• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.242-248
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• 2002

Previously, it was reported that the nonhomologous C-terminal regions of the D-hydantoinases are nonessential for catalysis, but affect the oligomeric structure of the enzyme [3]. In an effort to further confirm the above observation, the C-terminal region-inserted enzyme was constructed by attaching a peptide (22 residues) at the C-terminal of the D-hydantoinase from Bacillus thermocatenulatus GH2, and its structural and biochemical properties were compared with both the wild-type and C-terminal region-truncated enzymes. As a result, native tetrameric D-hydantoinase was dimerized as the truncated enzyme, and the inserted mutant with a new sequence was expressed as a catalytically active form in E. coli. Expression level of the inserted and truncated enzymes were found to be significantly increased compared to the level of the wild-type enzyme, and this appears to be due to the reduced toxic effect of the mutant enzymes on host cells. Dimerized enzymes exhibited increased thermo- and pH stabilities considerably when compared with the corresponding wild-type enzyme. Comparison of the substrate specificity between the mutant and wild-type enzymes suggests that the substrate specificity of the D-hydantoinase is closely linked with the oligomeric structure.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.607-611
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• 2004

Glycinin, one of the predominant storage proteins in soybeans, was examined as to whether it could be used as a calcium-binding mediator after chemical phosphorylation and enzymatic hydrolysis. Glycinin is composed of six subunits. One of the proglycinin subunits $(A_{la}B_{lb})$ was overexpressed in E. coli to obtain nonphosphorylated proteins with homogeneity. To investigate the enhanced calcium-binding properties of the phosphopeptides, the proglycinin was purified, phosphorylated, and hydrolyzed with trypsin. The proglycinin expressed in E. coli was purified by ammonium sulfate precipitation, ion-exchange chromatography, and cryoprecipitation. Chemical phosphorylation by sodium trimetaphosphate was performed to obtain phosphorylated proglycinin. After the phosphorylation, one-dimensional isoelectric focusing gel electroanalysis confirmed the phosphorylation of the proglycinin. The phosphorylated peptides were then hydrolyzed with trypsin, followed by a binding reaction with calcium chloride. The calcium-bound phosphopeptides were finally separated using immobilized metal $(Ca^{2+})$ chromatography. Consequently, a limited tryptic hydrolysate of the isolated phosphopeptides exhibited an enhanced calcium-binding ability, suggesting the potential of glycinin phosphopeptides as a calcium-binding mediator with greater availability.

• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.1018-1023
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• 2007

Bacillus subtilis CH3-5 was isolated from cheonggukjang prepared according to traditional methods. CH3-5 secreted at least four different fibrinolytic proteases (63, 47, 29, and 20 kDa) into the culture medium. A fibrinolytic enzyme gene, aprE2, encoding a 29kDa enzyme was cloned from the genomic DNA of CH3-5, and the DNA sequence determined. aprE2 was overexpressed in heterologous B. subtilis strains deficient in extracellular proteases using a E. coli-Bacillus shuttle vector. A 29 kDa AprE2 band was observed and AprE2 seemed to exhibit higher activities towards fibrin rather than casein.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.5
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• pp.375-383
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• 2013

Hepatocellular carcinoma (HCC) related to hepatitis B virus (HBV) and hepatitis C virus (HCV) infections is thought to account for more than 80% of primary liver cancers. Both HBV and HCV can establish chronic liver inflammatory infections, altering hepatocyte and liver physiology with potential liver disease progression and HCC development. Cyclophilin A (CypA) has been identified as an essential host factor for the HCV replication by physically interacting with the HCV non structural protein NS5A that in turn interacts with RNA-dependent RNA polymerase NS5B. CypA, a cytosolic binding protein of the immunosuppressive drug cyclosporine A, is overexpressed in many cancer types and often associated with malignant transformation. Therefore, CypA can be a good target for molecular cancer therapy. Because of antiviral activity, the CypA inhibitors have been tested for the treatment of chronic hepatitis C. Nonimmunosuppressive Cyp inhibitors such as NIM811, SCY-635, and Alisporivir have attracted more interests for appropriating CypA for antiviral chemotherapeutic target on HCV infection. This review describes CypA inhibitors as a potential HCC treatment tool that is contrived by their obstructing chronic HCV infection and summarizes roles of CypA in cancer development.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.3
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• pp.1403-1410
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• 2014

Epigenetic regulators like histone deacetylases (1 and 2), and viral onco-proteins (E6/E7) are known to be overexpressed in cervical cancer cells. The present study was designed to investigate the effect of curcumin on HDACs (1 and 2) and HPV E6/E7 in the cervical cancer cell line SiHa and a drug resistant clone $SiHa^R$ (derived from SiHa). It was further intended to investigate whether curcumin could sensitize the cells towards cisplatin induced cell killing by modulation of multi drug resistant proteins like MRP1 and Pgp1. Curcumin inhibited HDACs, HPV expression and differentially increased acetylation and up-regulation of p53 in SiHa and $SiHa^R$, leading to cell cycle arrest at G1-S phase. Up-regulation of pRb, p21, p27 and corresponding inhibition of cyclin D1 and CDK4 were observed. Cisplatin resistance in $SiHa^R$ due to over-expression of MRP1 and Pgp1 was overcome by curcumin. Curcumin also sensitized both the cervical cancer cells towards cisplatin induced cell killing. Inhibition of HDACs and HPVs led to cell cycle arrest at G1/S phase by alteration of cell cycle regulatory proteins. Suppression of MRP1 and Pgp1 by curcumin resulted in sensitization of cervical cancer cells, lowering the chemotherapeutic dose of the drug cisplatin.

