Influence of glycine betaine on the transcriptional profile of the Bacillus subtilis SigB regulon
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ABSTRACT:
ORGANISM(S): Bacillus subtilis Bacillus subtilis subsp. subtilis str. 168
PROVIDER: GSE141882 | GEO | 2020/03/01
REPOSITORIES: GEO
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Project description:Glycine betaine (GB) is a potent osmoprotectant for salt stressed Bacillus subtilis cells, which possess three high-affinity uptake systems for GB. OpuA is the dominant transporter for this compatible solute. Northern blot analysis, primer extension experiments and opuA-treA reporter gene fusion studies demonstrated that opuA expression is strongly induced at high osmolality from a single SigA-type promoter. Promoter mutations that improve the match of the opuA promoter to the consensus sequence substantially increase basal-level expression but reduce inducibility by high salinity. Expression of opuA is sensitively controlled by GB, which causes significant repression of opuA transcription at low and high salinity. GB influences the kinetics as well as the final level of high salinity induction of opuA in a concentration-dependent fashion. The repressing effect of GB on opuA transcription requires the intracellular presence of GB, regardless whether it is taken up via OpuA or other transporters or synthesized from choline. Genome-wide transcriptional profiling of salt-stressed B. subtilis cells demonstrated that the repressive effect of GB targets only a subset of high-salinity induced genes. This group of GB-responsive genes comprises in essence the full set of genes with demonstrated functions in either the uptake or synthesis of compatible solutes. Four different samples (untreated, GB, NaCl, and GB + NaCl treated) were analyzed and each sample was hybridized in triplicate.
2010-05-15 | E-GEOD-17435 | biostudies-arrayexpress
Project description:Glycine betaine (GB) is a potent osmoprotectant for salt stressed Bacillus subtilis cells, which possess three high-affinity uptake systems for GB. OpuA is the dominant transporter for this compatible solute. Northern blot analysis, primer extension experiments and opuA-treA reporter gene fusion studies demonstrated that opuA expression is strongly induced at high osmolality from a single SigA-type promoter. Promoter mutations that improve the match of the opuA promoter to the consensus sequence substantially increase basal-level expression but reduce inducibility by high salinity. Expression of opuA is sensitively controlled by GB, which causes significant repression of opuA transcription at low and high salinity. GB influences the kinetics as well as the final level of high salinity induction of opuA in a concentration-dependent fashion. The repressing effect of GB on opuA transcription requires the intracellular presence of GB, regardless whether it is taken up via OpuA or other transporters or synthesized from choline. Genome-wide transcriptional profiling of salt-stressed B. subtilis cells demonstrated that the repressive effect of GB targets only a subset of high-salinity induced genes. This group of GB-responsive genes comprises in essence the full set of genes with demonstrated functions in either the uptake or synthesis of compatible solutes.
2009-08-01 | GSE17435 | GEO
Project description:In order to reveal so far unknown facets of the adaptation of B. subtilis to growth under high-salinity conditions, a whole-transcriptome analysis of B. subtilis BSB (168 Trp+) was performed using strand-specific tiling arrays (tiling step of 22 nucleotides). In addition, the effects of glycine betaine (GB) were analyzed under high salinity and standard growth conditions in a chemically defined medium. Important novel findings were a sustained low-level induction of the SigB-dependent general stress response and strong repression of biofilm matrix genes under high-salinity conditions. GB influences gene expression not only under high-salinity, but also under standard growth conditions without additional salt.
2020-05-18 | GSE145124 | GEO
Project description:Influence of glycine betaine on the transcriptional profile of the Bacillus subtilis SigB regulon
| PRJNA595089 | ENA
Project description:Glycine betaine (GBT) is a component of labile dissolved organic matter and a compatible solute in high concentrations in marine microbial populations. GBT has complex biochemical potential, but, once taken up from the environment, the cellular fate of the carbon and nitrogen from GBT is unknown. Here we determine the uptake kinetics and metabolism of GBT in two natural microbial communities characterized by different nitrate concentrations in the North Pacific transition zone. Dissolved GBT had maximum uptake rates of 0.36 and 0.56 nM hr -1 and half-saturation constants of 79 and 11 nM in the high nitrate and low nitrate stations, respectively. GBT taken into cells was predominantly retained as an untransformed compatible solute. A portion of GBT was transformed into other metabolites, through characterized and uncharacterized pathways. Where nitrate was scarce, GBT was primarily catabolized via the demethylation to glycine. Resulting metabolites were used to build protein biomass, and remineralized ammonia was re-assimilated into cells. Gene expression data from this region show that bacteria, especially SAR11, are the dominant organisms expressing the demethylation genes. Where nitrate concentrations were higher, more GBT was used for choline synthesis. Our data highlight undiscussed metabolic pathways and potential routes of microbial metabolite exchange.
