• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.336-339
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• 2002

A total of 100 Corynebacterial clones exerting a regulatory effect on the aceB promoter of Corynebacterium glutamicum were isolated by utilizing a reporter carrying the enteric lacZ gene fused to the promoter. The isolated clones were classified into 3 groups of A, B, and C, according to their color of colonies. Escherichia coli cells carrying clones in groups A and B showed a $90\%\;and\;50\%$ reduction in ${\beta}$-galactosidase activity, respectively. The introduction of group A clones into C. glutamicum also resulted in an almost complete reduction in the expression of the aceA and aceB genes, suggesting that the clones express repressor-like proteins for the genes. Although white colonies were formed on plates containing X-gal, E. coli cells carrying one of the clones in group C exhibited intact ${\beta}$-galactosidase activity. The result suggests that the clone may encode proteins that prevent the cells from accumulating the chromogenic compound, X-gal.

• Journal of Sericultural and Entomological Science
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• v.37 no.2
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• pp.181-185
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• 1995

To enhance expression of foreign gene by the novel expression vector, pBmKSK1, of Bombyx mori nuclear polyhedrosis virus, E. coli $\beta$-galactosidase gene expressing recombinant virus was infected in BmN-4 cells and various concentrations of silkworm hemolymph were added to the recombinant virus-infected BmN-4 cells containing fetal bovine serum. The expression efficiency of foreign gene was determined by $\beta$-galactosidase activity in the culture media. The results showed that the silkworm hemolymph was effective to expression of foreign gene in the BmN-4 cells, suggesting that the silkworm hemolymph could be substituted for fetal bovine serum in the BmN-4 cells to enhance expression of foreign gene.

• Archives of Pharmacal Research
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• v.16 no.4
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• pp.271-275
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• 1993

In order to prepare a novel human insulin analogue suhbstituted with homoserine at B$^{30}$ / position, (B$^{30}$ /-homoserine) human insulin, a synthetic gene was designed by linking directly a gene for B chain with that for A chain. This gene was constructed by enzymatic joining of 10 different synthetic oligonucleotides, and then inserted at the polylinker region of pUC19 plasmid. To achieve a high level of gene expression, the gene fusion technique region of pUC19 plasmid. To achieve a high level of gene expression, the gene fusion technique was employed using amino terminal regions of lacZ gene up to Clal or hpal, and either of them has been located under tac promoter. The chemical induction of these fused genes by isopropyl-.betha.-D-thiogalactopyranoside (IPTG) gave a satisfactory level of expression in Escherichia coli harboring the ocnstructed plasmids. It was observed that the fused gene product as a single chain insulin precusor was produced more than 30% of total cell protein of E. coli as a form of inclusion body.

• Applied Biological Chemistry
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• v.38 no.2
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• pp.111-117
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• 1995

In Escherichia coli, CRP forms a complex with cAMP and acts as a transcriptional regulator of many genes, including sugar metabolism operons. The E. coli MK2001, which is introduced the altered crp, is functional in the expression of lac, ara and man, in the absence of cAMP. However, the expression of mal gene is fully activated by the addition of cAMP or cGMP. The object of the study is cloning of the sfs (sugar fermentation stimulation) genes, which was involved in regulation of mal gene expression with the altered crp gene, and structural analysis and characterization of the genes at the molecular level. We have cloned 5 different E. coli genes which stimulate the maltose metabolism in a crp, cya::km (MK2001) background. Newly identified genes were designated as sfs. One of the sfs genes (pPC1), located at the 53.2 min map position on the E. coli chromosome, was further analyzed. Expression of the genes, which is involved in maltose metabolism, malQ (amylomaltase), was increased to 5.8-fold in the presence of a plasmid, pAP5, containing the subcloned sfs4 gene. The nucleotide seguence of a common 2,126 bp segment of the pPCM1 was determined and two open reading frames (ORF1 and ORF2) were detected. The ORF1 encodes the sfs4 gene and ORF2 encodes a truncated protein. Potential CRP binding site is located in the upstream of the putative promoter in the regulatory region. Expression of the cloned sfs4 gene was positively regulated by the cAMP-CRP complex.

• Journal of Microbiology
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• v.35 no.2
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• pp.149-151
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• 1997

A plasmid vector with combined features of yeast shuttle vector and mammalian expression vector was constructed to facilitate expression of cloned gene in both cell-types. All necessary elements required for plasmid maintenance and selection in E. coli, yeast and mammalian cells were size-economically arranged in this plasmid. The numan cytomegalovirus (CMV) immediate early promoter and yeast GAL1 promoter were sequentially placed in front of the gene to be expressed. The synthetic splicing donor and acceptor sequences were inserted into the immediate upstream and downstream of the GAL1 promotor, allowing the CMV promotor to direct the expression of a given gene in mammalian cell environment by splicing out the interfering GAL1 promotor sequence. When the resulting vector containing LacZ as a gene was introduced into yeast and mammalian cells, both cells efficiently produced .betha.-galactosidase, dimonstrating its dual host usage.

