RcsCDB His‐Asp phosphorelay system negatively regulates the flhDC operon in Escherichia coli

Abstract

SummaryThe genes involved in flagellum synthesis, motility and chemotaxis in Escherichia coli are expressed in a hierarchical fashion. At the top of the hierarchy lies the master regulator FlhDC, required for the expression of the whole set of genes. The operon flhDC is controlled by numerous regulators including H-NS, CRP, EnvZ/OmpR, QseBC and LrhA. In the present work, we report that the flhDC operon is also negatively regulated by the His-Asp phosphorelay system RcsCDB. The regulation is potentiated by the RcsB cofactor RcsA. Genetic analysis indicates that an RcsAB box, located downstream of the promoter, is required for the regulation. The binding of RcsB and RcsA to this site was demonstrated by gel retardation and DNase I protection assays. In addition, mutation analysis suggests that RcsA-specific determinants lie in the right part of the 'RcsAB box'.

Elevated levels of σ S inhibit biofilm formation in Escherichia coli: a role for the Rcs phosphorelay

“…Active RcsB represses the expression of the class I regulator of flagella biogenesis (FlhD 2 C 2 ) by binding to the promoter region of the flhDC operon, and motility was shown to be important for biofilm formation (Francez-Charlot et al, 2003;Pratt & Kolter, 1998). Using an flhD-lacZ fusion, we observed a clear correlation between strains that are deficient in biofilm formation and strains for which flhD is repressed ( Supplementary Fig.…”

“…As the expression of colanic acid is required for the maturation of biofilms formed by E. coli, this suggests a positive role for the Rcs phosphorelay in the regulation of biofilm maturation (Danese et al, 2000b). On the other hand, activation of the Rcs phosphorelay has been shown to repress the expression of genes encoding surface adhesins, such as antigen 43 (Ag43) and curli, and it has been reported that overproduction of RcsB (a situation that mimics the activation of the Rcs phosphorelay) inhibits the expression of the flhDC operon, encoding the master regulators of flagella biosynthesis (Ferrières & Clarke, 2003;Francez-Charlot et al, 2003;Vianney et al, 2005). Therefore, the activation of the Rcs phosphorelay would be expected to have a negative effect on the attachment of cells to a surface.…”

Virulence attenuation in Salmonella enterica rcsC mutants with constitutive activation of the Rcs system

“…Two decades later, this regulatory system has been shown to play roles in other physiological processes such as the regulation of the cell division genes ftsA and ftsZ (Carballès et al, 1999), the modulation of swarming (Takeda et al, 2001), and the control of flagella production (Francez-Charlot et al, 2003). In S. enterica serovar Typhi, the RcsB/C system modulates the expression of Vi antigen, flagellin and invasion proteins (Arricau et al, 1998;Houng et al, 1992;Virlogeux et al, 1995Virlogeux et al, , 1996.…”

“…Two sets of genes whose regulation by the Rcs system is well known, both in E. coli and in S. enterica serovar Typhimurium, are colanic acid genes (Brill et al, 1988;Cano et al, 2002), and genes involved in flagella synthesis and in chemotaxis (Cano et al, 2002;Francez-Charlot et al, 2003). Control of flagella and chemotaxis is exercised through the master operon flhDC (Macnab, 1996).…”

“…The sensor protein RcsC, a hybrid histidine kinase, and the transcriptional activator RcsB are the main components of the system, which also includes a second transcriptional activator, RcsA (Stout et al, 1991) and an intermediate phosphotransmitter, YojN (Takeda et al, 2001). The Rcs system is also a negative regulator of the flagellar master operon flhDC (Francez-Charlot et al, 2003), whose products are necessary for the expression of genes involved in flagellum synthesis, motility and chemotaxis.The first environmental signal shown to strongly and rapidly induce colanic acid synthesis was osmotic upshift (Sledjeski & Gottesman, 1996). This effect was mediated by the Rcs system.…”