• Journal of Microbiology and Biotechnology
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• 제6권3호
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• pp.219-220
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• 1996

The pKH2 isolated from the multidrug-resistant Staphylococcus aureus SA2 is a 40.98-kb plasmid and mediates resistance to ampicillin, clindamycin, erythromycin, kanamycin, and streptomycin. The 3.4-kb HindIII fragment conferring kanamycin resistance was cloned from the pKH2 into pBluescriptII $KS^+$ and partial sequence determination of that fragment was carried out. Sequence analysis revealed that the kanamycin resistance gene which encoded aminoglycoside 3'-phosphotransferase was linked to the streptothricin resistance gene. But a nonsense mutation was found in the streptothricin resistance gene and this mutation resulted in a truncated protein of streptothricin acetyltransferase. Homology comparison with nucleotide sequence databases revealed that the 3.4-kb HindIII fragment of pKH2 had been derived not from S. aureus but from Gram-negative Campylobacter coli.

• Molecules and Cells
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• 제43권8호
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• pp.694-704
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• 2020

HslUV is a bacterial heat shock protein complex consisting of the AAA+ ATPase component HslU and the protease component HslV. HslV is a threonine (Thr) protease employing the N-terminal Thr residue in the mature protein as the catalytic residue. To date, HslUV from Gram-negative bacteria has been extensively studied. However, the mechanisms of action and activation of HslUV from Gram-positive bacteria, which have an additional N-terminal sequence before the catalytic Thr residue, remain to be revealed. In this study, we determined the crystal structures of HslV from the Gram-positive bacterium Staphylococcus aureus with and without HslU in the crystallization conditions. The structural comparison suggested that a structural transition to the symmetric form of HslV was triggered by ATP-bound HslU. More importantly, the additional N-terminal sequence was cleaved in the presence of HslU and ATP, exposing the Thr9 residue at the N-terminus and activating the ATP-dependent protease activity. Further biochemical studies demonstrated that the exposed N-terminal Thr residue is critical for catalysis with binding to the symmetric HslU hexamer. Since eukaryotic proteasomes have a similar additional N-terminal sequence, our results will improve our understanding of the common molecular mechanisms for the activation of proteasomes.

• Journal of Microbiology and Biotechnology
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• 제33권5호
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• pp.698-705
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• 2023

Rapid diagnosis of methicillin-resistant Staphylococcus aureus (MRSA) is essential for guiding clinical treatment and preventing the spread of MRSA infections. Herein, we present a simple and rapid MRSA screening test based on the aggregation effect of mannose-binding lectin (MBL)-conjugated gold nanoparticles (AuNP), called the MRSA probe. Recombinant MBL protein is a member of the lectin family and part of the innate immune system. It can recognize wall teichoic acid (WTA) on the membrane of MRSA more specifically than that of methicillin-sensitive Staphylococcus aureus (MSSA) under optimized salt conditions. Thus, the MRSA probe can selectively bind to MRSA, and the aggregation of the probes on the surface of the target bacteria can be detected and analyzed by the naked eye within 5 min. To demonstrate the suitability of the method for real-world application, we tested 40 clinical S. aureus isolates (including 20 MRSA specimens) and recorded a sensitivity of 100%. In conclusion, the MRSA probe-based screening test with its excellent sensitivity has the potential for successful application in the microbiology laboratory.

• 약학회지
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• 제46권1호
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• pp.24-29
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• 2002

Enoyl-Acyl Carrier Protein Reductase (Fabl) of bacteria is hem as an important target for new antibacterial drugs and plays a determinant role in completing cycles of elongation in type-H fatty acid synthase system. In this study, a fabI gene from Staphylococcus aureus 6538p cloned in pET-l4b vector and FabI protein was over-produced in Escherichaia coli BL2l (DE3). $NH_2$-terminal His-tagged FabI protein was purified by nickel-nitrilotriacetic acid (Ni-NTA) metalaffinity chromatography Purified 6xHis-tagged FabI showed a catalytic activity on tram - 2 - octenoyl - N -acethlcysteamine by utilizing NADPH as a cofactor. For the discovery of new FabI inhibitors from chemical libraries, a target-oriented screening system using a 96-well plate was developed. About 10,000 chemical libraries from Korea Chemical Bank wore tested in this screening system, and 26 chemicals (0.25%) among them showed an inhibitory activity against FabI enzyme. This result showed that a new screening system can be used for the discovery of new FabI inhibitors.

