• 미생물학회지
• /
• 제27권3호
• /
• pp.169-175
• /
• 1989

포유동물 세포내에서 간염 바이러스의 내면항원의 발현과 전위내면 항원(precore) 부위의 역할을 규명하기 위하여 고등동물세포 발현용 벡터에 전위내면항원 부위를 갖거나 또는 갖지 않는 내면항원 유전자를 클로닝 하여 COS 세포내에서의 발현을 조사하였다. 전위내면항원 부위를 포함한 내면항원 유전자를 갖는 플라스미드로감염시킨 COS 세포는 항원들이 세포추출물과 배양액에서 검출되었다. 분비된 항원의 증가율은 감염후 2일과 3일 사이가 가장 높았고, 부분결실된 제조합 플라스미드 중 내면항원의 ATG codon에서 180bp 떨어진 것이 가장 발현이 잘 되었다. 전위내면항원을 갖지 않거나 하나의 염기가 첨가되어 변형된 전위내면항원을 갖는 제조합 플라스미드의 경우 항원들이 세포 추출물에서만 검출되었다. 이러한 사실은 전이내면항원 부위가 HBe 항원의 분비에 관여 한다는 경우 항원들이 세포 그러나 대장균이나 효모 세포의 경우는 전위내면항원의 존재와 상관없이 항상 세포추출물에서만 존재하는 것으로 보아 이들 세포의 경우에서는 전위내면항원 부위가 HBe 항원의 분비에 영향을 줄 수 없음을 의미한다.

• BMB Reports
• /
• 제33권2호
• /
• pp.166-171
• /
• 2000

Thioredoxin is a multifunctional protein that is ubiquitous in microorganisms, animals and plants. Previously, the expression of the Escherichia coli thioredoxin gene (trxA) was found to be negatively regulated by cAMP. In the present study, the effect of temperature on the expression of the E. coli trxA gene was investigated. In order to examine the temperature effect, the fusion plasmid pCL70 that harbors the E. coli trxA P1P2 promoter was used. The other two fusion plasmids, pJH3 and pMH521 that were constructed in different vectors which harbor the E. coli trxA P2 promoter, were also used. When the E. coli strain MC1061/pCL70 was grown in a rich medium at $25^{\circ}C$, $34^{\circ}C$ and $42^{\circ}C$, the cells grown at $42^{\circ}C$ gave the highest $\beta$-galactosidase activity. The E. coli MC1061/pJH3 and MC1061/pMG521 cells showed increased $\beta$-galactosidase activity after the shift of the culture temperature to $42^{\circ}C$. The wild-type trxA gene of the E. coli MC1061 cells produced much higher thioredoxin activity at the higher temperature. These results support the conclusion that the E. coli trxA gene is regulated in a temperature-dependent manner. Especially the expression from its P2 promoter appeared to be sensitive to temperature.

• Reproductive and Developmental Biology
• /
• 제28권3호
• /
• pp.191-196
• /
• 2004

본 실험에서는 외래 유전자의 효율적인 발현을 위하여 GFP 표지유전자를 이용하여 여러 종류의 promoter를 검정하였다. 또한, retrovirus vector에 WPRE 서열을 도입함으로써 GFP 유전자의 발현 증가 여부를 확인하였다. 모든 표적 세포에 있어서 UbC와 β-actin promoter에 비해 RSV와 CMV promoter 통제하의 GFP의 발현이 더 강하게 나타났으며, 특히 CEF 세포에서는 RSV promoter가 가장 우수한 것으로 확인되었다. WPRE의 도입으로 인한 발현율의 증가는 CEF를 제외한 세포주에서 promoter의 종류에 관계없이 확인되었다. 이상의 결과로 각 세포주는 promoter에 따라 발현 양상이 약간의 차이를 보이고 있으나 RSV와 CMV promoter에서 유전자의 발현이 보다 효율적이며, WPRE 서열이 도입된 경우에 HeLa와 PFF 세포에서 발현이 현저히 증가하는 것을 확인할 수 있었다. 이러한 연구 결과는 효율적인 유전자의 발현 체계를 확립하는데 기여함으로써 더 나아가 유전자 치료나 형질전환 동물생산에 적극적으로 활용되어질 수 있을 것이다.

