• KSBB Journal
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• 제30권6호
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• pp.345-349
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• 2015

Antifreeze proteins (AFP) inhibit growth and recrystallization of ice, and permit organisms to survive in cold environments. The AFP from an Antarctic bacterium, Flavobacterium frigoris PS1, FfIBP (Flavobacterium frigoris icebinding protein), was produced in E. coli using a cold shock induction system. The culture temperature was shifted from $37^{\circ}C$ to $15^{\circ}C$ and a 20 L culture scale was used. The final weights of dried cell and FfIBP were estimated to be 126 g and 8.4 g, respectively. The thermal hysteresis (TH) activity ($1.53^{\circ}C$) of the produced FfIBP was 3.6-fold higher than that of the LeIBP (Leucosporidium ice-binding protein) produced in Picha. The current study demonstrates that large-scale production of FfIBP was successful and the result could be extended to further application studies using recombinant AFPs.

• Parasites, Hosts and Diseases
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• 제47권4호
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• pp.359-367
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• 2009

Paramyosin is a myofibrillar protein present in helminth parasites and plays multifunctional roles in host-parasite interactions. In this study, we identified the gene encoding paramyosin of Clonorchis sinensis (CsPmy) and characterized biochemical and immunological properties of its recombinant protein. CsPmy showed a high level of sequence identity with paramyosin from other helminth parasites. Recombinant CsPmy (rCsPmy) expressed in bacteria had an approximate molecular weight of 100 kDa and bound both human collagen and complement 9. The protein was constitutively expressed in various developmental stages of the parasite. Imunofluorescence analysis revealed that CsPmy was mainly localized in the tegument, subtegumental muscles, and the muscle layer surrounding the intestine of the parasite. The rCsPmy showed high levels of positive reactions (74.6%, 56/75) against sera from patients with clonorchiasis. Immunization of experimental rats with rCsPmy evoked high levels of IgG production. These results collectively suggest that CsPmy is a multifunctional protein that not only contributes to the muscle layer structure but also to non-muscular functions in host-parasite interactions. Successful induction of host IgG production also suggests that CsPmy can be applied as a diagnostic antigen and/or vaccine candidate for clonorchiasis.

• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1197-1205
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• 2013

Urokinase (uPA) and its receptor (uPAR) play an important role in tumor growth and metastasis. Targeting the excessive activation of this system as well as the proliferation of the tumor vascular endothelial cell would be expected to prevent tumor neovasculature and halt the tumor development. In this regard, the amino-terminal fragment (ATF) of urokinase has been confirmed as effective to inhibit the proliferation, migration, and invasiveness of cancer cells via interrupting the interaction of uPA and uPAR. Previous studies indicated that ATF expressed in Escherichia coli was mainly contained in inclusion bodies and also lacked posttranslational modifications. In this study, the biologically active and soluble ATF was cloned and expressed in Pichia pastoris. The recombinant protein was purified to be homogenous and confirmed to be biologically active. The yield of the active ATF was about 30 mg/l of the P. pastoris culture medium. The recombinant ATF (rATF) could efficiently inhibit angiogenesis, endothelial cell migration, and tumor cell invasion in vitro. Furthermore, it could inhibit in vivo xenograft tumor growth and prolong the survival of tumor-bearing mice significantly by competing with uPA for binding to cell surfaces. Therefore, P. pastoris is a highly efficient and cost-effective expression system for large-scale production of biologically active rATFs for potential therapeutic application.

• 대한의생명과학회지
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• 제18권2호
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• pp.160-164
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• 2012

The baculovirus/insect cell expression system is of great value for the large-scale production of normal and mutant mammalian passive glucose-transport proteins heterologously for structural and functional studies. In most mammalian cells that express HepG2, this transporter isoform is predominantly located at the cell surface. However, it had been reported that heterologous expression of other membrane proteins using the baculovirus system induced highly vacuolated cytoplasmic membranes. Therefore, how a cell responds to the synthesis of large amounts of a glycoprotein could be an interesting area for investigation. In order to examine the subcellular location of the human HepG2 transport proteins when expressed in insect cells, immunofluorescence studies were carried out. Insect cells were infected with the recombinant baculovirus AcNPVHIS-GT or with wild-type virus at a MOI of 5, or were not exposed to viral infection. A high level of fluorescence displayed in cells infected with the recombinant virus indicated that transporters are expressed abundantly and present on the surface of infected Sf21 cells. The evidence for the specificity of the immunostaining was strengthened by the negative results shown in the negative controls. Distribution of the transporter protein expressed in insect cells was further revealed by making a series of optical sections through an AcNPVHIS-GT-infected cell using a confocal microscope, which permits optical sectioning of cell sample. These sections displayed intense cytoplasmic immunofluorecence surrounding the region occupied by the enlarged nucleus, indicating that the expressed protein was present not only at the cell surface but also throughout the cytoplasmic membranous structures.

