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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

Comparison in expression ratios of 22 randomly selected genes between microarray and real time-PCR.The array fold-changes (in dark grey box) were based on averages from six biological replications. The fold differences (ΔCT) in expression levels of the genes tested using real time-PCR (in light grey box) were calculated from triplicate reactions against CT value of housekeeping gene (rrsG) of S. Typhimurium. acrA, tolC and ompF are genes showing significant difference (≥2-fold with P≤0.01) in microarray data.
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pone-0022161-g001: Comparison in expression ratios of 22 randomly selected genes between microarray and real time-PCR.The array fold-changes (in dark grey box) were based on averages from six biological replications. The fold differences (ΔCT) in expression levels of the genes tested using real time-PCR (in light grey box) were calculated from triplicate reactions against CT value of housekeeping gene (rrsG) of S. Typhimurium. acrA, tolC and ompF are genes showing significant difference (≥2-fold with P≤0.01) in microarray data.

Mentions: Real-time quantitative RT-PCR was used to corroborate selected values from microarrays. The correlation in the expression ratios of 22 genes between the microarray and real time-PCR was measured using Student's t-test. The results showed that there was a high degree of concordance (r = 0.883) between data from the two methodologies (γ = 0.87, P<0.05) (Fig. 1).


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)

Comparison in expression ratios of 22 randomly selected genes between microarray and real time-PCR.The array fold-changes (in dark grey box) were based on averages from six biological replications. The fold differences (ΔCT) in expression levels of the genes tested using real time-PCR (in light grey box) were calculated from triplicate reactions against CT value of housekeeping gene (rrsG) of S. Typhimurium. acrA, tolC and ompF are genes showing significant difference (≥2-fold with P≤0.01) in microarray data.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0022161-g001: Comparison in expression ratios of 22 randomly selected genes between microarray and real time-PCR.The array fold-changes (in dark grey box) were based on averages from six biological replications. The fold differences (ΔCT) in expression levels of the genes tested using real time-PCR (in light grey box) were calculated from triplicate reactions against CT value of housekeeping gene (rrsG) of S. Typhimurium. acrA, tolC and ompF are genes showing significant difference (≥2-fold with P≤0.01) in microarray data.
Mentions: Real-time quantitative RT-PCR was used to corroborate selected values from microarrays. The correlation in the expression ratios of 22 genes between the microarray and real time-PCR was measured using Student's t-test. The results showed that there was a high degree of concordance (r = 0.883) between data from the two methodologies (γ = 0.87, P<0.05) (Fig. 1).

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