<i>Streptococcus pyogenes</i>CovRS Mediates Growth in Iron Starvation and in the Presence of the Human Cationic Antimicrobial Peptide LL-37

Froehlich, Barbara J.; Bates, Christopher S.; Scott, June R.

doi:10.1128/jb.01256-08

Cited by 43 publications

(29 citation statements)

References 57 publications

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“…A full description of the CodY regulon will be the subject of a separate publication. The CovRS global regulator is one of the beststudied regulatory systems in GAS (14) and is known to respond to (i) the presence of cationic antimicrobial peptides (23,26), (ii) low pH, (iii) high temperature, and (iv) changes in ion concentration (like the presence of Mg 2ϩ or Fe) (17,25). It has been suggested that the main environmental signal is envelope stress (23).…”

Section: Discussionmentioning

confidence: 99%

“…The CovRS global regulator is one of the beststudied regulatory systems in GAS (14) and is known to respond to (i) the presence of cationic antimicrobial peptides (23,26), (ii) low pH, (iii) high temperature, and (iv) changes in ion concentration (like the presence of Mg 2ϩ or Fe) (17,25). It has been suggested that the main environmental signal is envelope stress (23). A common route of GAS infection is invasion through the pharynx (51), where the cells are challenged with environmental fluctuations affecting not only the pH or ionic composition of the mucosal bathing saliva but also the availability of nutrients (9).…”

Section: Discussionmentioning

confidence: 99%

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Counteractive Balancing of Transcriptome Expression Involving CodY and CovRS in Streptococcus pyogenes

et al. 2011

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Counteractive Balancing of Transcriptome Expression Involving CodY and CovRS in Streptococcus pyogenes

et al. 2011

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“…In group A Streptococcus (Streptococcus pyogenes, or GAS), CsrRS is a major global regulatory system that can repress as many as 15% of chromosomal genes, including a number of surface-associated and secreted proteins that mediate virulence and host-pathogen interactions (3,16,18,33,39). Mg 2ϩ and the human cathelicidin antimicrobial peptide LL-37 have been identified as opposing signals that act through CsrS to regulate an extensive repertoire of GAS genes (17,(20)(21)(22). An orthologue of the CsrRS system has been identified in GBS (27,31).…”

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confidence: 99%

CsrRS Regulates Group BStreptococcusVirulence Gene Expression in Response to Environmental pH: a New Perspective on Vaccine Development

et al. 2009

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To identify factors involved in the response of group B streptococci (GBS) to environmental pH, we performed a comparative global gene expression analysis of GBS at acidic and neutral pHs. We found that the transcription of 317 genes was increased at pH 5.5 relative to that at pH 7.0, while 61 genes were downregulated. The global response to acid stress included the differential expression of genes involved in transport, metabolism, stress response, and virulence. Known vaccine candidates, such as BibA and pilus components, were also regulated by pH. We observed that many of the genes involved in the GBS response to pH are known to be controlled by the CsrRS two-component system. Comparison of the regulon of wild-type strain 2603 V/R with that of a csrRS deletion mutant strain revealed that the pH-dependent regulation of 90% of the downregulated genes and 59.3% of the up-regulated genes in strain 2603 V/R was CsrRS dependent and that many virulence factors were overexpressed at high pH. Beta-hemolysin regulation was abrogated by selective inactivation of csrS, suggesting the implication of the CsrS protein in pH sensing. These results imply that the translocation of GBS from the acidic milieu of the vagina to the neutral pH of the neonatal lung signals the up-regulation of GBS virulence factors and conversion from a colonizing to an invasive phenotype. In addition, the fact that increased exposure of BibA on the bacterial surface at pH 7.0 induced opsonophagocytic killing of GBS in immune serum highlights the importance of pH regulation in the protective efficacy of specific antibodies to surface-exposed GBS proteins.

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“…For most histidine kinases, this process is also reversible, since the histidine kinase can act as a phosphatase to remove the phosphate from the aspartate residue of its cognate response regulator. One of the TCSs studied in GAS is CovRS (control of virulence) (17), which is critical for growth under many stress conditions (general stress response) (8,9,18) and appears to respond to membrane stress. The CovRS system appears to be pivotal in determining disease outcome (24,28,69).…”

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confidence: 99%

Serine/Threonine Protein Kinase Stk Is Required for Virulence, Stress Response, and Penicillin Tolerance in Streptococcus pyogenes

et al. 2011

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Genes encoding one or more Ser/Thr protein kinases have been identified recently in many bacteria, including one (stk) in the human pathogen Streptococcus pyogenes (group A streptococcus [GAS]). We report that in GAS, stk is required to produce disease in a murine myositis model of infection. Using microarray and quantitative reverse transcription-PCR (qRT-PCR) studies, we found that Stk activates genes for virulence factors, osmoregulation, metabolism of ␣-glucans, and fatty acid biosynthesis, as well as genes affecting cell wall synthesis. Confirming these transcription studies, we determined that the stk deletion mutant is more sensitive to osmotic stress and to penicillin than the wild type. We discuss several possible Stk phosphorylation targets that might explain Stk regulation of expression of specific operons and the possible role of Stk in resuscitation from quiescence.

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Streptococcus pyogenesCovRS Mediates Growth in Iron Starvation and in the Presence of the Human Cationic Antimicrobial Peptide LL-37

Cited by 43 publications

References 57 publications

Counteractive Balancing of Transcriptome Expression Involving CodY and CovRS in Streptococcus pyogenes

Counteractive Balancing of Transcriptome Expression Involving CodY and CovRS in Streptococcus pyogenes

CsrRS Regulates Group BStreptococcusVirulence Gene Expression in Response to Environmental pH: a New Perspective on Vaccine Development

Serine/Threonine Protein Kinase Stk Is Required for Virulence, Stress Response, and Penicillin Tolerance in Streptococcus pyogenes

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