Open AccessInsights into the Extracytoplasmic Stress Response of Xanthomonas campestris pv. campestris : Role and Regulation of σ E -Dependent Activity
Author(s) -
Patricia Bordes,
Laure Lavatine,
Kounthéa Phok,
Roland Barriot,
Alice Boulanger,
Marie-Pierre Castanié-Cornet,
Guillaume Déjean,
Emmanuelle Lauber,
Anke Becker,
Matthieu Arlat,
Claude Gutierrez
Publication year - 2011
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.00884-10
Subject(s) - xanthomonas campestris , biology , regulon , sigma factor , xanthomonas campestris pv. campestris , periplasmic space , promoter , gene , transcription factor , genetics , xanthomonas , heat shock , transcription (linguistics) , microbiology and biotechnology , heat shock protein , gene expression , escherichia coli , linguistics , philosophy
Xanthomonas campestris pv.campestris is an epiphytic bacterium that can become a vascular pathogen responsible for black rot disease of crucifers. To adapt gene expression in response to ever-changing habitats, phytopathogenic bacteria have evolved signal transduction regulatory pathways, such as extracytoplasmic function (ECF) σ factors. The alternative sigma factor σE , encoded byrpoE , is crucial for envelope stress response and plays a role in the pathogenicity of many bacterial species. Here, we combine different approaches to investigate the role and mechanism of σE -dependent activation inX. campestris pv.campestris . We show that therpoE gene is organized as a single transcription unit with the anti-σ generseA and the protease genemucD and thatrpoE transcription is autoregulated.rseA andmucD transcription is also controlled by a highly conserved σE -dependent promoter within the σE gene sequence. The σE -mediated stress response is required for stationary-phase survival, resistance to cadmium, and adaptation to membrane-perturbing stresses (elevated temperature and ethanol). Using microarray technology, we started to define the σE regulon ofX. campestris pv.campestris . These genes encode proteins belonging to different classes, including periplasmic or membrane proteins, biosynthetic enzymes, classical heat shock proteins, and the heat stress σ factor σH . The consensus sequence for the predicted σE -regulated promoter elements is GGAACTN15-17 GTCNNA. Determination of therpoH transcription start site revealed thatrpoH was directly regulated by σE under both normal and heat stress conditions. Finally, σE activity is regulated by the putative regulated intramembrane proteolysis (RIP) proteases RseP and DegS, as previously described in many other bacteria. However, our data suggest that RseP and DegS are not only dedicated to RseA cleavage and that the proteolytic cascade of RseA could involve other proteases.