• Journal of Microbiology and Biotechnology
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• 제17권10호
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• pp.1607-1615
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• 2007

We investigated the applicability of the TEM-l ${\beta}$-lactamase fragment complementation (BFC) system to develop a strategy for the screening of protein-protein interactions in bacteria. A BFC system containing a human Fas-associated death domain (hFADD) and human Fas death domain (hFasDD) was generated. The hFADD-hFasDD interaction was verified by cell survivability in ampicillin-containing medium and the colorimetric change of nitrocefin. It was also confirmed by His pull-down assay using cell lysates obtained in selection steps. A coiled-coil helix coiled-coil domain-containing protein 5 (CHCH5) was identified as an interacting protein of human uracil DNA glycosylase (hUNG) from the bacterial BFC cDNA library strategy. The interaction between hUNG and CHCH5 was further confirmed with immunoprecipitation using a mammalian expression system. CHCH5 enhanced the DNA glycosylase activity of hUNG to remove uracil from DNA duplexes containing a U/G mismatch pair. These results suggest that the bacterial BFC cDNA library strategy can be effectively used to identify interacting protein pairs.

• 미생물학회지
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• 제24권3호
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• pp.302-307
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• 1986

내성 P.aeruginosa에 의해 생성되는 항생물질 파괴효소인 cephalosporinase는 cephaloridine을 기질로 하여 효소활성도는 $45^{\circ}C$와 pH 8.5에서 각기 최고의 활성도를 나타내었다. SDS. carbenicillin 빛 cephalosporin계 항생체에 의해 효소의 활성도는 현저하게 억제되었으며 효소의 cephaloridine에 대한 $V_{max}$ 값을 100으로 하였올때 cefo p perazone의 $V_{max}$ 값은 2.8로 나타났다. 측정된 효소의 분자량은 $37.500{\pm}3,000$이었다. 다른 Gram음성셰균이 분비하는 cephalosporinase와 비교해본 결과 균체 자체의 특성에 의해 cepha]osporinase는 서로 다름을 알 수 있였 으며 이로 인하여 각각의 균체가 cephalosporin계 항생제에 대한 내성의 차이를 나타내는 하나의 중요한 원인으로 판단되었다.

• 약학회지
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• 제41권1호
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• pp.126-131
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• 1997

To overcome the problems of the resistance to clavulanic acid, many researchers are developing novel inhibitors that are not sensitive to new mutant ${\beta}$-lactamases. In order to evaluate newly synthesized compound CH2150 (Sodium (3S.5R)-6(Z)-[1-{1-(2-{2-benzoxazoly}thioethyl)-l.2,3-txiazol-4-yl}methylene] penicillanate-1,1-dioxide) as a ${\beta}$-lactamase inhibitor, we examined inhibitory activity of CH2150 against ${\beta}$-lactamases of clinical isolates resistant to ampicillin/sulbactam(12 strains of Escherichia coli and 13 strains of Staphylococcus aureus), and compared with that of sulbactam. Nitrocefin was used as substrate for ${\beta}$-lactamases, and the increase of absorbance was measured spectrophotometerically at 482 nm. ${\beta}$-Lactarnase inhibition of CH2150 against ${\beta}$-lactamases was 73 ~ 96% in E. coli and 76 ~ 79% in S. aureus. Comparatively, that of sulbactam was 96 ~ 100% and 96 ~ 100%, respectively. The inhibitory activity of CH2150 was slightly lower than that of sulbactam. The MIC values of ampicillin combined with CH2150 (2:1) for the clinical isolates were 4~512 ${\mu}$g/ml for E. coli and 1.0 ~ 64 ${\mu}$g/ml for S. aureus, whereas 0.5~16 ${\mu}$g/ml for E. coli and 0.25~8 ${\mu}$g/ml for S. aureus when combined with sulbactam (2:1).

• Archives of Pharmacal Research
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• 제24권6호
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• pp.590-596
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• 2001

