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The PagN protein of Salmonella enterica serovar Typhimurium is an adhesin and invasin.

Lambert MA, Smith SG - BMC Microbiol. (2008)

Bottom Line: S. enterica sv Typhimurium pagN mutants display a reduction in adhesion to and invasion of epithelial cells.Typhimurium.Finally PagN can be added to an ever-growing repertoire of factors that contribute to the pathogenesis of Salmonella.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Clinical Microbiology, Trinity College Dublin, St James's Hospital, Dublin 8, Ireland. malamber79@gmail.com

ABSTRACT

Background: The pagN gene of Salmonella enterica serovar Typhimurium is a PhoP-regulated gene that is up-regulated during growth within macrophages and in vivo in murine models of infection. The PagN protein displays similarity to the Hek and Tia invasins/adhesins of Escherichia coli. Thus far no function has been ascribed to the PagN protein.

Results: Here we show that the outer membrane located PagN protein mediates agglutination of red blood cells and that this can be masked by LPS. When expressed in Escherichia coli the PagN protein supports adhesion to and invasion of mammalian cells in a manner that is dependent on cytoskeletal rearrangements. S. enterica sv Typhimurium pagN mutants display a reduction in adhesion to and invasion of epithelial cells. Finally, we demonstrate that over-expression of PagN in a SPI-1 mutant can partially compensate for the lack of a functional invasasome.

Conclusion: PagN is an outer membrane protein that may contribute to the virulence of S. Typhimurium. This protein is a haemagglutinin and contributes to the adherence to mammalian cells. In addition, PagN can mediate high-level invasion of CHO-K1 cells. Previously,pagN mutants have been shown to be less competitive in vivo and thus this may be due to their lessened ability to interact with mammalian cells. Finally PagN can be added to an ever-growing repertoire of factors that contribute to the pathogenesis of Salmonella.

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Invasion of CHO-K1 cells by rough S. Typhimurium lacking a functional SPI-1-encoded T3SS. Invasion levels were calculated for rough S. Typhimurium strains with a functional T3SS, CH133 (PagN+) and ML133 (PagN-) and strains without a functional T3SS, ML4 (PagN+, InvA-) and ML3 (PagN-, InvA-). Levels were also calculated for ML3 harboring pPagN2.3 or the vector plasmid pBSKII+. Data represents an average of triplicate wells and standard error bars are shown. * indicates statistical significance of P < 0.05.
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Figure 8: Invasion of CHO-K1 cells by rough S. Typhimurium lacking a functional SPI-1-encoded T3SS. Invasion levels were calculated for rough S. Typhimurium strains with a functional T3SS, CH133 (PagN+) and ML133 (PagN-) and strains without a functional T3SS, ML4 (PagN+, InvA-) and ML3 (PagN-, InvA-). Levels were also calculated for ML3 harboring pPagN2.3 or the vector plasmid pBSKII+. Data represents an average of triplicate wells and standard error bars are shown. * indicates statistical significance of P < 0.05.

Mentions: Haemagglutination by Salmonella expressing PagN was only observed in rough strains (see above). This was not the case for adherence to or invasion of mammalian cells since we could observe defects in these phenotypes for pagN mutants in the smooth S. Typhimurium strain SL1344. Nevertheless we examined if a rough strain might facilitate enhanced invasion and/or adhesion by PagN. In these studies we made use of strain CH133 a rough mutant of S. Typhimurium LT-2 (a rough mutant of strain SL1344 was not readily available for these analyses). A pagN rough mutant strain, ML133, displayed approximately a five-fold decrease in cell association which was greater than the defect due to loss of pagN in smooth strains (Fig. 8). The magnitude of the decrease in cell association in pagN rough mutants was similar to that seen for the loss of the SPI-1 encoded T3SS by mutating invA in strain ML4. Moreover, there was no additive effect of deleting both pagN and invA. Intriguingly, loss of both pagN and invA in strain ML3 could be complemented by introducing the PagN multicopy plasmid pPagN2.3. Indeed, the level of cell association for pPagN2.3/ML3 was greater than that of CH133.


