ArgR1 and AhrC Mediate Arginine-Dependent Regulation of Arginine Acquisition- and Virulence Genes in the Human Pathogen Streptococcus pneumoniae
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ABSTRACT:
ORGANISM(S): Streptococcus pneumoniae D39
PROVIDER: GSE33043 | GEO | 2011/11/02
SECONDARY ACCESSION(S): PRJNA149531
REPOSITORIES: GEO
Similar Datasets
Project description:This SuperSeries is composed of the following subset Series: GSE33033: ahrC mutant compared to D39 wild-type in Streptococcus pneumoniae in CDM + 10 mM arginine GSE33034: argR1 mutant compared to D39 wild-type in Streptococcus pneumoniae in CDM + 10 mM arginine GSE33035: argR1-ahrC mutant compared to D39 wild-type in Streptococcus pneumoniae in CDM + 10 mM arginine GSE33036: Streptococcus pneumoniae D39 wild-type grown in CDM+10 mM arginine compared to D39 wild type grown in CDM + 0.05 mM arginine Refer to individual Series
2011-11-02 | E-GEOD-33043 | biostudies-arrayexpress
Project description:In this study, we investigated for the first time the transcriptional response of the human pathogen Streptococcus pneumoniae to fluctuating concentrations of arginine, an essential amino acid for this bacterium. By means of DNA microarray analyses, several operons and genes were found, the expression of which was affected by the concentration of arginine in the medium. Five of the identified operons were demonstrated to be directly repressed in the presence of high arginine concentrations via the concerted action of the ArgR-type regulators ArgR1 and AhrC. These ArgR1/AhrC targets encompass the putative amino acid transport genes artPQ, abpA, abpB, and aapA; the arginine biosynthetic genes argGH; and the virulence genes aliB and lmB/adcAII-phtD encoding an oligopeptide-binding lipoprotein and cell surface Zn(2+)-scavenging units, respectively. In addition, the data indicate that three of the amino acid transport genes encode an arginine ATP-binding cassette transporter unit required for efficient growth during arginine limitation. Instead of regulating arginine biosynthetic and catabolic genes as has been reported for other Gram-positive bacteria, our findings suggest that the physiological function of ArgR1/AhrC in S. pneumoniae is to ensure optimal uptake of arginine from the surrounding milieu.
| S-EPMC3248006 | biostudies-literature
Project description:Previous studies have shown that the transcriptional regulator PsaR regulates the expression of the PsaR regulon consisting of genes encoding choline binding protein (PcpA), the extracellular serine protease (PrtA), and the Mn2+-uptake system (PsaBCA), in the presence of manganese (Mn2+), zinc (Zn2+), and cobalt (Co2+). In this study, we explore the Ni2+-dependent regulation of the PsaR regulon. We have demonstrated by qRT-PCR analysis, metal accumulation assays, ?-galactosidase assays, and electrophoretic mobility shift assays that an elevated concentration of Ni2+ leads to strong induction of the PsaR regulon. Our ICP-MS data show that the Ni2+-dependent expression of the PsaR regulon is directly linked to high, cell-associated, concentration of Ni2+, which reduces the cell-associated concentration of Mn2+. In vitro studies with the purified PsaR protein showed that Ni2+ diminishes the Mn2+-dependent interaction of PsaR to the promoter regions of its target genes, confirming an opposite effect of Mn2+ and Ni2+ in the regulation of the PsaR regulon. Additionally, the Ni2+-dependent role of PsaR in the regulation of the PsaR regulon was studied by transcriptome analysis.
| S-EPMC4643063 | biostudies-literature
Project description:The concentration of Mn2+ is 1,000-fold higher in secretions than it is at internal sites of the body, making it a potential signal by which bacteria can sense a shift from a mucosal environment to a more invasive site. PsaR, a metal-dependent regulator in Streptococcus pneumoniae, was found to negatively affect the transcription of psaBCA, pcpA, rrgA, rrgB, rrgC, srtBCD, and rlrA in the presence of Mn2+. psaBCA encode an ABC-type transporter for Mn2+. pcpA, rrgA, rrgB, and rrgC encode several outer surface proteins. srtBCD encode a cluster of sortase enzymes, and rlrA encodes a transcriptional regulator. Steady-state RNA levels are high under low Mn2+ concentrations in the wild-type strain and are elevated under both high and low Mn2+ concentrations in a psaR mutant strain. RlrA is an activator of rrgA, rrgB, rrgC, and srtBCD (D. Hava and A. Camilli, Mol. Microbiol. 45:1389-1406, 2002), suggesting that PsaR may indirectly control these genes through rlrA, while PsaR-dependent repression of psaBCA, pcpA, and rlrA transcription is direct. The impact of Mn2+-dependent regulation on virulence was further examined in mouse models of pneumonia and nasopharyngeal carriage. The abilities of DeltapsaR, pcpA, and DeltapsaR DeltapcpA mutant strains to colonize the lung were reduced compared to those of the wild type, confirming that both PcpA-mediated gene regulation and PsaR-mediated gene regulation are required for full virulence in the establishment of pneumonia. Neither PcpA nor PsaR was found to be required for colonization of the nasopharynx in a carriage model. This is the first demonstration of Mn2+ acting as a signal for the expression of virulence factors within different host sites.
