Project description:Copper is both essential and toxic to living beings, which therefore tightly control its intracellular concentration. At the host-pathogen interface, copper is used by phagocytic cells to kill invading microorganisms. We investigated copper homeostasis in the whooping cough agent Bordetella pertussis, which lives in the human respiratory mucosa and has no environmental reservoir. B. pertussis has considerably streamlined copper homeostasis mechanisms relative to other Gram-negative bacteria. Its single remaining defense line against copper intoxication consists in a metallochaperone diverted for copper passivation and two enzymes involved in peroxide detoxification, which together fight two stresses encountered in phagolysosomes. The three proteins are encoded by an original, composite operon assembled in an environmental ancestor and which is under sensitive control by copper. Interestingly, this system appears to play a role in persistent infection in the nasal cavity of B. pertussis-infected mice. Combining responses to co-occurring stresses in a tailored operon reveals a new strategy adopted by a host-restricted pathogen to optimize survival at minimal energy expenditure.
Project description:Bordetella pertussis is the bacterial causative agent of whooping cough, a serious respiratory illness. An extensive knowledge on its virulence regulation and metabolism is a key factor to ensure pertussis vaccine manufacturing process robustness. The aim of this study was to refine our comprehension of B. pertussis physiology along the fermentation process. A longitudinal multi-omics analysis was carried out over a 26-hour small-scale fermentation of B. pertussis. Fermentations were performed in batch mode and under culture conditions intending to mimic industrial processes. Putative cysteine and proline starvations were respectively observed at the beginning of the exponential phase (from 4h to 8h) and during the exponential phase (18h45). As revealed by multi-omics analyses, the proline starvation induced major molecular changes, including a transient metabolism with internal stock consumption. In the meantime, growth and specific total PT, PRN and Fim2 antigen productions were negatively affected. Interestingly, the master virulence-regulating two-component system of B. pertussis (BvgASR) was not evidenced as the sole virulence regulator in this in vitro growth condition. Indeed, novel intermediate regulators were identified as putatively involved in the expression of some virulence-activated genes (vags). Such longitudinal multi-omics analysis applied to B. pertussis fermentation process emerges as a powerful tool for characterization and incremental optimization of vaccine antigen production.
Project description:Bordetella pertussis, the etiological agent of whooping cough, regulates the expression of its virulence factors by the well-defined BvgA/S two-component regulatory system. Phosphorylated BvgA activates the virulence activated genes (vags) and represses via the activation of the bvgR gene the expression of the virulence repressed genes (vrgs). In the presence of MgSO4, known as modulating condition, the BvgA/S system is inactive, and the vrgs are expressed. Here, we show that, except for 6 genes of unknown function, the expression of all the vrgs depends on RisA, another transcriptional two-component regulator. In addition to the vrgs, RisA also regulates the expression of a many other genes. Whereas the expression of most vags was not affected by the deletion of risA, some vags, including the genes coding for pertactin, filamentous hemagglutinin, fimbriae and adenylate cyclase toxin, were surprisingly no longer modulated by MgSO4 in the risA- background. Yet another set of genes, mostly of unknown function, were modulated only in the risA- background. Finally, a large group of genes were up-regulated under modulating conditions only in the risA- background. They comprise genes of the chemotaxis and flagellar operons, iron-regulated genes, some of which are under the control of BvgA/S, while others are not. We identified RisK as the cognate RisA kinase, and found that most of the RisA-dependent genes also required RisK for expression, whereas a few genes were independent of RisK. These results were confirmed by the replacement of RisA with the phosphoablative RisAD60N analog and the phosphomimetic RisAD60E analog. Thus, according to its phosphorylation state, RisA regulates the expression of many genes, which may or may not also be regulated by the BvgA/S system, adding a new layer of complexity of B. pertussis gene regulation.
Project description:Bordetella pertussis is a Gram-negative, strictly human respiratory pathogen and the causative agent of whooping cough (pertussis). Similar to other Gram-negative pathogens, B. pertussis produces a functional type III secretion system, but its role in pathogenesis of B. pertussis is enigmatic and has not yet been elucidated. Here, we applied omics RNA-seq as well as LC-MS/MS techniques and co-immunoprecipitation method to identify and characterize the novel CesT family T3SS chaperone BP2265. Our results show that the chaperone BP2265 specifically interacts with the secreted T3SS anti-sigma factor BtrA. Moreover, in the absence of the chaperone, secretion but not production of BtrA and several early, intermediate, and late T3SS substrates is severely impaired. It appears that the role of BtrA in regulating T3SS is more complex and extends beyond its activity as an antagonist of the sigma factor BtrS. We propose to rename BP2265 as BtcB for the Bordetella type III chaperone of BtrA.