• Asian Pacific Journal of Cancer Prevention
• /
• 제13권6호
• /
• pp.2799-2806
• /
• 2012

The aim of this study was to elucidate the role of the integrin-linked kinase (ILK) gene in development of human bladder transitional cell carcinoma (BTCC). Expression of ILK protein and ILK mRNA in 56 cases of human BTCC tissue and in 30 cases of adjacent normal bladder tissue was detected by immunohistochemistry S-P and reverse transcription polymerase chain reaction (RT-PCR), respectively. Four specific miRNA RNAi vectors targeting human ILK were synthesized and transfected into BIU-87 cells by liposome to obtain stable expression cell strains. The influence of ILK on proliferation of BTCC was detected by MTT, FCM on athymic mouse tumorigenesis. The positive rate of ILK protein in BTCC tissue (53.6%) was much higher than adjacent normal bladder tissue (10.0%) (p<0.05). Similarly, expression of ILK mRNA in BTCC tissue ($0.540{\pm}0.083$) was significantly higher than in adjacent normal bladder tissue ($0.492{\pm}0.070$) (p<0.05). MTT showed that the proliferation ability of miRNA-ILK transfected group was clearly decreased (p<0.05), the cell cycle being arrested in G0/G1-S, an tumorigenesis in vivo was also significantly reduced (p<0.05). ILK gene transcription and protein expression may be involved in the development of BTCC, so that ILK might be the new marker for early diagnosis and the new target for gene treatment.

• Journal of Microbiology and Biotechnology
• /
• 제16권6호
• /
• pp.952-960
• /
• 2006

As a unicellular green alga that possesses many of the metabolic pathways present in higher plants, Chlorelia offers many advantages for expression of heterologous proteins. Since strong and constitutive promoters are necessary for efficient expression in heterologous expression systems, the development of such promoters for use in the Chlorella system was the aim of this study. Proteins encoded by the early genes of algal viruses are expressed before viral replication, probably by the host transcriptional machinery, and the promoters of these genes might be useful for heterologous expression in Chlorella. In this study, putative promoter regions of DNA polymerase, ATP-dependent DNA ligase, and chitinase genes were amplified from eight Korean Chlorella virus isolates by using primer sets designed based on the sequence of the genome of PBCV-1, the prototype of the Phycodnaviridae. These putative promoter regions were found to contain several cis-acting elements for transcription factors, including the TATA, CAAT, NTBBF1, GATA, and CCAAT boxes. The amplified promoter regions were placed into Chlorella transformation vectors containing a green fluorescence protein (GFP) reporter gene and the Sh ble gene for phleomycin resistance. C. vulgaris protoplasts were transformed and then selected with phleomycin. The GFP fluorescence intensities of cells transformed with chitinase, DNA polymerase, and DNA ligase gene promoter-GFP fusion constructs were 101.5, 100.8, and 95.8%, respectively, of that of CaMV 35S-GFP-transformed Chlorella cells. These results demonstrate that these viral promoters are active in transformed Chlorella.

• Journal of Microbiology and Biotechnology
• /
• 제25권7호
• /
• pp.953-962
• /
• 2015

Escherichia coli is the most preferred microorganism to express heterologous proteins for therapeutic use, as around 30% of the approved therapeutic proteins are currently being produced using it as a host. Owing to its rapid growth, high yield of the product, costeffectiveness, and easy scale-up process, E. coli is an expression host of choice in the biotechnology industry for large-scale production of proteins, particularly non-glycosylated proteins, for therapeutic use. The availability of various E. coli expression vectors and strains, relatively easy protein folding mechanisms, and bioprocess technologies, makes it very attractive for industrial applications. However, the codon usage in E. coli and the absence of post-translational modifications, such as glycosylation, phosphorylation, and proteolytic processing, limit its use for the production of slightly complex recombinant biopharmaceuticals. Several new technological advancements in the E. coli expression system to meet the biotechnology industry requirements have been made, such as novel engineered strains, genetically modifying E. coli to possess capability to glycosylate heterologous proteins and express complex proteins, including full-length glycosylated antibodies. This review summarizes the recent advancements that may further expand the use of the E. coli expression system to produce more complex and also glycosylated proteins for therapeutic use in the future.

• Journal of Periodontal and Implant Science
• /
• 제39권sup2호
• /
• pp.231-237
• /
• 2009

Purpose: Cytolethal distending toxin (CDT) is a family of heat-labile cytotoxins produced by several gram-negative mucosa-associated pathogens, including Aggregatibacter actinomycetemcomitans. CDT is well known to be capable of inducing growth arrest, morphological alterations, and eventually death in various cells. CDT belongs to a tripartite $AB_2$ toxin (CdtB: the enzymatic A subunit; CdtA and CdtC: the heterodimeric B subunit). Previous studies proposed that CdtA and CdtC together bind to a cell surface receptor and glycolipids act as a receptor for A. actinomycetemcomitans CDT (AaCDT). In this study, recombinant CdtA and CdtC proteins of AaCDT were co-expressed in a bacterial expression system and tested for their affinity for $GM_1$ ganglioside. Methods: The genes for CdtA and CdtC from A. actinomycetemcomitans Y4 were utilized to construct the expression vectors, pRSET-cdtA and pET28a-cdtC. Both CdtA and CdtC proteins were expressed in Escherichia coli BL21(DE3) and then purified using hexahistidine (His6) tag. The identity of purified protein was confirmed by anti-His6 antibody and monoclonal anti-CdtA antibody. Furthermore, the affinity of recombinant protein to $GM_1$ ganglioside was checked through ELISA. Results: Recombinant CdtA and CdtC proteins were expressed as soluble proteins and reacted to anti-His6 and monoclonal anti-CdtA antibodies. ELISA revealed that purified soluble CdtA-CdtC protein bound to $GM_1$ ganglioside, while CdtA alone did not. Conclusions: Co-expression of CdtA and CdtC proteins enhanced the solubility of the proteins in E. coli, leading to convenient preparation of active CdtA-CdtC, a critical material for the study of AaCDT pathogenesis.

