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Differential gene expression by RamA in ciprofloxacin-resistant Salmonella Typhimurium.

Zheng J, Tian F, Cui S, Song J, Zhao S, Brown EW, Meng J - PLoS ONE (2011)

Bottom Line: The study confirmed at the transcriptional level that the constitutive expression of ramA was directly associated with increased expression of multidrug efflux pump AcrAB-TolC and decreased expression of porin protein OmpF, thereby conferring multiple drug resistance phenotype.The PM analysis also uncovered that the ramA mutant was better in utilization of 10 carbon sources and 5 phosphorus sources.This study suggested that the constitutive expression of ramA locus regulate not only multidrug efflux pump and accessory genes but also genes involved in carbon metabolic pathways.

View Article: PubMed Central - PubMed

Affiliation: Joint Institute for Food Safety and Applied Nutrition, and Department of Nutrition and Food Science, University of Maryland, College Park, Maryland, United States of America.

ABSTRACT
Overexpression of ramA has been implicated in resistance to multiple drugs in several enterobacterial pathogens. In the present study, Salmonella Typhimurium strain LTL with constitutive expression of ramA was compared to its ramA-deletion mutant by employing both DNA microarrays and phenotype microarrays (PM). The mutant strain with the disruption of ramA showed differential expression of at least 33 genes involved in 11 functional groups. The study confirmed at the transcriptional level that the constitutive expression of ramA was directly associated with increased expression of multidrug efflux pump AcrAB-TolC and decreased expression of porin protein OmpF, thereby conferring multiple drug resistance phenotype. Compared to the parent strain constitutively expressing ramA, the ramA mutant had increased susceptibility to over 70 antimicrobials and toxic compounds. The PM analysis also uncovered that the ramA mutant was better in utilization of 10 carbon sources and 5 phosphorus sources. This study suggested that the constitutive expression of ramA locus regulate not only multidrug efflux pump and accessory genes but also genes involved in carbon metabolic pathways.

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Related in: MedlinePlus

Growth kinetics of S. Typhimurium LTL and its ramA mutant grown in M9 minimal medium containing1×M9 salts, 2 mM MgSO4, and 0.1 mM CaCl2 with 0.2% N-Acetyl-D-Glucosamine, 0.2% D-galactose, and Adenosine-2′,3′-cyclic monophosphate, as carbon source or phosphate source, respectively.Growth curves were performed with a Bioscreen C Microbiology Reader from Labsystems. Cell growth was monitored at 37°C with shaking. Absorbance at OD 600 nm (A600) was measured and recorded every 20 min for 24 hrs.
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pone-0022161-g002: Growth kinetics of S. Typhimurium LTL and its ramA mutant grown in M9 minimal medium containing1×M9 salts, 2 mM MgSO4, and 0.1 mM CaCl2 with 0.2% N-Acetyl-D-Glucosamine, 0.2% D-galactose, and Adenosine-2′,3′-cyclic monophosphate, as carbon source or phosphate source, respectively.Growth curves were performed with a Bioscreen C Microbiology Reader from Labsystems. Cell growth was monitored at 37°C with shaking. Absorbance at OD 600 nm (A600) was measured and recorded every 20 min for 24 hrs.

Mentions: Several findings in the PM analysis were subsequently confirmed by additional assays (Fig. 2 and Table 3). For example, in growth studies, parental strain LTL was defective (P<0.5) in using 0.2% N-Acetyl-D-glucosamine or 0.2% D-galactose as a carbon source, and 20 mM adenosine 2′, 3′ cyclic monophosphate (cAMP) as a phosphorus source (Fig. 2). By determining MICs using agar dilution, the ramA mutant showed increased susceptibility to promethazine (160 ug/ml), a cyclic nucleotide phosphodiesterase inhibitor [49], propranolol (240 ug/ml), a non-selective beta-adrenergic blocker, and acriflavine (16 µg/ml), a DNA intercalating agent.


