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Agr ‐independent regulation of fibronectin‐binding protein(s) by the regulatory locus sar in Staphylococcus aureus
Author(s) -
Wolz Christiane,
PöhlmannDietze Petra,
Steinhuber Andrea,
Chien YuehTyng,
Manna Adhar,
Van Wamel Willem,
Cheung Ambrose
Publication year - 2000
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2000.01853.x
Subject(s) - biology , mutant , microbiology and biotechnology , northern blot , blot , transcription (linguistics) , electrophoretic mobility shift assay , enhancer , binding site , transcription factor , gene , gene expression , genetics , linguistics , philosophy
Fibronectin‐binding proteins (FnBPs) are thought to be important for the attachment of Staphylococcus aureus during infection. The regulation of the genes fnb A and fnb B by the global regulatory loci sar and agr was examined using site‐specific regulatory mutants of S. aureus strain Newman. The results from binding assays using both aqueous and solid‐phase fibronectin as well as ligand blotting with biotinylated fibronectin showed that the expression of FnBPA is enhanced in the agr mutant but inhibited in the sar mutant and the sar – agr double mutant. The same regulatory pattern was observed in Northern blot analysis using fnb A‐specific probes. The introduction of sar on a multicopy plasmid increased the already enhanced fnb A transcription of the agr mutant. FnBPB was not detectable by ligand blotting and the fnb B promoter activity in promoter fusion assays was not affected by either sar or agr . The sequence encompassing ORF3 located upstream of sar A was found to be essential for the activation of fnb A transcription. We hypothesize that this sequence may modulate SarA expression and/or activity on the post‐transcriptional level. Gel shift assays demonstrated that SarA binds to the fnbA promoter fragments, probably as a dimer. DNase I footprinting assays with SarA revealed a protected area of 102 bp upstream of fnb A.