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Role of nucleoid-associated proteins Hha and H-NS in expression of Salmonella enterica activators HilD, HilC, and RtsA required for cell invasion.
J Bacteriol. 2007 Oct; 189(19):6882-90.JB

Abstract

The coordinate expression of Salmonella enterica invasion genes on Salmonella pathogenicity island 1 is under the control of the complex circuits of regulation that involve the AraC/XylS family transcriptional activators HilD, HilC, and RtsA and nucleoid-associated proteins. Single-copy transcription fusions were used to assess the effects of nucleoid-associated proteins Hha and H-NS on hilD, hilC, and rtsA expression. The data show that all three genes, hilD, hilC, and rtsA, were repressed by H-NS and/or Hha. The repression of rtsA was the highest among tested genes. The level of rtsA-lac was equally elevated in hns and hha mutants and was further enhanced in the hns hha double mutant under low-osmolarity conditions. Electrophoretic mobility shift experiments showed that H-NS and Hha directly bind to the rtsA promoter. In addition to the negative control that was exerted by H-NS/Hha under low-osmolarity conditions, the homologous virulence activators HilD, HilC, and RtsA (Hil activators) induced rtsA-lac expression in a high-salt medium. A DNase footprinting assay of the rtsA promoter revealed one common DNA-binding site for all three Hil activators centered at position -54 relative to the transcriptional start site. In the absence of Hha and H-NS, however, osmoregulation of the rtsA promoter was lost, and Hil activators were not required for rtsA transcription. These results taken together suggest that the HilD, HilC, and RtsA proteins induce the transcription of the rtsA promoter by counteracting H-NS/Hha-mediated repression.

Authors+Show Affiliations

Department of Microbiology, University of Virginia School of Medicine, PO Box 800734, Charlottesville, VA 22908-0734, USA. io4n@virginia.eduNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

17675384

Citation

Olekhnovich, Igor N., and Robert J. Kadner. "Role of Nucleoid-associated Proteins Hha and H-NS in Expression of Salmonella Enterica Activators HilD, HilC, and RtsA Required for Cell Invasion." Journal of Bacteriology, vol. 189, no. 19, 2007, pp. 6882-90.
Olekhnovich IN, Kadner RJ. Role of nucleoid-associated proteins Hha and H-NS in expression of Salmonella enterica activators HilD, HilC, and RtsA required for cell invasion. J Bacteriol. 2007;189(19):6882-90.
Olekhnovich, I. N., & Kadner, R. J. (2007). Role of nucleoid-associated proteins Hha and H-NS in expression of Salmonella enterica activators HilD, HilC, and RtsA required for cell invasion. Journal of Bacteriology, 189(19), 6882-90.
Olekhnovich IN, Kadner RJ. Role of Nucleoid-associated Proteins Hha and H-NS in Expression of Salmonella Enterica Activators HilD, HilC, and RtsA Required for Cell Invasion. J Bacteriol. 2007;189(19):6882-90. PubMed PMID: 17675384.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Role of nucleoid-associated proteins Hha and H-NS in expression of Salmonella enterica activators HilD, HilC, and RtsA required for cell invasion. AU - Olekhnovich,Igor N, AU - Kadner,Robert J, Y1 - 2007/08/03/ PY - 2007/8/7/pubmed PY - 2008/3/28/medline PY - 2007/8/7/entrez SP - 6882 EP - 90 JF - Journal of bacteriology JO - J Bacteriol VL - 189 IS - 19 N2 - The coordinate expression of Salmonella enterica invasion genes on Salmonella pathogenicity island 1 is under the control of the complex circuits of regulation that involve the AraC/XylS family transcriptional activators HilD, HilC, and RtsA and nucleoid-associated proteins. Single-copy transcription fusions were used to assess the effects of nucleoid-associated proteins Hha and H-NS on hilD, hilC, and rtsA expression. The data show that all three genes, hilD, hilC, and rtsA, were repressed by H-NS and/or Hha. The repression of rtsA was the highest among tested genes. The level of rtsA-lac was equally elevated in hns and hha mutants and was further enhanced in the hns hha double mutant under low-osmolarity conditions. Electrophoretic mobility shift experiments showed that H-NS and Hha directly bind to the rtsA promoter. In addition to the negative control that was exerted by H-NS/Hha under low-osmolarity conditions, the homologous virulence activators HilD, HilC, and RtsA (Hil activators) induced rtsA-lac expression in a high-salt medium. A DNase footprinting assay of the rtsA promoter revealed one common DNA-binding site for all three Hil activators centered at position -54 relative to the transcriptional start site. In the absence of Hha and H-NS, however, osmoregulation of the rtsA promoter was lost, and Hil activators were not required for rtsA transcription. These results taken together suggest that the HilD, HilC, and RtsA proteins induce the transcription of the rtsA promoter by counteracting H-NS/Hha-mediated repression. SN - 0021-9193 UR - https://www.unboundmedicine.com/medline/citation/17675384/Role_of_nucleoid_associated_proteins_Hha_and_H_NS_in_expression_of_Salmonella_enterica_activators_HilD_HilC_and_RtsA_required_for_cell_invasion_ L2 - http://jb.asm.org/cgi/pmidlookup?view=long&pmid=17675384 DB - PRIME DP - Unbound Medicine ER -