Project description:An updated representation of S. meliloti metabolism that was manually-curated and encompasses information from 240 literature sources, which includes transposon-sequencing (Tn-seq) data and Phenotype MicroArray data for wild-type and mutant strains.
2020-06-01 | MODEL2003240001 | BioModels
Project description:Comparative transposon sequencing of high (p)ppGpp and cell division mutants
Project description:One of the first steps in bacterial cell division is the polymerization of the tubulin-like protein FtsZ at midcell. The dynamics of FtsZ polymerization is regulated by a set of proteins among which ZapA. A zapA mutation does not result in a clear phenotype in Bacillus subtilis. In this study we used a synthetic-lethal screen to find genes that become essential when ZapA is absent. Three transposon insertions were found in yvcL. Deletion of yvcL in a wild type background had only a mild effect on growth, but a yvcL zapA double mutant is very filamentous and sick. This filamentation is caused by a strong reduction in FtsZ polymerization, suggesting that YvcL is involved in an early stage of cell division. YvcL is 25 % identical and 50 % similar to the Streptomyces coelicolor transcription factor WhiA. WhiA is required for septation of aerial hyphae during sporulation. Using GFP fusions, we show that YvcL localizes at the nucleoid. Surprisingly, transcriptome analyses in combination with a ChIP on chip assay did not provide clear evidence that YvcL functions as a transcription factor. To gain more insight into the function of YvcL, we searched for suppressors of the filamentous phenotype of a M-bM-^HM-^FyvcL M-bM-^HM-^FzapA mutant. Transposon insertions in gtaB and pgcA restored normal cell division of the double mutant. The corresponding proteins have been implemented in the metabolic sensing of cell division. We conclude that YvcL (WhiA) is involved in cell division in B. subtilis through an as yet unknown mechanism. Comparing wild tpe Bascillus subtilus (n=3) with Bascillus Subtilis KS400 (n=2) and Bascillus subtilis KS696 (n=2)
Project description:One of the first steps in bacterial cell division is the polymerization of the tubulin-like protein FtsZ at midcell. The dynamics of FtsZ polymerization is regulated by a set of proteins among which ZapA. A zapA mutation does not result in a clear phenotype in Bacillus subtilis. In this study we used a synthetic-lethal screen to find genes that become essential when ZapA is absent. Three transposon insertions were found in yvcL. Deletion of yvcL in a wild type background had only a mild effect on growth, but a yvcL zapA double mutant is very filamentous and sick. This filamentation is caused by a strong reduction in FtsZ polymerization, suggesting that YvcL is involved in an early stage of cell division. YvcL is 25 % identical and 50 % similar to the Streptomyces coelicolor transcription factor WhiA. WhiA is required for septation of aerial hyphae during sporulation. Using GFP fusions, we show that YvcL localizes at the nucleoid. Surprisingly, transcriptome analyses in combination with a ChIP on chip assay did not provide clear evidence that YvcL functions as a transcription factor. To gain more insight into the function of YvcL, we searched for suppressors of the filamentous phenotype of a ∆yvcL ∆zapA mutant. Transposon insertions in gtaB and pgcA restored normal cell division of the double mutant. The corresponding proteins have been implemented in the metabolic sensing of cell division. We conclude that YvcL (WhiA) is involved in cell division in B. subtilis through an as yet unknown mechanism.
Project description:Transposable genetic elements are ubiquitous, yet their presence or absence at any given position within a genome can vary between individual cells, tissues, or strains. Transposable elements have profound impacts on host genomes by altering gene expression, assisting in genomic rearrangements, causing insertional mutations, and serving as sources of phenotypic variation. Characterizing a genome?s full complement of transposons requires whole genome sequencing, precluding simple studies of the impact of transposition on interindividual variation. Here, we describe a global mapping approach for identifying transposon locations in any genome, using a combination of transposon-specific DNA extraction and microarray- based comparative hybridization analysis. We use this approach to map the repertoire of endogenous transposons in different laboratory strains of Saccharomyces cerevisiae and demonstrate that transposons are a source of extensive genomic variation. We also apply this method to mapping bacterial transposon insertion sites in a yeast genomic library. This unique whole genome view of transposon location will facilitate our exploration of transposon dynamics, as well as defining bases for individual differences and adaptive potential. Keywords: transposon mapping
Project description:Mutations in the rifampicin (Rif)-binding site of RNA polymerase (RNAP) impart antibiotic resistance and inextricably affect transcription initiation, elongation, and termination properties as well. At each step of the transcription cycle, RNAP responds to non-essential transcription factors, signaling molecules, and substrate availability. As such, the non- essential genome and its impact on fitness cost potentially represent an untapped resource for new combination therapies. Using transposon sequencing (Tn-seq), we present a genome- wide analysis of resistance cost in a clinically common rpoB H526Y mutant. Our data show that cost-compounding genes include factors that promote high transcription elongation rate, whereas cost-mitigating genes function in cell wall synthesis and division. We demonstrate that cell wall synthesis and division defects in rpoB H526Y are a consequence of an abnormally high transcription elongation rate, which is further exacerbated by superfluous activity of the uracil salvage pathway and indifference of the mutant RNAP to alarmone ppGpp. Leveraging on this knowledge, we identified drugs that are highly potent against rpoB H526Y and other RifR alleles from the same phenotypic class. Thus, genome-wide analysis of fitness cost of antibiotic resistant mutants should expedite discovery of new combination therapies and delineate cellular pathways that underlie molecular mechanisms of cost.
