Structural basis of virulence activation in Francisella tularensis
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ABSTRACT:
PROVIDER: PRJNA634110 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR11818941.fastq.gz | Fastqsanger.gz | |||
| SRR11818942.fastq.gz | Fastqsanger.gz | |||
| SRR11818943.fastq.gz | Fastqsanger.gz | |||
| SRR11818944.fastq.gz | Fastqsanger.gz | |||
| SRR11818945.fastq.gz | Fastqsanger.gz |
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Project description:The bacterium, Francisella tularensis (Ft), is one of the most infectious agents known and classified as a category A bioweapon. Ft virulence is controlled by a unique set of transcription regulators, the MglA-SspA heterodimer, PigR, and the stress signal, ppGpp. These factors activate Francisella pathogenicity island (FPI) gene expression, which is required for virulence. MglA-SspA is expressed during infection and constitutively associates with the σ70 associated RNAP holoenzyme (RNAPσ70), indicating that RNAPσ70-(MglA-SspA) is a virulence specific polymerase. How virulence activation is mediated by these components, however, is unknown. Here we report cryo-EM structures of FtRNAPσ70, FtRNAPσ70-(MglA-SspA) and RNAPσ70-(MglA-SspA)-ppGpp-PigR complexes with promoter DNA. FtRNAPσ70-DNA and FtRNAPσ70-(MglA-SspA)-DNA structures and RT-PCR analyses show MglA-SspA stabilizes σ70 binding to DNA to regulate FPI-independent, virulence-enhancing genes. Strikingly, an Escherichia coli RNAPσ70 complex with EcSspA suggests this is a general mechanism for SspA-like regulation of bacterial RNAPσ70. Finally, our FtRNAP-σ70-(MglA-SspA)-ppGpp-PigR-DNA structure reveals that ppGpp binds to MglA-SspA to tether the DNA-binding activator, PigR, to FPI promoters. PigR in turn recruits FtRNAP CTDs to two DNA upstream (UP) elements, generating stable FPI transcription complexes. Thus, these studies unveil a novel paradigm for pathogenesis in Ft involving a virulence-specific RNAP that employs two (MglA-SspA)-based strategies to activate virulence genes.
2020-11-05 | GSE150932 | GEO
Project description:Differential expression in human peripheral blood monocytes between F. novicida-infected and uninfected, and between Francisella tularensis tularensis isolate Schu S4 and uninfected. The goal was to examine genomewide transcriptional reponses to these two strains, and identify differentially-regulated genes that may help explain the virulence of Schu S4. Keywords: Immune Response, Human Monocytes, Bacteria, Francisella
2008-08-13 | GSE12108 | GEO
Project description:The highly infectious bacterium Francisella tularensis is a facultative intracellular pathogen, whose virulence requires proliferation inside host cells, including macrophages. Although some Francisella determinants of intracellular growth have been identified, much remains to be understood about the pathogenesis of this organism. In particular, how Francisella responds to its intracellular environment could provide clues about its intracellular biology and reveal pathogenic determinants based on their intracellular expression profiles. Here we have performed a global transcriptional profiling of the highly virulent F. tularensis subsp. tularensis Schu S4 strain during its intracellular cycle within primary murine macrophages. Phagocytosed bacteria rapidly responded to their intracellular environment and progressively altered their transcriptional profile over time. Differential gene expression profiles were revealed that correlated with specific intracellular locations of the bacteria. Upregulation of general and oxidative stress response genes was a hallmark of the early phagosomal and late endosomal stages, while induction of a subset of transport and metabolic genes characterized the cytosolic replication stages. Expression of the Francisella Pathogenicity Island (FPI) genes, the functions of which are associated with intracellular proliferation, increased during the intracellular cycle. Similarly, 27 chromosomal loci putatively encoding hypothetical, secreted, outer membrane proteins or transcriptional regulators were identified as upregulated during the intracellular cycle. In-frame deletion of FTT0383, the Schu S4 ortholog of fevR, of FTT0369c or FTT1676 abolished the ability of Schu S4 to either survive or proliferate intracellularly, demonstrating that bacterial factors of intracellular pathogenesis can be identified based on their intracellular expression profile. In conclusion, establishing the intracellular transcriptome of Francisella has revealed important aspects of its intracellular biology and identified novel virulence determinants of this pathogen. Keywords: Time series
2009-05-05 | GSE12663 | GEO
