• Journal of Microbiology and Biotechnology
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• 제20권6호
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• pp.974-977
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• 2010

Cyclophilins contain the conserved activity of cis-trans peptidyl-prolyl isomerase, which is implicated in protein folding, and function as molecular chaperones. When the yeast cyclophilin A gene (cpr1) was subcloned into the prokaryotic expression vector pKM260, it was found that the expression of Cpr1 drastically increased the cell viability of E. coli BL21 when under abiotic stress conditions, as in the presence of cadmium, copper, hydrogen peroxide, heat, and SDS. Therefore, this study illustrates the importance of Cpr1 as a molecular chaperone that can improve the cellular stress responses when E. coli cells are exposed to adverse conditions, while also demonstrating its potential to increase the stability of E. coli strains utilized for the production of recombinant proteins.

• 미생물학회지
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• 제46권1호
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• pp.68-72
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• 2010

Bacillus licheniformis B1의 ${\beta}$-1,4-glucanase 유전자는 Escherichia coli BL21에서 발현되어, 이로부터 수용성의 50 kDa 단백질이 과량생산되었다. 반면에 B. licheniformis에서는 37 kDa의 형태가 분비되었다. E. coli에서 발현된 ${\beta}$-1,4-glucanase는 leader peptide가 제거되지 않고 포함되어 있고 Bacillus에서는 효소의 carboxy 말단에서 processing이 일어난 것으로 보인다. E. coli에서 생산된 ${\beta}$-1,4-glucanase의 최적온도는 $40^{\circ}C$이었지만, $60^{\circ}C$에서도 최대치의 76% 활성을 유지하였다. 효소의 최적 pH는 7이었고, 효소의 활성은 전체적으로 보면 약산성, 중성 및 약알칼리 영역에 널리 걸쳐 있었다. Cellulase는 식품, 세제, 펄프, 제지, 섬유산업 등 다양한 분야에서 주로 산성의 곰팡이계 효소가 이용되고 있으나, 중성 및 알칼리성 cellulase 연구 및 개발은 미흡한 편이다. 본 연구에서 개발된 중성 cellulase가 바이오 연료 개발 등의 분야에서 활용되기를 기대해 본다.

• 생명과학회지
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• 제28권4호
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• pp.478-482
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• 2018

인간 rotavirus는 영아에게 급성 설사를 일으키는 병원체의 하나이다. 본 연구에서는 Escherichia coli의 코돈 선호도를 따라서 인간 rotavirus A (serotype 1 strain WA)의 $VP8^*$ 단백질을 일부분 암호화하도록 인공적인 유전자를 합성하였다. 합성된 $VP8^*$ 유전자는 코돈을 번역틀에 일치시키고 클로닝이 용이하도록 하기 위한 NdeI 및 HindIII 제한효소 절단 부위와 친화적 정제를 위한 6-히스티딘 암호화 서열을 C-말단에 보유하고 있다. 합성된 $VP8^*$ DNA 절편을 pT7-7 발현 벡터에 삽입하여 E. coli BL21 (DE3)로 형질전환한 후에 최종 농도 0.05 mM IPTG로 생산을 유도한 결과 예상했던 대로 19.7-kDa 크기의 $VP8^*$ 단백질이 고농도로 발현되었다. SDS-PAGE에 전개된 단백질들을 대상으로 mouse anti-rotavirus capsid antibody를 사용한 Western blotting의 결과 ~20-kDa $VP8^*$ 단백질 밴드가 관찰되었다. 인공 $Vp8^*$ 단백질이 피하 주사된 토끼의 polyclonal antibody 혈장을 이용한 조사에서도 동일한 크기의 단백질 밴드를 확인할 수 있었다. 이는 합성된 유전자가 바이러스성 질환을 통제할 항원성 백신 후보의 생산 혹은 진단용 항체를 개발하기 위한 쉽고 빠른 방법을 제공할 수 있다는 의미이다.