A new extended-spectrum ${\beta}-lactamase$ with an isoelectric point (pl) of 6.2 was detected in Klebsiella pneumoniae Fl 61 that was isolated from a patient with infection. This strain was highly resistant to the third or fourth generation cephalosporins such as cceftazidime ceftriaxone, cefoperzaone, and cefpirome. Analysis of this strain by the double disk diffusion test showed synergies between amoxicillin-clavulanate (AMX-CA) and cefotaxime, and AMX-CA and aztreonam, which suggested that this strain produced a extended-spectrum ${\beta}-lactamase$ (ESBL). Cenetic analysis revealed that the resistance was due to the presence of a 9.4-kb plasmic, designated as pkpl 61, encoding for new ${\beta}-lactamase$ gene (bla). Sequence analysis showed that a new bla gene of pkpl 61 differed from $bla_{TEM-1}$ by three mutations leading to the following amino acid substitutions: $Val_{84}{\rightarrow}lie,{\;}Ala_{184}{\rightarrow}Val,{\;}and{\;}Gly_{238}{\rightarrow}Ser$. These mutations have not been reported previously in the TIM type ${\beta}-lactamases$ produced by clinical strains. The novel ${\beta}-lactamase$ was overexpressed in E. coli and purified by ion exchange chromatography on Q-Sepharose and CM-Sepharose, and then further purified by gel filtration on Sehadex G-200. The catalytic activity of th8 purified ${\beta}-lactamase$ was confirmed by the nitrocefin disk.

• Journal of Microbiology
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• 제44권4호
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• pp.423-431
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• 2006

Among 53 Acinetobacter baumannii isolates collected in 2004, nine imipenem-resistant isolates were obtained from clinical specimens taken from patients hospitalized in Busan, Korea. Nine carbapenemase-producing isolates were further investigated in order to determine the mechanisms underlying resistance. These isolates were then analyzed via antibiotic susceptibility testing, microbiological tests of carbapenemase activity, pI determination, transconjugation test, enterobacterial repetitive consensus (ERIC)-PCR, and DNA sequencing. One outbreak involved seven cases of infection by A. baumannii producing OXA-23 ${\beta}-lactamase$, and was found to have been caused by a single ERIC-PCR clone. During the study period, the other outbreak involved two cases of infection by A. baumannii producing IMP-1 ${\beta}-lactamase$. The two clones, one from each of the outbreaks, were characterized via a modified cloverleaf synergy test and an EDTA-disk synergy test. The isoelectric focusing of the crude bacterial extracts detected nitrocefin-positive bands with pI values of 6.65 (OXA-23) and 9.0 (IMP-1). The PCR amplification and characterization of the amplicons via direct sequencing showed that the clonal isolates harbored $bla_{IMP-1}$ or $bla_{oxA-23}$ determinants. The two clones were characterized by a multidrug resistance phenotype that remained unaltered throughout the outbreak. This resistance encompassed penicillins, extended-spectrum cephalosporins, carbapenems, monobactams, and aminoglycosides. These results appear to show that the imipenem resistance observed among nine Korean A. baumannii isolates could be attributed to the spread of an IMP-lor OXA-23-producing clone. Our microbiological test of carbapenemase activity is a simple method for the screening of clinical isolates producing class D carbapenemase and/or class B $metallo-{\beta}-lactamase$, in order both to determine their clinical impact and to prevent further spread.

• Journal of Microbiology and Biotechnology
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• 제16권9호
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• pp.1377-1383
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• 2006

Among 46 Acinetobacter baumannii isolates collected in 2004, two imipenem-resistant isolates were obtained from clinical specimens taken from patients hospitalized in Busan, Republic of Korea. Two carbapenemase-producing isolates were further investigated to determine the mechanism of resistance. These isolates were analyzed by antibiotic susceptibility testing, microbiological tests of carbapenemase activity, determination of pI, transconjugation test, enterobacterial repetitive consensus (ERIC)-PCR, and DNA sequencing. Two cases of infection by A. baumannii producing the IMP-1 ${\beta}$-lactamase were detected. The isolates were characterized by a modified cloverleaf synergy test and EDTA-disk synergy test. Isoelectric focusing of crude bacterial extracts revealed nitrocefin-positive bands with a pI value of 9.0. PCR amplification and characterization of the amplicons by direct sequencing indicated that the isolates carried a $bla_{IMP-l}$ determinant. The isolates were characterized by a multidrug resistance phenotype, including penicillins, extended-spectrum cephalosporins, carbapenems, and aminoglycosides. These results indicate that the observed imipenem resistance of two Korean A. baumannii isolates was due to the spread of an IMP-1-producing clone. Our microbiological test of carbapenemase activity is simple to screen class B metallo-${\beta}$-lactamase-producing clinical isolates to determine their clinical impact and to prevent further spread. This study shows that the $bla_{IMP-l}$ resistance determinant, which is emerging in Korea, may become an emerging therapeutic problem, since clinicians are advised not to use extended-spectrum cephalosporins, imipenem, and aminoglycosides. This observation emphasizes the importance of having effective control measures in Asian hospitals, such as early detection of colonized patients, isolation procedures, and a judicious use of antibiotics.