Project description:Comparison of the transcriptome of Bacillus subtilis under going membrane protein overproduction in the wild type, sigW and cssRS deletion strains. We demonstrate that the dynamics of the stress systems involved in membrane overproduction are far more complicated than was first hypothesised and that many more systems than SigW and CssRS are involved in membrane protein overexpression stress. Interestingly the cssRS genes are repressed in the sigW deletion strain.
Project description:In this study, we have applied the top-down approach to reduce the genome of B. subtilis in order to obtain minimal strains with robust growth on complex medium at 37°C. For this purpose, we have evaluated the function of each gene of the B. subtilis genome and identified essential, important and dispensable genomic regions. Using an efficient markerless and scarless deletion method and a system allowing induction of genetic competence in the complete cell population, we have constructed two genome-reduced strains lacking about 36% of dispensable genetic information. Multi-omics analyses with the genome-reduced strains revealed substantial changes in the transcriptome, the proteome and in the metabolome. The massive reorganization of metabolism in the two genome-reduced strains can be explained by the underlying genotypes that were determined by genome re-sequencing. Moreover, the transcriptome and proteome analyses uncovered novel dispensable genomic regions that can be removed to further streamline the B. subtilis genome. In conclusion, both minimal strains show interesting metabolic features and they serve as excellent starting points to generate an ultimate reduced-genome B. subtilis cell containing only genes required for robust growth on complex medium.
Project description:Five batch cultures of Bacillus subtilis were subjected to laboratory evolution for 6,000 generations under conditions repressing sporulation in complex liquid medium containing glucose. Between 1,000 and 2,000 generations, variants with a distinct small-colony morphology arose and swept through four of the five populations. To understand the nature of adaptation in these variants, individual strains were isolated from one population before (WN715) and after (WN716) the sweep. In addition to colony morphology, strains WN715 and WN716 differed in their motility, aerotaxis, and cell morphology. Competition experiments of WN715 vs. WN716 showed that WN716 had gained a distinct fitness advantage during growth and the transition to stationary phase, which was more pronounced when WN715 was present in co-culture. Microarray analyses revealed candidate genes in which mutations may have produced some of the observed phenotypes.
Project description:The narrow-specificity endoribonuclease RNase III and the 5’ exonuclease RNase J1 have been recently found to be not essential in the Gram-positive model organism, Bacillus subtilis. In this study, we performed a global analysis of internal 5’ ends that are generated or acted upon by these enzymes. An RNA-Seq protocol known as PARE (Parallel Analysis of RNA Ends) was used to capture 5’ monophosphorylated RNA ends in ribonuclease wild-type and mutant strains. Comparison of PARE peaks in strains with RNase III present or absent showed that, in addition to its well-known role in ribosomal (rRNA) processing, many coding sequences and intergenic regions were direct targets of RNase III. A set of regular RNA-seq experiments were performed to investigate RNA profiles in these strains and used to account for the changes in RNA abundance indirectly caused by the loss of RNase III in PARE. The PARE analysis also revealed an accumulation of 3’-proximal peaks that correlated with the absence of RNase J1, confirming the importance of RNase J1 in degrading RNA fragments that contain the transcription terminator structure. In addition, an endonuclease cleavage just two nucleotides downstream of the 16S rRNA 3’ end was discovered with PARE analysis. This latter observation begins to answer, at least for B. subtilis, a long-standing question on the exonucleolytic vs. endonucleolytic nature of 16S rRNA maturation
Project description:The Bacillus subtilis genome encodes four 3’ exoribonucleases: polynucleotide phosphorylase (PNPase), RNase R, RNase PH, and YhaM. Previous work showed that PNPase, encoded by the pnpA gene, is the major 3’ exonuclease involved in mRNA turnover; in a pnpA deletion strain, numerous mRNA decay intermediates accumulate. Whether B. subtilis mRNA decay occurs in the context of a degradosome complex is controversial. In this study, global mapping of mRNA decay intermediate 3’ ends within coding sequences was performed in strains that were either deleted for, or had an inactivating point mutation in, the pnpA gene. The pattern of 3’ end accumulation in these strains was highly similar, suggesting that mRNA decay was not occurring in the context of a degradosome, whose structure would be affected by the absence of PNPase. A comparison with mapped 3’ ends in a strain lacking CshA, the major RNA helicase, indicated that different mRNAs may require both PNPase and CshA for efficient decay. RNA-seq analysis of strains lacking RNase R suggested that this enzyme did not play a major role in mRNA turnover in the wild-type strain. Strains were constructed that contained only one of the four known 3’ exoribonucleases. When RNase R was the only 3’ exonuclease present, it was able to degrade a model mRNA efficiently, showing processive decay even through a strong stem-loop structure that inhibits PNPase processivity. Strains containing only RNase PH or only YhaM were also insensitive to this RNA secondary structure, suggesting the existence of another, as-yet unidentified, 3’ exoribonuclease.
