The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Yi Liu - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the mechanism of the Staphylococcus aureus cell envelope by Bacitracin and Bacitracin-metal ions.
The Journal of Membrane Biology, 2008Co-Authors: Yi Lin, Bo Zhou, Xiaodi Ren, Dai-wen Pang, Yi LiuAbstract:Bacitracin is a metal-dependent dodecapeptide antipeptide produced by Bacillus species. Microcalorimetry was used to study the antimicrobial activity of Bacitracin and Bacitracin–metal ion complexation inhibited on Staphylococcus aureus at 37°C. The affinity of metal ions binding to Bacitracin was investigated by isothermal titration calorimetry and was as follows: Cu(II) ≥ Ni(II) > Co(II) > Zn(II) ≥ Mn(II). The metal ion binding affinity is not relative to the antimicrobial activity of Bacitracin–metal complexation. Atomic force microscopic images revealed that the surface of S. aureus treated by Bacitracin–Zn(II) was rather rough compared to that treated by Bacitracin only. The central cell surface displayed small depressed grooves around the septal annulus at the onset of division. Bacitracin mainly inhibited the splitting system within the thick cross walls as seen by transmission electron microscopy (TEM). The inhibition mechanism of Bacitracin may be relative to the assistance of Zn(II) coordination with the cell surface as seen by TEM. We can put forward that the activity of Bacitracin only inhibited growth and division initially from the synthesis of the cell wall, especially the cell wall of the septal annulus. The divalent metal ions function to increase the adsorption of Bacitracin onto the cell surface.
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Characterization of the mechanism of the Staphylococcus aureus cell envelope by Bacitracin and Bacitracin-metal ions.
The Journal of membrane biology, 2008Co-Authors: Yi Lin, Bo Zhou, Xiaodi Ren, Dai-wen Pang, Yi LiuAbstract:Bacitracin is a metal-dependent dodecapeptide antipeptide produced by Bacillus species. Microcalorimetry was used to study the antimicrobial activity of Bacitracin and Bacitracin-metal ion complexation inhibited on Staphylococcus aureus at 37 degrees C. The affinity of metal ions binding to Bacitracin was investigated by isothermal titration calorimetry and was as follows: Cu(II) >or= Ni(II) > Co(II) > Zn(II) >or= Mn(II). The metal ion binding affinity is not relative to the antimicrobial activity of Bacitracin-metal complexation. Atomic force microscopic images revealed that the surface of S. aureus treated by Bacitracin-Zn(II) was rather rough compared to that treated by Bacitracin only. The central cell surface displayed small depressed grooves around the septal annulus at the onset of division. Bacitracin mainly inhibited the splitting system within the thick cross walls as seen by transmission electron microscopy (TEM). The inhibition mechanism of Bacitracin may be relative to the assistance of Zn(II) coordination with the cell surface as seen by TEM. We can put forward that the activity of Bacitracin only inhibited growth and division initially from the synthesis of the cell wall, especially the cell wall of the septal annulus. The divalent metal ions function to increase the adsorption of Bacitracin onto the cell surface.
Yi Lin - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the mechanism of the Staphylococcus aureus cell envelope by Bacitracin and Bacitracin-metal ions.
The Journal of Membrane Biology, 2008Co-Authors: Yi Lin, Bo Zhou, Xiaodi Ren, Dai-wen Pang, Yi LiuAbstract:Bacitracin is a metal-dependent dodecapeptide antipeptide produced by Bacillus species. Microcalorimetry was used to study the antimicrobial activity of Bacitracin and Bacitracin–metal ion complexation inhibited on Staphylococcus aureus at 37°C. The affinity of metal ions binding to Bacitracin was investigated by isothermal titration calorimetry and was as follows: Cu(II) ≥ Ni(II) > Co(II) > Zn(II) ≥ Mn(II). The metal ion binding affinity is not relative to the antimicrobial activity of Bacitracin–metal complexation. Atomic force microscopic images revealed that the surface of S. aureus treated by Bacitracin–Zn(II) was rather rough compared to that treated by Bacitracin only. The central cell surface displayed small depressed grooves around the septal annulus at the onset of division. Bacitracin mainly inhibited the splitting system within the thick cross walls as seen by transmission electron microscopy (TEM). The inhibition mechanism of Bacitracin may be relative to the assistance of Zn(II) coordination with the cell surface as seen by TEM. We can put forward that the activity of Bacitracin only inhibited growth and division initially from the synthesis of the cell wall, especially the cell wall of the septal annulus. The divalent metal ions function to increase the adsorption of Bacitracin onto the cell surface.
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Characterization of the mechanism of the Staphylococcus aureus cell envelope by Bacitracin and Bacitracin-metal ions.
