• Molecules and Cells
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• v.37 no.7
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• pp.562-567
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• 2014

Human Hertwig's epithelial root sheath/epithelial rests of Malassez (HERS/ERM) cells are epithelial remnants of teeth residing in the periodontium. Although the functional roles of HERS/ERM cells have yet to be elucidated, they are a unique epithelial cell population in adult teeth and are reported to have stem cell characteristics. Therefore, HERS/ERM cells might play a role as an epithelial component for the repair or regeneration of dental hard tissues; however, they are very rare population in periodontium and the primary isolation of them is considered to be difficult. To overcome these problems, we immortalized primary HERS/ERM cells isolated from human periodontium using SV40 large T antigen (SV40 LT) and performed a characterization of the immortalized cell line. Primary HERS/ERM cells could not be maintained for more than 6 passages; however, immortalized HERS/ERM cells were maintained for more than 20 passages. There were no differences in the morphological and immunophenotypic characteristics of HERS/ERM cells and immortalized HERS/ERM cells. The expression of epithelial stem cell and embryonic stem cell markers was maintained in immortalized HERS/ERM cells. Moreover, immortalized HERS/ERM cells could acquire mesenchymal phenotypes through the epithelial-mesenchymal transition via TGF-${\beta}1$. In conclusion, we established an immortalized human HERS/ERM cell line with SV40 LT and expect this cell line to contribute to the understanding of the functional roles of HERS/ERM cells and the tissue engineering of teeth.

• YAKHAK HOEJI
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• v.32 no.4
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• pp.213-221
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• 1988

Inducible MLS resistance gene of Bacillus licheniformis specified by erm K was subcloned in Bacillus subtilis and the DNA sequence corresponding to its control region was determined. The determinant erm K was in Pvu II=Hind III fragment, which was 1.3 kb. The leader region is capable of forming a complex series of inverted complementary repeat sequences (ICRS) centering on at least six axes of symmetry, some of them mutually exclusive, in a way that resulted ultimately in post-transcriptional unmasking of the ribosome loading site for methylase synthesis.

• YAKHAK HOEJI
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• v.41 no.4
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• pp.533-537
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• 1997

The characteristics of the resistance phenotypes of Bacillus subtilis having ermk and its terminator region mutants were determined. Wild type ermK(pEC101) and pECMT109(methylase SD-region mutant) showed typical inducible resistance phenotype. pECMF1(terminator1 region mutant) and pECMT2(terminator2 region mutant) showed constitutive resistance to Kitasamycin but inducible resistance to tylosin. In contrast, pECMT3(terminator1 and terminator2 double mutant) and pECMT309(terminator1, terminator2 and methylase SD region triple mutant) showed constitutive resistance both to kitasamycin and tylosin.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.335.1-335.1
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• 2002

The ermK gene from Bacillus lichenformis encodes an inducible rANA methylase that confers resistance to the macrolide-lincosamide-streptograminB antibiotics. The ermKmANA leader sequence has a total length of 357 nucleotides and encodes a 14-amino acid leader peptide together with its ribosome binding site. The secondary structure of erm leader RNA and a leader peptide have been reported as the elements that control expression. (omitted)

• Archives of Pharmacal Research
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• v.15 no.1
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• pp.58-61
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• 1992

Bacillus anthracis 590 having an inducibla resistance determinant to MLS antibiotics was isolated from a soli sample in Korea. The resistance gene (ernJ) was cloned by Southern blotting of chromosomal DNA fragment digested by various restriction enzymes and coloy hybridization method and the cloned plasmid was named as pBA423. The size of inserted DNA fragment of pBS42 vector was about 2.9 kb and the DNA sequence of the subcloned fragment (Hinc II-Hinc II, 1.4kb) WAS determined. The DNA sequence of ernJ was composed of 357 bp for leader region and 861 bp for the structural gene. Because the leader sequence of ernJ was homologous to that of ermK, the expression of ernJ is also thought to be controlled by a transcriptionl attenuation mechanism.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.200-208
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• 2011

Most problematic antibiotic resistance mechanism for MLS (macrolide-lincosamide-streptogramn B) antibiotics encountered in clinical practice is mono- or dimethylation of specific adenine residue at 2058 (E. coli coordinate) of 23S rRNA which is performed by Erm (erythromycin ribosome resistance) protein through which bacterial ribosomes reduce the affinity to the antibiotics and become resistant to them. ErmSF is one of the four gene products produced by Streptomyces fradiae to be resistant to its own antibiotic, tylosin. Unlike other Erm proteins, ErmSF harbors idiosyncratic long N-terminal end region (NTER) 25% of which is comprised of arginine well known to interact with RNA. Furthermore, NTER was found to be important because when it was truncated, most of the enzyme activity was lost. Based on these facts, capability of NTER peptide to inhibit the enzymatic activity of ErmSF was sought. For this, expression system for two different proteins to be expressed in one cell was developed. In this system, two plasmids, pET23b and pACYC184 have unique replication origins to be compatible with each other in a cell. And expression system harboring promoter, ribosome binding site and transcription termination signal is identical but disparate amount of protein could be expressed according to the copy number of each vector, 15 for pACYC and 40 for pET23b. Expression of NTER peptide in pET23b together with ErmSF in pACYC 184 in E. coli successfully gave more amounts of NTER than ErmSF but no inhibitory effects were observed suggesting that there should be dynamicity in interaction between ErmSF and rRNA rather than simple and fixed binding to each other in methylation of 23S rRNA by ErmSF.

• KSBB Journal
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• v.20 no.3
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• pp.220-227
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• 2005

Doxorubicin is an anthracycline-family polyketide compound with a very potent anti-cancer activity, typically produced by Streptomyces peucetius. To understand the potential target biosynthetic genes critical for the doxorubicin everproduction, a doxorubicin-specific DNA microarray chip was fabricated and applied to reveal the growth-phase-dependent expression profiles of biosynthetic genes from two doxorubicin-overproducing strains along with the wild-type strain. Two doxorubicin-overproducing 5. peucetius strains were generated via over-expression of a dnrl (a doxorubicin-specific positive regulatory gene) and a doxA (a gene involved in the conversion from daunorubicin to doxorubicin) using a streptomycetes high expression vector containing a strong ermE promoter. Each doxorubicin-overproducing strain was quantitatively compared with the wild-type doxorubicin producer based on the growth-phase-dependent doxorubicin productivity as well as doxorubicin biosynthetic gene expression profiles. The doxorubicin-specific DNA microarray chip data revealed the early-and-steady expressions of the doxorubicin-specific regulatory gene (dnrl), the doxorubicin resistance genes (drrA, drrB, drrC), and the doxorubicin deoxysugar biosynthetic gene (dnmL) are critical for the doxorubicin overproduction in S. peucetius. These results provide that the relationship between the growth-phase-dependent doxorubicin productivity and the doxorubicin biosynthetic gene expression profiles should lead us a rational design of molecular genetic strain improvement strategy.

• YAKHAK HOEJI
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• v.38 no.3
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• pp.293-299
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• 1994

Forty nine clinical isolates of S. aureus showing resistance to erythromycin(EM) were selected from 83 strains isolated recently in Korea. Fourteen strains of S. aureus showing inducible resistance to MLS antibiotics were selected by disc agar diffusion method. Colony hydridization was executed using two MLS inducible resistance genes, ermA and ermC, identified previously from S. aureus as probes. S. aureus 375 and S. aureus 507 whose genes were not homologous to those probes were finally selected. It was confirmed that the resistance genes of S. aureus 375 and S. aureus 507 had no homology with those probes in southern hybridization test using ermA, ermC and ermAM as probes. It was determined that S. aureus 375 had a plasmid whose size was about 35 kb. To know if the plasmid may have the genes related to inducible resistance to MLS antibiotics, it was attempted to transform Bacillus subtillis BR151 and S. aureus RN4220 with the plasmid isolated from S. aureus 375. It was shown that the gene related to inducible resistance to MLS antibiotics did not exist in this plasmid. These results indicate that two clinical isolates of S. aureus showing inducible resistance to MLS antibiotics have novel genes that have no homology with MLS resistance genes identified so far. It is assumed that these genes may exist in chromosomal DNA.

• Journal of Microbiology
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• v.37 no.2
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• pp.102-110
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• 1999

Genetic determinant for the secondary metabolism was studied in heterologous expression in Streptomyces lividans TK-24 using Streptomyces griseus ATCC 10137 as a donor strain. Chromosomal DNA of S. griseus was ligated into the high-copy number Streptomyces shuttle plasmid, pWHM3, and introduced into S. lividans TK-24. A plasmid clone with 4.3-kb BamHI DNA of S. griseus (pMJJ201) was isolated by detecting for stimulatory effect on actinorhodin production by visual inspection. The 4.3-kb BamHI DNA was cloned into pWHM3 under the control of the strong constitutive ermEp promoter in both directions (pMJJ202); ermEp promoter-mediated transcription for coding sequence reading right to left: pMJJ203; ermEp promoter-mediated transcription for coding sequence reading left to right) and reintroduced into S. lividans TK-24. The production of actinorhodin was markedly stimulated due to introduction of pMJJ202 on regeneration agar. The introduction of pMJJ202 also stimulated production of actinorhodin and undecylproidigiosin in submerged culture employing the actinorhodin production medium. Introduction of pMJJ203 resulted in a marked decrease of production of the two pigments. Nucleotide sequence analysis of the 4.3-kb region revealed three coding sequences: two coding sequences reading left to right, ORF1 and ORF2, one coding sequence reading right to left, ORF3. Therefore, it was suggested that the ORF3 product was responsible for the stimulation of antibiotic production. The C-terminal region of ORF3 product showed a local alignment with Myb-related transcriptional factors, which implicated that the ORF3 product might be a novel DNA-binding protein related to the regulation of secondary metabolism in Streptomyces.

• YAKHAK HOEJI
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• v.34 no.2
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• pp.139-146
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• 1990

Streptococcus sp. TR-1 which has inducible resistance to MLS antibiotics was isolated from soil samples in Korea. Streptococcus sp. TR-1 was cultured in Lysis broth, then a plasmid was isolated by modified Elliker method. Bacillus subtilis UOTO277 was transformed with that plasmid. This result showed that the plasmid has the gene relating with inducible resistance to MLS antibiotics. It was named pMB4 and its size was determined about 2.4 Kb by results of digestion with various restriction enzymes. Restriction endonuclease cleavage site map of pMB4 plasmid was made by double digestion of the plasmid. pMB4 plasmid has different restriction endonuclease site map from the other plasmids that have been discovered in Streptococcus sp. so far. And it could be identified that pMB4 plasmid does not have homology with ermK of Bacillus licheniformis EMR but has homology with ermC of Staphylococcus aureus from the results of Southern hybridization.