Portal de Periódicos da CAPES

SrfJ, a Salmonella Type III Secretion System Effector Regulated by PhoP, RcsB, and IolR

2012; American Society for Microbiology; Volume: 194; Issue: 16 Linguagem: Inglês

10.1128/jb.00173-12

1098-5530

Mar Cordero-Alba, Joaquín Bernal-Bayard, Francisco Ramos‐Morales,

Escherichia coli research studies

ABSTRACT Virulence-related type III secretion systems are present in many Gram-negative bacterial pathogens. These complex devices translocate proteins, called effectors, from the bacterium into the eukaryotic host cell. Here, we identify the product of srfJ , a Salmonella enterica serovar Typhimurium gene regulated by SsrB, as a new substrate of the type III secretion system encoded by Salmonella pathogenicity island 2. The N-terminal 20-amino-acid segment of SrfJ was recognized as a functional secretion and translocation signal specific for this system. Transcription of srfJ was positively regulated by the PhoP/PhoQ system in an SsrB-dependent manner and was negatively regulated by the Rcs system in an SsrB-independent manner. A screen for regulators of an srfJ-lacZ transcriptional fusion using the T-POP transposon identified IolR, the regulator of genes involved in myo -inositol utilization, as an srfJ repressor. Our results suggest that SrfJ is synthesized both inside the host, in response to intracellular conditions, and outside the host, in myo -inositol-rich environments.