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Proteomic analysis of Salmonella enterica serovar Enteritidis following propionate adaptation.

Calhoun LN, Liyanage R, Lay JO, Kwon YM - BMC Microbiol. (2010)

Bottom Line: However, we found the acid resistance to be fully restorable after genetic complementation.This work reveals a significant difference in the proteomes of PA adapted and unadapted S.Enteritidis and affirms the contribution of Dps and CpxR in PA induced acid resistance.

View Article: PubMed Central - HTML - PubMed

Affiliation: Cell and Molecular Biology Program, Department of Poultry Science, University of Arkansas, 1260 W, Maple Avenue, Fayetteville, AR 72701, USA.

ABSTRACT

Background: Salmonella Enteritidis is a highly prevalent and persistent foodborne pathogen and is therefore a leading cause of nontyphoidal gastrointestinal disease worldwide. A variety of stresses are endured throughout its infection cycle, including high concentrations of propionate (PA) within food processing systems and within the gut of infected hosts. Prolonged PA exposure experienced in such milieus may have a drastic effect on the proteome of Salmonella Enteritidis subjected to this stress.

Results: In this study, we used 2 D gel electrophoresis to examine the proteomes of PA adapted and unadapted S. Enteritidis and have identified five proteins that are upregulated in PA adapted cultures using standard peptide mass fingerprinting by MALDI-TOF-MS and sequencing by MALDI LIFT-TOF/TOF tandem mass spectrometry. Of these five, two significant stress-related proteins (Dps and CpxR) were shown (via qRT-PCR analysis) to be upregulated at the transcriptional level as well. Unlike the wild type when adapted to PA (which demonstrates significant acid resistance), PA adapted S. Enteritidis ∆dps and S. Enteritidis ∆cpxR were at a clear disadvantage when challenged to a highly acidic environment. However, we found the acid resistance to be fully restorable after genetic complementation.

Conclusions: This work reveals a significant difference in the proteomes of PA adapted and unadapted S. Enteritidis and affirms the contribution of Dps and CpxR in PA induced acid resistance.

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Related in: MedlinePlus

2 D gel images of the soluble protein fractions from PA adapted and unadapted S. Enteritidis cultures. (a) Unadapted gel, (b) PA adapted gel. Proteins upregulated in PA gel selected for further examination are circled. Proteins restricted to PA adapted gels are designated with an asterisk (*) in gel (b). Labeled Proteins were identified as (1) CpxR, (2) RplE, (3) RplF, (4) SodA, (5) Dps.
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Figure 2: 2 D gel images of the soluble protein fractions from PA adapted and unadapted S. Enteritidis cultures. (a) Unadapted gel, (b) PA adapted gel. Proteins upregulated in PA gel selected for further examination are circled. Proteins restricted to PA adapted gels are designated with an asterisk (*) in gel (b). Labeled Proteins were identified as (1) CpxR, (2) RplE, (3) RplF, (4) SodA, (5) Dps.

Mentions: The soluble proteins from PA adapted and unadapted cultures were visualized by 2 D gel electrophoresis (Figure 2). Because our objective was to identify proteins that were upregulated in response to PA, we concentrated on spots that were solely detected (after silver staining) on PA adapted gels or those that showed significant overexpression in PA adapted gels. In all, a combined total of 207 proteins were detected and their expressions on PA adapted and unadapted gels (or lack thereof) were evaluated. Although the analysis software determined that the differential expression of twenty-four spots was statistically significant (p < 0.05), we focused our attention on five spots (RplE, RplF, SodA, Dps and CpxR; Table 2) with pronounced overexpression in PA adapted gels and targeted them for identification. With respect to the overexpression of RplE and RplF in PA adapted gels, it should be noted that in general, the spot variances of basic proteins separated by 2 D gel electrophoresis have a low confidence level when a comprehensive analysis of total soluble proteins is intended. However, the results of 2 D gel experiments in this study were highly reproducible. Therefore, it is the opinion of the authors that these proteins were truly overexpressed following long-term PA exposure. The data obtained and the reproducibility of the presented gels support this notion.


