Project description:Background: Streptococcus dysgalactiae subsp. equisimilis (SDSE), similar to Lancefield group A Streptococcus pyogenes (GAS), causes invasive diseases such as life-threatening streptococcal toxic shock syndrome (STSS). Despite their similar genome sequences, SDSE lacks several important virulence factors of GAS, suggesting that SDSE has specific disease-causing systems. Using microarray analysis, we analyzed SDSE for specific transcriptional regulatory systems involved in stress responses, such as the LytSR/LrgAB system, and their transcriptional profiles under stress conditions. Methods: Transcriptional profiling was performed using microarrays to test the effects of eight antibiotics and five growth conditions. These findings were compared with those obtained during intraperitoneal infection in mice. Results: Genes encoding LrgAB, which modulates the murein hydrolase activity of CidAB and inhibits autolysis in Staphylococcus aureus, were upregulated by exposure to antibacterial agents, phosphate buffered saline (PBS) and stationary phase conditions and during intraperitoneal infection in mice. Starvation and anaerobic conditions stimulated the expression of the streptolysin S operon and polysaccharide lyases in SDSE. Catabolite-responsive elements (cre) were present in the promoter regions of these genes, suggesting that carbon catabolite repression (CCR) is involved in regulating SDSE virulence factors. Comparative genome analysis showed the presence in SDSE of the LytSR/LrgAB system and an additional sigma factor (SDEG_0623), both of which were absent from the GAS genome. Conclusions: These results suggest that the LytSR/LrgAB and CCR play important roles in bacterial resistance to stress microenvironments. Microarray data also indicated that starvation and low oxygen tension partly mimic the microenvironment present during invasive diseases.
Project description:Streptococcus dysgalactiae subsp. equeisimilis (SDSE) has Lancefield group G or C antigens. Recent epidemiological studies reveal that invasive SDSE infections have been increasing in Asia, Europe and US. Although SDSE possesses similar virulence factors to S. pyogenes including streptolysin S (SLS) and streptolysin O (SLO), some important S. pyogenes virulence factors including active superantigens, SpeB and a hyarulonic acids capsule are missing in SDSE genome. The mechanisms and the key virulence factors for causing invasive diseases by SDSE are poorly understood. Here, we analyzed the transcriptome of SDSE in vivo using the murine sepsis model, revealing the strategy of SDSE to destruct host tissues with the virulence factors and to scavenge depleted nutrients. The expression of SLO operon increased at relatively early stage of infection while the SLS and hyaluronidases upregulated after 4h post infection. Microarray data suggested that SDSE degraded host tissue polysaccharides by streptococcal-secreting poly/oligosaccharide lyases and simultaneously used the Entner-Doudoroff pathway to metabolize acquired carbohydrates. A global negative virulence gene regulator CsrRS of SDSE modulated the expressions of genes encoding SLS and the carbohydrate metabolism enzymes. Moreover, csrS deficient mutant induced sever systemic hemolysis in mice. The most frequently isolated stG6792 strains from invasive disease secreted abundant SLS and SLO rather than other SDSE emm types, indicating the relationship between the SLS and SLO productions and poor outcome by the stG6792 strain infection. Our findings suggest that the concomitant regulation of virulence factors destructing the host tissues and metabolic enzymes play an important role to produce invasive diseases by SDSE.
Project description:Streptococcus dysgalactiae subsp. equeisimilis (SDSE) has Lancefield group G or C antigens. Recent epidemiological studies reveal that invasive SDSE infections have been increasing in Asia, Europe and US. Although SDSE possesses similar virulence factors to S. pyogenes including streptolysin S (SLS) and streptolysin O (SLO), some important S. pyogenes virulence factors including active superantigens, SpeB and a hyarulonic acids capsule are missing in SDSE genome. The mechanisms and the key virulence factors for causing invasive diseases by SDSE are poorly understood. Here, we analyzed the transcriptome of SDSE in vivo using the murine sepsis model, revealing the strategy of SDSE to destruct host tissues with the virulence factors and to scavenge depleted nutrients. The expression of SLO operon increased at relatively early stage of infection while the SLS and hyaluronidases upregulated after 4h post infection. Microarray data suggested that SDSE degraded host tissue polysaccharides by streptococcal-secreting poly/oligosaccharide lyases and simultaneously used the Entner-Doudoroff pathway to metabolize acquired carbohydrates. A global negative virulence gene regulator CsrRS of SDSE modulated the expressions of genes encoding SLS and the carbohydrate metabolism enzymes. Moreover, csrS deficient mutant induced sever systemic hemolysis in mice. The most frequently isolated stG6792 strains from invasive disease secreted abundant SLS and SLO rather than other SDSE emm types, indicating the relationship between the SLS and SLO productions and poor outcome by the stG6792 strain infection. Our findings suggest that the concomitant regulation of virulence factors destructing the host tissues and metabolic enzymes play an important role to produce invasive diseases by SDSE. To analyze gene expressions in group G streptococci with the murine infection model, we developed a custom microarray for Streptococcus dysgalactiae subsp. equisimilis (SDSE) based on the genome sequences of three SDSE strains; GGS_124, ATCC12923 and RE378. We intraperitoneally inoculated 10^8 CFU of GGS_124 stain and the csrS deficient mutant into ddY mice. Bacterial cells were collected from the abdominal cavity at 0, 2, 4 and 8 h post infection. GGS_124 cells were also collected from OD600=0.6 culture in brain heart infusion broth as a control.
Project description:A genome reduced E. coli strain MDS42ΔgalK::Ptet-gfp-kan were applied for the comparative transcriptome analysis. Genome-wide transcriptional changes under high osmotic prresure, high temperature condition and starvation were evaluated.
Project description:To validate the functions that iron might play in B cell proliferation and function we used deferoxamine (DFO, a widely used iron chelator) to create an iron-deficient environment for cell culture in vitro.