗,ELISA法检测抗体效价,Western blot法检测抗体特异性。结果 成功构建了pET30a(+)-Tenascin-Raa454-1069原核表达载体,原核蛋白Tenascin-Raa454-1069以包涵体形式在大肠杆菌高水平表达,通过复性与亲和层析获得纯度在90%以上的融合蛋白,蛋白浓度为1 600mg/L,制备的抗Tenascin-Raa454-1069多抗效价高达1∶1.6 ×106,Western blot鉴定其具有良好的特异性。结论 获得高纯度Tenascin-Raa454-1069蛋白并成功制备特异性pAb,为进一步研究Tenascin-R的生物学功能提供实验基础。     

BLCAP蛋白多克隆抗体制备及其免疫学特性鉴定

目的:利用大肠杆菌BL21(DE3)表达BLCAP融合蛋白并制备和鉴定其多克隆抗体。方法:构建原核表达重组质粒pET32a(+)-BLCAP并转化到宿主菌BL21中,诱导表达带有His标签的目的融合蛋白,经Ni2+亲和层析纯化回收后免疫日本大耳白兔制备多克隆抗体,用ELISA测定抗体的效价,Western blot检测抗体的特异性和亲和性。结果:成功获得分子质量约为28 kU纯化的融合蛋白,免疫日本大耳白兔后得到抗BLCAP的多克隆抗体。ELISA测定显示抗体效价可达到1∶10 000。通过Western blot检测证明该抗体有较好的针对BLCAP蛋白的专一性。结论:重组质粒表达的BLCAP融合蛋白具有良好的抗原性。制备的特异性和效价良好的抗BLCAP的多克隆抗体,能够满足针对BLCAP免疫印迹和细胞免疫组化检测等实验要求,为今后深入研究BLCAP蛋白性质与功能提供了有用的实验工具。     

人巨细胞病毒US31蛋白特异性抗体的制备及鉴定

目的：探讨人巨细胞病毒（HCMV）US31蛋白及其多克隆抗体的制备及鉴定方法。方法：HCMV US31基因经原核密码子优化后进行全基因合成,克隆至pET21a（+）原核表达载体,构建pET21a（+）/HCMV US31重组质粒,测序鉴定;将重组质粒转化大肠杆菌BL21（DE3）,IPTG诱导目的蛋白表达,Ni-NTA亲和层析法纯化US31蛋白,免疫新西兰兔制备多克隆抗体,ELISA、Western blot及免疫荧光方法检测抗体效价和特异性。结果：在大肠杆菌中诱导出高表达的HCMV US31融合蛋白,经Ni-NTA亲和纯化后获得高纯度的目的蛋白;免疫新西兰兔诱导产生特异性的IgG抗体,效价为1:49 600;经ELISA、Western blot以及免疫荧光均证实制备的特异性抗体可识别细胞中表达的US31蛋白。结论：成功制备了HCMV US31蛋白及特异性抗体,为进一步研究US31蛋白的生物学功能奠定了基础。     

人肠三叶肽在大肠杆菌中的表达

目的 构建三叶肽(TFF)原核重组质粒pET32a-TFF3,实现TFF3融合蛋白在大肠杆菌中的高效表达并鉴定表达产物.方法 用Trlzol试剂提取人结肠组织mRNA,逆转录后经PCR扩增得到不含信号肽的TFF3编码序列,插入原核表达载体pET32a,构建pET32a-TFF3重组质粒,转化大肠杆菌BL-21(DE3),异丙基-β-D-硫代半乳糖苷(IPTG)诱导重组蛋白表达,用SDS-PAGE和Western blot检测表达蛋白.结果 酶切和测序证实pET32a-TFF3重组质粒构建成功.SDS-PAGE分析表明在IPTG浓度为1 mmol/L时,诱导6 h后蛋白表达量最大.Western blot分析表明,TFF3融合蛋白相对分子质量约为24×10~3,其能与兔源TFF3抗体特异性结合.结论 成功构建了pET32a-TFF3重组质粒,实现了该基因在大肠杆菌中的高效表达,为后续深入研究TFF3奠定了基础.     

颗粒溶素的表达纯化及生物学活性分析

目的:采用原核表达系统对颗粒溶素(granulysin,GNLY)进行体外表达,纯化及活性鉴定.方法:以体外培养的人外周血单个核细胞(PBMC)为模板,RT-PCR扩增编码GNLY的cDNA片段,插入pMD-18-T 载体,测序正确后再亚克隆到质粒pET28a( ) 中,构建重组表达质粒pET28a( )-GNLY,转化大肠杆菌BL21(DE3) plysS,IPTG诱导表达融合蛋白,包涵体经变复性后用Ni亲和层析纯化,CFU法测定蛋白活性.结果:成功地将GNLY cDNA片段插入载体pET28a( )中,构建了表达质粒pET28a( )-GNLY.经诱导在原核表达系统中以包涵体形式高效表达了相对分子质量为9 000的融合蛋白,变复性纯化后的GNLY蛋白经CFU法检测,发现其具有细胞毒活性且细胞毒作用具有剂量依赖性.结论:本实验利用原核表达系统成功地表达了具有生物学活性的GNLY,为研究其功能、作用机制及临床应用奠定了基础.     