Proteomic analysis of Salmonella enterica serovar Enteritidis following propionate adaptation.

Calhoun LN, Liyanage R, Lay JO, Kwon YM - BMC Microbiol. (2010)

2 D gel images of the soluble protein fractions from PA adapted and unadapted S. Enteritidis cultures. (a) Unadapted gel, (b) PA adapted gel. Proteins upregulated in PA gel selected for further examination are circled. Proteins restricted to PA adapted gels are designated with an asterisk (*) in gel (b). Labeled Proteins were identified as (1) CpxR, (2) RplE, (3) RplF, (4) SodA, (5) Dps.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2957393&req=5

Figure 2: 2 D gel images of the soluble protein fractions from PA adapted and unadapted S. Enteritidis cultures. (a) Unadapted gel, (b) PA adapted gel. Proteins upregulated in PA gel selected for further examination are circled. Proteins restricted to PA adapted gels are designated with an asterisk (*) in gel (b). Labeled Proteins were identified as (1) CpxR, (2) RplE, (3) RplF, (4) SodA, (5) Dps.
Mentions: The soluble proteins from PA adapted and unadapted cultures were visualized by 2 D gel electrophoresis (Figure 2). Because our objective was to identify proteins that were upregulated in response to PA, we concentrated on spots that were solely detected (after silver staining) on PA adapted gels or those that showed significant overexpression in PA adapted gels. In all, a combined total of 207 proteins were detected and their expressions on PA adapted and unadapted gels (or lack thereof) were evaluated. Although the analysis software determined that the differential expression of twenty-four spots was statistically significant (p < 0.05), we focused our attention on five spots (RplE, RplF, SodA, Dps and CpxR; Table 2) with pronounced overexpression in PA adapted gels and targeted them for identification. With respect to the overexpression of RplE and RplF in PA adapted gels, it should be noted that in general, the spot variances of basic proteins separated by 2 D gel electrophoresis have a low confidence level when a comprehensive analysis of total soluble proteins is intended. However, the results of 2 D gel experiments in this study were highly reproducible. Therefore, it is the opinion of the authors that these proteins were truly overexpressed following long-term PA exposure. The data obtained and the reproducibility of the presented gels support this notion.

Bottom Line: However, we found the acid resistance to be fully restorable after genetic complementation.This work reveals a significant difference in the proteomes of PA adapted and unadapted S.Enteritidis and affirms the contribution of Dps and CpxR in PA induced acid resistance.

View Article: PubMed Central - HTML - PubMed

Affiliation: Cell and Molecular Biology Program, Department of Poultry Science, University of Arkansas, 1260 W, Maple Avenue, Fayetteville, AR 72701, USA.

ABSTRACT

Background: Salmonella Enteritidis is a highly prevalent and persistent foodborne pathogen and is therefore a leading cause of nontyphoidal gastrointestinal disease worldwide. A variety of stresses are endured throughout its infection cycle, including high concentrations of propionate (PA) within food processing systems and within the gut of infected hosts. Prolonged PA exposure experienced in such milieus may have a drastic effect on the proteome of Salmonella Enteritidis subjected to this stress.

Results: In this study, we used 2 D gel electrophoresis to examine the proteomes of PA adapted and unadapted S. Enteritidis and have identified five proteins that are upregulated in PA adapted cultures using standard peptide mass fingerprinting by MALDI-TOF-MS and sequencing by MALDI LIFT-TOF/TOF tandem mass spectrometry. Of these five, two significant stress-related proteins (Dps and CpxR) were shown (via qRT-PCR analysis) to be upregulated at the transcriptional level as well. Unlike the wild type when adapted to PA (which demonstrates significant acid resistance), PA adapted S. Enteritidis ∆dps and S. Enteritidis ∆cpxR were at a clear disadvantage when challenged to a highly acidic environment. However, we found the acid resistance to be fully restorable after genetic complementation.

Conclusions: This work reveals a significant difference in the proteomes of PA adapted and unadapted S. Enteritidis and affirms the contribution of Dps and CpxR in PA induced acid resistance.

Show MeSH
Related in: MedlinePlus