Dataset Information

Salmonella enterica virulence genes are required for bacterial attachment to plant tissue.

ABSTRACT: Numerous Salmonella enterica food-borne illness outbreaks have been associated with contaminated vegetables, in particular sprouted seeds, and the incidence of reported contamination has steadily risen. In order to understand the physiology of S. enterica serovar Newport on plants, a screen was developed to identify transposon mutants that were defective in attachment to alfalfa sprouts. Twenty independent mutants from a pool of 6,000 were selected for reduced adherence to alfalfa sprouts. Sixty-five percentage of these mutants had insertions in uncharacterized genes. Among the characterized genes were strains with insertions in the intergenic region between agfB, the surface-exposed aggregative fimbria (curli) nucleator, and agfD, a transcriptional regulator of the LuxR superfamily, and rpoS, the stationary-phase sigma factor. Both AgfD and RpoS have been reported to regulate curli and cellulose production and RpoS regulates other adhesins such as pili. The intergenic and rpoS mutants were reduced in initial attachment to alfalfa sprouts by 1 log unit compared to the wild type. Mutations of agfA, curli subunit, and agfB in S. enterica serovar Enteritidis differentially affected attachment to plant tissue. The agfA mutation was not reduced in ability to attach to or colonize alfalfa sprouts, whereas the agfB mutation was reduced. Thus, agfB alone can play a role in attachment of S. enterica to plant tissue. These results reveal that S. enterica genes important for virulence in animal systems are also required for colonization of plants, a secondary host that can serve as a vector of S. enterica from animal to animal.

SUBMITTER: Barak JD

PROVIDER: S-EPMC1265987 | biostudies-literature | 2005 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Salmonella enterica virulence genes are required for bacterial attachment to plant tissue.

Barak Jeri D JD Gorski Lisa L Naraghi-Arani Pejman P Charkowski Amy O AO

Applied and environmental microbiology 20051001 10

Numerous Salmonella enterica food-borne illness outbreaks have been associated with contaminated vegetables, in particular sprouted seeds, and the incidence of reported contamination has steadily risen. In order to understand the physiology of S. enterica serovar Newport on plants, a screen was developed to identify transposon mutants that were defective in attachment to alfalfa sprouts. Twenty independent mutants from a pool of 6,000 were selected for reduced adherence to alfalfa sprouts. Sixty ...[more]

PMID: 16204476

Similar Datasets

Project description:We have shown that the ligand-responsive MarR family member SlyA plays an important role in transcription activation of multiple virulence genes in Salmonella enterica serovar Typhimurium by responding to guanosine tetraphosphate (ppGpp). Here, we demonstrate that another MarR family member, EmrR, is required for virulence of S. Typhimurium and another enteric bacterium, Yersinia pestis EmrR is found to activate transcription of an array of virulence determinants, including Salmonella pathogenicity island 2 (SPI-2) genes and several divergent operons, which have been shown to be activated by SlyA and the PhoP/PhoQ two-component system. We studied the regulatory effect of EmrR on one of these genetic loci, i.e., the pagC-pagD divergent operon, and characterized a catecholamine neurotransmitter, dopamine, as an EmrR-sensed signal. Dopamine acts on EmrR to reduce its ability to bind to the target promoters, thus functioning as a negative signal to downregulate this EmrR-activated transcription. EmrR can bind to AT-rich sequences, which particularly overlap the SlyA and PhoP binding sites in the pagC-pagD divergent promoter. EmrR is a priming transcription regulator that binds its target promoters prior to successive transcription activators, by which it displaces universal silencer H-NS from these promoters and facilitates successive regulators to bind these regions. Regulation of the Salmonella-specific gene in Escherichia coli and Y. pestis reveals that EmrR-dependent regulation is conserved in enteric bacteria. These observations suggest that EmrR is a transcription activator to control the expression of virulence genes, including the SPI-2 genes. Dopamine can act on the EmrR-mediated signal transduction, thus downregulating expression of these virulence factors.IMPORTANCE In this study, MarR family regulator EmrR is identified as a novel virulence factor of enteric bacteria, here exemplified by Salmonella enterica serovar Typhimurium and Yersinia pestis EmrR exerts an essential effect as a transcription activator for expression of virulence determinants, including Salmonella pathogenicity island 2 genes and a set of horizontally acquired genetic loci that formed divergent operons. EmrR senses the neurotransmitter dopamine and is subsequently released from target promoters, resulting in downregulation of the virulence gene expression. Through this action on EmrR, dopamine can weaken Salmonella resistance against host defense mechanisms. This provides an explanation for the previous observation that dopamine inhibits bacterial infection in animal gastrointestinal tracts. Our findings provide evidence that this neurotransmitter can modulate bacterial gene expression through interaction with virulence regulator EmrR.

Dataset Information

Salmonella enterica virulence genes are required for bacterial attachment to plant tissue.

Publications

Salmonella enterica virulence genes are required for bacterial attachment to plant tissue.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets