Project description:We used RNA-Seq to assess how the presence/absence of the RD2 pathogenicity island influences global gene expression in the parental serotype M1 GAS isolate MGAS2221 and the parental serotype M49 isolate NZ131
Project description:Small non-coding RNAs (sRNAs) have attracted attention as a new class of gene regulators in eukaryotes and in bacteria. In this study, we identified novel sRNAs of the human pathogen Streptococcus pyogenes M49 (GAS M49). A temporal expression profile of potential sRNAs was determined for (GAS M49). Cells were grown in chemical defined medium (CDM), Todd-Hewitt broth (Invitrogen) supplemented with 0.5% yeast extract (THY) or Brain-Heart-Infusion (BHI) complex medium using tiling arrays representing the intergenic regions of the GAS M49 genome. We identified 55 putative sRNAs in GAS M49 that were expressed during growth. Of those, 35 sRNAs were novel, whereas 20 sRNAs were known. Already described sRNAs included molecules belonging to one of the common non-coding RNA families covered by the rfam collection and streptococcal sRNAs that have been detected in previous studies. Comparison to a recently published bioinformatics screen showed a low overlap between putative sRNA genes. This is in accordance with the results from other studies, which underlines the fact that a comprehensive analysis of sRNAs expressed by a given organism requires the complementary use of different methods and the investigation of several environmental conditions. Despite a high conservation of sRNA genes within streptococci, the expression of sRNAs is rather strain specific.
Project description:GAS is a highly virulent Gram-positive bacterium. For the successful infection GAS express many virulence factors, which are clustered together with transcriptional regulators in distinct genomic regions. Ralp3 is a central regulator of the ERES region. In this study, we investigated the role of Ralp3 in GAS pathogenesis. To characterize the Ralp3 regulatory function on the whole genome level, GAS M49 wild type and Äralp3 mutant strains were comprehensively compared by two colour microarray analysis. Samples were taken from cultures in the transition phase.
Project description:ABSTRACT Streptococcus pyogenes strain 591 is a clinical isolate belonging to the genotype emm49. It has been intensively studied for its pathogenicity traits. In this study, the complete genome of strain 591 was sequenced. It consists of a chromosome of 1,762,765 bp with a G+C content of 38.5%.
Project description:The 1,815,783-bp genome of a serotype M49 strain of Streptococcus pyogenes (group A streptococcus [GAS]), strain NZ131, has been determined. This GAS strain (FCT type 3; emm pattern E), originally isolated from a case of acute post-streptococcal glomerulonephritis, is unusually competent for electrotransformation and has been used extensively as a model organism for both basic genetic and pathogenesis investigations. As with the previously sequenced S. pyogenes genomes, three unique prophages are a major source of genetic diversity. Two clustered regularly interspaced short palindromic repeat (CRISPR) regions were present in the genome, providing genetic information on previous prophage encounters. A unique cluster of genes was found in the pathogenicity island-like emm region that included a novel Nudix hydrolase, and, further, this cluster appears to be specific for serotype M49 and M82 strains. Nudix hydrolases eliminate potentially hazardous materials or prevent the unbalanced accumulation of normal metabolites; in bacteria, these enzymes may play a role in host cell invasion. Since M49 S. pyogenes strains have been known to be associated with skin infections, the Nudix hydrolase and its associated genes may have a role in facilitating survival in an environment that is more variable and unpredictable than the uniform warmth and moisture of the throat. The genome of NZ131 continues to shed light upon the evolutionary history of this human pathogen. Apparent horizontal transfer of genetic material has led to the existence of highly variable virulence-associated regions that are marked by multiple rearrangements and genetic diversification while other regions, even those associated with virulence, vary little between genomes. The genome regions that encode surface gene products that will interact with host targets or aid in immune avoidance are the ones that display the most sequence diversity. Thus, while natural selection favors stability in much of the genome, it favors diversity in these regions.