• BMB Reports
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• 제31권5호
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• pp.453-458
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• 1998

Human thrombopoietin (hTPO) was expressed to high levels in insect cells using the baculovirus expression system. Full-length hTPO cDNA containing a native signal peptide sequence was amplified by PCR from a human fetal liver cDNA library and cloned into the Autographa californica nuclear polyhedrosis virus (AcNPV) expression vector. Immunoblot analysis with antiserum against hTPO indicated that an approximately 55 kDa protein was produced in recombinant AcNPV infected insect cells. Recombinant hTPO was produced 4-fold higher in Trichoplusia ni (Tn5) cells than in Spodoptera frugiperda (Sf9) cells. with most of the hTPO produced in Tn5 cells secreted into the culture medium. Addition of tunicamycin in the culture medium resulted in the reduction of the size of hTPO to 35-38 kDa, and most of the protein remained within the cell. These results suggest that N-glycosylation of hTPO is required for the secretion of the protein into the culture medium in insect cells. hTPO produced in insect cells induced proliferation and maturation of megakaryocyte progenitors, indicating that it is in a biologically active form.

• 원예과학기술지
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• 제32권4호
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• pp.544-549
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• 2014

Lily symptomless virus (LSV), Lily mottle virus (LMoV), and Cucumber mosaic virus (CMV) are the most prevalent viruses infecting lilies in Korea. Leaf and bulb samples showing characteristic symptoms of virus infection were collected in 2012, and 80 field samples were analyzed by reverse transcription polymerase chain reaction (RT-PCR). The infection frequencies were 79% for LMoV, 5% for LSV, and 3% for CMV. The LMoV coat protein gene was amplified and cloned into the pET21d(+) expression vector to develop serological diagnostic tools to detect LMoV. The resulting carboxy-terminal His-tagged coat proteins were expressed in Escherichia coli strain BL21 (DE3) by induction with IPTG. The recombinant proteins were purified using Ni-NTA agarose beads and used as an antigen to produce polyclonal antibodies in laying hens. The resulting egg yolk immunoglobulin (IgY) specifically recognized LMoV from infected plant tissues in immunoblotting assays and had comparable sensitivity to that of a mammalian antibody. In addition, method of immunocapture RT-PCR using this IgY was developed for sensitive, efficient, and rapid detection of LMoV. Based on these results, large-scale bulb tests and detection of LMoV in epidemiological studies can be performed routinely using this IgY. This is the first report of production of a polyclonal IgY against a plant virus and its use for diagnosis.

• Journal of Microbiology and Biotechnology
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• 제28권10호
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• pp.1749-1759
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• 2018

Recombinant (rec) prion protein (PrP) is an extremely useful resource for studying protein misfolding and subsequent protein aggregation events. Here, we report mass production of high-purity rec-polypeptide encoding the C-terminal globular domain of PrP; (90-230) for human and (89-231) for murine PrP. These proteins were expressed as His-tagged fusion proteins in E. coli cultured by a high cell-density aerobic fermentation method. RecPrPs recovered from inclusion bodies were slowly refolded under reducing conditions. Purification was performed by a sequence of metal-affinity, cation-exchange, and reverse-phase chromatography. The current procedure yielded several dozens of milligrams of recPrP per liter with >95% purity. The purified recPrPs predominantly adopted an ${\alpha}$-helix-rich conformation and were functionally sufficient as substrates to measure the seeding activity of human and animal prions. Establishment of a procedure for high-level production of high-purity recPrP supports the advancement of in vitro investigations of PrP including diagnosis for prion diseases.

• 생명과학회지
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• 제21권12호
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• pp.1778-1783
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• 2011

