• Title/Summary/Keyword: MurA

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Identification of Novel Irreversible Inhibitors of UDP-N-Acetylglucosamine Enolpyruvyl Transferase (MurA) from Haemophilus influenzae

  • Han, Seong-Gu;Lee, Won-Kyu;Jin, Bong-Suk;Lee, Ki-In;Lee, Hyeong Ho;Yu, Yeon Gyu
    • Journal of Microbiology and Biotechnology
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    • v.23 no.3
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    • pp.329-334
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    • 2013
  • Uridinediphospho-N-acetylglucosamine enolpyruvyl transferase (MurA, E.C. 2.5.1.7) is an essential bacterial enzyme that catalyzes the first step of the cell wall biosynthetic pathway, which involves the transfer of an enolpyruvyl group from phosphoenolpyruvate to uridinediphospho-Nacetylglucosamine. In this study, novel inhibitors of Haemophilus influenzae MurA (Hi MurA) were identified using high-throughput screening of a chemical library from the Korea Chemical Bank. The identified compounds contain a quinoline moiety and have much lower effective inhibitory concentrations ($IC_{50}$) than fosfomycin, a wellknown inhibitor of MurA. These inhibitors appear to covalently modify the sulfhydryl group of the active site cysteine (C117), since the C117D mutant Hi MurA was not inhibited by these compounds and excess dithiothreitol abolished their inhibitory activities. The increased mass value of Hi MurA after treatment with the identified inhibitor further confirmed that the active-site cysteine residue of Hi MurA is covalently modified by the inhibitor.

Structural Characterization of Physiologically Active Polysaccharides from Natural Products (Arabidopsis)

  • Shin, Kwang-Soon;Darvill, Alan G.
    • Food Science and Biotechnology
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    • v.15 no.3
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    • pp.447-452
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    • 2006
  • To determine the functions of specific cell wall polysaccharides, polysaccharides of three mutants, mur3-1, mur3-2, and mur3-3, obtained from Arabidopsis wild type, underwent structural characterization. Upon sequential separation of pectins (RG-I and RG-II) and cross-linking glycans (xyloglucan, XG), only XG was affected by the mud mutation. Wild-type XG contained a considerable amount of fucose, whereas the fucose level in mur3 XGs was less than 20% that of wild type. Further analysis of XGs by matrix-assisted laser-induced/ionization time-of-flight (MALDI-TOF) mass spectrometry indicated that mud lines considerably or completely lost the fucosylated XG oligosaccharides such as XXFG and XLFG and the double-galactosylated oligosaccharide XLLG $^1H$-NMR spectroscopic analyses of the XG oligosaccharides from mur3-3 plant revealed the absence of fucose and a galactose level in the galactosylated side chain that was reduced by 40% compared to that of Arabidopsis wild-type plant. In contrast, 85% less fucose and a slight loss of galactose were observed in the mur3-1 and mur3-2 lines which show normal growth habit. Of the three Arabidopsis mur3 lines studied here, mur3-3 is disrupted by a T-DNA insertion in the exon of MUR3 which encodes XG-specific galactosyltransferase, and exhibits slight dwarfism. These results indicated that the T-DNA insertion at the MUR3 locus did not induce the complete loss of galactose in XG, and that galactose, rather than fucose, in the XG side chains made a major contribution to overall wall strength.

Kinetic Properties of Wild-type and C117D Mutant UDP-N-Acetylglucosamine Enolpyruvyl Transferase (MurA) from Haemophilus influenzae

  • Han, Seong-Gu;Jin, Bong-Suk;Lee, Won-Kyu;Yu, Yeon-Gyu
    • Bulletin of the Korean Chemical Society
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    • v.32 no.8
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    • pp.2549-2552
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    • 2011
  • In this study, the kinetic properties of wild-type and C117D mutant H. influenzae MurA (Hi MurA), which catalyzes the first reaction in the biosynthetic pathway of the cell wall, were characterized. Purified recombinant Hi MurA was active at pH values ranging from pH 5.5 to pH 10, and its $K_m$ (UNAG), $K_m$ (PEP), and $k_{cat}$ values were measured to be 31 ${\mu}M$, 24 ${\mu}M$, and 210 $min^{-1}$, respectively. Hi MurA activity was effectively inhibited by fosfomycin with an $IC_{50}$ value of 60 ${\mu}M$. Hi MurA contains a cysteine residue (C117) at the loop region near the PEP binding, whereas MurA from fosfomycin resistant Mycobaterium tuberculosis or Chlamydia trachomatis contain an aspartate residue instead of the cysteine at the corresponding site. Aspartate substitution of Cys117 in Hi MurA shifted its optimum pH from 7.8 to 6.0. In addition, the $K_m$ values for UNAG and PEP were increased to 160 ${\mu}M$ and 150 ${\mu}M$, respectively, and the $k_{cat}$ value was significantly reduced to 41 $min^{-1}$. Furthermore, the C117D mutant form of Hi MurA was not inhibited by 1 mM fosfomycin. These results indicate that the Cys117 of Hi MurA is the binding site of fosfomycin and plays an important role in the fast turnover of the catalytic reaction.

