Project description:We sequenced mRNA transcripts from three isogenic M3 serotype GAS strains, parental (MGAS10870), complement (10870::rocAM1), and deletion (10870?rocA). There were no significant changes between the parental and revertant strain. Comparison of the parental and complemented strain revealed several virulence factors were up-regulated in the parental strain where RocA function was diminished. We concluded that RocA, through direct or indirect mechanisms, is able to control numerous virulence genes and this lack of RocA regulation increases expression of virulence factors, which contributes to the hyper-virulent state of serotype M3 GAS. GAS strains were grown to mid-exponential phase, total RNA isolated, rRNA depleted, cDNA libraries synthesized, and libraries analyzed using Illumina MiSeq and CLC Genomics Workbench version 7.5.1 RNA-seq software.
Project description:We sequenced mRNA transcripts from three isogenic M3 serotype GAS strains, parental (MGAS10870), complement (10870::rocAM1), and deletion (10870ΔrocA). There were no significant changes between the parental and revertant strain. Comparison of the parental and complemented strain revealed several virulence factors were up-regulated in the parental strain where RocA function was diminished. We concluded that RocA, through direct or indirect mechanisms, is able to control numerous virulence genes and this lack of RocA regulation increases expression of virulence factors, which contributes to the hyper-virulent state of serotype M3 GAS.
Project description:This transcriptional analysis is a follow up to a population genomic investigation of 3615 Streptococcus pyogenes serotype M1 strains whch are responsible for an epidemic of human invasive infections (www.pnas.org/cgi/doi/10.1073/pnas.1403138111), The goal was to assess gene expression differences between predecessor pre-epidemic M1 strains and their descendent epidemic M1 strains to gain insights into the underlying genetic basis for the shift in the frequency and severity of human infections caused by these pathogenic bacteria The transcriptomes of 7 GAS M1 strains, 4 pre-epidemic and 3 epidemic, were compared at two phases of growth, mid-exponential and early-stationary, using 3 biologial replicates, to identify genes differentially expressed between the pre-epidemic and epidemic isolates with the goal of to gaining insight into the underlying genetic basis for the evolutionary emergence, increased frequency and severity of the epidemic strains relative to the pre-epidemic strains
Project description:Streptococcus pyogenes (group A Streptococcus, GAS) responds to environmental changes in a manner that results in an adaptive regulation of the transcriptome. Global transcriptional regulators are able to integrate important extracellular and intracellular information and are responsible for modulation of the transcriptional network. The roles of several global transcriptional regulators in adaptation and virulence gene expression have been described. In this study we used microarray to investigate the regulatory roles of CodY and CovRS played in Streptococcus pyogenes. keywords: genetic modification Streptococcus pyogenes NZ131 wild-type cells, ΔcodY, ΔcovRS and ΔcodYcovRS strains were grown in C-medium until mid-exponential phase or early-stationary phase. The transcriptional profile of the whole genome was examined with microarray.
Project description:The overall gene expression of a CvfA- mutant of Streptococcus pyogenes grown in C medium was compared to that of the wild type (HSC5spc). Stationary phase cells (8 hrs post-inoculation) were used because the gene expression of the CvfA- mutant was most different from that of the wild type at stationary phase, while the difference of gene expression between the CvfA- mutant and the wild type was negligible at exponential phase.
Project description:A new variant of group A Streptococcus (GAS) serotype M1 (designated ‘M1UK’) has been reported in the United Kingdom, linked with seasonal scarlet fever surges, marked increase in invasive infections, and exhibiting enhanced expression of the superantigen SpeA. The progenitor GAS ‘M1global’ and M1UK clones can be differentiated by 27 SNPs and 4 indels, yet the mechanism for speA upregulation is unknown. Here we investigate the previously unappreciated expansion of M1UK in Australia, now isolated from the majority of serious infections caused by serotype M1 GAS. M1UK sub-lineages circulating in Australia also contain a novel toxin repertoire associated with epidemic scarlet fever causing GAS in Asia. A single SNP in the M1UK tmRNA gene ssrA drives enhanced SpeA superantigen expression as a result of ssrA terminator readthrough in the M1UK lineage. This represents a new paradigm of toxin expression and urges enhanced international surveillance.
Project description:Streptococcus pyogenes chromosomal island M1 (SpyCIM1) integrates by site-specific recombination into the 5’ end of DNA mismatch repair (MMR) gene mutL in strain SF370SmR, blocking transcription of it and the downstream operon genes. During exponential growth, SpyCIM1 excises from the chromosome and replicates as an episome, restoring mutL transcription. This process is reversed in stationary phase with SpyCIM1 re-integrating into mutL, returning the cells to a mutator phenotype. Here we show that elimination of SpyCIM1 relieves this mutator phenotype. The downstream MMR operon genes, multidrug efflux pump lmrP, Holliday junction resolution helicase ruvA, and DNA base excision repair glycosylase tag, are also restored to constitutive expression by elimination of SpyCIM1. The presence of SpyCIM1 alters global transcription patterns in SF370SmR. RNA sequencing (RNA-Seq) demonstrated that loss of SpyCIM1 in the SpyCIM1 deletion mutant, CEM1∆4, impacted the expression of many genes both in early exponential phase, when the SpyCIM1 is episomal, as well as at the onset of stationary phase, when SpyCIM1 has reintegrated into mutL. Among these changes, the up regulation of the genes for the antiphagocytic M protein (emm1), streptolysin O (slo), capsule operon (hasABC), and streptococcal pyrogenic exotoxin (speB), are particularly notable. The expression pattern of the DNA mismatch repair (MMR) operon confirmed our earlier observations that these genes are transcribed in early exponential phase but silenced as stationary phase is approached. The direct role of SpyCIM1 in causing the mutator phenotype is confirmed by these studies, and its influence upon the biology of S. pyogenes was found to impact multiple genes in addition to the MMR operon. We suggest that such chromosomal islands are a remarkable evolutionary adaptation to promote the survival of its S. pyogenes host cell in changing environments.