• BMB Reports
• /
• 제33권3호
• /
• pp.195-201
• /
• 2000

A human gene has been reported that may encode the enzyme acetohydroxyacid synthase. Previously this enzyme was thought to be absent from animals although it is present in plants and many microorganisms. In plants, this enzyme is the target of a number of commercial herbicides and the use of these compounds may need to be reassessed if the human enzyme exists and proves to be susceptible to inhibition. Here we report the construction of several plasmid vectors containing the cDNA sequence for this protein, and their expression in Escherichia coli. High levels of expression were observed, but most of the protein proved to be insoluble. The small amounts of soluble protein contained little or no acetohydroxyacid synthase activity. Attempts to refold the insoluble protein were successful insofar as the protein became soluble. However, the refolded protein did not gain any acetohydroxyacid synthase activity. In vivo complementation tests of an E. coli mutant produced no evidence that the protein is active. Incorrect folding, or the lack of another subunit, may explain the data but we favor the interpretation that this gene does not encode an acetohydroxyacid synthase.

• Toxicological Research
• /
• 제18권3호
• /
• pp.249-257
• /
• 2002

Cytochrome P450 3As such as 3A4 and 3A5 metabolize a wide range of pharmaceutical compounds. The vectors for the expression of fusion protein containing an N-terminal human P450 3A4 or P450 3A5 sequences and a C-terminal rat NADPH-cytochrome P450 reductase moiety were constructed. These plasmids were used to express the fusion protein in Escherichia coli DH5$\alpha$ cells. High levels of expression were achieved (100~200 nmol/liter) and the expressed fusion protein in E. coli membranes were catalytically active for nifedipine oxidation, a typical enzymatic activity of P450 3A4. The NADPH-P450 reductase activities of these fusion protein were also determined by measuring reduction of cytochrome c. To fine a specific Inhibitor of P450 3A4 from naturally occurring chemicals, a series of isothiocyanate compounds were evaluated for the inhibitory activity of P450 using the fusion proteins in E. coli membranes. Of the five isothiocyanates (phenethyl isothiocyanate, phenyl isothiocyanate, benzol isothiocyanate, benzoyl isothiocyanate and cyclohexyl isothiocyanate) tested, benzoyl isothiocyanate showed a strong inhibition of P450 3A4 with an $IC_{50}$value of 2.8 $\mu\textrm{M}$. Our results indicate that the self-sufficient fusion protein will be very useful tool to study the drug metabolism and benzyl isothiocyanate may be valuable for characterizing the enzymatic properties of P450 3A4.

• 대한바이러스학회지
• /
• 제27권2호
• /
• pp.115-128
• /
• 1997

Three cDNA fragments located within NS5 region of HCV were synthesized by RT using viral RNA extracted from blood sample of Korean patient as a template. The cDNAs were amplified by PCR, cloned into the T-vector, and the nucleotide sequences were determined. Comparative analysis of the nucleotide and amino acid sequence of NS5 cDNAs showed that it is closely related with HCV type 1b. The cloned NS5 cDNA showed 91-94% homology at the nucleotide sequence level and 96-98% homology at the amino acid sequence level with several strains of the HCV type 1b. The NS5 cDNAs were subcloned into E. coli expression vectors to construct pRSETA5-1, pTHAN5-1, pRSETC5-2, pRSETBB1, pRESTCB1 and pRSETB-H3. Expression of the NS5 proteins was achieved by inducing the promoter with isopropyl-thio-${\beta}$-D-galactoside (IPTG) and confirmed by SDS-polyacrylamide gel electrophoresis. The NS5 proteins were immunoreactive against sera from Korean hepatitis C patients in Western blot analysis. Among the recombinant NS5 proteins, pRSETAS-1 plasmid derived protein, coded from aa2022 to aa2521 of HCV polyprotein, showed the strongest immunoreactivity against sera from Korean hepatitis C patients in immunoblot analysis. These results suggest that NS5 proteins would be useful as an antigen for detection of antibody against HCV in the blood samples.