Comparison with SAR Patterns of Biological Objects Contacted with Coaxial Waveguide Antenna Using MUR and GPML ABCs in the FDTD Method (유한차분법에서 MUR과 GPML 흡수경계조건을 이용한 동축 도파관 안테나에 접촉된 생체의 SAR 패턴 비교)

  • 구성모;권광희;이창원;원철호;조진호
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.9 no.2
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    • pp.149-158
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    • 1998
  • The SAR patterns of biological objects contacted with coaxial waveguide antennal has been investigated, in which the biological object was modeled by a homogeneous and four-layered lossy human body. We derived the finite-difference time-domain(FDTD) algorithm and equation of MUR and generalized perfectly matched layer(GPML) ABCs in cylindrical coordination. The coupling between coaxial waveguide antenna and a biological object was analyzed by use of MUR and GPML ABCs in the FDTD method to obtain the absorbed power patterns in the media. The specific absorption rates (SAR) distribution which was corresponding to the temperature distribution was calculated in each region by use of the steady-state response in the FDTD method. The SAR patterns of the FDTD method using MUR absorbing boundary conditions(ABCs) was compared with those of the FDTD method using GPML ABCs. The comparison exhibits that the penetration depth of the SAR patterns using MUR ABCs is deeper than that of the SAR patterns using GPML ABCs because of loss in free space. However, the spread in the lateral directions of the SAR patterns using GPML ABCs is smaller than of the SAR patterns using MUR ABCs.

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Inhibitory Mechanism of Novel Inhibitors of UDP-N-Acetylglucosamine Enolpyruvyl Transferase from Haemophilus influenzae

  • Jin, Bong-Suk;Han, Seong-Gu;Lee, Won-Kyu;Ryoo, Sung-Weon;Lee, Sang-Jae;Suh, Se-Won;Yu, Yeon-Gyu
    • Journal of Microbiology and Biotechnology
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    • v.19 no.12
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    • pp.1582-1589
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    • 2009
  • Bacterial UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) catalyzes the transfer of enolpyruvate from phosphoenolpyruvate (PEP) to uridine diphospho-N-acetylglucosamine (UNAG), which is the first step of bacterial cell wall synthesis. We identified thimerosal, thiram, and ebselen as effective inhibitors of Haemophilus influenzae MurA by screening a chemical library that consisted of a wide range of bioactive compounds. When MurA was preincubated with these inhibitors, their 50% inhibitory concentrations ($IC_{50}s$) were found to range from 0.1 to $0.7\;{\mu}M$. In particular, thimerosal suppressed the growth of several different Gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhimurium at a concentration range of $1-2\;{\mu}g/ml$. These inhibitors covalently modified the cysteine residue near the active site of MurA. This modification changed the open conformation of MurA to a more closed configuration, which may have prevented the necessary conformational change from occurring during the enzyme reaction.

An Analysis of A Circularly Polarized Conformal Microstrip Parch Antenna Using The Unsplit Anisotropic Perfectly Matched Layer(UAPML) (비분리형 비등방성 완전 정합층(UAPML)을 이용한 원형편파 등각 마이크로스트립 패치 안테나의 해석)

  • 박동희;김정기
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.9 no.6
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    • pp.813-823
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    • 1998
  • This paper analyzed the circularly polarized conformal microstrip patch antennal using the unsplit anisotropic perfectly matched layer(UAPML) method. Also, this paper are treated effectively the edge and corner parts on the 3 dimensional UAPML. Especially, to analyze microstrip patch antennas with the coaxial feeder line, it was applied to mixed the UAPML with Mur's first order absorbing boundary condition. Therefore this paper suggest the new the method to mix the UAPML with Mur's first order absorbing boundary condition. The results show the time responses of electromagnetics $E_z$ and $H\chi'$, input impedances of coaxial cable and radiation patterns of strip parchs on the single and the array patchs with central frequencies 1.575 GHz, 1.778 GHz and 4.8 GHz in L-band and C-band for mobile communication. The results of this paper shows that its results was compared the Mur's first order abc and mixed the second order dispersion boundary condition(SDBC) with the Mur's first order absorbing boundary condition. In accordance with, the validity of the method is confirmed.

