Transcriptional autoregulation of the RcsCDB phosphorelay system in Salmonella enterica serovar Typhimurium

MARÍA DE LAS MERCEDES PESCARETTI; FABIÁN ENRIQUE LÓPEZ; ROBERTO MORERO; MONICA A. DELGADO

MICROBIOLOGY-UK

SOC GENERAL MICROBIOLOGY

Año: 2010 vol. 156 p. 3513 - 3521

1350-0872

The RcsCDB (Rcs) phosphorelay system is involved in the regulation of many envelope genes, such as those responsible for capsule synthesis, flagella production and O-antigen chain length, as well as in other cellular activities of several enteric bacteria. The system is composed of three proteins: the sensor RcsC, the response regulator RcsB, and the phospho-transfer intermediary protein RcsD. Previously, we reported two important aspects of this system: (a) rcsB gene expression is under the control of PrcsDB and PrcsB promoters, and (b) rcsD gene transcription decreases when the bacteria reach high levels of the RcsB regulator. In the present work, we demonstrate that the RcsB protein represses rcsD gene expression by binding directly to the PrcsDB promoter, negatively autoregulating the Rcs system. Furthermore, we report the physiological role of the RcsB regulator, which is able to modify bacterial swarming behavior when expressed under the control of the PrcsB promoter.