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Architecture of the vir regulons of group A streptococci parallels opacity factor phenotype and M protein class.

ABSTRACT: Group A streptococci have traditionally been categorized into two broad groups based on the presence or absence of serum opacity factor (OF). Recent studies show that these two groups vary in a number of properties in addition to the OF phenotype, including sequence variations in the constant region of the antiphagocytic M protein genes, the presence or absence of immunoglobulin G Fc receptor proteins, and the presence or absence of multiple M protein-like genes situated in a tandem array. The M protein genes (emm) in OF- streptococcal strains are known to be part of a regulon of virulence-related genes controlled by the trans-acting positive regulatory gene, virR, situated just upstream of emm. In OF+ strains, however, the region adjacent to virR is occupied by an M protein-related, type IIa immunoglobulin G Fc receptor gene (fcrA), and the relative position of emm has not been determined. To further define the vir regulon in OF+ streptococci, we used the polymerase chain reaction to show that fcrA49 is situated immediately upstream of emm49 in the OF+ type 49 strain CS101. This result shows for the first time the separate identity and genetic linkage of these two genes in the vir regulon of an OF+ group A streptococcal strain and confirms our previous hypothesis that emm49 exists as the central gene in a trio of emm-like genes. Additionally, using DNA hybridizations, we found considerable sequence divergence between OF- and OF+ group A streptococci in virR and in the noncoding sequences between virR and the emm or fcrA expression site. We found, however, a high degree of sequence conservation in this region within each of the two groups of strains.

SUBMITTER: Haanes EJ

PROVIDER: S-EPMC206310 | biostudies-other | 1992 Aug

REPOSITORIES: biostudies-other

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Architecture of the vir regulons of group A streptococci parallels opacity factor phenotype and M protein class.

Haanes E J EJ Heath D G DG Cleary P P PP

Journal of bacteriology 19920801 15

Group A streptococci have traditionally been categorized into two broad groups based on the presence or absence of serum opacity factor (OF). Recent studies show that these two groups vary in a number of properties in addition to the OF phenotype, including sequence variations in the constant region of the antiphagocytic M protein genes, the presence or absence of immunoglobulin G Fc receptor proteins, and the presence or absence of multiple M protein-like genes situated in a tandem array. The M ...[more]

PMID: 1385809

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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.

Dataset Information

Architecture of the vir regulons of group A streptococci parallels opacity factor phenotype and M protein class.

Publications

Architecture of the vir regulons of group A streptococci parallels opacity factor phenotype and M protein class.

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