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Regulation of cytotoxin expression by converging eukaryotic-type and two-component signalling mechanisms in Streptococcus agalactiae.
- Source :
-
Molecular microbiology [Mol Microbiol] 2006 Nov; Vol. 62 (4), pp. 941-57. Date of Electronic Publication: 2006 Sep 27. - Publication Year :
- 2006
-
Abstract
- Signal transducing mechanisms are essential for regulation of gene expression in both prokaryotic and eukaryotic organisms. Regulation of gene expression in eukaryotes is accomplished by serine/threonine and tyrosine kinases and cognate phosphatases. In contrast, gene expression in prokaryotes is controlled by two-component systems that comprise a sensor histidine kinase and a cognate DNA binding response regulator. Pathogenic bacteria utilize two-component systems to regulate expression of their virulence factors and for adaptive responses to the external environment. We have previously shown that the human pathogen Streptococcus agalactiae (Group B Streptococci, GBS) encodes a single eukaryotic-type serine/threonine kinase Stk1, which is important for virulence of the organism. In this study, we aimed to understand how Stk1 contributes to virulence of GBS. Our results indicate that Stk1 expression is important for resistance of GBS to human blood, neutrophils and oxidative stress. Consistent with these observations, Stk1 positively regulates transcription of a cytotoxin, beta-haemolysin/cytolysin (beta-H/C) that is critical for survival of GBS in the bloodstream and for resistance to oxidative stress. Interestingly, positive regulation of beta-H/C by Stk1 requires the two-component regulator CovR. Further, we show that Stk1 can negatively regulate transcription of CAMP factor in a CovR-dependent manner. As Stk1 phosphorylates CovR in vitro, these data suggest that serine/threonine phosphorylation impacts CovR-mediated regulation of GBS gene expression. In summary, our studies provide novel information that a eukaryotic-type serine/threonine kinase regulates two-component-mediated expression of GBS cytotoxins.
- Subjects :
- Bacterial Proteins metabolism
Blood Bactericidal Activity
Hemolysin Proteins metabolism
Histidine Kinase
Humans
Hydrogen Peroxide
Phagocytosis
Pigments, Biological biosynthesis
Protein Kinases metabolism
Protein Serine-Threonine Kinases genetics
Streptococcus agalactiae immunology
Transcription Factors metabolism
Virulence genetics
Cytotoxins genetics
Gene Expression Regulation, Bacterial
Hemolysin Proteins genetics
Protein Serine-Threonine Kinases physiology
Signal Transduction
Streptococcus agalactiae genetics
Streptococcus agalactiae metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0950-382X
- Volume :
- 62
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Molecular microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 17005013
- Full Text :
- https://doi.org/10.1111/j.1365-2958.2006.05431.x