Project description:Francisella tularensis is a Gram-negative bacterium that causes a fatal human disease known as tularemia. The Centers for Disease Control have classified F. tularensis as Category A Tier-1 Select Agent. The virulence mechanisms of Francisella are not entirely understood. Francisella possesses very few transcription regulators, and most of these regulate the expression of genes involved in intracellular survival and virulence. The F. tularensis genome sequence analysis reveals an AraC (FTL_0689) transcriptional regulator homologous to the AraC/XylS family of transcriptional regulators. In Gram-negative bacteria, AraC activates genes required for L-arabinose utilization and catabolism. The role of the FTL_0689 regulator in F. tularensis is not known. In this study, we characterized the role of FTL_0689 in gene regulation of F. tularensis and investigated its contribution to intracellular survival and virulence. The results demonstrate that FTL_0689 in Francisella is not required for L-arabinose utilization. Instead, FTL_0689 specifically regulates the expression of the oxidative and global stress response, virulence, metabolism, and other key pathways genes required by Francisella when exposed to oxidative stress. The FTL_0689 mutant is attenuated for intramacrophage growth, and mice infected with the FTL_0689 mutant survive better than wild-type F. tularensis LVS infected mice. Based on the deletion mutant phenotype, FTL_0689 was termed osrR (oxidative stress response regulator). Altogether, this study elucidates the role of the osrR transcriptional regulator in tularemia pathogenesis.
2021-10-13 | GSE183001 | GEO
Project description:These samples are part of an experiment comparing the expression profiles of Francisella tularensis novicida grown in chemically defined medium and bacteria isolated 24 hours post infection of J774 macrophages to identify virulence factors
2017-05-02 | GSE75689 | GEO
Project description:The highly infectious bacterium Francisella tularensis is a facultative intracellular pathogen, whose virulence requires proliferation inside host cells, including macrophages. Although some Francisella determinants of intracellular growth have been identified, much remains to be understood about the pathogenesis of this organism. In particular, how Francisella responds to its intracellular environment could provide clues about its intracellular biology and reveal pathogenic determinants based on their intracellular expression profiles. Here we have performed a global transcriptional profiling of the highly virulent F. tularensis subsp. tularensis Schu S4 strain during its intracellular cycle within primary murine macrophages. Phagocytosed bacteria rapidly responded to their intracellular environment and progressively altered their transcriptional profile over time. Differential gene expression profiles were revealed that correlated with specific intracellular locations of the bacteria. Upregulation of general and oxidative stress response genes was a hallmark of the early phagosomal and late endosomal stages, while induction of a subset of transport and metabolic genes characterized the cytosolic replication stages. Expression of the Francisella Pathogenicity Island (FPI) genes, the functions of which are associated with intracellular proliferation, increased during the intracellular cycle. Similarly, 27 chromosomal loci putatively encoding hypothetical, secreted, outer membrane proteins or transcriptional regulators were identified as upregulated during the intracellular cycle. In-frame deletion of FTT0383, the Schu S4 ortholog of fevR, of FTT0369c or FTT1676 abolished the ability of Schu S4 to either survive or proliferate intracellularly, demonstrating that bacterial factors of intracellular pathogenesis can be identified based on their intracellular expression profile. In conclusion, establishing the intracellular transcriptome of Francisella has revealed important aspects of its intracellular biology and identified novel virulence determinants of this pathogen. Keywords: Time series Intracellular cycle within primary murine macrophages using the time series of zero, one, two, four, eight, twelve, sixteen and twenty-four hours
2010-05-19 | E-GEOD-12663 | biostudies-arrayexpress
Project description:Differential expression in human peripheral blood monocytes between F. novicida-infected and uninfected, and between Francisella tularensis tularensis isolate Schu S4 and uninfected. The goal was to examine genomewide transcriptional reponses to these two strains, and identify differentially-regulated genes that may help explain the virulence of Schu S4. Experiment Overall Design: Human monocytes were infected with the Schu S4 isolate of Francisella tularensis tularensis (n=4), with F. tularensis subspecies novicida isolate U112 (n=4) or were left uninfected (n=6). Gene expression values were calculated using the gcrma package in R and BioConductor, and limma to identify differentially expressed genes. Submitted here are expression values calculated using R 2.7.1 and BioConductor 2.2 (FreeBSD/amd64) but the original were done using R 2.6.1 and BioConductor 2.1 (FreeBSD/amd64). Twelve other chips were pooled with these 14 for preprocessing.