肺炎链球菌自溶素基因的克隆、表达及蛋白纯化

 目的 克隆肺炎链球菌自溶素（LytA）基因并在大肠埃希菌中表达及蛋白纯化。方法 用PCR方法从肺炎链球菌基因组中克隆肺炎链球菌自溶素基因,然后将其插入原核表达载体pET32a（+）,构建pET32a(+) - LytA重组质粒,经IPTG诱导使该基因在大肠埃希菌BL21 (DE3)中表达,亲和层析法纯化目的蛋白,将获得的蛋白用Western blot鉴定门结果扩增出的DNA序列与GenBank中的LytA基因序列一致,成功构建了pET32a(+) - LytA重组质粒并在大肠埃希菌中高效表达,所表达的蛋白经Western blot证实为肺炎链球菌自溶素融合蛋白。结论 成功克隆了肺炎链球菌自溶素基因,并将其在大肠埃希菌中表达、纯化,为新型肺炎链球菌疫苗的研制奠定了基础。     

新基因ZNFD的克隆及其多克隆抗体的制备

目的:PCR扩增得到新基因ZNFD(Znf domain containing protein),构建pET32a-ZNFD原核表达载体,诱导蛋白表达及制备多克隆抗体。方法:通过PCR的方法克隆新基因ZNFD,选取部分抗原免疫原性较高的部分ORF序列,克隆到原核表达载体pET32a上,利用大肠杆菌Rosetta-gami(DE3)表达系统表达ZNFD融合蛋白。纯化目的蛋白免疫家兔,制备多克隆抗体。通过琼脂糖双向扩散实验和Western blot鉴定其效价和特异性。结果:经测序鉴定已成功克隆ZNFD基因。通过构建原核表达载体pET32a-ZNFD,在大肠杆菌Rosetta-gami(DE3)中使用IPTG诱导表达,得到相对分子质量约为45 kD的融合蛋白。纯化蛋白免疫家兔,制备的多克隆抗体具有较强的免疫特异性。结论:得到纯化的ZNFD蛋白,制备的多克隆抗体达到了一定的效价,且具有高特异性,为进一步研究ZNFD的功能奠定了实验基础。     

转录因子Blimp-1的原核表达、纯化及抗体制备

目的获得B limp-1纯化蛋白,制备多克隆抗体,为研究浆细胞发育的调控奠定基础。方法采用PCR方法从B limp-1质粒中克隆B limp-1编码前350个氨基酸的基因片段,构建B limp-1与6个H is的融合蛋白原核表达质粒,进行原核表达与蛋白纯化后,免疫动物,制备B limp-1多抗。采用ELISA方法检测其效价,W estern检验抗体特异性及在骨髓瘤细胞株中的表达。结果构建了表达B limp-1前350个氨基酸的原核表达质粒PQE-B limp-1,经过大肠杆菌表达、镍亲和层析柱纯化,得到分子量约46×103的融合蛋白,免疫家兔后得到多抗血清。ELISA显示抗体效价达1/20 000。W esternb lot结果显示此多克隆抗体与B limp-1蛋白特异性结合,并在骨髓瘤细胞中表达。结论本研究获得B limp-1纯化蛋白,制备了B limp-1多克隆抗体,为进一步研究B limp-1的作用机制及与血液疾病间的关系奠定了基础。     

小鼠白介素17受体A胞外段的表达、纯化及鉴定

目的:分别克隆小鼠白介素17受体A胞外段(mIL-17RAaa32-322)及小鼠IgG2AFc(mIgG2AFc)基因,构建mIL-17RAaa32-322-mIgG2AFc融合蛋白原核表达载体,并在体外表达、纯化及鉴定。方法:利用基因重组技术构建pET32a(+)-mIL-17RAaa32-322-mIgG2AFc原核表达载体,并在E.coli Rosetta中表达mIL-17RAaa32-322-mIgG2AFc融合蛋白,经镍离子螯合层析分离纯化后,用SDS-PAGE电泳和蛋白质印迹法进行鉴定。结果:成功构建pET32a(+)-mIL-17RAaa32-322-mIgG2AFc原核表达载体,获得高效表达的融合蛋白,且蛋白质印迹证实为目的蛋白。结论:获得mIL-17RAaa32-322-mIgG2AFc融合蛋白,为进一步研究其生物学功能奠定基础。     

人转录因子sp1在大肠杆菌中的表达与体外纯化

目的：在大肠杆菌中表达人源转录因子spl蛋白,并进行体外纯化。方法：首先将人源sp1真核表达质粒pCMV-sp1中的sp1 cDNA用限制性内切酶切开,连入原核表达质粒pET28b,构建原核表达重组质粒pET28b-sp1-699c;然后将重组质粒转化入大肠杆菌BL21（DE3）菌株,经IPTG诱导表达带His-Tag的融合蛋白His-sp1（88-786aa）,通过包涵体的变复性和Ni-IDA亲和层析纯化后,SDS-PAGE鉴定纯化后的蛋白。结果：融合蛋白His-sp1在大肠杆菌内得到高效表达,纯化后可得到较高纯度的蛋白。结论：本研究获得了较高纯度的融合蛋白His-sp1,为进一步研究sp1蛋白对靶基因的转录调控奠定了基础。