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Ethanolamine Signaling Promotes Salmonella Niche Recognition and Adaptation during Infection.

Anderson CJ, Clark DE, Adli M, Kendall MM - PLoS Pathog. (2015)

Bottom Line: Our findings reveal that S.Typhimurium co-opts ethanolamine as a signal to coordinate metabolism and then virulence.Because the ability to sense ethanolamine is a conserved trait among pathogenic and commensal bacteria, our work indicates that ethanolamine signaling may be a key step in the localized adaptation of bacteria within their mammalian hosts.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America.

ABSTRACT
Chemical and nutrient signaling are fundamental for all cellular processes, including interactions between the mammalian host and the microbiota, which have a significant impact on health and disease. Ethanolamine is an essential component of cell membranes and has profound signaling activity within mammalian cells by modulating inflammatory responses and intestinal physiology. Here, we describe a virulence-regulating pathway in which the foodborne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) exploits ethanolamine signaling to recognize and adapt to distinct niches within the host. The bacterial transcription factor EutR promotes ethanolamine metabolism in the intestine, which enables S. Typhimurium to establish infection. Subsequently, EutR directly activates expression of the Salmonella pathogenicity island 2 in the intramacrophage environment, and thus augments intramacrophage survival. Moreover, EutR is critical for robust dissemination during mammalian infection. Our findings reveal that S. Typhimurium co-opts ethanolamine as a signal to coordinate metabolism and then virulence. Because the ability to sense ethanolamine is a conserved trait among pathogenic and commensal bacteria, our work indicates that ethanolamine signaling may be a key step in the localized adaptation of bacteria within their mammalian hosts.

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Related in: MedlinePlus

EutR regulates SPI-2 expression.(A), Schematic of SPI-2. (B) qRT-PCR analysis of SPI-2-encoded and associated (sifA) genes from RNA isolated from S. Typhimurium (AJK61) or the ΔeutR (CJA023) strains after 5 h phagocytosis in RAW macrophages. n = 3; error bars represent the geometric mean ± SD; strB was used as the endogenous control. (C) EMSAs of ssrB and amp (ampicillin) with EutR::MBP. (D) EMSAs of ssrB with MBP or EutR::MBP. Also, competition EMSAs with EutR::MBP. The assay was performed with increasing amounts of unlabeled ssrB promoter probe. A competition assay was also performed using the kan promoter as a negative control. The ratios represent hot:cold probe. (E) qPCR showing enrichment of eutS, ssrB, and strB from in vivo ChIP of EutR::MBP (n = 2). *, P ≤ 0.05; **, P ≤ 0.005; ***, P ≤0.0005; P > 0.05 = ns.
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ppat.1005278.g004: EutR regulates SPI-2 expression.(A), Schematic of SPI-2. (B) qRT-PCR analysis of SPI-2-encoded and associated (sifA) genes from RNA isolated from S. Typhimurium (AJK61) or the ΔeutR (CJA023) strains after 5 h phagocytosis in RAW macrophages. n = 3; error bars represent the geometric mean ± SD; strB was used as the endogenous control. (C) EMSAs of ssrB and amp (ampicillin) with EutR::MBP. (D) EMSAs of ssrB with MBP or EutR::MBP. Also, competition EMSAs with EutR::MBP. The assay was performed with increasing amounts of unlabeled ssrB promoter probe. A competition assay was also performed using the kan promoter as a negative control. The ratios represent hot:cold probe. (E) qPCR showing enrichment of eutS, ssrB, and strB from in vivo ChIP of EutR::MBP (n = 2). *, P ≤ 0.05; **, P ≤ 0.005; ***, P ≤0.0005; P > 0.05 = ns.

Mentions: SPI-2 contains four major operons that encode a T3SS, chaperone and effector proteins, as well as the transcriptional regulator SsrB (Fig 4A). To test our hypothesis, we examined transcription of ssrB and one gene from each of the other major operons encoded in SPI-2 using RNA harvested from phagocytized WT or ΔeutR S. Typhimurium strains. Transcription of ssrB was significantly decreased in the ΔeutR strain compared to WT (Fig 4B and S7 Fig), and we measured a concomitant decrease in expression of all the SPI-2 operons, as well as the SPI-2-associated effector sifA (Fig 4B and S8 Fig). Expression of SPI-2 encoded and associated factors enhances the intrinsic ability of S. Typhimurium to withstand and disrupt host defense mechanisms [37,38], and these data revealed that EutR influences this critical aspect of S. Typhimurium virulence.