• 한국자원식물학회지
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• 제30권2호
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• pp.133-143
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• 2017

와송 ethylacetate 분획추출물의 폴리페놀 함량은 $634.48{\mu}g/mg$, 플라보노이드 함량은 $205.20{\mu}g/mg$로 나타났다. 또한 항산화 활성을 보면, ethylacetate 분획추출물의 1 mg/ml 농도에서 DPPH radical, ABTS radical 소거능은 95% 이상으로, ascorbic acid의 97%의 소거능과 거의 유사한 결과를 보여 높은 항산화능을 확인할 수 있었다. 항산화효소 활성의 경우, APX 및 CAT 효소 활성은 $1125.89{\mu}mol$ ascorbate oxidized/min/mg protein, 119.87mmol $H_2O_2$ decomposed/min/mg protein 으로 높은 것으로 나타났다. 항균활성은 Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus, Malassezia furfur 균주에서 항생제 kanamycin보다 큰 저해환을 형성하여 높은 항균력이 확인되었다. 또한 와송의 용매분획별 추출물의 인체암 세포주에 대한 세포증식억제 효과는 특히 ethylacetate 분획추출물에서 폐암, 유방암에 대해 높은 효과를 나타냈다. 이와 같은 결과들을 종합하면 와송의 ethylacetate 분획추출물을 이용한 천연 항산화제와, 천연 항균제로서의 개발 가치가 높은 것으로 기대되어 경제성 있는 천연소재가 될 것으로 사료된다.

• IMMUNE NETWORK
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• 제23권4호
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• pp.31.1-31.18
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• 2023

Evidence suggests that the human respiratory tract, as with the gastrointestinal tract, has evolved to its current state in association with commensal microbes. However, little is known about how the airway microbiome affects the development of airway immune system. Here, we uncover a previously unidentified mode of interaction between host airway immunity and a unique strain (AIT01) of Staphylococcus epidermidis, a predominant species of the nasal microbiome. Intranasal administration of AIT01 increased the population of neutrophils and monocytes in mouse lungs. The recruitment of these immune cells resulted in the protection of the murine host against infection by Pseudomonas aeruginosa, a pathogenic bacterium. Interestingly, an AIT01-secreted protein identified as GAPDH, a well-known bacterial moonlighting protein, mediated this protective effect. Intranasal delivery of the purified GAPDH conferred significant resistance against other Gram-negative pathogens (Klebsiella pneumoniae and Acinetobacter baumannii) and influenza A virus. Our findings demonstrate the potential of a native nasal microbe and its secretory protein to enhance innate immune defense against airway infections. These results offer a promising preventive measure, particularly relevant in the context of global pandemics.

• 미생물학회지
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• 제54권1호
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• pp.77-78
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• 2018

포도상구균(Staphylococcus aureus)은 그람양성이고 구형의 박테리아로 Firmicutes 문에 속하며, 피부나 호흡기 감염 그리고 식중독의 주요 감염원 중에 하나이다. 포도상구균을 감염시키는 박테리오파지는 포도상구균 감염에 효과적인 처방으로 쓰일 수 있다. 본 연구에서는 충청남도에 위치한 가축 농장의 오수에서 분리된 포도상구균 박테리오파지 SA7 균주의 유전체 초안을 분석하였다. 본 균주는 G + C 비율이 34.1%이며, 34,730 bp 로 구성된 dsDNA 를 지니고 있었다. 염색체에서 53 개의 단백질 코딩 유전자가 확인되었으며, 이 중 23 개의 유전자는 BLASTp 분석으로부터 기능을 가지고 있다고 추정되었다. 나머지는 가설 단백질 혹은 보존 단백질이었다.

