The Virulence Effect of CpxRA in Citrobacter rodentium Is Independent of the Auxiliary Proteins NlpE and CpxP
Citrobacter rodentium is a murine pathogen used to model the intestinal infection caused by Enteropathogenic and Enterohemorrhagic Escherichia coli (EPEC and EHEC), two diarrheal pathogens responsible for morbidity and mortality in developing and developed countries, respectively. During infection,...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Frontiers Media S.A.
2018-09-01
|
| Series: | Frontiers in Cellular and Infection Microbiology |
| Subjects: | |
| Online Access: | https://www.frontiersin.org/article/10.3389/fcimb.2018.00320/full |
| _version_ | 1819079535908356096 |
|---|---|
| author | Natalia Giannakopoulou Nilmini Mendis Lei Zhu Samantha Gruenheid Sebastien P. Faucher Hervé Le Moual |
| author_facet | Natalia Giannakopoulou Nilmini Mendis Lei Zhu Samantha Gruenheid Sebastien P. Faucher Hervé Le Moual |
| author_sort | Natalia Giannakopoulou |
| collection | DOAJ |
| description | Citrobacter rodentium is a murine pathogen used to model the intestinal infection caused by Enteropathogenic and Enterohemorrhagic Escherichia coli (EPEC and EHEC), two diarrheal pathogens responsible for morbidity and mortality in developing and developed countries, respectively. During infection, these bacteria must sense and adapt to the gut environment of the host. In order to adapt to changing environmental cues and modulate expression of specific genes, bacteria can use two-component signal transduction systems (TCS). We have shown that the deletion of the Cpx TCS in C. rodentium leads to a marked attenuation in virulence in C3H/HeJ mice. In E. coli, the Cpx TCS is reportedly activated in response to signals from the outer-membrane lipoprotein NlpE. We therefore investigated the role of NlpE in C. rodentium virulence. We also assessed the role of the reported negative regulator of CpxRA, CpxP. We found that as opposed to the ΔcpxRA strain, neither the ΔnlpE, ΔcpxP nor the ΔnlpEΔcpxP strains were significantly attenuated, and had similar in vivo localization to wild-type C. rodentium. The in vitro adherence of the Cpx auxiliary protein mutants, ΔnlpE, ΔcpxP, ΔnlpEΔcpxP, was comparable to wild-type C. rodentium, whereas the ΔcpxRA strain showed significantly decreased adherence. To further elucidate the mechanisms behind the contrasting virulence phenotypes, we performed microarrays in order to define the regulon of the Cpx TCS. We detected 393 genes differentially regulated in the ΔcpxRA strain. The gene expression profile of the ΔnlpE strain is strikingly different than the profile of ΔcpxRA with regards to the genes activated by CpxRA. Further, there is no clear inverse correlation in the expression pattern of the ΔcpxP strain in comparison to ΔcpxRA. Taken together, these data suggest that in these conditions, CpxRA activates gene expression in a largely NlpE- and CpxP-independent manner. Compared to wildtype, 161 genes were downregulated in the ΔcpxRA strain, while being upregulated or unchanged in the Cpx auxiliary protein deletion strains. This group of genes, which we hypothesize may contribute to the loss of virulence of ΔcpxRA, includes T6SS components, ompF, the regulator for colanic acid synthesis, and several genes involved in maltose metabolism. |
| first_indexed | 2024-12-21T19:30:32Z |
| format | Article |
| id | doaj.art-19e07e9941fa44f783201bea666acec3 |
| institution | Directory Open Access Journal |
| issn | 2235-2988 |
| language | English |
| last_indexed | 2024-12-21T19:30:32Z |
| publishDate | 2018-09-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Cellular and Infection Microbiology |
| spelling | doaj.art-19e07e9941fa44f783201bea666acec32022-12-21T18:52:43ZengFrontiers Media S.A.Frontiers in Cellular and Infection Microbiology2235-29882018-09-01810.3389/fcimb.2018.00320396871The Virulence Effect of CpxRA in Citrobacter rodentium Is Independent of the Auxiliary Proteins NlpE and CpxPNatalia Giannakopoulou0Nilmini Mendis1Lei Zhu2Samantha Gruenheid3Sebastien P. Faucher4Hervé Le Moual5Department of Microbiology and Immunology, McGill University, Montreal, QC, CanadaDepartment of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, CanadaDepartment of Microbiology and Immunology, McGill University, Montreal, QC, CanadaDepartment of Microbiology and Immunology, McGill University, Montreal, QC, CanadaDepartment of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, CanadaDepartment of Microbiology and Immunology, McGill University, Montreal, QC, CanadaCitrobacter rodentium is a murine pathogen used to model the intestinal infection caused by Enteropathogenic and