| S-EPMC1360317 | biostudies-literature
Project description:Streptococcus pneumoniae is the major cause of bacterial pneumonia, and it is also responsible for otitis media and meningitis in children. Apart from the capsule, the virulence factors of this pathogen are not completely understood. Recent technical advances in the field of bacterial pathogenesis (in vivo expression technology and signature-tagged mutagenesis [STM]) have allowed a large-scale identification of virulence genes. We have adapted to S. pneumoniae the STM technique, originally used for the discovery of Salmonella genes involved in pathogenicity. A library of pneumococcal chromosomal fragments (400 to 600 bp) was constructed in a suicide plasmid vector carrying unique DNA sequence tags and a chloramphenicol resistance marker. The recent clinical isolate G54 was transformed with this library. Chloramphenicol-resistant mutants were obtained by homologous recombination, resulting in genes inactivated by insertion of the suicide vector carrying a unique tag. In a mouse pneumonia model, 1.250 candidate clones were screened; 200 of these were not recovered from the lungs were therefore considered virulence-attenuated mutants. The regions flanking the chloramphenicol gene of the attenuated mutants were amplified by inverse PCR and sequenced. The sequence analysis showed that the 200 mutants had insertions in 126 different genes that could be grouped in six classes: (i) known pneumococcal virulence genes; (ii) genes involved in metabolic pathways; (iii) genes encoding proteases; (iv) genes coding for ATP binding cassette transporters; (v) genes encoding proteins involved in DNA recombination/repair; and (vi) DNA sequences that showed similarity to hypothetical genes with unknown function. To evaluate the virulence attenuation for each mutant, all 126 clones were individually analyzed in a mouse septicemia model. Not all mutants selected in the pneumonia model were confirmed in septicemia, thus indicating the existence of virulence factors specific for pneumonia.
| S-EPMC108710 | biostudies-literature
Project description:Previous studies have shown that the transcriptional regulator PsaR regulates the expression of the PsaR regulon consisting of genes encoding choline binding protein (PcpA), the extracellular serine protease (PrtA), and the Mn2+-uptake system (PsaBCA), in the presence of manganese (Mn2+), zinc (Zn2+), and cobalt (Co2+). In this study, we explore the Ni2+-dependent regulation of the PsaR regulon. We have demonstrated by qRT-PCR analysis, metal accumulation assays, β-galactosidase assays, and electrophoretic mobility shift assays that an elevated concentration of Ni2+ leads to strong induction of the PsaR regulon. Our ICP-MS data show that the Ni2+-dependent expression of the PsaR regulon is directly linked to high, cell-associated, concentration of Ni2+, which reduces the cell-associated concentration of Mn2+. In vitro studies with the purified PsaR protein showed that Ni2+ diminishes the Mn2+-dependent interaction of PsaR to the promoter regions of its target genes, confirming an opposite effect of Mn2+ and Ni2+ in the regulation of the PsaR regulon. Additionally, the Ni2+-dependent role of PsaR in the regulation of the PsaR regulon was studied by transcriptome analysis.
2015-11-20 | GSE73818 | GEO
Project description:Previous studies have shown that the transcriptional regulator PsaR regulates the expression of the PsaR regulon consisting of genes encoding choline binding protein (PcpA), the extracellular serine protease (PrtA), and the Mn2+-uptake system (PsaBCA), in the presence of manganese (Mn2+), zinc (Zn2+), and cobalt (Co2+). In this study, we explore the Ni2+-dependent regulation of the PsaR regulon. We have demonstrated by qRT-PCR analysis, metal accumulation assays, β-galactosidase assays, and electrophoretic mobility shift assays that an elevated concentration of Ni2+ leads to strong induction of the PsaR regulon. Our ICP-MS data show that the Ni2+-dependent expression of the PsaR regulon is directly linked to high, cell-associated, concentration of Ni2+, which reduces the cell-associated concentration of Mn2+. In vitro studies with the purified PsaR protein showed that Ni2+ diminishes the Mn2+-dependent interaction of PsaR to the promoter regions of its target genes, confirming an opposite effect of Mn2+ and Ni2+ in the regulation of the PsaR regulon. Additionally, the Ni2+-dependent role of PsaR in the regulation of the PsaR regulon was studied by transcriptome analysis. Comparison of the Streptococcus pneumoniae D39 wild-type vs D39 ÎpsaR in CDM Plus 0.3 mM Ni2+ Two condition design including a dye swap
2015-11-20 | E-GEOD-73818 | biostudies-arrayexpress
