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Two AraC/XylS family members can independently counteract the effect of repressing sequences upstream of the hilA promoter.
Mol Microbiol. 1999 May; 32(3):629-42.MM

Abstract

During infection of its hosts, Salmonella enterica serovar Typhimurium (S. typhimurium) enters the epithelial cells of the small intestine. This process requires a number of invasion genes encoded on Salmonella pathogenicity island 1 (SPI1), a 40 kb stretch of DNA located near minute 63 of the S. typhimurium chromosome. Expression of S. typhimurium SPI1 invasion genes is activated by the transcription factor HilA. hilA is tightly regulated in response to many environmental conditions, including oxygen, osmolarity and pH. Regulation of hilA expression may serve to limit invasion gene expression to the appropriate times during Salmonella infection. We have mapped the transcription start site of hilA and identified regions of the promoter that are required for the repression of hilA expression by conditions unfavourable for Salmonella invasion. We have also identified two SPI1-encoded genes, hilC and hilD, that can independently derepress hilA expression. HilC and HilD are both members of the AraC/XylS family of transcriptional regulators. A mutation in hilD significantly reduces the ability of S. typhimurium to enter tissue culture cells, whereas a mutation in hilC only modestly affects Salmonella invasion. Based on these results, we have updated our model of Salmonella SPI1 invasion gene regulation. We also speculate on the possible significance of this model for Salmonella pathogenesis.

Authors+Show Affiliations

Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

10320584

Citation

Schechter, L M., et al. "Two AraC/XylS Family Members Can Independently Counteract the Effect of Repressing Sequences Upstream of the hilA Promoter." Molecular Microbiology, vol. 32, no. 3, 1999, pp. 629-42.
Schechter LM, Damrauer SM, Lee CA. Two AraC/XylS family members can independently counteract the effect of repressing sequences upstream of the hilA promoter. Mol Microbiol. 1999;32(3):629-42.
Schechter, L. M., Damrauer, S. M., & Lee, C. A. (1999). Two AraC/XylS family members can independently counteract the effect of repressing sequences upstream of the hilA promoter. Molecular Microbiology, 32(3), 629-42.
Schechter LM, Damrauer SM, Lee CA. Two AraC/XylS Family Members Can Independently Counteract the Effect of Repressing Sequences Upstream of the hilA Promoter. Mol Microbiol. 1999;32(3):629-42. PubMed PMID: 10320584.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Two AraC/XylS family members can independently counteract the effect of repressing sequences upstream of the hilA promoter. AU - Schechter,L M, AU - Damrauer,S M, AU - Lee,C A, PY - 1999/5/13/pubmed PY - 1999/5/13/medline PY - 1999/5/13/entrez SP - 629 EP - 42 JF - Molecular microbiology JO - Mol Microbiol VL - 32 IS - 3 N2 - During infection of its hosts, Salmonella enterica serovar Typhimurium (S. typhimurium) enters the epithelial cells of the small intestine. This process requires a number of invasion genes encoded on Salmonella pathogenicity island 1 (SPI1), a 40 kb stretch of DNA located near minute 63 of the S. typhimurium chromosome. Expression of S. typhimurium SPI1 invasion genes is activated by the transcription factor HilA. hilA is tightly regulated in response to many environmental conditions, including oxygen, osmolarity and pH. Regulation of hilA expression may serve to limit invasion gene expression to the appropriate times during Salmonella infection. We have mapped the transcription start site of hilA and identified regions of the promoter that are required for the repression of hilA expression by conditions unfavourable for Salmonella invasion. We have also identified two SPI1-encoded genes, hilC and hilD, that can independently derepress hilA expression. HilC and HilD are both members of the AraC/XylS family of transcriptional regulators. A mutation in hilD significantly reduces the ability of S. typhimurium to enter tissue culture cells, whereas a mutation in hilC only modestly affects Salmonella invasion. Based on these results, we have updated our model of Salmonella SPI1 invasion gene regulation. We also speculate on the possible significance of this model for Salmonella pathogenesis. SN - 0950-382X UR - https://www.unboundmedicine.com/medline/citation/10320584/Two_AraC/XylS_family_members_can_independently_counteract_the_effect_of_repressing_sequences_upstream_of_the_hilA_promoter_ DB - PRIME DP - Unbound Medicine ER -