Project description:Expression of ykrL of Bacillus subtilis, encoding a close homologue of the Escherichia coli membrane protein quality control protease HtpX, was shown to be upregulated under membrane protein overproduction stress. Using DNA affinity chromatography, two proteins were found to bind to the promoter region of ykrL: Rok, known as a repressor of competence and genes for extracytoplasmic functions, and YkrK, a novel type of regulator encoded by the gene adjacent to ykrL, but divergently transcribed. Electrophoretic mobility shift assays showed Rok and YkrK binding to the ykrL promoter region as well as YkrK binding to the ykrK promoter region. Comparative bioinformatic analysis of the ykrL promoter regions in related Bacillus species revealed a consensus motif, which was demonstrated to be the binding site of YkrK. Deletion of rok and ykrK in a PykrL-gfp reporter strain showed that both proteins are repressors of ykrL expression. In addition, conditions which activated PykrL (membrane protein overproduction, dissipation of the membrane potential, salt- and phenol stress) point to the involvement of YkrL in membrane protein quality control. Samples for transcriptome analyses were induced at the exponential-growth phase (OD600 = 0.8) with 0.1% subtilin (subtilin containing supernatant of subtilin producing B. subtilis strain ATCC 6633). Cells were harvested 30 min after induction. Three independent cultures of each strain (target strains and controls) were used, and cells were sampled for microarray experiment. One of each strain was collected in double volume for technical replicates.
Project description:Transcriptome comparison of Bacillus subtilis Natto under sliding permissive (0.7% agar) and restrictive (1.5% agar or spo0A mutant strain) conditions.
Project description:We have previously shown that the Cdc14 phosphatase is essential for an efficient repair of a DNA lesion, however we still missing how the phosphatase exerts this molecular functions and what are its targets during the repair process. To identify Cdc14 phospho-targets in response to DNA damage, we performed mass spectrometry analysis of Wild-type and Cdc14 deficient cells before and after inducing a single DSBs by expressing the HO endonuclease. Wild-type and a thermosensitive allele cdc14-1 were grown overnight and blocked in G2/M by using nocodazole to avoid cell cycle-dependent changes in protein phosphorylation between both strains. After the block was attained, cells were transfer to 37C to deplete Cdc14 activity prior HO induction. By, using this approach we have screened for proteins containing quantitate low levels of phosphorylated residues after the induction of the DNA lesion that occurs only when Cdc14 is active.
Project description:Identification of the specific WalR (YycF) binding regions on the B. subtilis chromosome during exponential and phosphate starvation growth phases. The data serves to extend the WalRK regulon in Bacillus subtilis and its role in cell wall metabolism, as well as implying a role in several other cellular processes. For each sample analyzed in this study three biological replicates were performed. Three different samples were taken from a strain expressing the WalR-SPA protein as well as from wild-type (168) without a tagged WalR. Samples were taken from exponentially growing cells in low phosphate medium (LPDM) as well as from phosphate-limited cells (T2). Each sample compares ChIP DNA vs. Total DNA from the same cells.