title: Salmonella biofilm development depends on the phosphorylation status of RcsB.
abstract: The Rcs phosphorelay pathway is a complex signaling pathway involved in the regulation of many cell surface structures in enteric bacteria. In response to environmental stimuli, the sensor histidine kinase (RcsC) autophosphorylates and then transfers the phosphate through intermediary steps to the response regulator (RcsB), which, once phosphorylated, regulates gene expression. Here, we show that Salmonella biofilm development depends on the phosphorylation status of RcsB. Thus, unphosphorylated RcsB, hitherto assumed to be inactive, is essential to activate the expression of the biofilm matrix compounds. The prevention of RcsB phosphorylation either by the disruption of the phosphorelay at the RcsC or RcsD level or by the production of a nonphosphorylatable RcsB allele induces biofilm development. On the contrary, the phosphorylation of RcsB by the constitutive activation of the Rcs pathway inhibits biofilm development, an effect that can be counteracted by the introduction of a nonphosphorylatable RcsB allele. The inhibition of biofilm development by phosphorylated RcsB is due to the repression of CsgD expression, through a mechanism dependent on the accumulation of the small noncoding RNA RprA. Our results indicate that unphosphorylated RcsB plays an active role for integrating environmental signals and, more broadly, that RcsB phosphorylation acts as a key switch between planktonic and sessile life-styles in Salmonella enterica serovar Typhimurium.
authors.affiliation: Instituto de Agrobiotecnología, Idab, Universidad Pública de Navarra-CSIC-Gobierno de Navarra, Pamplona, Navarra, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Latasa
authors.forename: Begoña
authors.initials: B
authors.lastname: García
authors.forename: Maite
authors.initials: M
authors.lastname: Echeverz
authors.forename: Alejandro
authors.initials: A
authors.lastname: Toledo-Arana
authors.forename: Jaione
authors.initials: J
authors.lastname: Valle
authors.forename: Susana
authors.initials: S
authors.lastname: Campoy
authors.forename: Francisco
authors.initials: F
authors.lastname: García-del Portillo
authors.forename: Cristina
authors.initials: C
authors.lastname: Solano
authors.forename: Iñigo
authors.initials: I
authors.lastname: Lasa
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D004926:Escherichia coli / Q000145:classification / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D009154:Mutation; D010766:Phosphorylation / Q000502:physiology; D012477:Salmonella enteritidis / Q000502:physiology*; D012486:Salmonella typhimurium / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; C074889:RcsB protein, Bacteria