Ontology highlight
ABSTRACT:
PROVIDER: PRJNA495129 | ENA |
REPOSITORIES: ENA
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Project description:The control of virulence two-component gene regulatory system (CovRS) is critical to the pathogenesis of many medically important streptococci. In emm1 group A streptococci (GAS), CovR directly binds the promoters of numerous GAS virulence factor encoding genes. Elimination of CovS phosphatase activity increases CovR phosphorylation (CovR~P) levels and abrogates GAS virulence. Given the emm type-specific diversity of CovRS function, herein we used ChIP-seq to define global CovR DNA occupancy in the wild-type emm3 strain MGAS10870 (medium CovR~P) and its CovS phosphatase-negative derivative 10870-CovS-T284A (high CovR~P). In the wild-type emm3 strain, 89% of the previously identified emm1 CovR binding sites present in the emm3 genome were also enriched; additionally, we ascertained unique CovR binding, primarily to genes in mobile genetic elements and other sites of inter-strain chromosomal differences. Elimination of phosphatase activity specifically increased CovR occupancy at the promoters of a broad array of CovR repressed virulence factor encoding genes, including those encoding the key GAS regulator Mga and M protein. However, a limited number of promoters had augmented enrichment at low CovR~P levels. Differential motif searches using sequences enriched at high vs. low CovR~P levels revealed two distinct binding patterns. At high CovR~P, a pseudo-palindromic AT-rich consensus sequence consistent with CovR binding as a dimer was determined. Conversely, sequences specifically enriched at low CovR~P contained isolated “ATTARA” motifs suggesting an interaction with a monomer. These data extend understanding of global CovR DNA occupancy beyond emm1 GAS and provide a mechanism for previous observations regarding hypovirulence induced by CovS phosphatase abrogation.
2023-05-31 | GSE230870 | GEO
Project description:Our group recently transcriptomically characterized coculture growth between Streptococcus mutans and several species of commensal streptococci (Rose et al, 2023). However, these experiments were carried out in our lab-based experimental medium, tryptone and yeast extract (TY-). To understand whether culturing these species within a medium that more closely mimics their natural environment alters the interaction, we evaluated both monoculture and coculture growth between the dental caries pathogen Streptococcus mutans and oral commensal species Streptococcus oralis in a half TY- / half human saliva mix that was optimally chosen based on our initial characterization of oral streptococci behaviors in medium mixes containing saliva. Our results surprising show that inclusion of saliva enhances the competition of Streptococcus mutans against commensal streptococci through upregulation of carbohydrate uptake and glycolytic pathways.
2023-08-22 | GSE239483 | GEO
Project description:Whole genome sequencing of viridans group streptococci associated with infective endocarditis and the human mouth.
| PRJNA817585 | ENA
Project description:Streptococcus agalactiae (group B streptococci) genome sequencing and assembly
| PRJNA551699 | ENA
Project description:Recent whole-genome sequencing of large populations of the same bacterial species has revealed significant disparity among genes in the frequency of single nucleotide polymorphisms (SNPs). For example, a previous analysis of invasive serotype M3 group A streptococci (GAS) found the highest frequency of SNPs in the gene (ropB) encoding the regulator of proteinase B (RopB). This finding led us to hypothesize that RopB polymorphisms contribute to altered GAS host-pathogen interactions. Sequencing of ropB in 171 invasive serotype M3 GAS strains from a surveillance study identified 19 distinct ropB alleles. Inactivation of the ropB gene in strains producing distinct RopB variants had dramatically different effects on GAS global gene expression. Further, analysis of laboratory-generated isoallelic GAS strains differing only by a single amino acid replacement in RopB confirmed that the variant protein affected the transcript level of the gene encoding streptococcal proteinase B, a major RopB-regulated virulence factor. Comparison of parental, RopB-inactivated, and RopB isoallelic strains in mouse infection models demonstrated that RopB polymorphisms significantly influence GAS virulence and disease manifestations. These studies detail a paradigm in which unbiased, whole-genome sequence analysis of populations of clinical bacterial isolates creates new avenues of productive investigation into the pathogenesis of common human infections.
2011-04-01 | GSE26655 | GEO
Project description:Streptococcus sanguinis is a major component of the oral flora and an important cause of infective endocarditis. The genome sequence of S. sanguinis strain SK36 was recently determined. A number of foreign genes acquired by natural transformation were detected, as well as orthologs of competence genes previously identified in other species. However, significant differences in the S. sanguinis competence system relative to that of other streptococci were noted. We sought to examine S. sanguinis genetic competence, to characterize the global transcriptional response to competence induction, and to compare our results with those obtained from previous analyses of other streptococci. A mutant possessing an in-frame deletion in the comC gene encoding the competence-stimulating peptide was created and confirmed to have the expected phenotype. Studies indicated that competence could be induced in this strain by addition of competence-stimulating peptide, and determined the optimal conditions to employ for this purpose. Expression was monitored by microarray analysis at multiple time points from 2.5 to 30 min after induction. Over 200 genes were identified whose expression was altered at least two-fold in at least one time point, with the majority upregulated. The “late” response was typical of that seen in previous studies. However, comparison of the “early” response in S. sanguinis with that of other streptococci revealed unexpected heterogeneity with regard to the number of genes induced, the nature of these genes, and their putative upstream regulatory sequences. S. sanguinis possesses a comparatively limited early response, which may define a minimal competence regulatory circuit.
2011-01-21 | GSE21619 | GEO