Project description:In Escherichia coli, the highly conserved enzymes MiaA and MiaB mediate the sequential prenylation and methylthiolation of adenosine-37 within tRNAs that decode UNN codons. We found that MiaA, but not MiaB, is critical to the fitness and virulence of extraintestinal pathogenic E. coli (ExPEC), a major cause of urinary tract and bloodstream infections. Deletion of miaA has pleiotropic effects, attenuating bacterial fitness and virulence within diverse host environments and rendering ExPEC especially sensitive to stressors like nitrogen and oxygen radicals and osmotic shock. We find that stress can stimulate striking changes in miaA expression. To assess how changing MiaA levels affect the pathogen proteome, we used MS to analyze the proteins express by the reference ExPEC isolate UTI89 and derivatives that either lack or overexpress MiaA.
Project description:We created a mutator protein, Evolugene with very fast in vivo mutation rate and gene specificity in E. coli. To comprehensively analyze the specificity and mutagenicity, we sequenced ~3.3 kb DNA around the target gene from cells taken at cycle 27 by Illumina sequencing.
Project description:lysozyme-untreated Salmonella spent media and lysozyme-treated salmonella supernatant have different effects on intestinal epithelial permeability. To analyze the content and the different between the two supernatants, we did the proteomics to identify the proteins.
Project description:Proteomics is the most suitable tool to study persisters with their complex underlying molecular mechanisms from a system-level perspective, but the number of persisters that present naturally is too few for proteomics analysis. Here, we utilized Evo3A, an evolved population with enriched persisters fraction from a recent adaptive laboratory evolution experiment, to study the mechanisms of persistence during ampicillin treatment and resuscitation. Interestingly, the enriched persisters on Evo3A exhibit filamentous morphology upon treatment with ampicillin, and the filaments are getting longer over time. Time-course proteomics study revealed that proteins involved in major carbohydrate metabolism are up-regulated, in particular those involved in the oxidative stress response and act as cellular response to DNA damage. As opposed to the proteome profile during antibiotic treatment, proteins involved in major metabolic processes and ATP generation are down-regulated, while translational proteins and porins are up-regulated in the filaments during resuscitation.
Project description:Cellular tolerance toward furfural is a complex phenotype involved many genes, and hard to be improved by manipulating individual genes. We previously established exogenous global regulator IrrE mutants that confer Escherichia coli with significantly enhanced tolerance to furfural stress. In order to elucidate the mechanism for enhancement of furfural tolerance in the mutants and to identify new genes and pathways that can be possible targets for engineering of furfural tolerance, we carried out comparative transcriptomic with the representative strains F1-37 and WT (harboring the furfural-tolerant mutant F1-37 of IrrE and the wild type IrrE, respectively). The data from transcriptome analyses were deposited here. Cells of furfural-tolerant mutant F1-37 and wild-type strain WT were grown in LB medium supplemented with furfural, and the cells were harvested in the exponential phase. The samples for both of these two strains were prepared in triplicate with biological replicates.
Project description:Bacterial toxin-antitoxin systems are thought to help bacteria to reduce their metabolism in various stressful conditions. Many toxins of the bacterial toxin-antitoxin systems are ribonucleases. Such toxins have been mostly viewed as degraders of mRNA, however recently it was demonstrated that they are also capable of cleaving non-coding RNA. MazF toxin is also hypothesized to reprogram E. colis translational machinery. Current cDNA libraries are part of a project which aims to identify the major RNA cleavage sites (in mRNA, rRNA and regulatory non-coding RNA) of MazF and MqsR toxins in E. coli. We wanted to elaborate on the roles of MazF and MqsR in E. coli: is MazF really involved in reprogramming the translational machinery or is MazF, along with MqsR, just a robust cleaver of RNA? We extracted total RNA from cultures where the expression of MazF or MqsR was induced for 2h and from cultures that had been recovering from toxin production for 30 minutes; RNA from log phase culture was used as the control. We used strand specific random primed paired end RNA sequencing data to locate the major cleavage sites. To map the cleavage sites, we counted 5’ end stacks of forward reads in each genomic position and compared them with total coverage. MazF and MqsR cleave at specific recognition sequences, ˇACA and GˇC respectively, which allowed us to eliminate the false positives. One of our initial aims was also to look for irregular RNA ligation events following toxin expression, thus we used long, 300 base reads in sequencing.