조혈에 관여하는 cytokine은 골수세포의 성장과 분화를 촉진시켜 혈구세포 생산을 조절한다. 이런 cytokine을 조혈성장인자(hematopoitic growth factor)이라고 하고, 그 중에서 호중구 세포(neutrophil) 성장에 관여하는 과립구 콜로니 자극 인자(granulocyte-colony stimulating factor, G-CSF)는 임상적 치료제로서 아주 중요하다. 왜냐하면 화학적 항암치료를 받는 환자들에게 심각한 호중구 세포가 감소하는 증세(neutropenia)가 발생하여 감염으로 인한 사망이 일어나기 때문이다. 두 종류의 G-CSF 재조합 단백질이 치료제로 승인 받아 사용되고 있으며, G-CSF 재조합 단백질 생산에 대한 연구가 지속적으로 이루어지고 있다. 선행연구에서 본 연구팀은 누에에서 유래된 Bm5 세포주에서 G-CSF의 생산을 증대하기 위해 누에 prophenoloxidase activating enzyme의 Endoplasmic reticulum targeting signal sequence유전자와 사람 G-CSF 유전자를 융합한 chimera 유전자를 제작하여 재조합 G-CSF 단백질을 생산하였다. 본 연구에서는 이 chimera 유전자가 생산하는 재조합 G-CSF 단백질의 N-말단에 3 개의 아미노산이 결여되는 3 종류의 돌연변이 유전자를 제작하여 G-CSF 단백질 생산에 미치는 영향을 조사하였다. 그 중 한 돌연변이 유전자에 의해 세포 밖으로 분비된 G-CSF 단백질의 생산이 현저히 감소하여, N-말단 부분이 이 단백질의 분비에 관여한다는 것을 알 수 있었다.

• 한국미생물·생명공학회지
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• 제49권1호
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• pp.75-87
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• 2021

Type I Interferons (IFNα) are known for their role as biological anticancer agents owing to their cell-apoptosis inducing properties. Development of an appropriate, cost-effective host expression system is crucial for meeting the increasing demand for proteins. Therefore, this study aims to develop codon-optimized IFNα-2b in L. lactis NZ3900. These cells express extracellular protein using the NICE system and Usp₄₅ signal peptide. To validate the mature form of the expressed protein, the recombinant IFNα-2b was screened in a human colorectal cancer cell line using the cytotoxicity assay. The IFNα-2b was successfully cloned into the pNZ8148 vector, thereby generating recombinant L. lactis pNZ8148-SP_Usp45-IFNα-2b. The computational analysis of codon-optimized IFNα-2b revealed no mutation and amino acid changes; additionally, the codon-optimized IFNα-2b showed 100% similarity with native human IFNα-2b, in the BLAST analysis. The partial size exclusion chromatography (SEC) of extracellular protein yielded a 19 kDa protein, which was further confirmed by its positive binding to anti-IFNα-2b in the western blot analysis. The crude protein and SEC-purified partial fraction showed IC₅₀ values of 33.22 ㎍/ml and 127.2 ㎍/ml, respectively, which indicated better activity than the metabolites of L. lactis NZ3900 (231.8 ㎍/ml). These values were also comparable with those of the regular anticancer drug tamoxifen (105.5 ㎍/ml). These results demonstrated L. lactis as a promising host system that functions by utilizing the pNZ8148 NICE system. Meanwhile, codon-optimized usage of the inserted gene increased the optimal protein expression levels, which could be beneficial for its large-scale production. Taken together, the recombinant L. lactis IFNα-2b is a potential alternative treatment for colorectal cancer. Furthermore, its activity was analyzed in the WiDr cell line, to assess its colorectal anticancer activities in vivo.

• 생명과학회지
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• 제9권5호
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• pp.556-563
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• 1999

Presence of antibody to the capsid protein p24 is the main diagnostic criterion, since this reflects reliable antibody response to HIV infection. However, it takes about 6-8 weeks for antibody production after infection and people who are infected but antibodies are not produced yet are classified as seronegative. Therefore, there is a strong need for an improved diagnostic method for better health security. As a first step for developing such an improved diagnostic system, gag protein of human immunodificiency virus type 1 was expressed in E. coli DH5$\alpha$. The gag fragment of HIV-1 (including a portion of p17 and whole p24) was amplified by polymerase chain reaction (PCR) and BamH I/EcoR I sites were created during PCR. The amplified DNA fragment was cleaved with BamH I/EcoR I and was subcloned into the GEX-2T vector which had been digested with BamHI/EcoRI, resulting gene fusion with gst gene of pGEX-2T. The recombinant DNA was transferred into E. coli DH5$\alpha$. The transformed bacteria were grown at 37$^{\circ}C$ for 3h and protein expression was induced with 0.1mM IPTG at $25^{\circ}C$ for 3h. Recombinant gag protein or GST-gag fusion protein was purified with glutathione-sepharose 4B bead and migrated as a single band when analyzed by 10% polyacrylamide gel. These proteins were confirmed by immunoblotting with anti-GST goat sera or Korean AIDS patients sera. The results of this study establish the expression and single step pulification of HIV-1 gag protein which can specifically bind with Korean AIDS patients sera.