Dataset Information

Identification, cloning, and expression of the CAMP factor gene (cfa) of group A streptococci.

ABSTRACT: The CAMP reaction is a synergistic lysis of erythrocytes by the interaction of an extracellular protein (CAMP factor) produced by some streptococcal species with the Staphylococcus aureus sphingomyelinase C (beta-toxin). Group A streptococci (GAS [Streptococcus pyogenes]) have been long considered CAMP negative, and this reaction commonly has been used to distinguish GAS from Streptococcus agalactiae. We here provide evidence that GAS possess this gene and produce an extracellular CAMP factor capable of participating in a positive CAMP reaction. The S. pyogenes CAMP factor is specified by a 774-bp open reading frame homologous to the CAMP factor genes from S. agalactiae and Streptococcus uberis. This gene, designated cfa, was isolated on a 1,256-bp fragment and cloned in Escherichia coli. Recombinant clones of E. coli expressing cfa secreted an active CAMP factor. The deduced 28.5-kDa protein encoded by cfa consists of 257 amino acids, with a predicted 28-amino-acid signal peptide. The cfa gene is widely spread among GAS: 82 of 100 clinical GAS isolates produced a positive CAMP reaction. Of the CAMP-negative strains, 17 of the 18 GAS strains contained the cfa gene. Additionally, CAMP activity was detected in streptococci from serogroups C, M, P, R, and U. The cfa gene was cloned and actively expressed in Escherichia coli and gene fusions were made, placing the beta-galactosidase gene (lacZ) under control of the cfa promoter. These cfa promoter-lacZ fusions were introduced into S. pyogenes via a bacteriophage-derived site-specific integration vector where they showed that the cfa gene has a strong promoter that may be subject to as-yet-unidentified regulatory factors. The results presented here, along with previous reports, indicate that the CAMP factor gene is fairly widespread among streptococci, being present at least in groups A, B, C, G, M, P, R, and U.

SUBMITTER: Gase K

PROVIDER: S-EPMC96801 | biostudies-literature | 1999 Sep

REPOSITORIES: biostudies-literature

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Identification, cloning, and expression of the CAMP factor gene (cfa) of group A streptococci.

Gase K K Ferretti J J JJ Primeaux C C McShan W M WM

Infection and immunity 19990901 9

The CAMP reaction is a synergistic lysis of erythrocytes by the interaction of an extracellular protein (CAMP factor) produced by some streptococcal species with the Staphylococcus aureus sphingomyelinase C (beta-toxin). Group A streptococci (GAS [Streptococcus pyogenes]) have been long considered CAMP negative, and this reaction commonly has been used to distinguish GAS from Streptococcus agalactiae. We here provide evidence that GAS possess this gene and produce an extracellular CAMP factor ca ...[more]

PMID: 10456923

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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.

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Dataset Information

Identification, cloning, and expression of the CAMP factor gene (cfa) of group A streptococci.

Publications

Identification, cloning, and expression of the CAMP factor gene (cfa) of group A streptococci.

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