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Chemogenomics Profiling of Drug Targets of Peptidoglycan Biosynthesis Pathway in Leptospira interrogans by Virtual Screening Approaches

  • Bhattacharjee, Biplab;Simon, Rose Mary;Gangadharaiah, Chaithra;Karunakar, Prashantha
    • Journal of Microbiology and Biotechnology
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    • v.23 no.6
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    • pp.779-784
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    • 2013
  • Leptospirosis is a worldwide zoonosis of global concern caused by Leptospira interrogans. The availability of ligand libraries has facilitated the search for novel drug targets using chemogenomics approaches, compared with the traditional method of drug discovery, which is time consuming and yields few leads with little intracellular information for guiding target selection. Recent subtractive genomics studies have revealed the putative drug targets in peptidoglycan biosynthesis pathways in Leptospira interrogans. Aligand library for the murD ligase enzyme in the peptidoglycan pathway has also been identified. Our approach in this research involves screening of the pre-existing ligand library of murD with related protein family members in the putative drug target assembly in the peptidoglycan biosynthesis pathway. A chemogenomics approach has been implemented here, which involves screening of known ligands of a protein family having analogous domain architecture for identification of leads for existing druggable protein family members. By means of this approach, one murC and one murF inhibitor were identified, providing a platform for developing an anti-leptospirosis drug targeting the peptidoglycan biosynthesis pathway. Given that the peptidoglycan biosynthesis pathway is exclusive to bacteria, the in silico identified mur ligase inhibitors are expected to be broad-spectrum Gram-negative inhibitors if synthesized and tested in in vitro and in vivo assays.

The Comparison with SAR Patterns of Biological Objects Contacted with Coaxial Waveguide Antenna Using the FDTD Method

  • Koo, S.M.;Kwon, K.H.;Lee, C.W.;Won, C.H.;Kim, M.N.;Cho, J.H.
    • Proceedings of the KOSOMBE Conference
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    • v.1997 no.11
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    • pp.272-275
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    • 1997
  • Noninvasive multifrequency microwave radiometry using coaxial waveguide antenna has been investigated for a homogeneous and our layer human body model. We derived finite-difference time-domain(FDTD) algorithm and equation of MUR and generalized perfectly matched layer(GPML) absorbing boundary conditions(ABCs) in cylindrical coordination. The coupling between coaxial waveguide antenna and a biological object was analyzed by use of the FDTD method using MUR and GPML ABCs to obtain the absorbed power patterns in the media. The specific absorption rates(SAR) distribution which was corresponding to the temperature distribution was calculated in each region by use of the steady-state response in FDTD method. The SAR patterns of FDTD method using MUR ABCs was compared with those of FDTD method using GPML ABCs.

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Contribution of the murI Gene Encoding Glutamate Racemase in the Motility and Virulence of Ralstonia solanacearum

  • Choi, Kihyuck;Son, Geun Ju;Ahmad, Shabir;Lee, Seung Yeup;Lee, Hyoung Ju;Lee, Seon-Woo
    • The Plant Pathology Journal
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    • v.36 no.4
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    • pp.355-363
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    • 2020
  • Bacterial traits for virulence of Ralstonia solanacearum causing lethal wilt in plants were extensively studied but are not yet fully understood. Other than the known virulence factors of Ralstonia solanacearum, this study aimed to identify the novel gene(s) contributing to bacterial virulence of R. solanacearum. Among the transposon-inserted mutants that were previously generated, we selected mutant SL341F12 strain produced exopolysaccharide equivalent to wild type strain but showed reduced virulence compared to wild type. In this mutant, a transposon was found to disrupt the murI gene encoding glutamate racemase which converts L-glutamate to D-glutamate. SL341F12 lost its motility, and its virulence in the tomato plant was markedly diminished compared to that of the wild type. The altered phenotypes of SL341F12 were restored by introducing a full-length murI gene. The expression of genes required for flagella assembly was significantly reduced in SL341F12 compared to that of the wild type or complemented strain, indicating that the loss of bacterial motility in the mutant was due to reduced flagella assembly. A dramatic reduction of the mutant population compared to its wild type was apparent in planta (i.e., root) than its wild type but not in soil and rhizosphere. This may contribute to the impaired virulence in the mutant strain. Accordingly, we concluded that murI in R. solanacearum may be involved in controlling flagella assembly and consequently, the mutation affects bacterial motility and virulence.

A Study on the Electromagnetic Wave Absorption Properties by the Composition Ratio and Sintering Condition of NiCuZn Ferrite (NiCuZn 페라이트의 조성 및 소결조건에 따른 전자파흡수 특성에 관한 연구)

  • 이영구;박찬규;이문수
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.5
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    • pp.994-1000
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    • 2001
  • With the development of electromagnetic communication technology and increased use of electromagnetic wave, the countermeasure of EMI(Electromagnetic Interference) becomes more important socially, and interest for the electromagnetic wave absorber has also increased. In this paper, we have studied characteristics of frequency dependency on complex permittivity and complex permeability according to the changes of composition rate and sintering temperature of NiCuZn ferrite also known as electromagnetic wave absorber and further looked into effect of electromagnetic wave absorption properties. From the measurement where the composition of $Fe_2O_3$ and ZnO of NiCuZn ferrite was fixed at 49 and 34 mol% respectively while composition of NiO and CuO has been varied at each test, we found out that Initial permeability and permittivity were high and the absorbing ability of electromagnetic wave recorded best with $loss tangent(=\mur"/\mur')$ displays more than 1 within the frequency band of 2MHz~9.5MHz when the composition ratio of NiO was ranged around 8.5~9.5 mol% and the sintering temperature was $1080^{\circ}C$.TEX>.

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