Premium
Cytolocalization of the PhoP response regulator in Salmonella enterica : modulation by extracellular Mg 2+ and by the SCV environment
Author(s) -
Sciara Mariela I.,
Spagnuolo Carla,
JaresErijman Elizabeth,
García Véscovi Eleonora
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06427.x
Subject(s) - response regulator , biology , salmonella enterica , mutant , extracellular , cytoplasm , virulence , microbiology and biotechnology , phosphorylation , phosphatase , regulator , vacuole , histidine kinase , kinase , biochemistry , gene , escherichia coli
Summary The PhoP/PhoQ two‐component system plays an essential role regulating numerous virulence phenotypes in Salmonella enterica . Previous work showed that PhoQ, the sensor protein, switches between the kinase‐ and the phosphatase‐dominant state in response to environmental Mg 2+ availability. This switch defines the PhoP phosphorylation status and, as a result, the transcriptional activity of this regulator. In this work, using the FlAsH labelling technique, we examine PhoP cytolocalization in response to extracellular Mg 2+ limitation in vitro and to the Salmonella ‐containing vacuole (SCV) environment in macrophage cells. We demonstrate that in these PhoP/PhoQ‐inducing environments PhoP displays preferential localization to one cell pole, while being homogeneously distributed in the bacterial cytoplasm in repressing conditions. Polar localization is lost in the absence of PhoQ or when a non‐phosphorylatable PhoP D52A mutant is expressed. However, when PhoP transcriptional activation is achieved in a Mg 2+ ‐ and PhoQ‐independent manner, PhoP regains asymmetric polar localization. In addition, we show that, in the analysed conditions, PhoQ cellular distribution does not parallel PhoP location pattern. These findings reveal that PhoP cellular location is dynamic and conditioned by its environmentally defined transcriptional status, showing a new insight in the PhoP/PhoQ system mechanism.