Project description:UnlabelledStreptococcus pneumoniae is auxotrophic for arginine, and molecular analysis of the pneumococcal genome showed that the gene encoding an arginine-ornithine antiporter (ArcD) is organized in a cluster together with the arcABC genes encoding the arginine deiminase system (ADS) of pneumococci. The ADS consists of the arginine deiminase (AD), the catabolic ornithine carbamoyltransferase (cOCT), and the carbamate kinase (CK). Pneumococcal genomes contain three ArgR-type regulators (ArgR1, ArgR2, and AhrC) that are supposed to be involved in the regulation of arginine metabolism. Here, we identified ArgR2 of TIGR4 as the regulator of the ADS and ArcD. ArgR2 binds to promoter sequences of the arc operon, and the deficiency of ArgR2 in TIGR4 abrogates expression of the ADS, including the arginine-ornithine antiporter ArcD. Intranasal infection of mice and real-time bioimaging revealed that deletion of the arcABCDT genes attenuates TIGR4. However, the acute-pneumonia model and coinfection experiments indicated that the arginine-ornithine antiporter ArcD is essential to maintain fitness, while the deficiency of ADS enzymes has a minor impact on pneumococcal fitness under in vivo conditions. Strikingly, argR2 mutant TIGR4 outcompeted the wild type in the respiratory tract, suggesting an increase in fitness and further regulatory functions of ArgR2. In contrast to TIGR4, other pneumococci, such as D39, lacking expression of ArgR2, constitutively express the ADS with a truncated nonfunctional AD. On the basis of these results, we propose that the arginine-ornithine antiporter is essential to maintain pneumococcal fitness and that the genes of the ADS cluster are positively regulated in a strain-specific manner by ArgR2.ImportancePneumococci are the major etiologic agents of community-acquired pneumonia, causing more than 1.5 million deaths annually worldwide. These versatile pathogens are highly adapted to the nutrients provided by the host niches encountered. Physiological fitness is of major importance for colonization of the nasopharyngeal cavity and dissemination during invasive infections. This work identifies the regulator ArgR2 as the activator of the S. pneumoniae TIGR4 ADS and the arginine-ornithine transporter ArcD, which is needed for uptake of the essential amino acid arginine. Although ArgR2 activates ArcD expression and uptake of arginine is required to maintain pneumococcal fitness, the deficiency of ArgR2 increases TIGR4 virulence under in vivo conditions, suggesting that other factors regulated by ArgR2 counterbalance the reduced uptake of arginine by ArcD. Thus, this work illustrates that the physiological homeostasis of pneumococci is complex and that ArgR2 plays a key role in maintaining bacterial fitness.
| S-EPMC4278536 | biostudies-literature
Project description:The transcriptional regulator GlnR of Streptococcus pneumoniae is involved in the regulation of glutamine and glutamate metabolism, controlling the expression of the glnRA and glnPQ-zwf operons, as well as the gdhA gene. To assess the contribution of the GlnR regulon to virulence, D39 wild-type and mutant strains lacking genes of this regulon were tested in an in vitro adherence assay and murine infection models. All of the mutants, except the DeltaglnR mutant, were attenuated in adherence to human pharyngeal epithelial Detroit 562 cells, suggesting a contribution of these genes to adherence during the colonization of humans. During murine colonization, only the DeltaglnA mutant and the glnP-glnA double mutant (DeltaglnAP) were attenuated, in contrast to DeltaglnP, indicating that the effect is caused by the lack of GlnA expression. In our pneumonia model, only DeltaglnP and DeltaglnAP showed a significantly reduced number of bacteria in the lungs and blood, indicating that GlnP is required for survival in the lungs and possibly for dissemination to the blood. In intravenously infected mice, glnP and glnA were individually dispensable for survival in the blood whereas the DeltaglnAP mutant was avirulent. Finally, transcriptome analysis of the DeltaglnAP mutant showed that many genes involved in amino acid metabolism were upregulated. This signifies the importance of glutamine/glutamate uptake and synthesis for full bacterial fitness and virulence. In conclusion, several genes of the GlnR regulon are required at different sites during pathogenesis, with glnA contributing to colonization and survival in the blood and glnP important for survival in the lungs and, possibly, efficient transition from the lungs to the blood.
| S-EPMC2258823 | biostudies-literature
Project description:As opposed to de novo mutation, β-lactam resistance in S. pneumoniae is often conferred via homologous recombination during horizontal gene transfer. We hypothesize that β-lactam resistance in pathogenic streptococci is restricted to naturally competent species via intra-/interspecies recombination due to in vivo fitness trade-offs of de novo penicillin-binding protein (PBP) mutations. We show that de novo mutant populations have abrogated invasive disease capacity and are difficult to evolve in vivo. Conversely, serially transformed recombinant strains efficiently integrate resistant oral streptococcal DNA, gain penicillin resistance and tolerance, and retain virulence in mice. Large-scale changes in pbp2X, pbp2B, and non-PBP-related genes occur in recombinant isolates. Our results indicate that horizontal transfer of β-lactam resistance engenders initially favorable or minimal cost changes in vivo compared with de novo mutation(s), underscoring the importance of recombination in the emergence of β-lactam resistance and suggesting why some pathogenic streptococci lacking innate competence remain universally susceptible.
| S-EPMC9850807 | biostudies-literature