The Virulence Regulator Sae of Staphylococcus aureus: Promoter Activities and Response to Phagocytosis-Related Signals
| Autor: | Christiane Wolz, Tobias Geiger, Markus Mainiero, Dirk Kraus, Christiane Goerke |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Molecular Biology of Pathogens
Staphylococcus aureus Virulence Factors Operon Effector Histidine kinase Virulence Gene Expression Regulation Bacterial Biology Microbiology Molecular biology Bacterial Proteins Phagocytosis Sigma factor Transcription (biology) Genes Regulator Promoter Regions Genetic Enhancer Molecular Biology Transcription factor Signal Transduction Transcription Factors |
| Zdroj: | Journal of Bacteriology. 190:3419-3428 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.01927-07 |
| Popis: | The two-component system SaeRS of Staphylococcus aureus is closely involved in the regulation of major virulence factors. However, little is known about the signals leading to saeRS activation. A total of four overlapping transcripts (T1 to T4) from three different transcription starting points are expressed in the sae operon. We used a β-galactosidase reporter assay to characterize the putative promoter regions within the saeRS upstream region. The main transcript T2 is probably generated by endoribonucleolytic processing of the T1 transcript. Only two distinct promoter elements (P1 and P3) could be detected within the saeRS upstream region. The P3 promoter, upstream of saeRS , generates the T3 transcript, includes a cis -acting enhancer element and is repressed by saeRS . The most distal P1 promoter is strongly autoregulated, activated by agr , and repressed by sigma factor B. In strain Newman a mutation within the histidine kinase SaeS leads to a constitutively activated sae system. Evaluation of different external signals revealed that the P1 promoter in strain ISP479R and strain UAMS-1 is inhibited by low pH and high NaCl concentrations but activated by hydrogen peroxide. The most prominent induction of P1 was observed at subinhibitory concentrations of α-defensins in various S. aureus strains, with the exception of strain ISP479R and strain COL. P1 was not activated by the antimicrobial peptides LL37 and daptomycin. In summary, the results indicate that the sensor molecule SaeS is activated by alteration within the membrane allowing the pathogen to react to phagocytosis related effector molecules. |
| Databáze: | OpenAIRE |
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