• Journal of Microbiology and Biotechnology
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• 제34권8호
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• pp.1718-1726
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• 2024

Development of novel antibacterial agents is imperative due to the increasing threat of antibiotic-resistant pathogens. This study aimed to develop the enhanced antibacterial activity and in-vivo efficacy of a novel truncated endolysin, CHAP^SAP26-161, derived from the endolysin Lys^SAP26, against multidrug-resistant bacteria. CHAP^SAP26-161 exhibited higher protein purification efficiency in E. coli and antibacterial activity than Lys^SAP26. Moreover, CHAP^SAP26-161 showed the higher lytic activity against A. baumannii with minimal bactericidal concentrations (MBCs) of 5-10 ㎍/ml, followed by Staphylococcus aureus with MBCs of 10-25 ㎍/ml. Interestingly, CHAP^SAP26-161 could lyse anaerobic bacteria, such as Clostridioides difficile, with MBCs of 25-50 ㎍/ml. At pH 4-8 and temperatures of 4℃-45℃, CHAP^SAP26-161 maintained antibacterial activity without remarkable difference. The lytic activity of CHAP^SAP26-161 was increased with Zn²⁺. In vivo tests demonstrated the therapeutic effects of CHAP^SAP26-161 in murine systemic A. baumannii infection model. In conclusion, CHAP^SAP26-161, a truncated endolysin that retains only the CHAP domain from Lys^SAP26, demonstrated enhanced protein purification efficiency and antibacterial activity compared to Lys^SAP26. It further displayed broad-spectrum antibacterial effects against S. aureus, A. baumannii, and C. difficile. Our in vitro and in-vivo results of CHAP^SAP26-161 highlights its promise as an innovative therapeutic option against those bacteria with multiple antibiotic resistance.

• Journal of Microbiology and Biotechnology
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• 제27권10호
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• pp.1820-1826
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• 2017

Lipoteichoic acid (LTA), a cell wall component of gram-positive bacteria, is recognized by Toll-like receptor 2, expressed on certain mammalian cell surfaces, initiating signaling cascades that include nuclear factor kappa-light-chain-enhancer of activated B cells (NF-${\kappa}B$) and mitogen-activated protein kinase. There are many structural and functional varieties of LTA, which vary according to the different species of gram-positive bacteria that produce them. In this study, we examined whether LTA isolated from Staphylococcus aureus (aLTA) affects the expression of junction proteins in keratinocytes. In HaCaT cells, tight junction-related gene expression was not affected by aLTA, whereas adherens junction-related gene expression was modified. High doses of aLTA induced the phosphorylation of extracellular signal-regulated protein kinases 1 and 2, which in turn induced the epithelial-mesenchymal transition (EMT) of HaCaT cells. When cells were given a low dose of aLTA, however, NF-${\kappa}B$ was activated and the total cell population increased. Taken together, our study suggests that LTA from S. aureus infections in the skin may contribute both to the outbreak of EMT-mediated carcinogenesis and to the genesis of wound healing in a dose-dependent manner.

• Journal of Microbiology and Biotechnology
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• 제28권9호
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• pp.1426-1432
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• 2018

Staphylococcus aureus causes a broad variety of diseases. The spread of multidrug-resistant S. aureus highlights the need to develop new ways to combat S. aureus infections. Sortase A (SrtA) can anchor proteins containing LPXTG binding motifs to the bacteria surface and plays a key role in S. aureus infections, making it a promising antivirulence target. In the present study, we used a SrtA activity inhibition assay to discover that isovitexin, a Chinese herbal product, can inhibit SrtA activity with an $IC_{50}$ of $28.98{\mu}g/ml$. Using a fibrinogen-binding assay and a biofilm formation assay, we indirectly proved the SrtA inhibitory activity of isovitexin. Additionally, isovitexin treatment decreased the amount of staphylococcal protein A (SpA) on the surface of the cells. These data suggest that isovitexin has the potential to be an anti-infective drug against S. aureus via the inhibition of sortase activity.