The Journal of membrane biology, 2008Co-Authors: Yi Lin, Bo Zhou, Xiaodi Ren, Dai-wen Pang, Yi LiuAbstract:Bacitracin is a metal-dependent dodecapeptide antipeptide produced by Bacillus species. Microcalorimetry was used to study the antimicrobial activity of Bacitracin and Bacitracin-metal ion complexation inhibited on Staphylococcus aureus at 37 degrees C. The affinity of metal ions binding to Bacitracin was investigated by isothermal titration calorimetry and was as follows: Cu(II) >or= Ni(II) > Co(II) > Zn(II) >or= Mn(II). The metal ion binding affinity is not relative to the antimicrobial activity of Bacitracin-metal complexation. Atomic force microscopic images revealed that the surface of S. aureus treated by Bacitracin-Zn(II) was rather rough compared to that treated by Bacitracin only. The central cell surface displayed small depressed grooves around the septal annulus at the onset of division. Bacitracin mainly inhibited the splitting system within the thick cross walls as seen by transmission electron microscopy (TEM). The inhibition mechanism of Bacitracin may be relative to the assistance of Zn(II) coordination with the cell surface as seen by TEM. We can put forward that the activity of Bacitracin only inhibited growth and division initially from the synthesis of the cell wall, especially the cell wall of the septal annulus. The divalent metal ions function to increase the adsorption of Bacitracin onto the cell surface.
Ryo Nagasawa - One of the best experts on this subject based on the ideXlab platform.
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potential risk of spreading resistance genes within extracellular dna dependent biofilms of streptococcus mutans in response to cell envelope stress induced by sub mics of Bacitracin
Applied and Environmental Microbiology, 2020Co-Authors: Ryo Nagasawa, Tsutomu Sato, Nobuhiko Nomura, Tomoyo Nakamura, Hidenobu SenpukuAbstract:Antibiotics are used to treat or prevent some types of bacterial infection. The inappropriate use of antibiotics unnecessarily promotes antibiotic resistance and increases resistant bacteria, and controlling these bacteria is difficult. While the emergence of drug-resistant bacteria is a serious problem, the behavior of drug-resistant bacteria is not fully understood. In this study, we investigated the behavior of Streptococcus mutans, a major etiological agent of dental caries that is resistant to Bacitracin, which is a cell wall-targeting antibiotic, and focused on biofilm formation in the presence of Bacitracin. S. mutans UA159 most strongly induced extracellular DNA (eDNA)-dependent biofilm formation in the presence of Bacitracin at 1/8× MIC. The ΔmbrC and ΔmbrD mutant strains, which lack Bacitracin resistance, also formed biofilms in the presence of Bacitracin at 1/2× MIC. This difference between the wild type and the mutants was caused by the induction of atlA expression in the mid-log phase. We also revealed that certain rgp genes involved in the synthesis of rhamnose-glucose polysaccharide related to cell wall synthesis were downregulated by Bacitracin. In addition, glucosyltransferase-I was also involved in eDNA-dependent biofilm formation. The biofilm led to increased transformation efficiencies and promoted horizontal gene transfer. Biofilms were also induced by ampicillin and vancomycin, antibiotics targeting cell wall synthesis, suggesting that cell envelope stress triggers biofilm formation. Therefore, the expression of the atlA and rgp genes is regulated by S. mutans, which forms eDNA-dependent biofilms, promoting horizontal gene transfer in response to cell envelope stress induced by sub-MICs of antibiotics.IMPORTANCE Antibiotics have been reported to induce biofilm formation in many bacteria at subinhibitory concentrations. Accordingly, it is conceivable that the MIC against drug-sensitive bacteria may promote biofilm formation of resistant bacteria. Since drug-resistant bacteria have spread, it is important to understand the behavior of resistant bacteria. Streptococcus mutans is Bacitracin resistant, and the 1/8× MIC of Bacitracin, which is a cell wall-targeted antibiotic, induced eDNA-dependent biofilm formation. The ΔmbrC and ΔmbrD strains, which are not resistant to Bacitracin, also formed biofilms in the presence of Bacitracin at 1/2× MIC, and biofilms of both the wild type and mutants promoted horizontal gene transfer. Another cell wall-targeted antibiotic, vancomycin, showed effects on biofilms and gene transfer similar to those of Bacitracin. Thus, treatment with cell wall-targeted antibiotics may promote the spread of drug-resistant genes in biofilms. Therefore, the behavior of resistant bacteria in the presence of antibiotics at sub-MICs should be investigated when using antibiotics.
Hiromasa Tsuda - One of the best experts on this subject based on the ideXlab platform.
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Bacitracin upregulates mbrAB transcription via mbrCD to confer Bacitracin resistance in Streptococcus mutans
Journal of pharmacological sciences, 2011Co-Authors: Yoshikazu Mikami, Naoto Suzuki, Tomihisa Takahashi, Kichibee Otsuka, Hiromasa TsudaAbstract:Streptococcus mutans is a bacterial cause of dental caries that is resistant to Bacitracin. The aim of this study was to elucidate the mbrABCD-related Bacitracin resistance mechanism of S. mutans. Transcriptome data demonstrated that the expression levels of 33 genes were induced more than twofold by Bacitracin. Fourteen genes were selected from the upregulated genes, and defective mutants of these genes were constructed for measurement of their sensitivity to Bacitracin. Among the mutants, only the mbrA- or mbrB-deficient mutants exhibited 100- to 121-fold greater sensitivity to Bacitracin when compared with the wild-type strain. Moreover, knockout of the mbrC and mbrD genes abolished the Bacitracin-induced mbrAB upregulation. These results suggest that both mbrC and mbrD are required for mbrAB upregulation that confers the Bacitracin-resistant phenotype on S. mutans.
