Project description:Transcriptional profiling to investigate the effect of drug treatment on the E. faecalis cells. For microarray analysis, E. faecalis OG1RF was grown in FMC medium supplemented with 10 mM glucose to an optical density at 600 nm (OD600) of 0.3 and the cultures were divided in 7 aliquots. One aliquot was collected by centrifugation and immediately frozen (untreated control cells). The other aliquots were treated for 30 or 60 min with 1.25 X the minimum inhibitory concentration (MIC) of one of the following CW inhibitors: ampicillin (20 μg ml-1), bacitracin (80 μg ml-1), or cephalothin (80 μg ml-1). After an exposure time of 30 or 60 minutes, each of these cultures was also centrifuged and the pellets frozen. RNA was then isolated from each pellet for microarray analysis. This process was repeated 3 additional times, for a total of four replicates of each condition.
Project description:Transcriptional profiling to investigate the effect of drug treatment on the E. faecalis cells. For microarray analysis, E. faecalis OG1RF was grown in FMC medium supplemented with 10 mM glucose to an optical density at 600 nm (OD600) of 0.3 and the cultures were divided in 7 aliquots. One aliquot was collected by centrifugation and immediately frozen (untreated control cells). The other aliquots were treated for 30 or 60 min with 1.25 X the minimum inhibitory concentration (MIC) of one of the following CW inhibitors: ampicillin (20 μg ml-1), bacitracin (80 μg ml-1), or cephalothin (80 μg ml-1). After an exposure time of 30 or 60 minutes, each of these cultures was also centrifuged and the pellets frozen. RNA was then isolated from each pellet for microarray analysis. This process was repeated 3 additional times, for a total of four replicates of each condition. RNA was extracted from four replicate samples of each condition of interest (control cells grown to OD600 = 0.3 in FMC medium supplemented with 10mM glucose, then treated with ampicillin, bacitracin, or cephalothin for 30 or 60 minutes) and labeled with Cy3. For each replicate, labeled RNA was hybridized to slides along with Cy5-labeled reference RNA, extracted from E. faecalis OG1RF cells grown in BHI medium to mid-log.
Project description:Transcriptional profiling to investigate the effect of drug treatment on the E. faecalis cells. For microarray analysis, E. faecalis OG1RF was grown in FMC medium supplemented with 10 mM glucose to an optical density at 600 nm (OD600) of 0.3 and the cultures were divided in 3 aliquots. One aliquot was collected by centrifugation and immediately frozen (untreated control cells). The other aliquots were treated for 30 or 60 min with 1.25 X the minimum inhibitory concentration (MIC) of vancomycin (10 μg ml-1). After an exposure time of 30 or 60 minutes, each of these cultures was also centrifuged and the pellets frozen. RNA was then isolated from each pellet for microarray analysis. This process was repeated 3 additional times, for a total of four replicates of each condition.
Project description:Transcriptional profiling to investigate the effect of drug treatment on the E. faecalis cells. For microarray analysis, E. faecalis OG1RF was grown in FMC medium supplemented with 10 mM glucose to an optical density at 600 nm (OD600) of 0.3 and the cultures were divided in 3 aliquots. One aliquot was collected by centrifugation and immediately frozen (untreated control cells). The other aliquots were treated for 30 or 60 min with 1.25 X the minimum inhibitory concentration (MIC) of vancomycin (10 M-NM-<g ml-1). After an exposure time of 30 or 60 minutes, each of these cultures was also centrifuged and the pellets frozen. RNA was then isolated from each pellet for microarray analysis. This process was repeated 3 additional times, for a total of four replicates of each condition. RNA was extracted from four replicate samples of each condition of interest (control cells grown to OD600 = 0.3 in FMC medium supplemented with 10mM glucose, then treated with vancomycin for 30 or 60 minutes) and labeled with Cy3. For each replicate, labeled RNA was hybridized to slides along with Cy5-labeled reference RNA, extracted from E. faecalis OG1RF cells grown in BHI medium to mid-log.