Differential gene expression by RamA in ciprofloxacin-resistant Salmonella Typhimurium.

Zheng J, Tian F, Cui S, Song J, Zhao S, Brown EW, Meng J - PLoS ONE (2011)

Growth kinetics of S. Typhimurium LTL and its ramA mutant grown in M9 minimal medium containing1×M9 salts, 2 mM MgSO4, and 0.1 mM CaCl2 with 0.2% N-Acetyl-D-Glucosamine, 0.2% D-galactose, and Adenosine-2′,3′-cyclic monophosphate, as carbon source or phosphate source, respectively.Growth curves were performed with a Bioscreen C Microbiology Reader from Labsystems. Cell growth was monitored at 37°C with shaking. Absorbance at OD 600 nm (A600) was measured and recorded every 20 min for 24 hrs.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3139621&req=5

pone-0022161-g002: Growth kinetics of S. Typhimurium LTL and its ramA mutant grown in M9 minimal medium containing1×M9 salts, 2 mM MgSO4, and 0.1 mM CaCl2 with 0.2% N-Acetyl-D-Glucosamine, 0.2% D-galactose, and Adenosine-2′,3′-cyclic monophosphate, as carbon source or phosphate source, respectively.Growth curves were performed with a Bioscreen C Microbiology Reader from Labsystems. Cell growth was monitored at 37°C with shaking. Absorbance at OD 600 nm (A600) was measured and recorded every 20 min for 24 hrs.
Mentions: Several findings in the PM analysis were subsequently confirmed by additional assays (Fig. 2 and Table 3). For example, in growth studies, parental strain LTL was defective (P<0.5) in using 0.2% N-Acetyl-D-glucosamine or 0.2% D-galactose as a carbon source, and 20 mM adenosine 2′, 3′ cyclic monophosphate (cAMP) as a phosphorus source (Fig. 2). By determining MICs using agar dilution, the ramA mutant showed increased susceptibility to promethazine (160 ug/ml), a cyclic nucleotide phosphodiesterase inhibitor [49], propranolol (240 ug/ml), a non-selective beta-adrenergic blocker, and acriflavine (16 µg/ml), a DNA intercalating agent.

Bottom Line: The study confirmed at the transcriptional level that the constitutive expression of ramA was directly associated with increased expression of multidrug efflux pump AcrAB-TolC and decreased expression of porin protein OmpF, thereby conferring multiple drug resistance phenotype.The PM analysis also uncovered that the ramA mutant was better in utilization of 10 carbon sources and 5 phosphorus sources.This study suggested that the constitutive expression of ramA locus regulate not only multidrug efflux pump and accessory genes but also genes involved in carbon metabolic pathways.

View Article: PubMed Central - PubMed

Affiliation: Joint Institute for Food Safety and Applied Nutrition, and Department of Nutrition and Food Science, University of Maryland, College Park, Maryland, United States of America.

ABSTRACT
Overexpression of ramA has been implicated in resistance to multiple drugs in several enterobacterial pathogens. In the present study, Salmonella Typhimurium strain LTL with constitutive expression of ramA was compared to its ramA-deletion mutant by employing both DNA microarrays and phenotype microarrays (PM). The mutant strain with the disruption of ramA showed differential expression of at least 33 genes involved in 11 functional groups. The study confirmed at the transcriptional level that the constitutive expression of ramA was directly associated with increased expression of multidrug efflux pump AcrAB-TolC and decreased expression of porin protein OmpF, thereby conferring multiple drug resistance phenotype. Compared to the parent strain constitutively expressing ramA, the ramA mutant had increased susceptibility to over 70 antimicrobials and toxic compounds. The PM analysis also uncovered that the ramA mutant was better in utilization of 10 carbon sources and 5 phosphorus sources. This study suggested that the constitutive expression of ramA locus regulate not only multidrug efflux pump and accessory genes but also genes involved in carbon metabolic pathways.

Show MeSH
Related in: MedlinePlus