Rcs and PhoPQ Regulatory Overlap in the Control of Salmonella enterica Virulence
Abstract
Rcs and PhoPQ Regulatory Overlap in the Control of Salmonella enterica Virulence ▿ Clara B. García-Calderón , Josep Casadesús , and Francisco Ramos-Morales * Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain ABSTRACT Genetic screens based on the use of Mu d J-generated lac fusions permitted the identification of novel genes regulated by the Rcs signal transduction system in Salmonella enterica serovar Typhimurium. Besides genes that are also found in the Escherichia coli genome, our screens identified Salmonella -specific genes regulated by RcsB, including bapA , siiE , srfA , and srfB . Here we show that the srfABC operon is negatively regulated by RcsB and by PhoP. In vivo studies using mutants with constitutive activation of the Rcs and/or PhoPQ system suggested that there is an overlap between these regulatory systems in the control of Salmonella virulence.