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HilE Interacts with HilD and Negatively Regulates hilA Transcription and Expression of the Salmonella enterica Serovar Typhimurium Invasive Phenotype
Journal article   Open access   Peer reviewed

HilE Interacts with HilD and Negatively Regulates hilA Transcription and Expression of the Salmonella enterica Serovar Typhimurium Invasive Phenotype

M. Aaron Baxter, Thomas F Fahlen, Rebecca L Wilson and Bradley D Jones
Infection and immunity, Vol.71(3), pp.1295-1305
03/2003
DOI: 10.1128/IAI.71.3.1295-1305.2003
PMCID: PMC148843
PMID: 12595445
url
https://doi.org/10.1128/IAI.71.3.1295-1305.2003View
Published (Version of record) Open Access

Abstract

The ability of Salmonella enterica serovar Typhimurium to traverse the intestinal mucosa of a host is an important step in its ability to initiate gastrointestinal disease. The majority of the genes required for this invasive characteristic are encoded on Salmonella pathogenicity island 1 (SPI1), and their expression is controlled by the transcriptional activator HilA, a member of the OmpR/ToxR family of proteins. A variety of genes ( hilC , hilD , fis , sirA / barA , csrAB , phoB , fadD , envZ / ompR , fliZ , hilE , ams , lon , pag , and hha ) have been identified that exert positive or negative effects on hilA expression, although the mechanisms by which these gene products function remain relatively unclear. Recent work indicates that the small DNA-binding protein, Hha, has a significant role in repressing hilA transcription and the invasive phenotype, particularly in response to osmolarity signals. We have characterized the Salmonella -specific gene, hilE , and found that it plays an important regulatory role in hilA transcription and invasion gene expression. Mutation of hilE causes derepression of hilA transcription, and overexpression of hilE superrepresses hilA expression and the invasive phenotype. Bacterial two-hybrid experiments indicate that the HilE protein interacts with HilD, suggesting a possible mechanism for HilE negative regulation of hilA gene expression and the Salmonella invasive phenotype. Finally, we have found that the hilE gene resides on a region of the serovar Typhimurium chromosome that has many characteristics of a pathogenicity island.
Molecular Pathogenesis

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