The conserved DNA-binding protein WhiA is involved in cell division in Bacillus subtilis
ABSTRACT: 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. Comparing wild tpe Bascillus subtilus (n=3) with Bascillus Subtilis KS400 (n=2) and Bascillus subtilis KS696 (n=2)
Project description:The past twenty years have seen tremendous advances in our understanding of the mechanisms underlying bacterial cytokinesis, particularly the composition of the division machinery and the factors controlling its assembly. At the same time, however, we understand very little about the relationship between cell division and other cell cycle events in bacteria. Here we report that inhibiting division in Bacillus subtilis and Staphylococcus aureus quickly leads to an arrest in the initiation of new rounds of DNA replication followed by a complete arrest in cell growth. Arrested cells are metabolically active but unable to initiate new rounds of either DNA replication or division when shifted to permissive conditions. Inhibiting DNA replication results in entry into a similar quiescent state, in which cells are unable to resume growth or division when returned to permissive conditions. Our findings suggest the presence of two cell cycle control points: one linking division to the initiation of DNA replication and another linking the initiation of DNA replication to division. Significantly, this evidence contradicts the prevailing view of the bacterial cell cycle as a series of coordinated but uncoupled events. Importantly, the terminal nature of the cell cycle arrest validates the bacterial cell cycle machinery as an effective target for antimicrobial development. Four-condition experiment: ftsZ induced for 1hr, ftsZ depleted for 1hr, ftsZ induced for 2hrs, ftsZ depleted for 2hrs. Biological replicates: 3-4 for each sample. Reference: a mixture of wt RNA from different growth phases and wt backgrounds.
Project description:The transcriptional factor Zur plays a key role in regulating zinc homeostasis in Bacillus subtilis. The genomic sites bound by Zur were mapped using a chromatine immunoprecipitation approach. This allowed the identification of 80 inter- and intragenic chromosomal sites bound by Zur. This data set contains 2 samples. Immunoprecipitated (IP) DNA from Bacillus subtilis BSAS36 strain (BSB1, a tryptophan-prototrophic derivative 168 strain expressing a SPA-tagged Zur protein) were extracted from bacterial cells in the exponential growth phase. IP and whole-cell extract DNA were hybridized on tiling array to generate ChIP-on-chip profiles. Two biological replicates were anlyzed.
Project description:Murine gene expression responses to Bordetella pertussis were determined in lung and spleen, between 0 and 28 days post infection. Data were compared to other parameters such as microarray, flow cytometry, multiplex immunoassays, and lung clearance. A 57 array study with 27 arrays for lung and 30 for spleen. For each tissue we used a common reference made from RNA samples of the same tissue. Please note that the reference samples are made by pooling RNA of all samples used for a tissue (either infected or uninfected). Thus, Lung and spleen each have their own reference.
Project description:Study to optimize our protocol for isolating RNA from skin biopsies from (hairless) SKH mice using different-diameter biopsy punches. Some mice were also treated with UVB radiation to check its effect on RNA yield. 4 mice total: 2 were irradiated with 300J/m2 UVB and 2 were non-irradiated. Post-mortem skin biopsies with 1.5mm, 2.0mm, and 2.5mm diameter punches were taken from the dorsal region.
Project description:The Ts1Cje mouse strain (Sago, 1998) contains a segmental trisomy of mouse chromosome 16 orthologous to the region of human chromosome 21 commonly associated with Down Syndrome. In this study, fetuses were obtained from wildtype mothers bred with either wildtype or Ts1Cje males. Gene expression profiles in fetal liver and placenta of wildtype and Ts1Cje fetuses were compared, to identify potential markers for application in human prenatal DS screening. A 48 array study with 24 arrays for placenta and 24 for fetal liver. For each tissue we used RNA from 24 individual embryos, i.e. six male and six female embryos from both genotypes.
Project description:Segregation of replicated chromosomes during cell division is an essential process in all organisms. Chromosome segregation is promoted by the action of the DNA-binding ParB protein in the rod-shaped model bacterium Bacillus subtilis. How oval shaped bacteria, such as the human pathogen Streptococcus pneumoniae, efficiently segregate their chromosomes is poorly understood. Here, we show that the pneumococcal homolog of ParB is enriched at four centromere-like DNA sequences (parS sites) that are present near the origin of replication. Amplified ChIP DNA was fluorescently labelled using the BioPrime Total Genomic Labeling kit from Invitrogen. Eluate DNA was labelled with AlexA Fluor 3 and input DNA with Alexa Fluor 5. Labelled DNA was hybridized to a DNA-microarray containing amplicons of all open reading frames of S. pneumoniae (Kloosterman et al., 2006).
Project description:Comparison of the whole genome gene expression level of an enrofloxacin and tetracycline resistant E. coli strain with the wildtype it was derived from. The process of drug adaptation of E. coli MG1655 wildtype cells is further descibed in van der Horst, M, J.M. Schuurmans, M. C. Smid, B. B. Koenders, and B. H. ter Kuile (2011) in Microb. Drug Resist. 17:141-147. Resistance to amoxicillin was induced in E. coli by growth in the presence of stepwise increasing antibiotic concentrations. To investigate consequences of the aquisition of amoxicillin resistance the transcriptomic profile of sensitive and resistant cells was compared in the absence and presence of sub-inhibitory (0.25xMIC) amoxicillin concentrations was compared. Total RNA of 3 biological replicates of E. coli MG1655 wildtype cells and drug resistant cells cultured with (0.25xMIC) or without the drug was hybridized on a 12x135k custom designed microarraychip against one common reference.
Project description:Comparison of the whole genome gene expression level of an amoxicillin resistant E. coli strain with the wildtype it was derived from. The process of amoxicillin adaptation of E. coli MG1655 wildtype cells is further descibed in van der Horst, M, J.M. Schuurmans, M. C. Smid, B. B. Koenders, and B. H. ter Kuile (2011) in Microb. Drug Resist. 17:141-147. Resistance to amoxicillin was induced in E. coli by growth in the presence of stepwise increasing antibiotic concentrations. To investigate consequences of the aquisition of amoxicillin resistance the transcriptomic profile of sensitive and resistant cells was compared in the absence and presence of sub-inhibitory (0.25xMIC) amoxicillin concentrations was compared. Total RNA of 3 biological replicates of E. coli MG1655 wildtype cells and amoxicillin resistant cells cultured with (0.25xMIC) or without amoxicillin was hybridized on a 12x135k custom designed microarraychip against one common reference.
Project description:In molecular biology, the design of mechanistic experiments has to be optimized by considering statistical and biological principles. In contrast to statistical principles, biological principles of experimental design are not universally formulated. In an attempt to pinpoint generally acceptable rules, we investigated the importance of determining the optimal ranges of scale of i.e. dose and time in gene expression experiments. We propose a protocol for executing small scale, genome wide, range finding studies, covering a wide range of the potentially relevant part of the design space to find the optimal ranges of experimentation. This protocol is executed and a proof-of-concept is presented, where this approach is tested for both an in-vitro and an in-vivo study that aim to unravel DNA repair mechanisms provoked after UV radiation. We identified four challenges of range finding studies in omics experimentation; (1) the modularity of biological processes, (2) their dynamics, (3) the extent to which end-points indicate biological processes, and (4) the costs associated with the assays, which are all addressed by our approach. 48 MEF samples having various combinations of 9 timepoints and 6 UV-C Doses without replication were used