title: The two-component signal transduction system RR06/HK06 regulates expression of cbpA in Streptococcus pneumoniae.
abstract: Streptococcus pneumoniae encounters a number of environmental niches in the body, including the nasopharynx, lungs, blood, middle ear, and brain. Recent studies have identified 13 putative two-component signal-transduction systems in S. pneumoniae, which are likely to be important for gene regulation in response to external stimuli. Here, we present conclusive evidence for the regulation of choline binding protein A (CbpA), a major pneumococcal virulence factor and protective antigen, by one of these two-component signal-transduction systems. We have demonstrated divergent expression of cbpA in unmarked hk06 and rr06 deletion mutants relative to wild-type S. pneumoniae D39 by using Western immunoblotting and real-time RT-PCR. Electrophoretic mobility-shift and solid-phase binding assays have demonstrated the binding of RR06 to the promoter region of cbpA, suggesting that RR06/HK06 directly regulates cbpA transcription. We have also shown that this system is important for the ability of the pneumococcus to adhere to epithelial cells in vitro and to survive and proliferate in an in vivo mouse model. Thus, the RR06/HK06 system has a significant role in pathogenesis, both in colonization and invasive disease.
authors.affiliation: Australian Bacterial Pathogenesis Program, School of Molecular and Biomedical Science, University of Adelaide, Adelaide SA 5005, Australia.
authors.forename: Alistair J
authors.initials: AJ
authors.lastname: Standish
authors.forename: Uwe H
authors.initials: UH
authors.lastname: Stroeher
authors.forename: James C
authors.initials: JC
authors.lastname: Paton
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002448:Cell Adhesion / Q000502:physiology; D004591:Electrophoresis, Polyacrylamide Gel; D024202:Electrophoretic Mobility Shift Assay; D004847:Epithelial Cells / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D051379:Mice; D009154:Mutation / Q000235:genetics; D009841:Oligonucleotides; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C490083:CbpA protein, bacteria; D009841:Oligonucleotides