2008-10-25 | E-GEOD-12108 | biostudies-arrayexpress
Project description:The facultative intracellular bacterium Francisella tularensis causes the zoonotic disease tularemia. F. tularensis resides within host macrophages in vivo and this ability is essential for pathogenesis. The transcription factor MglA is required for expression of several Francisella genes that are necessary for replication in macrophages and for virulence in mice. We hypothesized that identification of MglA-regulated genes in the Francisella genome by transcriptional profiling of wild-type and mglA mutant bacteria would lead to the discovery of new virulence factors utilized by F. tularensis. One hundred and two MglA-regulated genes were identified, the majority of which were positively regulated, including all of the Francisella Pathogenicity Island (FPI) genes. We mutated novel MglA-regulated genes and tested the mutants for their ability to replicate and to induce cytotoxicity in macrophages, and to grow in mice. Mutants in MglA-regulated genes within the FPI (pdpB and cds2), as well as outside the FPI (FTT0989, oppB, and FTT1209c), were either attenuated or hypervirulent in macrophages as compared to the wild-type strain. All of these mutants exhibited decreased fitness in vivo in competition experiments with wild-type bacteria. We have identified 5 new Francisella virulence genes and our results suggest that characterization of additional MglA-regulated genes will yield further insights into the pathogenesis of this bacterium. An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Keywords: all_pairs
2006-10-20 | GSE5468 | GEO
Project description:Francisella tularensis, is an extremely virulent bacterium that can be transmitted naturally by blood sucking arthropods. During mammalian infection, F. tularensis infects numerous types of host cells, including erythrocytes. As erythrocytes do not undergo phagocytosis or endocytosis, it remains unknown how F. tularensis invades these cells. Furthermore, the consequence of inhabiting the intracellular space of red blood cells has not been determined. Here, we provide evidence indicating that residing within an erythrocyte enhances the ability of F. tularensis to colonize ticks following a blood meal.
2017-05-24 | GSE93233 | GEO
Project description:The facultative intracellular bacterium Francisella tularensis causes the zoonotic disease tularemia. F. tularensis resides within host macrophages in vivo and this ability is essential for pathogenesis. The transcription factor MglA is required for expression of several Francisella genes that are necessary for replication in macrophages and for virulence in mice. We hypothesized that identification of MglA-regulated genes in the Francisella genome by transcriptional profiling of wild-type and mglA mutant bacteria would lead to the discovery of new virulence factors utilized by F. tularensis. One hundred and two MglA-regulated genes were identified, the majority of which were positively regulated, including all of the Francisella Pathogenicity Island (FPI) genes. We mutated novel MglA-regulated genes and tested the mutants for their ability to replicate and to induce cytotoxicity in macrophages, and to grow in mice. Mutants in MglA-regulated genes within the FPI (pdpB and cds2), as well as outside the FPI (FTT0989, oppB, and FTT1209c), were either attenuated or hypervirulent in macrophages as compared to the wild-type strain. All of these mutants exhibited decreased fitness in vivo in competition experiments with wild-type bacteria. We have identified 5 new Francisella virulence genes and our results suggest that characterization of additional MglA-regulated genes will yield further insights into the pathogenesis of this bacterium. An all pairs experiment design type is where all labeled extracts are compared to every other labeled extract. Keywords: all_pairs Computed
2010-07-01 | E-GEOD-5468 | biostudies-arrayexpress