• 미생물학회지
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• 제40권2호
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• pp.81-86
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• 2004

Streptomyces coelicolor의 전 유전체 청보를 분석한 결과(7), 유전자 ID1103135가 코드 하는 open reading frame SCO7697이 phytase[myo-inositol hexakisphosphate phosphohydrolase상동성 (3-6,8,23)]에 유의하게 유사한 것으로 판단되었다. S. coelicolor A3(2)M의 염색체 DNA를 주형으로 PCR 방법으로 SCO7697 전체를 포함하는 DNA 단편을 클로닝하였다. 두 가지의 서로 다른 길이를 갖는 클로닝 된 ID1103135 DNA 단편을 E. coli 발현용 벡터pET728a(+)에 삽입하여,두 종의 재조합 벡터 pET28-SP와 pET28-LP를 얻었다. pET28-SP 와 pET28-LP를 각각 E. coli BL2l에 도입하여, IPTG로 발현 유도된 단백질을 SDS-polyacrylamide 전기영동으로 확인한 결과, 발현은 성공적으로 이루어 졌으나 대부분불용체를 형성하고 분자량은 예상보다 약간 큰 것으로 나타났다. 불용체 형성은 단백질의 불활성화를 수반 함으로서, 배양 온도를 $37^{\circ}C$에서 $30^{\circ}C$로 변화시켜 배양하는 방법으로 발현된 단백질을 가용화 시켰다. 발현된 단백질을 추출하여 조추출물 또는 정제한 상태로 phytase활성을 측청하였으나 효소활성은 관찰할 수 없었다. 대장균 시스템에서의 발현이 효소 활성의 소실을 초래했을 가능성이 있으므로, ID1103135 유전자를 자신의 promoter를 함유하도록 PCR 클로닝하여, E. coli - Streptomyces의 shuttle vector인 pWHM3에 삽입하고, 이를 방선균 호스트인 S. lividans에 도입하였다. 형질 전환체의 세포조추출액 및 세포배양액의 phytase 활성을 측청하였으나, 역시 활성을 확인할수 없었다. 이와 같은 결과는 SCO7697이 아주 높은 확률(E value; $6e^{-89}$)로 phytase일 것으로 annotation 되었으나, 실제는 이와는 다른 기능을 함유하고 있음을 시사하고 있다.

• Journal of Microbiology and Biotechnology
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• 제25권10호
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• pp.1709-1713
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• 2015

Sepiapterin is a precursor for the synthesis of tetrahydrobiopterin (BH4), which is a wellknown cofactor for aromatic amino acid hydroxylation and nitric oxide synthesis in higher mammals. In this study, a recombinant Escherichia coli BL21(DE3) strain harboring cyanobacterial guanosine 5’-triphosphate cyclohydrolase 1 (GCH1) and human 6-pyruvoyltetrahydropterin synthase (PTPS) genes was constructed to produce sepiapterin. The optimum conditions for T₇ promoter–driven expression of GCH1 and PTPS were 30℃ and 0.1 mM isopropyl-β-D-thioglucopyranoside (IPTG). The maximum sepiapterin concentration of 88.1 ± 2.4 mg/l was obtained in a batch cultivation of the recombinant E. coli, corresponding to an 18-fold increase in sepiapterin production compared with the control condition (37℃ and 1 mM IPTG).

• Journal of Microbiology and Biotechnology
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• 제32권6호
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• pp.800-807
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• 2022

Four aprE genes encoding alkaline serine proteases from B. subtilis strains were used as template genes for family gene shuffling. Shuffled genes obtained by DNase I digestion followed by consecutive primerless and regular PCR reactions were ligated with pHY300PLK, an E. coli-Bacillus shuttle vector. The ligation mixture was introduced into B. subtilis WB600 and one transformant (FSM4) showed higher fibrinolytic activity. DNA sequencing confirmed that the shuffled gene (aprEFSM4) consisted of DNA mostly originated from either aprEJS2 or aprE176 in addition to some DNA from either aprE3-5 or aprESJ4. Mature AprEFSM4 (275 amino acids) was different from mature AprEJS2 in 4 amino acids and mature AprE176 in 2 amino acids. aprEFSM4 was overexpressed in E. coli BL21 (DE3) by using pET26b(+) and recombinant AprEFSM4 was purified. The optimal temperature and pH of AprEFSM4 were similar to those of parental enzymes. However, AprEFM4 showed better thermostability and fibrinogen hydrolytic activity than the parental enzymes. The results indicated that DNA shuffling could be used to improve fibrinolytic enzymes from Bacillus sp. for industrial applications.

