Resolvase-in vivo expression technology analysis of the Salmonella enterica serovar Typhimurium PhoP and PmrA regulons in BALB/c mice

Massimo Merighi; Craig D Ellermeier; James M Slauch; John S Gunn

doi:10.1128/JB.187.21.7407-7416.2005

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Resolvase-in vivo expression technology analysis of the Salmonella enterica serovar Typhimurium PhoP and PmrA regulons in BALB/c mice

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Resolvase-in vivo expression technology analysis of the Salmonella enterica serovar Typhimurium PhoP and PmrA regulons in BALB/c mice

Massimo Merighi, Craig D Ellermeier, James M Slauch and John S Gunn

Journal of bacteriology, Vol.187(21), pp.7407-7416

11/2005

DOI: 10.1128/JB.187.21.7407-7416.2005

PMCID: PMC1272988

PMID: 16237024

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Abstract

Salmonella enterica modulates resistance to antimicrobial peptides in part via covalent modifications of the lipopolysaccharide (LPS). The two-component systems PhoP/PhoQ and PmrA/PmrB are activated during infection and regulate several genes involved in LPS modifications by responding to signals such as pH, iron, magnesium, and antimicrobial peptides. A recombination-based in vivo expression technology approach was adopted to analyze the spatial-temporal patterns of in vivo expression of genes of the PhoP and PmrA regulons and to identify the in vivo signals modulating their transcription. In vitro, we showed PhoP- and/or PmrA-dependent induction of pmrH (LPS aminoarabinose modification operon) by acidic pH, low levels of magnesium, or high levels of Fe(III). Upregulation in cultured J774A.1 macrophages was shown for pmrH, pagP (LPS palmitate addition), and ssaB (pathogenicity island II secretion) but not for prgH (pathogenicity island I secretion). Increased levels of pmrH, phoP, and prgH transcription but not ssaB were observed in bacteria isolated from the lumen of the distal ileum. Bacteria isolated from spleens of orally inoculated mice showed no further induction of prgH but had the highest expression of pmrH, pagP, and ssaB. In vivo induction of pmrH was fully dependent on pmrA and phoP, and buffering stomach acidity, iron chelation, or low-iron diets did not affect the expression of pmrH in the intestinal lumen. The observation of pmrH and pagP expression in the intestine refutes the paradigm of PhoP/PhoQ and PmrA/PmrB in vivo expression as solely intracellularly induced and supports previous data demonstrating peroral virulence attenuation of pmrH mutants.

Adaptation, Physiological

Genes, Bacterial

Salmonella typhimurium - physiology

Salmonella typhimurium - genetics

Regulon - physiology

Bacterial Proteins - genetics

Lipopolysaccharides - metabolism

Gene Expression Profiling - methods

Iron

Bacterial Proteins - physiology

Animals

Intestines - microbiology

Virulence - genetics

Genes, Regulator

Salmonella Infections, Animal - microbiology

Female

Models, Animal

Transcription, Genetic

Mice

Mice, Inbred BALB C

Magnesium

Macrophages - microbiology

Hydrogen-Ion Concentration

Details

Title: Subtitle: Resolvase-in vivo expression technology analysis of the Salmonella enterica serovar Typhimurium PhoP and PmrA regulons in BALB/c mice
Creators: Massimo Merighi - Department of Molecular Virology, Immunology, and Medical Genetics, Columbus, OH 43210, USA
Craig D Ellermeier
James M Slauch
John S Gunn
Resource Type: Journal article
Publication Details: Journal of bacteriology, Vol.187(21), pp.7407-7416
DOI: 10.1128/JB.187.21.7407-7416.2005
PMID: 16237024
PMCID: PMC1272988
NLM abbreviation: J Bacteriol
ISSN: 0021-9193
eISSN: 1098-5530
Grant note: AI63230 / NIAID NIH HHS R29 AI043521 / NIAID NIH HHS R01 AI063230 / NIAID NIH HHS AI043521 / NIAID NIH HHS R01 AI043521 / NIAID NIH HHS
Language: English
Date published: 11/2005
Academic Unit: Microbiology and Immunology
Record Identifier: 9984083276502771

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