Project description:This SuperSeries is composed of the following subset Series: GSE31804: Expression data of enterotoxigenic (ETEC) isolate E24377A GSE31805: Global transcriptomics of enterotoxigenic E. coli strain E24377A Refer to individual Series
Project description:Because iron toxicity and deficiency are equally life threatening, maintaining intracellular iron levels within a narrow optimal range is critical for nearly all known organisms. However, regulatory mechanisms that establish homeostasis are not well understood in organisms that dwell in environments at the extremes of pH, temperature, and salinity. Under conditions of limited iron, the extremophile Halobacterium salinarum, a salt-loving archaeon, mounts a specific response to scavenge iron for growth. We have identified and characterized the role of two transcription factors (TFs), Idr1 and Idr2, in regulating this important response. An integrated systems analysis of TF knockout gene expression profiles and genome-wide binding locations in the presence and absence of iron has revealed that these TFs operate collaboratively to maintain iron homeostasis. In the presence of iron, Idr1 and Idr2 bind near each other at 24 loci in the genome, where they are both required to repress some genes. In contrast, Idr1 and Idr2 are both necessary to activate other genes in a putative a feed forward loop. Even at loci bound independently, the two TFs target different genes with similar functions in iron homeostasis. We discuss conserved and unique features of the Idr1-Idr2 system in the context of similar systems in organisms from other domains of life. Data in this GEO archive are linked to the publication: Schmid AK, Pan M, Sharma K, Baliga NS.2011. Two transcription factors are necessary for iron homeostasis in a salt-dwelling archaeon.Nucleic Acids Res.39(7):2519-33. The Δura3 parent, Δidr2 and Δidr1, and Δ idr1Δidr2 mutant strains were grown to mid-logarithmic phase (OD600 ~0.4 – 0.8) in CDM with all trace metals except iron. Cultures were split in half and FeSO4 was added to one half, while the other was continued under iron limitation. 8-mL samples were collected from each culture every 20 minutes for 60 minutes (see also experimental design, Supplementary Figure 1, Schmid et al., 2011). RNA from two biological replicate time courses were prepared, averages of these replicates are reported in the published study, whereas data from each replicate are reported here. The zero time point was harvested immediately before the addition of iron. Each Sample is based on two arrrays (one with dye-swap).
Project description:The cholera disease bacterium V. cholerae, can adopt planktonic or biofilm lifestyles depending on the intracellular concentration of the second messenger cyclic diguanylic acid (c-di-GMP). Biofilm formation protects Vibrios from stressful conditions and facilitates disease transmission by enhancing infectivity. The histone-like nucleoid structuring protein (H-NS) is a global regulator of genes associated with pathogenicity and responses to environmental stresses. H-NS represses the transcription of genes vpsT, vpsA and vpsL, which are required for the biosynthesis of the biofilm exopolysacchide matrix. Here we demonstrate that the c-di-GMP-binding protein VpsT disrupts H-NS nucleoprotein complexes at the vpsA and vpsL promoters and that this effect is enhanced by c-di-GMP. We used ChIP coupled with Next Generation Sequencing (ChIP-Seq) and transcriptome analysis (RNA-Seq) to identify additional loci repressed by H-NS affecting biofilm formation. This study showed that H-NS directly represses the transcription of genes encoding proteins present in the biofilm matrix such as the rbmA-F cluster, hemolysin and chitinase. Similar to vpsA and vpsL, the promoter region of vpsU, rbmA and rbmF exhibited overlapping H-NS and VpsT binding motifs. Deletion of vpsT increased H-NS occupancy at the vpsU, vpsA, vpsL, rbmA and rbmF promoters. Conversely, artificially increasing the c-di-GMP pool diminished H-NS occupancy at the above promoters. Deletion of vpsT did not affect H-NS occupancy at its own promoter. However, deletion of genes encoding the regulators AphA and VpsR significantly increased H-NS occupancy at the vpsT promoter. In sum, our study shows that c-di-GMP enhances biofilm formation by acting through VpsT to activate an H-NS anti-repression cascade. The Binding profile of V. cholerae H-NS to the genome was determined by ChIP followed by Next Generation Sequencing (ChIP-Seq) using the Illumina HiSeq2000 platform. V. cholerae C7258 cells expressing H-NS-FLAG fusion protein from the hns transcription and translation signals were collected from LB cultures grown to mid-exponential phase (OD600 0.5). An anti-FLAG Immunoprecipitation (IP) and an Input samples were used for the analysis.
Project description:With the evolution of the PylRS system, we identified the PylRS variants for incorporation of all synthesized Kacyl and Kacyl* in the full-length H3 protein both in E. coli and mammalian cells, which covered the tail domain (eg. K23, K27, K56) as well as the globular domain that are difficult for chemical synthesis (eg. K64, K79, K122).