The PagN protein of Salmonella enterica serovar Typhimurium is an adhesin and invasin.

Lambert MA, Smith SG - BMC Microbiol. (2008)

Invasion of CHO-K1 cells by rough S. Typhimurium lacking a functional SPI-1-encoded T3SS. Invasion levels were calculated for rough S. Typhimurium strains with a functional T3SS, CH133 (PagN+) and ML133 (PagN-) and strains without a functional T3SS, ML4 (PagN+, InvA-) and ML3 (PagN-, InvA-). Levels were also calculated for ML3 harboring pPagN2.3 or the vector plasmid pBSKII+. Data represents an average of triplicate wells and standard error bars are shown. * indicates statistical significance of P < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2553418&req=5

Figure 8: Invasion of CHO-K1 cells by rough S. Typhimurium lacking a functional SPI-1-encoded T3SS. Invasion levels were calculated for rough S. Typhimurium strains with a functional T3SS, CH133 (PagN+) and ML133 (PagN-) and strains without a functional T3SS, ML4 (PagN+, InvA-) and ML3 (PagN-, InvA-). Levels were also calculated for ML3 harboring pPagN2.3 or the vector plasmid pBSKII+. Data represents an average of triplicate wells and standard error bars are shown. * indicates statistical significance of P < 0.05.
Mentions: Haemagglutination by Salmonella expressing PagN was only observed in rough strains (see above). This was not the case for adherence to or invasion of mammalian cells since we could observe defects in these phenotypes for pagN mutants in the smooth S. Typhimurium strain SL1344. Nevertheless we examined if a rough strain might facilitate enhanced invasion and/or adhesion by PagN. In these studies we made use of strain CH133 a rough mutant of S. Typhimurium LT-2 (a rough mutant of strain SL1344 was not readily available for these analyses). A pagN rough mutant strain, ML133, displayed approximately a five-fold decrease in cell association which was greater than the defect due to loss of pagN in smooth strains (Fig. 8). The magnitude of the decrease in cell association in pagN rough mutants was similar to that seen for the loss of the SPI-1 encoded T3SS by mutating invA in strain ML4. Moreover, there was no additive effect of deleting both pagN and invA. Intriguingly, loss of both pagN and invA in strain ML3 could be complemented by introducing the PagN multicopy plasmid pPagN2.3. Indeed, the level of cell association for pPagN2.3/ML3 was greater than that of CH133.

Bottom Line: S. enterica sv Typhimurium pagN mutants display a reduction in adhesion to and invasion of epithelial cells.Typhimurium.Finally PagN can be added to an ever-growing repertoire of factors that contribute to the pathogenesis of Salmonella.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Clinical Microbiology, Trinity College Dublin, St James's Hospital, Dublin 8, Ireland. malamber79@gmail.com

ABSTRACT

Background: The pagN gene of Salmonella enterica serovar Typhimurium is a PhoP-regulated gene that is up-regulated during growth within macrophages and in vivo in murine models of infection. The PagN protein displays similarity to the Hek and Tia invasins/adhesins of Escherichia coli. Thus far no function has been ascribed to the PagN protein.

Results: Here we show that the outer membrane located PagN protein mediates agglutination of red blood cells and that this can be masked by LPS. When expressed in Escherichia coli the PagN protein supports adhesion to and invasion of mammalian cells in a manner that is dependent on cytoskeletal rearrangements. S. enterica sv Typhimurium pagN mutants display a reduction in adhesion to and invasion of epithelial cells. Finally, we demonstrate that over-expression of PagN in a SPI-1 mutant can partially compensate for the lack of a functional invasasome.

Conclusion: PagN is an outer membrane protein that may contribute to the virulence of S. Typhimurium. This protein is a haemagglutinin and contributes to the adherence to mammalian cells. In addition, PagN can mediate high-level invasion of CHO-K1 cells. Previously,pagN mutants have been shown to be less competitive in vivo and thus this may be due to their lessened ability to interact with mammalian cells. Finally PagN can be added to an ever-growing repertoire of factors that contribute to the pathogenesis of Salmonella.

Show MeSH
Related in: MedlinePlus