• Journal of Microbiology
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• v.40 no.2
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• pp.156-160
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• 2002

The whole gal/lae operon genes of Lactococcus lactis ssp. lactis 7962 were reported as follows: galA-galM-galK-galT-lacA -lacZ-galE. The galK gene encoding a galactokinase involved in one of the Leloir pathways for galactose metabolism was found to be 1,197 bp in length and encodes a protein of 43,822 Da calculated molecular mass. The deduced amino acid sequence showed over 50% homology with GaIK proteins from several other lactic acid bacteria. The galK gene was expressed in E. coli and the product was identified as a 43 kDa protein which corresponds to the estimated size from the DNA sequence. The galactokinase activity of recombinant 5. coli was about 8 times greater against that of the host strain and more than 3 times higher than the induced L. lactis 7962.

• Journal of Microbiology
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• v.33 no.2
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• pp.120-125
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• 1995

.betha.-galactosidase activity of Escherichia coli cells containing operon fusion nhaA'-'lacZ was monitored to study the regulation of expression of nhaA gene under various conditions. The expression of the fusion was enhanced only by chemicals containing Na$^{+}$ or Li$^{+}$. This Na$^{+}$ or Li$^{+}$. This Na$^{+}$(Li$^{+}$)-specific enhancement of .betha.-galactosidase activity represented the increase in the rate of synthesis of .betha.-galactosidase rather than the decrease in the breakdown rate. The induction pattern was influenced by copy numbers of the gene. Induction by Na$^{+}$ or Li$^{+}$ was concentration and time dependent, reaching maximum 5-6 fold induction after 2 hours at 0.4-0.5 M for Na$^{+}$ or at 0.25-0.35 M for Li$^{+}$, Although the expression was induced at much lower concentration of Na$^{+}$ at alkaline pH values than at neutral pH in the presence of Na$^{+}$, alkaline pH itself did ot induced the expression of the fusion in the absence of Na$^{+}$. Temperature shift and growth phase of culture did not affect the level of induction.he level of induction.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.5
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• pp.320-326
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• 2000

Promoters of the genes G3P, ICL1, POT1, POX1, POX2 and POX5 of the yeast Y. lipolytica were studied in respect to their regulations and activities during growth on different carbon sources. The aim of this study was to select suitable promoters for high expression of heterologous genes in this yeast. For this purpose the promoters were fused with the reporter gene lacZ of E. coli and integrated as single copies into the genome of Y. lipolytica strain PO1d. The measurement of expressed activities of ${\beta}$-galactosidase revealed that pICL1, pPOX2 and pPOT1 are the strongest regulable promoters available for Y. lipolytica, at present. pPOX2 and pPOT1 were highly induced during growth on oleic acid and were completely repressed by glucose and glycerol. pICL1 was strongly inducible by ethanol besides alkanes and fatty acids, however, not completely repressible by glucose or glycerol. Ricinoleic acid methyl ester appeared as a very strong inducer for pPOT1 and pPOX2, in spite of that it inhibited growth of Y. lipolytica transformants.

• Proceedings of the Microbiological Society of Korea Conference
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• 2000.10a
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• pp.24-31
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• 2000

In order to find out SoxR-reducing system in E. coli, we generated Tn10-insertion mutants and screened for constitutive expression of SoxS in a soxS-lacZ fusion strain. One mutation was mapped in rseB, a gene in rseABC (Regulation of SigmaE) operon. The constitutive soxS-expressing phenotype was due to the polar effect on the downstream gene, rseC. RseC is likely to function as a component of SoxR reduction system because SoxR was kept in oxidized form to activate soxS expression in rseC mutant. RseC is an integral membrane protein with an N-terminal cysteine-rich domain in the cytoplasm. The functionally critical cysteines were determined by substitution mutagenesis. The truncated N-terminal domain of RseC reduced the soxS transcription by $50\%$ as judged by in vitro transcription assay. Currently RseC is believed to be a reducing factor for SoxR. However, the mechanism for the reduction needs further investigation.

• Applied Biological Chemistry
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• v.39 no.3
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• pp.195-199
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• 1996

We have cloned several E. coli sfs genes which stimulate mal gene expression with $crp^{{\ast}1}$). One the genes (pPVC2) was sequenced and potential CRP binding site is located in the upstream of the putative promoter in the regulatory region. In order to investigate the regulation of the sfs1 gene by the cAMP-CRP complex, we have constructed the sfs-lacZ fusion gene in this research. The overall transcriptional stimulations of sfs1 gene in the presence cAMP were confirmed by ${\beta}-galactosidase$ activity and Western blot analysis of sfs1-lacZ fusion gene. Transcriptional regulation by cAMP-CRP was also confirmed by Northern blot analysis. End-labelled DNA of the DNA fragment in sfs1 regulation region were used for gel retardation assay to examine the CRP-DNA complex in the presence of cAMP. Results here indicate that CRP binding site in the regulatory region of sfs1 gene is positive regulator for the expression of sfs1 gene.