• Molecules and Cells
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• 제38권2호
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• pp.180-186
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• 2015

Escherichia coli AcrAB-TolC is a multidrug efflux pump that expels a wide range of toxic substrates. The dynamic nature of the binding or low affinity between the components has impeded elucidation of how the three components assemble in the functional state. Here, we created fusion proteins composed of AcrB, a transmembrane linker, and two copies of AcrA. The fusion protein exhibited acridine pumping activity, suggesting that the protein reflects the functional structure in vivo. To discern the assembling mode with TolC, the AcrBA fusion protein was incubated with TolC or a chimeric protein containing the TolC aperture tip region. Three-dimensional structures of the complex proteins were determined through transmission electron microscopy. The overall structure exemplifies the adaptor bridging model, wherein the funnel-like AcrA hexamer forms an intermeshing cogwheel interaction with the ${\alpha}$-barrel tip region of TolC, and a direct interaction between AcrB and TolC is not allowed. These observations provide a structural blueprint for understanding multidrug resistance in pathogenic Gram-negative bacteria.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2006년도 International Meeting of the Microbiological Society of Korea
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• pp.29-31
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• 2006

In a previous report, we showed that enzyme $IIA^{Glc}(EIIA^{Glc}$ of Escherichia coli phosphotransferase system (PTS) interacts with and regulates activity of FrsA (fermentation/respiration switch protein). A BLAST search revealed that orthologs of FrsA exist only in some Gram-negative bacteria such as E. coli, Salmonella typhimurium, Shigella flexneri, Yersinia pestis, Vibrio cholerae, Vibrio vulnificus, Vibrio parahemeolyticus, and Photorhabdus luminescens and all of these species are facultative anaerobes belonging to the ${\gamma}-proteobacterial$ group, and most of them are highly pathogenic. Ligand-fishing experiments using $EIIA^{Glc}$ of Vibrio vulnificus ($vEIIA^{Glc}$) as bait revealed that $vEIIA^{Glc}$ also interacts with vFrsA in a phosphorylation state-dependent manner. The frsA mutant of Vibrio vulnificus showed remarkably reduced cytotoxicity to HeLa cells and reduced lethality to mice compared to wild type. Comparison of extracellular proteomes between the mutant and wild type indicated that hemolysin was not produced in the frsA mutant. Characterization of another protein interacting with $vEIIA^{Glc}$ will be discussed.

• 미생물학회지
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• 제54권2호
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• pp.149-151
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• 2018

Clostridium perfringens는 그람 양성, 막대 모양, 혐기성, 포자 형성을 하는 병원균으로서 Clostridiaceae과에 속한다. C. perfringens는 인간의 장관과 척추동물 내에서 식중독을 포함하는 질병을 유발한다. 높은 특이성으로 목표 세균을 죽이는 박테리오파지는 병원세균을 제어하는 방법들 중 하나로 여겨져 왔다. 본 연구에서는 C. perfringens를 감염시킬 수 있는 박테리오 파지 CP3의 유전체 염기서열 초안을 보고한다. 본 박테리오파지의 G + C 비율은 34.0%이며, 52,068 bp로 구성된 유전체 DNA를 지니고 있었다. 이 유전체는 74개의 단백질 유전자를 포함하고 있었으며, RNA는 확인되지 않았다.

• 미생물학회지
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• 제54권2호
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• pp.152-154
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• 2018

Klebsiella pneumoniae는 그람 음성균에 속하고 막대 형태를 가지며 인간이나 동물의 폐에 감염하여 병을 일으키는 균이다. K. pneumoniae는 흔히 항생제 내성을 나타내는데 이로 인해 항생제를 통한 치료가 어려워지게 된다. 이런 상황에서 숙주 균에 특이적이고 민감하게 반응하는 박테리오파지는 항생제 내성균의 치료에 대한 대체적인 접근법으로 제안될 수 있다. 박테리오파지 KP1은 하수처리장에서 분리되었으며 K. pneumoniae에 대해 특정적인 감염성이 있다. 본 연구에서는 Klebsiella pneumoniae 박테리오파지 KP1의 유전체 초안 분석을 수행하였다. KP1의 유전체 초안은 167,989 bp의 길이, 39.6%의 G + C 비율로 구성되어있다. 295개의 예측된 ORF들과 14개의 tRNA 유전자를 가지고 있다. 또한 이들은 lysozyme, 그리고 holin과 같은 다양한 세포 용해 관련 효소들을 포함하고 있다.