Project description:Transcriptional profiling to define the stringent response regulon and significance of basal (p)ppGpp levels in E. faecalis OG1RF. RNA was extracted from four replicate samples of each strain of interest and labeled with Cy3. For each replicate, labeled RNA was hybridized to slides along with Cy5-labeled reference RNA, extracted from E. faecalis OG1RF cells grown to mid-log.
Project description:Liquid cultures of Enterococcus faecalis OG1RF and OG1RF Δbph were grown in tryptic soy broth without added dextrose (TSB-D) for 2 and 4 hr. At each time point, the transcriptomes were compared to identify differentially expressed genes in the Δbph mutant.
Project description:Vancomycin resistance is conferred upon vancomycin-resistant enterococci (VRE) through the replacement of peptidoglycan (PG) stem terminal d-Ala-d-Ala with d-Ala-d-Lac. The d-Ala-d-Lac incorporation can affect both the fitness and virulence of VRE. Here we comprehensively investigate the changes to PG composition in vancomycin-resistant Enterococcus faecalis following the growth in presence of vancomycin using liquid chromatography-mass spectrometry. Using high-resolution mass spectrometry, 104 unique muropeptides fragments were identified and the relative abundance of each fragment was accurately quantified by integrating the ion current of a selected ion using extracted-ion chromatogram. The analysis indicates reduced PG cross-linking, increased carboxypeptidase activities, increased N-deacetylation, and increased O-acetylation in VRE when grown in the presence of vancomycin. We found that O-acetylation preferentially occurred on muropeptides fragments with reduced cross-linking with a pentapeptide stem that terminated in d-Ala-d-Lac. These findings show that O-acetylation preferentially occurred in regions of the cell wall with reduced PG cross-linking on PG units that have stems terminating in d-Ala-d-Lac, serving as markers to prevent both the PG-stem modification by carboxypeptidases and the cell wall degradation by autolysins. Accurate quantitative PG composition analysis provided compositional insights into altered cell wall biosynthesis and modification processes in VRE that contribute to lysozyme resistance and enhanced virulence for VRE grown in the presence of vancomycin.
Project description:Enterococcus faecium clinical isolates A902 and BM4538, which were resistant to relatively high levels of vancomycin (128 and 64 microg/ml, respectively) and to low levels of teicoplanin (4 microg/ml), and Enterococcus faecalis clinical isolates BM4539 and BM4540, which were resistant to moderate levels of vancomycin (16 microg/ml) and susceptible to teicoplanin (0.25 microg/ml), were studied. They were constitutively resistant by synthesis of peptidoglycan precursors ending with d-alanyl-d-lactate and harbored a chromosomal vanD gene cluster which was not transferable by conjugation to other enterococci. VanX(D) activity, which is not required in the absence of d-Ala-d-Ala, was low in the four strains, although none of the conserved residues was mutated; and the constitutive VanY(D) activity in the membrane fractions was inhibited by penicillin G. The mutations E(13)G in the region of d-alanine:d-alanine ligase (which is implicated in d-Ala1 binding in A902) and S(319)N of the serine involved in ATP binding in BM4538 and a 7-bp insertion at different locations in BM4539 and BM4540 (which led to putative truncated proteins) led to the production of an impaired enzyme and accounted for the lack of d-Ala-d-Ala-containing peptidoglycan precursors. The same 7-bp insertion in vanS(D) of BM4539 and BM4540 and a 1-bp deletion in vanS(D) of A902, which in each case led to a putative truncated and presumably nonfunctional protein, could account for the constitutive resistance. Strain BM4538, with a functional VanS(D), had a G(140)E mutation in VanR(D) that could be responsible for constitutive glycopeptide resistance. This would represent the first example of constitutive van gene expression due to a mutation in the structural gene for a VanR transcriptional activator. Study of these four additional strains that could be distinguished on the basis of their various assortments of mutations confirmed that all VanD-type strains isolated so far have mutations in the ddl housekeeping gene and in the acquired vanS(D) or vanR(D) gene that lead to constitutive resistance to vancomycin.