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Single cell, super-resolution imaging reveals an acid pH-dependent conformational switch in SsrB regulates SPI-2
After Salmonella is phagocytosed, it resides in an acidic vacuole. Its cytoplasm acidifies to pH 5.6; acidification activates pathogenicity island 2 (SPI-2). SPI-2 encodes a type three secretion system whose effectors modify the vacuole, driving endosomal tubulation. Using super-resolution imaging i...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
eLife Sciences Publications, Ltd
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6557628/ https://www.ncbi.nlm.nih.gov/pubmed/31033442 http://dx.doi.org/10.7554/eLife.45311 |
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author | Liew, Andrew Tze Fui Foo, Yong Hwee Gao, Yunfeng Zangoui, Parisa Singh, Moirangthem Kiran Gulvady, Ranjit Kenney, Linda J |
author_facet | Liew, Andrew Tze Fui Foo, Yong Hwee Gao, Yunfeng Zangoui, Parisa Singh, Moirangthem Kiran Gulvady, Ranjit Kenney, Linda J |
author_sort | Liew, Andrew Tze Fui |
collection | PubMed |
description | After Salmonella is phagocytosed, it resides in an acidic vacuole. Its cytoplasm acidifies to pH 5.6; acidification activates pathogenicity island 2 (SPI-2). SPI-2 encodes a type three secretion system whose effectors modify the vacuole, driving endosomal tubulation. Using super-resolution imaging in single bacterial cells, we show that low pH induces expression of the SPI-2 SsrA/B signaling system. Single particle tracking, atomic force microscopy, and single molecule unzipping assays identified pH-dependent stimulation of DNA binding by SsrB. A so-called phosphomimetic form (D56E) was unable to bind to DNA in live cells. Acid-dependent DNA binding was not intrinsic to regulators, as PhoP and OmpR binding was not pH-sensitive. The low level of SPI-2 injectisomes observed in single cells is not due to fluctuating SsrB levels. This work highlights the surprising role that acid pH plays in virulence and intracellular lifestyles of Salmonella; modifying acid survival pathways represents a target for inhibiting Salmonella. |
format | Online Article Text |
id | pubmed-6557628 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | eLife Sciences Publications, Ltd |
record_format | MEDLINE/PubMed |
spelling | pubmed-65576282019-06-12 Single cell, super-resolution imaging reveals an acid pH-dependent conformational switch in SsrB regulates SPI-2 Liew, Andrew Tze Fui Foo, Yong Hwee Gao, Yunfeng Zangoui, Parisa Singh, Moirangthem Kiran Gulvady, Ranjit Kenney, Linda J eLife Microbiology and Infectious Disease After Salmonella is phagocytosed, it resides in an acidic vacuole. Its cytoplasm acidifies to pH 5.6; acidification activates pathogenicity island 2 (SPI-2). SPI-2 encodes a type three secretion system whose effectors modify the vacuole, driving endosomal tubulation. Using super-resolution imaging in single bacterial cells, we show that low pH induces expression of the SPI-2 SsrA/B signaling system. Single particle tracking, atomic force microscopy, and single molecule unzipping assays identified pH-dependent stimulation of DNA binding by SsrB. A so-called phosphomimetic form (D56E) was unable to bind to DNA in live cells. Acid-dependent DNA binding was not intrinsic to regulators, as PhoP and OmpR binding was not pH-sensitive. The low level of SPI-2 injectisomes observed in single cells is not due to fluctuating SsrB levels. This work highlights the surprising role that acid pH plays in virulence and intracellular lifestyles of Salmonella; modifying acid survival pathways represents a target for inhibiting Salmonella. eLife Sciences Publications, Ltd 2019-04-29 /pmc/articles/PMC6557628/ /pubmed/31033442 http://dx.doi.org/10.7554/eLife.45311 Text en © 2019, Liew et al http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/This article is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use and redistribution provided that the original author and source are credited. |
spellingShingle | Microbiology and Infectious Disease Liew, Andrew Tze Fui Foo, Yong Hwee Gao, Yunfeng Zangoui, Parisa Singh, Moirangthem Kiran Gulvady, Ranjit Kenney, Linda J Single cell, super-resolution imaging reveals an acid pH-dependent conformational switch in SsrB regulates SPI-2 |
title | Single cell, super-resolution imaging reveals an acid pH-dependent conformational switch in SsrB regulates SPI-2 |
title_full | Single cell, super-resolution imaging reveals an acid pH-dependent conformational switch in SsrB regulates SPI-2 |
title_fullStr | Single cell, super-resolution imaging reveals an acid pH-dependent conformational switch in SsrB regulates SPI-2 |
title_full_unstemmed | Single cell, super-resolution imaging reveals an acid pH-dependent conformational switch in SsrB regulates SPI-2 |
title_short | Single cell, super-resolution imaging reveals an acid pH-dependent conformational switch in SsrB regulates SPI-2 |
title_sort | single cell, super-resolution imaging reveals an acid ph-dependent conformational switch in ssrb regulates spi-2 |
topic | Microbiology and Infectious Disease |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6557628/ https://www.ncbi.nlm.nih.gov/pubmed/31033442 http://dx.doi.org/10.7554/eLife.45311 |
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