Fis is required for proper regulation of ssaG expression in Salmonella enterica serovar Typhimurium

Salmonella pathogenicity island 2 (SPI2) encodes a type III secretion system (TTSS) necessary for bacterial survival and replication in intracellular environment of host cells. SPI2 genes are transcribed preferentially after Salmonella enters the host cells. Transcriptional regulation of ssaG encodi...

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Bibliographic Details
Published in:Microbial pathogenesis 2006-07, Vol.41 (1), p.33-42
Main Authors: Lim, Sangyong, Kim, Byeongkwan, Choi, Hyun-Sook, Lee, Younghoon, Ryu, Sangryeol
Format: Article
Language:English
Subjects:
Animals
Bacterial Proteins - genetics
Bacterial Proteins - metabolism
Bacteriology
Base Sequence
Biological and medical sciences
Cell Line
Factor For Inversion Stimulation Protein - genetics
Fis
Fundamental and applied biological sciences. Psychology
Gene Expression Regulation, Bacterial
Genes, Bacterial
Membrane Proteins - genetics
Membrane Proteins - metabolism
Mice
Microbiology
Miscellaneous
Molecular Sequence Data
Promoter Regions, Genetic
Protein Binding - genetics
Salmonella enterica
Salmonella pathogenicity island 2
Salmonella typhimurium - genetics
Salmonella typhimurium - growth & development
SsaG
Virulence gene
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Summary:Salmonella pathogenicity island 2 (SPI2) encodes a type III secretion system (TTSS) necessary for bacterial survival and replication in intracellular environment of host cells. SPI2 genes are transcribed preferentially after Salmonella enters the host cells. Transcriptional regulation of ssaG encoding the component of SPI2–TTSS apparatus was studied in vivo and in vitro. Fis, one of the major components of bacterial nucleoid, activated the stationary phase-specific expression of ssaG when Salmonella was grown in LB media. Gel-shift and footprinting analysis showed Fis bound to four distinct sites of the ssaG promoter region with different affinities. All four Fis-binding sites were required for timely transcription activation of ssaG after Salmonella entered macrophage cells. Gentamicin protection experiments using bacteria grown to stationary phase prior to infection showed that the ability of the fis mutant strain to replicate within the RAW264.7 macrophage cells was lower than the wild type. These observations confirm that Fis plays an important role in regulations of SPI2 as well as SPI1 for an efficient regulation of the virulence genes.
ISSN:0882-4010
1096-1208
DOI:10.1016/j.micpath.2006.03.005