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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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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• v.18 no.2
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• pp.283-286
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• 2008

The methylenetetrahydrofolate dehydrogenase/cyclohydrolase (MTHFDC) from the thermoacidophilic archaeon Thermoplasma acidophilum is a 30.6kDa molecular-mass enzyme that sequentially catalyzes the conversion of formyltetrahydrofollate to methylenetetrahydrofolate, with a preference for NADP as a cofactor, rather than NAD. In order to elucidate the functional and structural features of MTHFDC from archaeons at a molecular level, it was overexpressed in Escherichia coli and crystallized in the presence of its cofactor, NADP, at 295K using polyethylene glycol (PEG) 4000 as a precipitant. The crystal is a member of the monoclinic space group $P2_1$, with the following unit cell parameters: $a=66.333{\AA},\;b=52.868{\AA},\;c=86.099{\AA},\;and\;{\beta}=97.570^{\circ}$, and diffracts to a resolution of at least $2.40{\AA}$ at the synchrotron. Assuming a dimer in the crystallographic asymmetric unit, the calculated Matthews parameter $(V_M)\;was\;2.44{\AA}^3/Da$ and the solvent content was 49.7%.

• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.295-298
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• 2008

Creatine kinase (CK; E.C. 2.7.3.2) is an important enzyme that catalyzes the reversible transfer of a phosphoryl group from ATP to creatine in energy homeostasis. The brain-type cytosolic isoform of creatine kinase (BB-CK), which is found mainly in the brain and retina, is a key enzyme in brain energy metabolism, because high-energy phosphates are transfered through the creatine kinase/phosphocreatine shuttle system. The recombinant human BB-CK protein was overexpressed as a soluble form in Escherichia coli and crystallized at $22^{\circ}C$ using PEG 4000 as a precipitant. Native X-ray diffraction data were collected to $2.2{\AA}$ resolution using synchrotron radiation. The crystals belonged to the tetragonal space group $P4_32_12$, with cell parameters of a=b=97.963, $c=164.312{\AA},\;and\;{\alpha}={\beta}={\gamma}=90^{\circ}$. The asymmetric unit contained two molecules of CK, giving a crystal volume per protein mass $(V_m)$ of $1.80{\AA}^3\;Da^{-1}$ and a solvent content of 31.6%.

• Journal of Microbiology and Biotechnology
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• v.19 no.2
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• pp.121-127
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• 2009

Sequencing analysis of a 5-kb DNA fragment from Streptomyces venezuelae ATCC 15439 revealed the presence of one 3.1-kb open reading frame(ORF), designated as afsR-sv. The deduced product of afsR-sv(1,056 aa) was found to have high homology with the global regulatory protein AfsR. Homology-based analysis showed that aftR-sv represents a transcriptional activator belonging to the Streptomyces antibiotic regulatory protein(SARP) family that includes an N-terminal SARP domain containing a bacterial transcriptional activation domain(BTAD), an NB-ARC domain, and a C-terminal tetratricopeptide repeat domain. Gene expression analysis by reverse transcriptase PCR(RT-PCR) demonstrated the activation of transcription of genes belonging to pikromycin production, when aftR-sv was overexpressed in S. venezuelae. Heterologous expression of the aftR-sv in different Streptomyces strains resulted in increased production of the respective antibiotics, suggesting that afsR-sv is a positive regulator of antibiotics biosynthesis.

• Journal of Microbiology and Biotechnology
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• v.19 no.2
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• pp.136-139
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• 2009

Avermectin and its analogs are major commercial antiparasitic agents in the fields of animal health, agriculture, and human infections. Previously, comparative transcriptome analysis between the low-producer S. avermitilis ATCC31267 and the high-producer S. avermitilis ATCC31780 using a S. avermitilis whole genome chip revealed that 50 genes were overexpressed at least two-fold higher in S. avermitilis ATCC31780. To verify the biological significance of some of the transcriptomics-guided targets, five putative regulatory genes were individually cloned under the strong-and-constitutive promoter of the Streptomyces expression vector pSE34, followed by the transformation into the low-producer S. avermitilis ATCC31267. Among the putative genes tested, three regulatory genes including SAV213, SAV3818, and SAV4023 exhibited stimulatory effects on avermectin production in S. avermitilis ATCC31267. Moreover, overexpression of SAV3818 also stimulated actinorhodin production in both S. coelicolor M145 and S. lividans TK21, implying that the SAV3818, a putative TetR-family transcriptional regulator, could be a global upregulator acting in antibiotic production in Streptomyces species.