Project description:DNA methylation is a key epigenetic regulator in all domains of life, yet the effects of most bacterial DNA methyltransferases on cellular processes are largely undefined. Here, we used diverse techniques, including bisulfite sequencing, transcriptomics, and transposon insertion site sequencing to extensively characterize a 5-methylcytosine (5mC) methyltransferase, VchM, in the cholera pathogen, Vibrio cholerae. We have comprehensively defined VchM's DNA targets, its genetic interactions and the gene networks that it regulates. Although VchM is a relatively new component of the V. cholerae genome, it is required for optimal V. cholerae growth in vitro and during infection. Unexpectedly, the usually essential ÏE cell envelope stress pathway is dispensable in ÎvchM V. cholerae, likely due to its lower activation in this mutant and the capacity for VchM methylation to limit expression of some cell envelope modifying genes. Our work illuminates how an acquired DNA methyltransferase can become integrated within complex cell circuits to control critical housekeeping processes. Duplicates samples were analyzed for wildtype cells grown under 3 conditions: exponential phase, stationary phase and rabbit intestinal infection
Project description:The goal of this project was to identify bacterial transporters responsible for uptake of environmentally relevant marine metabolites. We used the model marine heterotrophic bacterium Ruegeria pomeroyi DSS-3, for which an arrayed library of single gene knockout mutants has been generated by selecting isolated from a barcoded transposon mutant library (BasSeq). Knockout mutants of putative transporters were grown on minimal medium with a single substrate as sole carbon source. Mutant defect was assessed by comparing the substrate drawdown of isolated mutants to drawdown by a pooled mutant library (BarSeq), a proxy for wildtype fitness.
Project description:We wanted to identify Francisella tularensis bacterial mutants that are negatively selected in vivo in the lungs of mice. Mice were infected with a Francisella transposon mutant library where each gene in the genome has been mutated via the insertion of a kanamycin resistance cassette with 2 outward facing T7 promoters. 2 days post infection, infected lungs were harvested and the bacteria present in the infected lungs were collected. Bacterial genomic DNA was isolated and subjected to an in vitro T7 transcription reaction, reverse transcribed and the resulting cDNA was hybridized to our Francisella microarray. Infection: The goal of the study was to identify Francisella genes that are negatively selected in the lungs of mice post infection with a Francisella transposon mutant library. Resulting bacterial cDNA was hybridized to the Francisella microarray.
Project description:Lipid intermediates derived from sphingolipid metabolism are crucial regulators of mitochondrial function from yeast to humans. Among these intermediates, trans-2-hexadecenal (t-2hex) within the sphingolipid degradation pathway exhibits remarkable efficiency in inducing mitochondria-mediated cell death. In yeast cell cultures, the addition of t-2-hex triggers complete disintegration of the mitochondrial network, leading to subsequent cell death. This effect is particularly pronounced in yeast cells lacking the activity of the t-2-hex degrading enzyme, Hfd1. However, the molecular mechanisms of t-2-hex induction of mitochondrial dysfunction are completely unknown. In this project, we want to exploit the unprecedented power of yeast genetics to unveil novel genetic determinants involved in t-2-hex's pro-apoptotic function. To accomplish this, we employed the SATAY method, which combines saturated transposon mutagenesis with high-throughput sequencing to functionally explore the yeast genome. In our screening approach, hfd1 mutant cells harboring a plasmid-encoded inducible MiniDs transposon were induced by galactose, resulting in extensive integration of the transposon throughout the yeast genome. Cells with the plasmid excised and the transposon genomically integrated were pooled together, creating a high-density transposon library comprising approximately 2.3E+06 independent insertion mutants. Subsequently, the pooled mutant library was subjected to treatment with the mitochondria-mediated death inducer, t-2-hexadecenal. As a control, cells were also incubated with the solvent dimethyl sulfoxide (DMSO), in which hexadecenal is dissolved. Following the treatments, cells were collected for genomic DNA extraction and digestion, using restriction enzymes with frequent four-base pair recognition sites. The resulting library fragments were circularized using T4 DNA ligase, and the transposon-genome junctions were selectively amplified through PCR with outward-facing primers specific to the transposon. Finally, the pooled and purified amplicons were subjected to massive sequencing on an Illumina MiSeq platform. The obtained sequences were then aligned to the reference genome of Saccharomyces cerevisiae, allowing for the mapping of transposon insertions and the calculation of transposon counts per gene. This project enabled the identification of genes required for the resistance and toxicity to t-2hex.