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Pathways leading from BarA/SirA to motility and virulence gene expression in Salmonella.
J Bacteriol. 2003 Dec; 185(24):7257-65.JB

Abstract

The barA and sirA genes of Salmonella enterica serovar Typhimurium encode a two-component sensor kinase and a response regulator, respectively. This system increases the expression of virulence genes and decreases the expression of motility genes. In this study, we examined the pathways by which SirA affects these genes. We found that the master regulator of flagellar genes, flhDC, had a positive regulatory effect on the primary regulator of intestinal virulence determinants, hilA, but that hilA had no effect on flhDC. SirA was able to repress flhDC in a hilA mutant and activate hilA in an flhDC mutant. Therefore, although the flhDC and hilA regulatory cascades interact, sirA affects each of them independently. A form of BarA lacking the two N-terminal membrane-spanning domains, BarA198, autophosphorylates in the presence of ATP and transfers the phosphate to purified SirA. Phosphorylated SirA was found to directly bind the hilA and hilC promoters in gel mobility shift assays but not the flhD, fliA, hilD, and invF promoters. Given that the CsrA/csrB system is known to directly affect flagellar gene expression, we tested the hypothesis that SirA affects flagellar gene expression indirectly by regulating csrA or csrB. The sirA gene did not regulate csrA but did activate csrB expression. Consistent with these results, phosphorylated SirA was found to directly bind the csrB promoter but not the csrA promoter. We propose a model in which SirA directly activates virulence expression via hilA and hilC while repressing the flagellar regulon indirectly via csrB.

Authors+Show Affiliations

Department of Microbiology, The Ohio State University, Columbus, Ohio 43210-1292, 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

14645287

Citation

Teplitski, Max, et al. "Pathways Leading From BarA/SirA to Motility and Virulence Gene Expression in Salmonella." Journal of Bacteriology, vol. 185, no. 24, 2003, pp. 7257-65.
Teplitski M, Goodier RI, Ahmer BM. Pathways leading from BarA/SirA to motility and virulence gene expression in Salmonella. J Bacteriol. 2003;185(24):7257-65.
Teplitski, M., Goodier, R. I., & Ahmer, B. M. (2003). Pathways leading from BarA/SirA to motility and virulence gene expression in Salmonella. Journal of Bacteriology, 185(24), 7257-65.
Teplitski M, Goodier RI, Ahmer BM. Pathways Leading From BarA/SirA to Motility and Virulence Gene Expression in Salmonella. J Bacteriol. 2003;185(24):7257-65. PubMed PMID: 14645287.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Pathways leading from BarA/SirA to motility and virulence gene expression in Salmonella. AU - Teplitski,Max, AU - Goodier,Robert I, AU - Ahmer,Brian M M, PY - 2003/12/4/pubmed PY - 2004/1/8/medline PY - 2003/12/4/entrez SP - 7257 EP - 65 JF - Journal of bacteriology JO - J Bacteriol VL - 185 IS - 24 N2 - The barA and sirA genes of Salmonella enterica serovar Typhimurium encode a two-component sensor kinase and a response regulator, respectively. This system increases the expression of virulence genes and decreases the expression of motility genes. In this study, we examined the pathways by which SirA affects these genes. We found that the master regulator of flagellar genes, flhDC, had a positive regulatory effect on the primary regulator of intestinal virulence determinants, hilA, but that hilA had no effect on flhDC. SirA was able to repress flhDC in a hilA mutant and activate hilA in an flhDC mutant. Therefore, although the flhDC and hilA regulatory cascades interact, sirA affects each of them independently. A form of BarA lacking the two N-terminal membrane-spanning domains, BarA198, autophosphorylates in the presence of ATP and transfers the phosphate to purified SirA. Phosphorylated SirA was found to directly bind the hilA and hilC promoters in gel mobility shift assays but not the flhD, fliA, hilD, and invF promoters. Given that the CsrA/csrB system is known to directly affect flagellar gene expression, we tested the hypothesis that SirA affects flagellar gene expression indirectly by regulating csrA or csrB. The sirA gene did not regulate csrA but did activate csrB expression. Consistent with these results, phosphorylated SirA was found to directly bind the csrB promoter but not the csrA promoter. We propose a model in which SirA directly activates virulence expression via hilA and hilC while repressing the flagellar regulon indirectly via csrB. SN - 0021-9193 UR - https://www.unboundmedicine.com/medline/citation/14645287/Pathways_leading_from_BarA/SirA_to_motility_and_virulence_gene_expression_in_Salmonella_ L2 - https://journals.asm.org/doi/10.1128/JB.185.24.7257-7265.2003?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -