title: Complex regulation of csgD promoter activity by global regulatory proteins.
abstract: The starvation-induced csgD gene of Salmonella typhimurium encodes for the positive transcriptional regulator of extracellular matrix components curli fimbriae and cellulose. To analyse regulatory elements of csgD promoter (PcsgD) response genetic studies combined with in vitro experiments were performed. Six binding sites (D1 to D6) for OmpR, a transcriptional regulator, were identified by gel shifts and DNase I footprints. While ompR is required for PcsgD expression, binding of OmpR-P to D2 centred immediately upstream of D1 at position -70.5 is proposed to repress PcsgD activity. The elevated expression of regulated and semiconstitutive PcsgD in response to microaerophilic conditions required integration host factor (IHF). Subsequently, two IHF-binding sites were identified up- and downstream of PcsgD. IHF competes with OmpR-P for binding at its upstream site IHF1, which overlaps with D3-D6 and thereby modulates the response to microaerophilic conditions. A complex regulatory network involving IHF, H-NS and OmpR is proposed whereby the nucleo-complex composition in the csgD-csgBA intergenic region is altered in response to oxygen tension.
authors.affiliation: Microbiology and Tumorbiology Center, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Gerstel
authors.forename: Chankyu
authors.initials: C
authors.lastname: Park
authors.forename: Ute
authors.initials: U
authors.lastname: Römling
mesh_terms: D000332:Aerobiosis; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D018983:DNA Footprinting; D024202:Electrophoretic Mobility Shift Assay; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D005798:Genes, Bacterial; D005809:Genes, Regulator; D034982:Integration Host Factors / Q000378:metabolism*; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics; D010100:Oxygen / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D012486:Salmonella typhimurium / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D034982:Integration Host Factors; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; C440508:integration host factor, Salmonella; C112177:osmolarity response regulator proteins; D010100:Oxygen