title: Contribution of the SirA regulon to biofilm formation in Salmonella enterica serovar Typhimurium.
abstract: Orthologues of the Salmonella enterica serovar Typhimurium (S. typhimurium) BarA/SirA two-component system are important for biofilm formation and virulence in many gamma-Proteobacteria. In S. typhimurium, SirA activates the csrB and csrC carbon storage regulatory RNAs and the virulence gene regulators hilA and hilC. The regulatory RNAs antagonize the activity of the CsrA protein, allowing translation of those same virulence genes, and inhibiting the translation of flagellar genes. In this report, it was determined that SirA and the Csr system also control the fim operon that encodes type 1 fimbriae. sirA orthologues in other bacterial species, and the fim operon of S. typhimurium, are known to play a role in biofilm formation; therefore, all members of the S. typhimurium sirA regulon were tested for in vitro biofilm production. A sirA mutant, a csrB csrC double mutant, and a fimI mutant, were all defective in biofilm formation. Conversely, inactivation of flhDC increased biofilm formation. Therefore, SirA activates csrB, csrC and the fim operon to promote biofilm formation. In turn, csrB and csrC promote the translation of the fim operon, while at the same time inhibiting the translation of flagella, which are inhibitory to biofilm formation.
authors.affiliation: Soil and Water Science Department, IFAS, University of Florida, Gainesville, FL 32611-0290, USA.
authors.forename: Max
authors.initials: M
authors.lastname: Teplitski
authors.affiliation: Soil and Water Science Department, IFAS, University of Florida, Gainesville, FL 32611-0290, USA.
authors.forename: Ali
authors.initials: A
authors.lastname: Al-Agely
authors.affiliation: Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210-1292, USA.
authors.forename: Brian M M
authors.initials: BMM
authors.lastname: Ahmer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D018441:Biofilms / Q000254:growth & development*; D036781:Fimbriae Proteins / Q000235:genetics; D010861:Fimbriae, Bacterial / Q000235:genetics; D005407:Flagella / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D009154:Mutation; D018085:Regulon / Q000235:genetics / Q000502:physiology*; D012486:Salmonella typhimurium / Q000235:genetics / Q000502:physiology*; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; C104847:SirA protein, Salmonella; D015534:Trans-Activators; D036781:Fimbriae Proteins