• Journal of Microbiology and Biotechnology
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• 제11권1호
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• pp.92-96
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• 2001

Effect of environmental factors on the expression of soluble forms of Bacillus macerans cyclodextrin glycosyltransferase in recombinant Escherichia coli BL21(DE3)pLysE:pTCGT1 were investigated. The amount of soluble CGTase produced in the cell was measured by determining its enzymatic activity. The soluble fractionof the enzyme was increased by lowering the culture temperature to $30{\circ}C$ and medium pH to 5.8 compared to the enzyme production in LB medium at $37^{\circ}C$ and pH7.0. Addition of 0.2 M NaCl enhanced enzyme expression levels at the expense of cell growth. Glycine betaine that was added after 3 h of induction protected not only the cell growth from hig osmotic pressue but also hepld in vivo folding of CGTase in recombinant E. coli. Addition of 1 mM $CaCl_2$ was also effective in the expression of soluble CGTase, resulting in 15 U/ml of the enzyme activity.

• 한국미생물·생명공학회지
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• 제24권4호
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• pp.478-484
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• 1996

Recombinant human epidermal growth factor (rhEGF) was produced by E. coli BL21 harboring a plasmid pYHB101. The maximum production was 68.7 mg/l when the E. coli strain was cultured at 25$\circ$C for 48 hours in the modified MBL medium containing 10 g/l glucose with 1 mM IPTG induction at 2 hours after inoculation. The rhEGF was purified upto 267 folds by Amberlite XAD- 7 chromatography, ultrafiltration, and DEAE Sepharose fast flow ion exchange chromatography with an overall yield of 66.6%. The purified rhEGF was further separated into two fractions by HPLC. The N-terminal amino acid sequence of the second fraction was Asn-Ser-Asp-Ser-Glu-Cys-Pro-Leu-Ser-His. The effect of rhEGF on the DNA synthesis was examined using in vitro biological assay based on the incorporation of 5'-bromo-2'- deoxy-uridine (BrdU). The purified rhEGF shows no difference with natural human epidermal growth factor (nhEGF) in N-terminal amino acids residues and biological activity. From the results, we concluded that rhEGF produced from E. coli harboring the plasmid pYHB101 was apparently the same as nhEGF.

• Journal of Microbiology and Biotechnology
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• 제25권12호
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• pp.2034-2042
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• 2015

A one-pot process of enzymatic synthesis of deoxythymidine-5'-triphosphate (5'-dTTP) employing whole cells of recombinant Escherichia coli coexpressing thymidylate kinase (TMKase) and acetate kinase (ACKase) was developed. Genes tmk and ack from E. coli were cloned and inserted into pET28a(+), and then transduced into E. coli BL21 (DE3) to form recombinant strain pTA in which TMKase and ACKase were simultaneously overexpressed. It was found that the relative residual specific activities of TMKase and ACKase, in pTA pretreated with 20 mM ethylene diamine tetraacetic acid (EDTA) at 25℃ for 30 min, were 94% and 96%, respectively. The yield of 5'-dTTP reached above 94% from 5 mM deoxythymidine 5'-monophosphate (5'-dTMP) and 15 mM acetyl phosphate catalyzed with intact cells of pTA pretreated with EDTA. The process was so effective that only 0.125 mM adenosine-5'-triphosphate was sufficient to deliver the phosphate group from acetyl phosphate to dTMP and dTDP.

• Journal of Microbiology and Biotechnology
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• 제29권3호
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• pp.401-409
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• 2019

Heat-resistant microbial hosts are required for bioprocess development using high cell density cultivations at the industrial scale. We report that the thermotolerance of Escherichia coli can be enhanced by overexpressing ybeD, which was known to encode a hypothetical protein of unknown function. In the wild-type E. coli BL21(DE3), ybeD transcription level increased over five-fold when temperature was increased from $37^{\circ}C$ to either $42^{\circ}C$ or $46^{\circ}C$. To study the function of ybeD, a deletion strain and an overexpression strain were constructed. At $46^{\circ}C$, in comparison to the wild type, the ybeD-deletion reduced cell growth half-fold, and the ybeD-overexpression promoted cell growth over two-fold. The growth enhancement by ybeD-overexpression was much more pronounced at $46^{\circ}C$ than $37^{\circ}C$. The ybeD-overexpression was also effective in other E. coli strains of MG1655, W3110, DH10B, and BW25113. These findings reveal that ybeD gene plays an important role in enduring high-temperature stress, and that ybeD-overexpression can be a prospective strategy to develop thermotolerant microbial hosts.