Enterohemorrhagic Escherichia coli (EPEC and EHEC), two diarrheal pathogens responsible for morbidity and mortality in developing and developed countries, respectively. During infection, these bacteria must sense and adapt to the gut environment of the host. In order to adapt to changing environmental cues and modulate expression of specific genes, bacteria can use two-component signal transduction systems (TCS). We have shown that the deletion of the Cpx TCS in C. rodentium leads to a marked attenuation in virulence in C3H/HeJ mice. In E. coli, the Cpx TCS is reportedly activated in response to signals from the outer-membrane lipoprotein NlpE. We therefore investigated the role of NlpE in C. rodentium virulence. We also assessed the role of the reported negative regulator of CpxRA, CpxP. We found that as opposed to the ΔcpxRA strain, neither the ΔnlpE, ΔcpxP nor the ΔnlpEΔcpxP strains were significantly attenuated, and had similar in vivo localization to wild-type C. rodentium. The in vitro adherence of the Cpx auxiliary protein mutants, ΔnlpE, ΔcpxP, ΔnlpEΔcpxP, was comparable to wild-type C. rodentium, whereas the ΔcpxRA strain showed significantly decreased adherence. To further elucidate the mechanisms behind the contrasting virulence phenotypes, we performed microarrays in order to define the regulon of the Cpx TCS. We detected 393 genes differentially regulated in the ΔcpxRA strain. The gene expression profile of the ΔnlpE strain is strikingly different than the profile of ΔcpxRA with regards to the genes activated by CpxRA. Further, there is no clear inverse correlation in the expression pattern of the ΔcpxP strain in comparison to ΔcpxRA. Taken together, these data suggest that in these conditions, CpxRA activates gene expression in a largely NlpE- and CpxP-independent manner. Compared to wildtype, 161 genes were downregulated in the ΔcpxRA strain, while being upregulated or unchanged in the Cpx auxiliary protein deletion strains. This group of genes, which we hypothesize may contribute to the loss of virulence of ΔcpxRA, includes T6SS components, ompF, the regulator for colanic acid synthesis, and several genes involved in maltose metabolism.https://www.frontiersin.org/article/10.3389/fcimb.2018.00320/fullCitrobacter rodentiumvirulencetwo component systemsintestinal infectionCpxRAbacterial gene expression |
| spellingShingle | Natalia Giannakopoulou Nilmini Mendis Lei Zhu Samantha Gruenheid Sebastien P. Faucher Hervé Le Moual The Virulence Effect of CpxRA in Citrobacter rodentium Is Independent of the Auxiliary Proteins NlpE and CpxP Frontiers in Cellular and Infection Microbiology Citrobacter rodentium virulence two component systems intestinal infection CpxRA bacterial gene expression |
| title | The Virulence Effect of CpxRA in Citrobacter rodentium Is Independent of the Auxiliary Proteins NlpE and CpxP |
| title_full | The Virulence Effect of CpxRA in Citrobacter rodentium Is Independent of the Auxiliary Proteins NlpE and CpxP |
| title_fullStr | The Virulence Effect of CpxRA in Citrobacter rodentium Is Independent of the Auxiliary Proteins NlpE and CpxP |
| title_full_unstemmed | The Virulence Effect of CpxRA in Citrobacter rodentium Is Independent of the Auxiliary Proteins NlpE and CpxP |
| title_short | The Virulence Effect of CpxRA in Citrobacter rodentium Is Independent of the Auxiliary Proteins NlpE and CpxP |
| title_sort | virulence effect of cpxra in citrobacter rodentium is independent of the auxiliary proteins nlpe and cpxp |
| topic | Citrobacter rodentium virulence two component systems intestinal infection CpxRA bacterial gene expression |
| url | https://www.frontiersin.org/article/10.3389/fcimb.2018.00320/full |
| work_keys_str_mv | AT nataliagiannakopoulou thevirulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT nilminimendis thevirulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT leizhu thevirulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT samanthagruenheid thevirulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT sebastienpfaucher thevirulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT hervelemoual thevirulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT nataliagiannakopoulou virulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT nilminimendis virulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT leizhu virulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT samanthagruenheid virulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT sebastienpfaucher virulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp AT hervelemoual virulenceeffectofcpxraincitrobacterrodentiumisindependentoftheauxiliaryproteinsnlpeandcpxp |