• KSBB Journal
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• 제21권2호
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• pp.164-169
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• 2006

제주도 자생식물의 열수 추출물 10종의 항균 효과 및 항산화 효과를 검색하였다. 실험 대상 식물은 생체 채집하여 음건 한 후 열수 추출하여 시료화하여 어류 질병미생물에 대한 항균실험과 각 식물의 열수 추출물의 항산화 효과를 측정 하였다. 항균 실험은 어류 질병미생물로 분류된 그람 음성균 12종과 그람 양성균 1종에 대하여 디스크 확산법으로 측정하였는데 그 결과 두메꿀풀 꽃 추출물에서 가장 강한 항균효과를 나타내었고 다음으로 풀고사리 잎과 돌잔고사리 잎, 들깨 잎, 들깨 열매 순으로 나타났으며 큰천남성 뿌리나 왕모시풀 잎, 열매에서는 눈에 띄는 항균 효과를 나타내지는 않았다. 그리고 항산화 효과를 측정하기 위해 DPPH radical 소거능과 SOD 유사활성, Hydroxyl radical 소거 활성을 실험하였다. 각 식물의 열수 추출물을 농도별로 희석하여 측정한 결과 농도가 높아질수록 항산화 효과가 증가하는 것을 확인 할 수가 있었으며 2.0%(20 mg/ml)농도에서 두메꿀풀 잎과 열매 그리고 들깨 잎과 열매, 돌잔고사리 잎은 합성 항산화제인 BHT, BHA와 높거나 유사한 항산화 효과를 나타내었다.

• 한국식품영양과학회지
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• 제38권4호
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• pp.509-516
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• 2009

메주로부터 곰팡이 및 세균 등에 생육 저해활성을 나타내는 균주 B. polyfermenticus CJ6을 분리 동정하였다. 분리 균주 B. polyfermenticus CJ6는 2단 대수기를 나타내는 생육 곡선상 특이점을 나타내었으며 배양 30시간 이후부터 최대 활성을 나타내었고 사멸기 이후 활성이 다소 감소되었으나 120시간까지 활성을 유지하였다. B. polyfermenticus CJ6의 항진균 활성 물질은 $70^{\circ}C$ 이상에서 활성이 감소되었으나 $121^{\circ}C$에서 15분간 열처리 시 역가가 완전히 소실되지 않았다. pH 안정성 실험에서는 pH $3.0{\sim}9.0$ 구간에서 안정한 활성을 나타내었으며, 각종 효소에 대한 영향에서 항진균 활성물질은 proteinase K, protease, ${\alpha}$-chymotrypsin 등의 단백분해효소 처리로 역가를 상실하거나 일부 감소되어 단백질성 물질임을 추정하였다. 균주의 항진균 활성 물질을 $C_{18}$ Sep-Pak column으로 부분 정제한 후 Tricine-SDS-PAGE 및 direct detection 실험을 통하여 분자량이 약 1.4 kDa의 물질임을 확인하였다. B. polyfermenticus CJ6가 생산하는 항진균 활성 물질은 기존에 거의 보고되지 않은 B. polyfermenticus 유래의 단백질성 항진균 활성 물질로서 천연보존제 및 천연항균제재로 사용이 기대되며, 이를 위하여 항진균 활성 물질들의 정제 및 구조분석 등의 연구가 필요하다.

• Genomics & Informatics
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• 제13권2호
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• pp.53-59
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• 2015

In developing countries threat of cholera is a significant health concern whenever water purification and sewage disposal systems are inadequate. Vibrio cholerae is one of the responsible bacteria involved in cholera disease. The complete genome sequence of V. cholerae deciphers the presence of various genes and hypothetical proteins whose function are not yet understood. Hence analyzing and annotating the structure and function of hypothetical proteins is important for understanding the V. cholerae. V. cholerae O139 is the most common and pathogenic bacterial strain among various V. cholerae strains. In this study sequence of six hypothetical proteins of V. cholerae O139 has been annotated from NCBI. Various computational tools and databases have been used to determine domain family, protein-protein interaction, solubility of protein, ligand binding sites etc. The three dimensional structure of two proteins were modeled and their ligand binding sites were identified. We have found domains and families of only one protein. The analysis revealed that these proteins might have antibiotic resistance activity, DNA breaking-rejoining activity, integrase enzyme activity, restriction endonuclease, etc. Structural prediction of these proteins and detection of binding sites from this study would indicate a potential target aiding docking studies for therapeutic designing against cholera.