2021-12-01 | ST002008 | MetabolomicsWorkbench
Project description:Background: The Bacillus cereus Sigma B (SigB) dependent general stress response is activated via the two-component RsbKY system, which involves a phosphate transfer from RsbK to RsbY. It has been hypothesized that the Hpr-like phosphocarrier protein (Bc1009) encoded by bc1009 in the SigB gene cluster may play a role in this transfer, thereby acting as a regulator of SigB activation. Alternatively, Bc1009 may be involved in the activation of a subset of SigB regulon members. Results: We first investigated the potential role of bc1009 to act as a SigB regulator but ruled out this possibility as the deletion of bc1009 did not affect the expression of sigB and other SigB gene cluster members. The SigB-dependent functions of Bc1009 were further examined in B. cereus ATCC14579 via comparative proteome profiling (backed up by transcriptomics) of wt, Δbc1009 and ΔsigB deletion mutants under heat stress at 42°C. This revealed 284 proteins displaying SigB-dependent alterations in protein expression levels in heat-stressed cells, including a subgroup of 138 proteins for which alterations were also Bc1009-dependent. Next to proteins with roles in stress defense, newly identified SigB and Bc1009-dependent proteins have roles in cell motility, signal transduction, transcription, cell wall biogenesis, and amino acid transport and metabolism. Analysis of lethal stress survival at 50°C after pre-adaptation at 42°C showed intermediate survival efficacy of Δbc1009 cells, highest survival of wt, and lowest survival of ΔsigB cells, respectively. Additional comparative proteome analysis of non-stressed wt and mutant cells at 30°C revealed 96 proteins with SigB and Bc1009-dependent differences in levels, 51 were also identified under heat stress, and 45 showed significant differential expression at 30°C, including proteins with roles in carbohydrate/ion transport and metabolism. Overlapping functions at 30°C and 42°C included proteins involved in motility, and ΔsigB and Δbc1009 cells showed reduced motility compared to wt cells in swimming assays at both temperatures. Conclusion: our results extend the B. cereus SigB regulon to >300 members, with a novel role of SigB-dependent Bc1009 in the activation of a subregulon of >180 members, conceivably via phosphotransfer-based interactions with other transcriptional regulatory networks.
2023-03-02 | GSE213958 | GEO
Project description:We studied degradation of glycine betaine by salt marsh microbes and the formation of trimethylamine and methane from glycine betaine
| PRJEB28840 | ENA
Project description:Betaine (trimethylglycine) is a non-toxic, highly water-soluble organic osmolyte widely used in skin care due to its assumed moisturizing and protective properties, but only few studies have addressed its specific effects in skin. Here, the cellular and molecular targets of betaine were analyzed by genome-wide expression analysis in organotypic cultures of rat epidermal keratinocytes (REK). In this model, we also examined whether betaine modifies the impacts of acute UVB exposure. The expression of several genes relevant to epidermal biology, proliferation/differentiation or malignancy as well as solute transport were verified by independent methods (qRT-PCR, western blotting). The data concerning changes in calcium metabolism after UVB exposure has been published separately (Bart et al., Br. J. Dermatol. 171:376-387, 2014). Organotypic cultures of rat epidermal keratinocytes (REK) were prepared by plating cells on a collagen-coated insert (submerged in medium), lifting the confluent cell layer to the air-liquid interface 3 days after plating. These 3D cultures were divided in four treatment groups with three replicates in each: control, betaine (10 mM), UVB (30 mJ/cm2) and betaine + UVB. Betaine was added to the cultures for 11 days, starting from day 4 until sample collection. UVB exposure was performed 24 h prior to sample collection for 2-week-old 3D cultures with a well-formed epidermal layer. For further details on the experimental set-up and characteristics of the UV source, please refer to Bart et al. (Br. J. Dermatol. 171:376-387, 2014) and Rauhala et al. (J. Biol. Chem. 288:17999-18012, 2013).
2015-10-26 | E-GEOD-63004 | biostudies-arrayexpress
Project description:Betaine (trimethylglycine) is a non-toxic, highly water-soluble organic osmolyte widely used in skin care due to its assumed moisturizing and protective properties, but only few studies have addressed its specific effects in skin. Here, the cellular and molecular targets of betaine were analyzed by genome-wide expression analysis in organotypic cultures of rat epidermal keratinocytes (REK). In this model, we also examined whether betaine modifies the impacts of acute UVB exposure. The expression of several genes relevant to epidermal biology, proliferation/differentiation or malignancy as well as solute transport were verified by independent methods (qRT-PCR, western blotting). The data concerning changes in calcium metabolism after UVB exposure has been published separately (Bart et al., Br. J. Dermatol. 171:376-387, 2014).
2015-10-26 | GSE63004 | GEO
Project description:Listeria monocytogenes SigB and PrfA are pleiotropic regulators of stress response and virulence gene expression, which have been shown to co-regulate genes in L. monocytogenes. We performed whole genome transcriptional profiling in the presence of PrfA* and active SigB, to identify the overlaps between the PrfA virulence regulon and the SigB stress response regulon. In L. monocytogenes, the PrfA* allele contributes to the activation of virulence genes to a level comparable to that of intracellular growing L. monocytogenes. Our results showed that the core PrfA regulon consists of 12 genes previously described as PrfA regulated. Furthermore, we found that the role of SigB during virulence gene regulation changes, dependent on the presence or absence of PrfA*. In the absence of PrfA*, SigB activated the transcription of virulence genes such as inlA and inlB. In the presence of PrfA*, SigB negatively influenced the transcription of genes in the PrfA core regulon. The observed effect of SigB on the transcript level of PrfA regulated genes was shown to reduce the cytotoxic effect of the PrfA* allele in HepG-2 cells. Our results indicate that the SigB-PrfA regulatory network is important for the adjustment of virulence gene transcription to ensure L. monocytogenes success as an intracellular pathogen. Keywords: comparison of gene expression of regulatory mutants
2008-10-01 | GSE11347 | GEO