Ethanolamine Signaling Promotes Salmonella Niche Recognition and Adaptation during Infection.

Anderson CJ, Clark DE, Adli M, Kendall MM - PLoS Pathog. (2015)

EutR regulates SPI-2 expression.(A), Schematic of SPI-2. (B) qRT-PCR analysis of SPI-2-encoded and associated (sifA) genes from RNA isolated from S. Typhimurium (AJK61) or the ΔeutR (CJA023) strains after 5 h phagocytosis in RAW macrophages. n = 3; error bars represent the geometric mean ± SD; strB was used as the endogenous control. (C) EMSAs of ssrB and amp (ampicillin) with EutR::MBP. (D) EMSAs of ssrB with MBP or EutR::MBP. Also, competition EMSAs with EutR::MBP. The assay was performed with increasing amounts of unlabeled ssrB promoter probe. A competition assay was also performed using the kan promoter as a negative control. The ratios represent hot:cold probe. (E) qPCR showing enrichment of eutS, ssrB, and strB from in vivo ChIP of EutR::MBP (n = 2). *, P ≤ 0.05; **, P ≤ 0.005; ***, P ≤0.0005; P > 0.05 = ns.
© Copyright Policy
Related In: Results  -  Collection

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ppat.1005278.g004: EutR regulates SPI-2 expression.(A), Schematic of SPI-2. (B) qRT-PCR analysis of SPI-2-encoded and associated (sifA) genes from RNA isolated from S. Typhimurium (AJK61) or the ΔeutR (CJA023) strains after 5 h phagocytosis in RAW macrophages. n = 3; error bars represent the geometric mean ± SD; strB was used as the endogenous control. (C) EMSAs of ssrB and amp (ampicillin) with EutR::MBP. (D) EMSAs of ssrB with MBP or EutR::MBP. Also, competition EMSAs with EutR::MBP. The assay was performed with increasing amounts of unlabeled ssrB promoter probe. A competition assay was also performed using the kan promoter as a negative control. The ratios represent hot:cold probe. (E) qPCR showing enrichment of eutS, ssrB, and strB from in vivo ChIP of EutR::MBP (n = 2). *, P ≤ 0.05; **, P ≤ 0.005; ***, P ≤0.0005; P > 0.05 = ns.
Mentions: SPI-2 contains four major operons that encode a T3SS, chaperone and effector proteins, as well as the transcriptional regulator SsrB (Fig 4A). To test our hypothesis, we examined transcription of ssrB and one gene from each of the other major operons encoded in SPI-2 using RNA harvested from phagocytized WT or ΔeutR S. Typhimurium strains. Transcription of ssrB was significantly decreased in the ΔeutR strain compared to WT (Fig 4B and S7 Fig), and we measured a concomitant decrease in expression of all the SPI-2 operons, as well as the SPI-2-associated effector sifA (Fig 4B and S8 Fig). Expression of SPI-2 encoded and associated factors enhances the intrinsic ability of S. Typhimurium to withstand and disrupt host defense mechanisms [37,38], and these data revealed that EutR influences this critical aspect of S. Typhimurium virulence.

Bottom Line: Our findings reveal that S.Typhimurium co-opts ethanolamine as a signal to coordinate metabolism and then virulence.Because the ability to sense ethanolamine is a conserved trait among pathogenic and commensal bacteria, our work indicates that ethanolamine signaling may be a key step in the localized adaptation of bacteria within their mammalian hosts.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America.

ABSTRACT
Chemical and nutrient signaling are fundamental for all cellular processes, including interactions between the mammalian host and the microbiota, which have a significant impact on health and disease. Ethanolamine is an essential component of cell membranes and has profound signaling activity within mammalian cells by modulating inflammatory responses and intestinal physiology. Here, we describe a virulence-regulating pathway in which the foodborne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) exploits ethanolamine signaling to recognize and adapt to distinct niches within the host. The bacterial transcription factor EutR promotes ethanolamine metabolism in the intestine, which enables S. Typhimurium to establish infection. Subsequently, EutR directly activates expression of the Salmonella pathogenicity island 2 in the intramacrophage environment, and thus augments intramacrophage survival. Moreover, EutR is critical for robust dissemination during mammalian infection. Our findings reveal that S. Typhimurium co-opts ethanolamine as a signal to coordinate metabolism and then virulence. Because the ability to sense ethanolamine is a conserved trait among pathogenic and commensal bacteria, our work indicates that ethanolamine signaling may be a key step in the localized adaptation of bacteria within their mammalian hosts.

Show MeSH
Related in: MedlinePlus