• Korean Journal of Microbiology
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• v.30 no.1
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• pp.60-64
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• 1992

The secretion vector with promoter and signal sequence region of neutral protease gene (npr) from Bacillus amyloliquefaciens was constructed by the technique of polymerase chain reaction (PCR). A unique restriction iste was introduced into the 3' of the signal coding region by the synthesis of PCR primer. To demonstrate the function of cloned promoter and signal sequence, we used the E. coli .betha.-lactamase structural gene as a foreign gene. The signal sequence of .betha.-lactamase gene was deleted by Bal31 exonuclease and only mature region was introduced into the secretion vector. Bacillus subtilis cells transformed by the recombinant vector synthesized the fusion protein and were also capable of removing the signal peptide from the original fusion protein, as judged by the assay of .betha.-lactamase activity and secretion into the growth medium by western blotting.

• YAKHAK HOEJI
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• v.47 no.6
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• pp.456-460
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• 2003

In vitro $\beta$-lactamase inhibitory activity of 6-exomethylenepenam compounds ( 1, 2, 3, 4 and 5) was compared with clavulanic acid, sulbactam and tazobactam. The inhibitory activity of compound 3 was stronger than those of sulbactam and clavulanic acid against Type I and II enzymes and stronger than tazobactam against Type III, IV, TEM enzymes. The inhibitory activity of 5 was stronger than sulbactam and clavulanic acid against Type I and II enzymes and stronger than tazobactam against Type III, and IV enzymes. The in vitro antimicrobial activity of 3, 4 and 5 combined with ampicillin and cefoperazone was compared with the sulbactam against $\beta$-lactamase producing 27 strains. But, synergistic activity of 3 and 5 was inferior to tazobactam.

• Journal of Periodontal and Implant Science
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• v.21 no.1
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• pp.176-176
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• 1991

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.624-629
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• 2009

It is the most important step to screen soluble and insoluble proteins when we attempt to improve the solubility of recombinant proteins through directed evolution approach. Here we show that the solubility of a recombinant protein in vivo can be examined by expressing the recombinant protein with beta-lactamase as a fusion partner. First we constructed an expression system which can produc a fusion protein with the C-terminal of beta-lactamase. Two soluble proteins, i.e. adenine deaminase and aspartate aminotransferase, and insoluble GlcNAc-2-epimerase were cloned into the developed expression vector, respectively. We investigated the effect of the expression of the three recombinant fusion proteins on the growth of E. coli, and confirmed that the solubilities of the recombinant proteins correlated with cell growth rates.

• YAKHAK HOEJI
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• v.34 no.2
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• pp.106-111
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• 1990

The isolation and identification of an antibacterial component, from the leaves of Liriodendron tulipifera. K. Kotch against a cariogenic bacterium Streptococcus mutans OMZ 176, were carried out for developing of anticariogenic agents. The bioactive component was elucidated as ${\beta}-liriodenolide$, which was isolated newly from the leaves of L. tulipifera. The minimal inhibitory concentration (MIC) of ${\beta}-liriodenolide$ was $100\;{\mu}g/ml$ and the antibacterial activity was stronger than that of berberine. ${\beta}-Liriodenolide$ inhibited ${\beta}-lactamase$ activity, 50, 100 and $200\;{\mu}M$ ${\beta}-liriodenolide$ did ${\beta}-lactamase$ activity as 0.7, 3.5 and 19.7%, respectively. The toxicity of ${\beta}-liriodenolide$ was not found with the method of photohemolysis.

• Korean Journal of Microbiology
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• v.40 no.2
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• pp.104-110
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• 2004

To determine evolution and genotype of new chromosomal AmpC $\beta$-lactamases among clinical isolates of Enterobacter species, we performed antibiotic susceptibility testing, pI determination, sequencing, and phy-logenetic analysis using developed expression/secretion vector. Six isolates have shown to produce AmpC $\beta$-lactamases. Six genes of AmpC $\beta$-lactamases that are responsible for the resistance to cephamycins (cefoxitin and cefotetan), amoxicillin, cephalothin, and amoxicillin-clavulanic acid were cloned and characterized in pMSG12119. Insert fragment containing the ampC genes was sequenced and found to have an open reading frame coding for 381-amino-acid $\beta$-lactamase. The nucleotide sequence of four ampC genes ($bla_EcloK992004.l$, $bla_EcloK995120.1$, $bla_EcloK99230$, and $bla_EareK9911729$) shared considerable homology with that of chromosomal ampC gene ($bla_EcloMHN1$) of E. cloacae MHN1 (more than 99.6% identity). The sequences of two ampC genes ($bla_EcloK9973$ and $bla_EcloK9914325$) showed close similarity to the chromosomal ampC gene ($bla_EcloQ908R$) of E. clo-acae 908R (99.7% identity). The results from phylogenetic analysis suggested that six ampC genes could be originated from $bla_EcloMHN1$ / or $bla_EcloQ908R$ / MIC patterns and exact pI values of six transformants indicated that the developed expression/secretion vector (pMSG1219) was suitable for the characterization of foreign genes in E. coli strain.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.1
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• pp.20-25
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• 2009

Thirty-eight Vibrio spp. were isolated from the sea waters harvested from the 22 stations located on the west coast of the Korean peninsula in September 2006. The isolates consisted of V. parahaemolyticus (n=21), V. alginolyticus (n= 16) and V. cholerae non-01 (n=1), among which 35 isolates displayed resistance against two of the tested antibiotics. Among the 38 isolates, 18 isolates exhibited multi-drug resistance against more than four 4 antibiotics. In particular, minimum inhibitory concentration $(MIC)_{50}$ and $MIC_{90}$ of ampicillin-resistant isolates were as high as $2,048{\mu}g{\cdot}mL^{-1}$ and $4,096{\mu}g{\cdot}mL^{-1}$ respectively. $\beta$-lactamase production was examined to analyze the ampicillin-resistance. Some Vibrio spp. isolates produced $\beta$-lactamase, however antibiotics resistance pattern and $\beta$-lactamase production were not clearly related to each other. A genetic relationship between resistance and gene expression was confirmed in the ampicillin-resistant isolates.

• The Journal of the Korean Society for Microbiology
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• v.34 no.5
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• pp.445-452
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• 1999

Eight strains of multidrug-resistant (MDR) Salmonella typhi were isolated from Kyonggi area during January-February, 1997. They were resistant to ampicillin, amoxicillin, carbenicillin, tetracycline, chloramphenicol, trimethoprim/sulfamethoxazole, trimethoprim. Eight strains had one plasmid respectively which size was approximately M.W 220 kb and showed same restriction pattern by endonuclease HindIII. The plasmid was similar to the plasmid in size that was related to multidrug resistant S. typhi isolated from southeast Asia. It were transferred by conjugation to recipient E. coli K-12 in frequency of $2.43{\times}10^4-1.73{\times}10^{-2}$ and transconjugant showed same drug-resistant pattern with donor cells. All of 8 strains produced ${\beta}$-lactamase that was assummed to TEM-l type by isoelectric focusing and PCR.

• Bulletin of the Korean Chemical Society
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• v.14 no.4
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• pp.491-496
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• 1993

A class A ${\beta}$-lactamase from Staphylococcus aureus PC1 complexed with 3R,5R-clavulanate is studied. The starting geometry for the computation is the crystal structure of the ${\beta}$-lactamase. Docking of the clavulanate to the enzyme is done exploiting the requirements of electrostatic and shape complementarity between the enzyme and clavulanate. This structure is then hydrated by water molecules and refined by energy minimization and short molecular dynamics simulation. In the energy refined structure of this complex, the carboxyl group of the clavulanate is hydrogen bonded to Lys-234, and the the carbonyl carbon atom of the clavulanate is adjacent to the $O_{\gamma}$ of Ser-70. It is found that a crystallographic water molecule initially located at the oxyanion hole, which is formed by the two -NH group of Ser-70 and Gln-237, is replaced by the carbonyl oxygen atom of the 3R,5R-clavulanate after docking and energy reginement. The crystallographic water molecules are proved to be important in ligand binding. Glu-166 residue is found to be repulsive to the binding of clavulanate, which is in agreement with experimental observation. Arg-244 residue is found to be important to the binding of clavulanate as well as to interaction with C2 side chain of the clavulanate. The electron density redistribution of the clavulanate on binding to the ${\beta}$-lactamase in studied by an ab initio quantum-mechanical calculation. A significant redistribution of electron density of the clavulanate is induced by the enzyme, toward the enzyme, toward the transition state of the enzymatic reaction.

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.1154-1162
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• 2015

The emergence of carbapenem resistance among Pseudomonas aeruginosa is an increasing problem in many parts of the world. In particular, metallo-$\beta$-lactamases (MBLs) and AmpC $\beta$lactamases are responsible for high-level resistance to carbapenem and cephalosporin. We studied the diversity and frequency of $\beta$-lactamases and characterized chromosomal AmpC $\beta$lactamase from carbapenem-resistant P. aeruginosa isolates. Sixty-one carbapenem-resistant P. aeruginosa isolates were collected from patients in a tertiary hospital in Daejeon, Korea, from January 2011 to June 2014. Minimum inhibitory concentrations (MICs) of four antimicrobial agents were determined using the agar-dilution method. Polymerase chain reaction and sequencing were used to identify the various $\beta$-lactamase genes, class 1 integrons, and chromosomally encoded and plasmid-mediated ampC genes. In addition, the epidemiological relationship was investigated by multilocus sequence typing. Among 61 carbapenem-resistant P. aeruginosa isolates, 25 isolates (41.0%) were MBL producers. Additionally, 30 isolates producing PDC (Pseudomonas-derived cephalosporinase)-2 were highly resistant to ceftazidime (MIC₅₀ = $256{\mu}g/ml$) and cefepime (MIC₅₀ = $256{\mu}g/ml$). Of all the PDC variants, 25 isolates harboring MBL genes showed high levels of cephalosporin and carbapenem resistance, whereas 36 isolates that did not harbor MBL genes revealed relatively low-level resistance (ceftazidime, p < 0.001; cefepime, p < 0.001; imipenem, p = 0.003; meropenem, p < 0.001). The coexistence of MBLs and AmpC $\beta$-lactamases suggests that these may be important contributing factors for cephalosporin and carbapenem resistance. Therefore, efficient detection and intervention to control drug resistance are necessary to prevent the emergence of P. aeruginosa possessing this combination of $\beta$-lactamases.