• 한국미생물·생명공학회지
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• 제28권5호
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• pp.279-284
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• 2000

This study was per-formed to screen lactic acid bacteria poultry for the probiotic use. Among the previously obtained acid tolerant, 139 strains, 111 strains were selected with MRS medium containing 0.3% oxgall. 34 strains of 111 was re-selected by Gram-staining and acid producing ability. These strains was identified by MIDI Sherlock Microbial Identification System. Among the identified 34 strains Lactobacillus fermenum YL-3 was selected for the final pro-biotic use because of the good growth and high survival rate at pH 2.0. 60%, 50% and 40% cells of Lactobacillus fermentum YL-3 survived at pH 3.0, 2.5 and 2.0, respectively. More than $10^{7}$ / CFU/ml survived when exposed with the number of $10^{8}$ CFU/ml at pH 2.0 after 12 hr. L.fermenum YL-3 maintained growth in MRS broth containing 0.3, 0.5, 1.0 and 2.0% oxgall for 24 hr. L.fermenum YL-3 showed an inhibitory effect against pathogenic strains of Sal. enteritidis and E. coli O157:H7. In mixed culture with L.fermenum YL-3 Sal. enteritidis lost ability com-pletely in 15 hrs and E. coil O157:H7 in 16 hrs.

• Journal of Microbiology and Biotechnology
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• 제30권9호
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• pp.1305-1309
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• 2020

Insects possess biological defense systems that can effectively combat the invasion of external microorganisms and viruses, thereby supporting their survival in diverse environments. Antimicrobial peptides (AMPs) represent a fast-acting weapon against invading pathogens, including various bacterial or fungal strains. A 37-residue antimicrobial peptide, papiliocin, derived from the swallowtail butterfly Papilio xuthus larvae, showed significant antimicrobial activities against several human pathogenic bacterial and fungal strains. Jelleines, isolated as novel antibacterial peptides from the Royal Jelly (RJ) of bees, exhibit broad-spectrum protection against microbial infections. In this study, we developed a novel antimicrobial peptide, PAJE (RWKIFKKPFKISIHL-NH₂), which is a hybrid peptide prepared by combining 1-7 amino acid residues (RWKIFKK-NH₂) of papiliocin and 1-8 amino acid residues (PFKISIHL-NH₂) of Jelleine-1 to alter length, charge distribution, net charge, volume, amphipaticity, and improve bacterial membrane interactions. This novel peptide exhibited increased hydrophobicity and net positive charge for binding effectively to the negatively charged membrane. PAJE demonstrated antimicrobial activity against both gram-negative and gram-positive bacteria, with very low toxicity to eukaryotic cells and an inexpensive process of synthesis. Collectively, these findings suggest that this novel peptide possesses great potential as an antimicrobial agent.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제20권1호
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• pp.7-14
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• 2014

Purpose: In this study, we performed ventilation simulations for a standard isolation ward including three intensive care rooms, one anteroom(buffer room), and its recommended ventilation equipments. The purpose of this study is to predict outflow of pathogenic bacteria from patient breath to verify the reliability and the safety of the isolation ward. Methods: We suppose three scenarios of the movement of medical staff. The leakage of patient's breath to out of the ward is predicted in these scenarios using CFD simulations. Results: The patient's breath leakage rate to out of the ward in scenario 1 according to room air changes per hour(ACH : 6 and 12) is predicted to be 0.000057% and 0.00002%, respectively. The patient's breath leakage rate to out of the ward in scenario 2 according to room air changes(ACH : 6 and 12) is predicted to be 0.00063% and 0.00019%, respectively. The patient's breath leakage rate to out of the ward in scenario 3, which is the worst case(6 room air changes) is predicted to be 0.1%. Implications: Through the ventilation simulation like that in this study, the reliability and the safety on isolation performance of various plan of isolation ward are predicted quantitatively.