Host cell type-dependent translocation and PhoP-mediated positive regulation of the effector SseK1 of <i>Salmonella enterica</i>
<i>Salmonella enterica</i> expresses two virulence-related type III secretion systems (T3SSs) encoded in <i>Salmonella</i> pathogenicity island 1 (SPI1) and SPI2, respectively. SseK1 is a poorly characterized substrate of the SPI2-encoded T3SS. Here, we show that this effecto...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2015-04-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fmicb.2015.00396/full |
| _version_ | 1819030762608918528 |
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| author | Fernando eBaisón-Olmo María eGalindo-Moreno Francisco eRamos-Morales |
| author_facet | Fernando eBaisón-Olmo María eGalindo-Moreno Francisco eRamos-Morales |
| author_sort | Fernando eBaisón-Olmo |
| collection | DOAJ |
| description | <i>Salmonella enterica</i> expresses two virulence-related type III secretion systems (T3SSs) encoded in <i>Salmonella</i> pathogenicity island 1 (SPI1) and SPI2, respectively. SseK1 is a poorly characterized substrate of the SPI2-encoded T3SS. Here, we show that this effector is essential to get full virulence both in oral and intraperitoneal mice infections, in spite of not having a role in invasion or intracellular proliferation in cultured mammalian cells. <i>In vitro</i>, expression of <i>sseK1</i> was higher in media mimicking intracellular conditions, when SPI2 was induced, but it was also significant under SPI1 inducing conditions. A detailed analysis of translocation of SseK1 into host cells unveiled that it was a substrate of both, T3SS1 and T3SS2, although with different patterns and kinetics depending on the specific host cell type (epithelial, macrophages or fibroblasts). The regulation of the expression of <i>sseK1</i> was examined using <i>lacZ</i> and bioluminescent <i>lux</i> fusions. The two-component system PhoQ/PhoP is a positive regulator of this gene. A combination of sequence analysis, directed mutagenesis and electrophoretic mobility shift assays showed that phosphorylated PhoP binds directly to the promoter region of <i>sseK1</i> and revealed a PhoP binding site located upstream of the predicted -35 hexamer of this promoter. |
| first_indexed | 2024-12-21T06:35:19Z |
| format | Article |
| id | doaj.art-a8e5ec63da344c7e815c946a4744f134 |
| institution | Directory Open Access Journal |
| issn | 1664-302X |
| language | English |
| last_indexed | 2024-12-21T06:35:19Z |
| publishDate | 2015-04-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Microbiology |
| spelling | doaj.art-a8e5ec63da344c7e815c946a4744f1342022-12-21T19:12:53ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2015-04-01610.3389/fmicb.2015.00396141012Host cell type-dependent translocation and PhoP-mediated positive regulation of the effector SseK1 of <i>Salmonella enterica</i>Fernando eBaisón-Olmo0María eGalindo-Moreno1Francisco eRamos-Morales2Universidad de SevillaUniversidad de SevillaUniversidad de Sevilla<i>Salmonella enterica</i> expresses two virulence-related type III secretion systems (T3SSs) encoded in <i>Salmonella</i> pathogenicity island 1 (SPI1) and SPI2, respectively. SseK1 is a poorly characterized substrate of the SPI2-encoded T3SS. Here, we show that this effector is essential to get full virulence both in oral and intraperitoneal mice infections, in spite of not having a role in invasion or intracellular proliferation in cultured mammalian cells. <i>In vitro</i>, expression of <i>sseK1</i> was higher in media mimicking intracellular conditions, when SPI2 was induced, but it was also significant under SPI1 inducing conditions. A detailed analysis of translocation of SseK1 into host cells unveiled that it was a substrate of both, T3SS1 and T3SS2, although with different patterns and kinetics depending on the specific host cell type (epithelial, macrophages or fibroblasts). The regulation of the expression of <i>sseK1</i> was examined using <i>lacZ</i> and bioluminescent <i>lux</i> fusions. The two-component system PhoQ/PhoP is a positive regulator of this gene. A combination of sequence analysis, directed mutagenesis and electrophoretic mobility shift assays showed that phosphorylated PhoP binds directly to the promoter region of <i>sseK1</i> and revealed a PhoP binding site located upstream of the predicted -35 hexamer of this promoter.http://journal.frontiersin.org/Journal/10.3389/fmicb.2015.00396/fullEpithelial CellsFibroblastsMacrophagesSalmonellabioluminescenceType III Secretion |
| spellingShingle | Fernando eBaisón-Olmo María eGalindo-Moreno Francisco eRamos-Morales Host cell type-dependent translocation and PhoP-mediated positive regulation of the effector SseK1 of <i>Salmonella enterica</i> Frontiers in Microbiology Epithelial Cells Fibroblasts Macrophages Salmonella bioluminescence Type III Secretion |
| title | Host cell type-dependent translocation and PhoP-mediated positive regulation of the effector SseK1 of <i>Salmonella enterica</i> |
| title_full | Host cell type-dependent translocation and PhoP-mediated positive regulation of the effector SseK1 of <i>Salmonella enterica</i> |
| title_fullStr | Host cell type-dependent translocation and PhoP-mediated positive regulation of the effector SseK1 of <i>Salmonella enterica</i> |
| title_full_unstemmed | Host cell type-dependent translocation and PhoP-mediated positive regulation of the effector SseK1 of <i>Salmonella enterica</i> |
| title_short | Host cell type-dependent translocation and PhoP-mediated positive regulation of the effector SseK1 of <i>Salmonella enterica</i> |
| title_sort | host cell type dependent translocation and phop mediated positive regulation of the effector ssek1 of lt i gt salmonella enterica lt i gt |
| topic | Epithelial Cells Fibroblasts Macrophages Salmonella bioluminescence Type III Secretion |
| url | http://journal.frontiersin.org/Journal/10.3389/fmicb.2015.00396/full |
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