Project description:Growth curves and (p)ppGpp accumulation assays showed that RelA inactivation could influence S. suis growth and led to incapacity of (p)ppGpp synthesis during glucose starvation. To identify the roles of RelA/(p)ppGpp in global gene regulation in S. suis, we compared the transcriptional profiles of SC-19 [a (p)ppGpp+ strain] and ΔrelA [a (p)ppGpp0 strain during glucose starvation] in both glucose-abundant and -deficient CDM in exponential phase by microarray analysis. A less stringent cut-off limit, 2-fold change, was used. qRT-PCR validation displayed the same trends observed in the microarrays
Project description:Growth curves and (p)ppGpp accumulation assays showed that RelA inactivation could influence S. suis growth and led to incapacity of (p)ppGpp synthesis during glucose starvation. To identify the roles of RelA/(p)ppGpp in global gene regulation in S. suis, we compared the transcriptional profiles of SC-19 [a (p)ppGpp+ strain] and ΔrelA [a (p)ppGpp0 strain during glucose starvation] in both glucose-abundant and -deficient CDM in exponential phase by microarray analysis. A less stringent cut-off limit, 2-fold change, was used. qRT-PCR validation displayed the same trends observed in the microarrays relA mutant strain and its parents strain SC-19 were cultured in both glucose-abundant CDM (CDM containing 1% glucose) and glucose-deficient CDM (CDM containing 2% glucose) respectively. The bacteriain in exponential phase were collected for microarray analysis. Three independent experiments were performed.
Project description:The production of (p)ppGpp by Streptococcus mutans UA159 is catalyzed by three gene products, RelA, RelP and RelQ. Here, we investigate the role of the RelA (Rel) homologue of S. mutans in the stringent response and in global control of gene expression. RelA of S. mutans was shown to synthesize pppGpp in vitro from GTP and ATP in the absence of added ribosomes, as well as in vivo in an E. coli relA-spoT mutant. Mupirocin (MUP) was shown to induce high levels of (p)ppGpp production in S. mutans in a relA-dependent manner, with a concommitant reduction in GTP pools. Keywords: (p)ppGpp, nutrient starvation, biofilm, virulence, stress
Project description:Streptococcus suis is an important zoonotic pathogen that can cause meningitis and sepsis in both pigs and humans. In this study,we evaluated the genetic difference of 40 Streptococcus suis strains belonging to various sequence types by comparative genomic hybridization to identify genes associated with the variation in pathogenicity using NimbleGen’s tilling microarray platform. Application of Comparative Phylogenomics to Identify Genetic Differences Relating to Pathogenicity of Streptococcus suis
Project description:Streptococcus suis is a major pig pathogen as well as an emerging zoonotic pathogen. Previous work has demonstrated that the S. suis extracellular amylopullulanase enzyme (ApuA) that degrades {alpha}-glucans also functions as an adhesin for porcine epithelial cells. To identify the mechanisms linking carbohydrate metabolism and virulence, we first compared the transcriptome of S. suis in minimal medium supplemented with glucose to minimal medium containing a complex carbohydrate pullulan as a carbon source. The relative expression of eighteen virulence genes including suilysin and apuA was increased during growth in presence of pullulan, compared to growth in glucose. Increased virulence potential of S. suis grown in pullulan was demonstrated using hemolytic assays and increased adhesion and invasion of porcine epithelial cells in vitro. A metabolic map of S. suis was generated and combined with transcriptome data to visualize the metabolic adaption of S. suis during adhesion and invasion of the porcine epithelial cells representing an in vitro model of infection. The role of carbon catabolite control in virulence gene regulation was investigated and the molecular mechanism of transcriptional regulation was elucidated for apuA. We demonstrate that relief of CcpA repression is a crucial transcriptional control mechanism linking carbohydrate mechanism and virulence. The model for the transcriptional regulation of two important virulence factors apuA and suilysin was verified by qPCR analysis of gene expression in S. suis recovered from the organs and blood of infected pigs.
