Project description:In this work we conducted RNET-seq on Wild Type, NusA depletion, nusG deletion, and NusA depletion nusG deletion strains of B. subtilis. Using this data we analysed the transcriptome-wide effects of NusA on RNA polymerase pausing and found that NusA has modest pause stimulating as well as suppressing effects throughout the genome.
Project description:To obtain an insight into the in vivo dynamics of RNA polymerase (RNAP) on the B. subtilis genome, we analyzed the distribution of ?A and ? subunits of RNAP and the NusA elongation factor on the genome in exponentially growing cells, using the ChAP (Chromatin Affinity Precipitation)-chip method. In contrast to E. coli RNAP, which often accumulates at the promoter-proximal region, B. subtilis RNAP is evenly distributed from the promoter to the coding sequences in the majority of genes. This finding suggests that B. subtilis RNAP recruited to the promoter promptly translocates away from the promoter to form the elongation complex. We detected RNAP accumulation in the promoter-proximal regions of some genes, most of which are attributed to transcription attenuation systems in the leader region. Our findings suggest that the differences in RNAP behavior during initiation and early elongation steps between E. coli and B. subtilis result in distinct strategies for post-initiation control of transcription. The E. coli mechanism involves trapping at the promoter and promoter-proximal pausing of RNAP in addition to transcription attenuation, whereas transcription attenuation in leader sequences is mainly employed in B. subtilis. Wild-type strain, Bacillus subtilis 168, was also used for RNA and genomic DNA extraction and analysis - RNA data was divided by genome DNA data to normalize (1) PCR bias and (2) copy number of RNA molecule per genome for multi-copy genome of exponentially growing bacteria.
Project description:Canonical bacterial intrinsic terminators do not require additional factors for efficient transcription termination, although the general transcription elongation factor NusA was known to increase the termination efficiency slightly in vitro. We found that the effect of NusA varies widely among different terminators and identified a subclass of weak non-canonical terminators that largely depend on NusA for recognition by RNA polymerase. Using genome-wide 3â end-mapping on an engineered Bacillus subtilis NusA depletion strain, we identified >2000 intrinsic terminators, hundreds of which are NusA-dependent. Our in vitro and in vivo characterization showed that terminators with weak RNA hairpins and distal U-tract interruptions tend to be NusA-dependent. Our observations indicate that the lethality associated with deletion of nusA is caused by global readthrough of NusA-dependent terminators, resulting in misregulation of physiologically important downstream genes. We also show that nusA expression is autoregulated by a transcription attenuation mechanism that is mediated by NusA-dependent termination. 3' end-mapping and mRNA profiling of stationary phase B. subtilis NusA-depletion (PLBS802) strain in NusA expressing and depleted conditions, 6 replicates each.
Project description:Ribosome pausing slows down translation and can affect protein synthesis. Improving translation efficiency can therefore be of commercial value. Here, we investigated the occurrence of ribosome pausing during amylase secretion by the industrial production organism Bacillus subtilis under semi fed-batch fermentation conditions. We first assessed our ribosome profiling setup by inducing ribosome stalling at isoleucine codons using the antibiotic mupirocin, and found a pause preference for isoleucine codons preceded by E and P site codons with guanosine residues in their first nucleotide position. Interestingly, when we applied standard ribosomal profiling conditions we found again an enrichment of guanosine residues in the E and P site of ribosome pause sites, but this time also upstream of the ribosome pause site. This sequence motif deviates from previously described ribosome pausing motifs. For the highly expressed amylase gene amyM several strong ribosome pausing sites were detected, which remained present during the 64-hour long fermentation, and were neither related to rare codons nor to secondary protein structures. When surveying the genome, an interesting finding was the presence of strong ribosome pausing sites in several toxins genes. These potential ribosome stall sites may function in preventing inadvertent activity in the cytosol.
Project description:Ribosome pausing slows down translation and can affect protein synthesis. Improving translation efficiency can therefore be of commercial value. Here, we investigated the occurrence of ribosome pausing during amylase secretion by the industrial production organism Bacillus subtilis under semi fed-batch fermentation conditions. We first assessed our ribosome profiling setup by inducing ribosome stalling at isoleucine codons using the antibiotic mupirocin, and found a pause preference for isoleucine codons preceded by E and P site codons with guanosine residues in their first nucleotide position. Interestingly, when we applied standard ribosomal profiling conditions we found again an enrichment of guanosine residues in the E and P site of ribosome pause sites, but this time also upstream of the ribosome pause site. This sequence motif deviates from previously described ribosome pausing motifs. For the highly expressed amylase gene amyM several strong ribosome pausing sites were detected, which remained present during the 64-hour long fermentation, and were neither related to rare codons nor to secondary protein structures. When surveying the genome, an interesting finding was the presence of strong ribosome pausing sites in several toxins genes. These potential ribosome stall sites may function in preventing inadvertent activity in the cytosol.
Project description:Canonical bacterial intrinsic terminators do not require additional factors for efficient transcription termination, although the general transcription elongation factor NusA was known to increase the termination efficiency slightly in vitro. We found that the effect of NusA varies widely among different terminators and identified a subclass of weak non-canonical terminators that largely depend on NusA for recognition by RNA polymerase. Using genome-wide 3’ end-mapping on an engineered Bacillus subtilis NusA depletion strain, we identified >2000 intrinsic terminators, hundreds of which are NusA-dependent. Our in vitro and in vivo characterization showed that terminators with weak RNA hairpins and distal U-tract interruptions tend to be NusA-dependent. Our observations indicate that the lethality associated with deletion of nusA is caused by global readthrough of NusA-dependent terminators, resulting in misregulation of physiologically important downstream genes. We also show that nusA expression is autoregulated by a transcription attenuation mechanism that is mediated by NusA-dependent termination.
Project description:To explore the effects of different stress conditions on Bacillus subtilis str.168, a selection of conditions were applied to the organism and RNA-seq data gathered. A matrix of gene counts was produced as a basis for further analysis into the transcription profiles of Bacillus subtilis str.168.
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.