Project description:Bordetella pertussis is the causative agent of human whooping cough, a highly contagious respiratory disease which despite vaccination programs remains the major cause of infant morbidity and mortality. The requirement of the RNA chaperone Hfq for virulence of B. pertussis suggested that Hfq-dependent small regulatory RNAs are involved in the modulation of gene expression. High-throughput RNA sequencing revealed hundreds of putative noncoding RNAs including the RgtA sRNA. Abundance of RgtA is strongly decreased in the absence of the Hfq protein and its expression is modulated by the activities of the two-component regulatory system BvgAS and another response regulator RisA. Whereas RgtA levels were elevated under modulatory conditions or in the absence of bvg genes, deletion of the risA gene completely abolished RgtA expression. Profiling of the ΔrgtA mutant in the ΔbvgA genetic background identified the BP3831 gene encoding a periplasmic amino acid-binding protein of an ABC transporter as a possible target gene. The results of site-directed mutagenesis and in silico analysis indicate that RgtA base-pairs with the region upstream of the start codon of the BP3831 mRNA and thereby weakens the BP3831 protein production. Furthermore, our data suggest that the function of the BP3831 protein is related to transport of glutamate, an important metabolite in the B. pertussis physiology. We propose that the BvgAS/RisA interplay regulates the expression of RgtA which upon infection, when glutamate might be scarce, attenuates translation of the glutamate transporter and thereby assists in adaptation of the pathogen to other sources of energy.
Project description:Purpose: Within the past 20 years, outbreaks of whooping cough, caused by Bordetella pertussis, have led to respiratory disease and infant mortalities, despite good vaccination coverage. This is due at least in part to the introduction of a less effective acellular vaccine in the 1990’s. It is crucial then to understand the molecular basis of B. pertussis growth and infection. The two-component system BvgA/BvgS is the B. pertussis master regulator that regulates the expression of various virulence genes. Previous genome wide studies to identify the bvgAS regulon in B. pertussis have been limited to microarray analyses. The goal of this study is to define the bvgAS regulon using NGS based RNA-seq analysis and RT-qPCR and to compare the differences with the previous microarray data. Method: To define the bvgAS regulon, transcriptomes were generated using B. pertussis Tohama I BP536 (WT) and a ΔbvgAS derivative in the presence and absence of phosphorylated BvgA. Bacteria were grown either under modulating (50 mM MgSO4) conditions, in which phosphorylated BvgA is undetectable (Bvg- mode), or non-modulating (no MgSO4) conditions in which BvgA is phosphorylated (Bvg+ mode). After total RNA extraction and rRNA removal, strand-specific DNA libraries were prepared for Illumina sequencing using the ScriptSeq 2.0 kit (Illumina) in duplicates. Libraries were sequenced using a HiSeq 2000 sequencer (Illumina; University of Buffalo Next Generation Sequencing Core Facility). Sequence reads were mapped to the reference genome (NC_002929.2) and normalized against total reads. Differential expression analyses were performed using CLC Biomedical Genomic Workbench version 3.5.4 with default parameters. Differential gene expression profiles were obtained after Empirical DGE statistical test with FDR p-value. RT–qPCR validation was performed using SYBR Green assays. Result: Using CLC Biomedical Genomic Workbench version 3.5.4, ~ 20-25 million reads per sample were mapped to the reference B. pertussis genome (NC_002929.2). RNA-seq analyses identified >550 genes (15% of genome) that were regulated in a bvgAS-dependent manner with a fold difference ≥ 1.6 and FDR p-value < 0.05. RT-qPCR was used for confirmatory analyses for 80 genes. Overall, we identified 245 genes that were positively regulated and 326 genes that were negatively regulated by bvgAS. 362 members of the bvgAS regulon were newly identified by our study. Most importantly, our analyses indicated that the expression of dozens of transcriptional regulators increases, while the expression of multiple metabolic genes decreases in the presence of BvgA~P. Conclusion: We report here the first RNA-seq analysis of the bvgAS regulon in B. pertussis, revealing that > 550 genes are regulated by bvgAS. Our results suggest that metabolic changes in the Bvg- mode (absence of BvgA phosphorylation) may be participating in bacterial survival, transmission, and/or persistence and identify over 200 new genes negatively regulated by bvgAS that can be tested for function.
Project description:Bordetella pertussis is the etiological agent of whooping cough, a bacterial infection of especially children, which may be fatal without treatment. In frame of studies to investigate putative effects of vaccination on host-pathogen interaction and clonal distribution of strains, in addition to Corynebacterium diphtheriae and Clostridium tetani toxoid vaccines, also whole-cell and acellular pertussis vaccines were analyzed by mass spectrometry.