Project description:Streptococcus suis is an important zoonotic pathogen that can cause meningitis and sepsis in both pigs and humans. In this study,we evaluated the genetic difference of 40 Streptococcus suis strains belonging to various sequence types by comparative genomic hybridization to identify genes associated with the variation in pathogenicity using NimbleGenM-bM-^@M-^Ys tilling microarray platform. Application of Comparative Phylogenomics to Identify Genetic Differences Relating to Pathogenicity of Streptococcus suis Comparative genomic analysis on the 40 S.suis strains of different serotypes and ST types through tilling arrays
Project description:Identification of Genes and Genomic Islands Correlated with High Pathogenicity through Tilling Microarray-Based Comparative Genomics in S. suis. Streptococcus suis is an important zoonotic pathogen that can cause meningitis and sepsis in both pigs and humans. S. suis isolates have been categorized into groups of different levels of pathogenicity, with sequence type (ST) ST1 clonal complex strains having a higher degree of virulence than other STs. However, the genetic basis of the differences in pathogenicity is still poorly understood. In this study, a comprehensive genomic comparison of 31 S. suis strains from different clinical sources with the genome sequence of the high pathogenicity (HP) strain GZ1 was conducted using NimbleGen’s tilling microarray platform.
Project description:Streptococcus suis is a major pig pathogen as well as an emerging zoonotic pathogen. Previous work has demonstrated that the S. suis extracellular amylopullulanase enzyme (ApuA) that degrades {alpha}-glucans also functions as an adhesin for porcine epithelial cells. To identify the mechanisms linking carbohydrate metabolism and virulence, we first compared the transcriptome of S. suis in minimal medium supplemented with glucose to minimal medium containing a complex carbohydrate pullulan as a carbon source. The relative expression of eighteen virulence genes including suilysin and apuA was increased during growth in presence of pullulan, compared to growth in glucose. Increased virulence potential of S. suis grown in pullulan was demonstrated using hemolytic assays and increased adhesion and invasion of porcine epithelial cells in vitro. A metabolic map of S. suis was generated and combined with transcriptome data to visualize the metabolic adaption of S. suis during adhesion and invasion of the porcine epithelial cells representing an in vitro model of infection. The role of carbon catabolite control in virulence gene regulation was investigated and the molecular mechanism of transcriptional regulation was elucidated for apuA. We demonstrate that relief of CcpA repression is a crucial transcriptional control mechanism linking carbohydrate mechanism and virulence. The model for the transcriptional regulation of two important virulence factors apuA and suilysin was verified by qPCR analysis of gene expression in S. suis recovered from the organs and blood of infected pigs. Four-condition experiment (bacteria grown in THB or in CM supplemented with three different carbon sources), at two different timepoints (early exponential or late exponential growth phase). One replicate per array.
Project description:In the intracellular pathogen Brucella spp., the activation of the stringent response, a global regulatory network providing rapid adaptation to a variety of growth-affecting stress conditions such as nutrient deficiency, is essential for replication in the host. A single, bi-functional enzyme Rsh catalyzes synthesis and hydrolysis of the alarmone (p)ppGpp, responsible for differential gene expression under stringent conditions. cDNA microarray analysis allowed characterization of the transcriptional profiles of the B. suis 1330 wild-type and rsh mutant in a synthetic minimal medium, partially mimicking the nutrient-poor environment of the intramacrophagic vacuole. A total of 379 genes (11.6% of the genome) were differentially expressed in a rsh-dependent manner, of which 52% were up-regulated and 48% were down-regulated. The pleiotropic character of the response was confirmed, as the genes encoded factors belonging to various functional groups, comprising an important number of transcriptional regulators, cell envelope proteins, stress factors, transport systems, and energy metabolism proteins. Several virulence genes were under the positive control of (p)ppGpp. Methionine was the only amino acid whose biosynthesis was absolutely dependent on stringent response in B. suis. The study illustrated the complexity of the processes involved in adaptation to nutrient starvation, and contributed to a better understanding of the correlation between stringent response and Brucella virulence. Most interestingly, it clearly indicated (p)ppGpp-dependent cross-talk between at least three stress responses playing a central role in Brucella adaptation to the host: nutrient, oxidative, and low-oxygen stress.