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Genes Involved in Bacitracin Resistance in Streptococcus mutans
Antimicrobial agents and chemotherapy, 2002Co-Authors: Hiromasa Tsuda, Yoshihisa Yamashita, Yukie Shibata, Yoshio Nakano, Toshihiko KogaAbstract:Streptococcus mutans is resistant to Bacitracin, which is a peptide antibiotic produced by certain species of Bacillus. The purpose of this study was to clarify the Bacitracin resistance mechanism of S. mutans. We cloned and sequenced two S. mutans loci that are involved in Bacitracin resistance. The rgp locus, which is located downstream from rmlD, contains six rgp genes (rgpA to rgpF) that are involved in rhamnose-glucose polysaccharide (RGP) synthesis in S. mutans. The inactivation of RGP synthesis in S. mutans resulted in an approximately fivefold-higher sensitivity to Bacitracin relative to that observed for the wild-type strain Xc. The second Bacitracin resistance locus comprised four mbr genes (mbrA, mbrB, mbrC, and mbrD) and was located immediately downstream from gtfC, which encodes the water-insoluble glucan-synthesizing enzyme. Although the Bacitracin sensitivities of mutants that had defects in flanking genes were similar to that of the parental strain Xc, mutants that were defective in mbrA, mbrB, mbrC, or mbrD were about 100 to 120 times more sensitive to Bacitracin than strain Xc. In addition, a mutant that was defective in all of the mbrABCD genes and rgpA was more sensitive to Bacitracin than either the RGP or Mbr mutants. We conclude that RGP synthesis is related to Bacitracin resistance in S. mutans and that the mbr genes modulate resistance to Bacitracin via an unknown mechanism that is independent of RGP synthesis.
Thorsten Mascher - One of the best experts on this subject based on the ideXlab platform.
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immediate and heterogeneous response of the liafsr two component system of bacillus subtilis to the peptide antibiotic Bacitracin
PLOS ONE, 2013Co-Authors: Sara Kesel, Thorsten Mascher, Andreas Mader, Carolin Hofler, Madeleine LeisnerAbstract:Two-component signal transduction systems are one means of bacteria to respond to external stimuli. The LiaFSR two-component system of Bacillus subtilis consists of a regular two-component system LiaRS comprising the core Histidine Kinase (HK) LiaS and the Response Regulator (RR) LiaR and additionally the accessory protein LiaF, which acts as a negative regulator of LiaRS-dependent signal transduction. The complete LiaFSR system was shown to respond to various peptide antibiotics interfering with cell wall biosynthesis, including Bacitracin. Here we study the response of the LiaFSR system to various concentrations of the peptide antibiotic Bacitracin. Using quantitative fluorescence microscopy, we performed a whole population study analyzed on the single cell level. We investigated switching from the non-induced 'OFF' state into the Bacitracin-induced 'ON' state by monitoring gene expression of a fluorescent reporter from the RR-regulated liaI promoter. We found that switching into the 'ON' state occurred within less than 20 min in a well-defined switching window, independent of the Bacitracin concentration. The switching rate and the basal expression rate decreased at low Bacitracin concentrations, establishing clear heterogeneity 60 min after Bacitracin induction. Finally, we performed time-lapse microscopy of single cells confirming the quantitative response as obtained in the whole population analysis for high Bacitracin concentrations. The LiaFSR system exhibits an immediate, heterogeneous and graded response to the inducer Bacitracin in the exponential growth phase.
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Bacitracin sensing in Bacillus subtilis.
Molecular microbiology, 2008Co-Authors: Eva Rietkötter, Diana Hoyer, Thorsten MascherAbstract:The extracellular presence of antibiotics is a common threat in microbial life. Their sensitive detection and subsequent induction of appropriate resistance mechanisms is therefore a prerequisite for survival. The Bacitracin stress response network of Bacillus subtilis consists of four signal-transducing systems, the two-component systems (TCS) BceRS, YvcPQ and LiaRS, and the extracytoplasmic function (ECF) sigma factor sigma(M). Here, we investigated the mechanism of Bacitracin perception and the response hierarchy within this network. The BceRS-BceAB TCS/ABC transporter module is the most sensitive and efficient Bacitracin resistance determinant. The ABC transporter BceAB not only acts as a Bacitracin detoxification pump, but is also crucial for Bacitracin sensing, indicative of a novel mechanism of stimulus perception, conserved in Firmicutes bacteria. The Bce system seems to respond to Bacitracin directly (drug sensing), whereas the LiaRS TCS and sigma(M) respond only at higher concentrations and indirectly to Bacitracin action (damage sensing). The YvcPQ-YvcRS system is subject to cross-activation via the paralogous Bce system, and is therefore only indirectly induced by Bacitracin. The Bacitracin stress response network is optimized to respond to antibiotic gradients in a way that maximizes the gain and minimizes the costs of this stress response.