The YvfTU Two-component System is involved in <it>plcR </it>expression in <it>Bacillus cereus</it>
2008
Nguyen-the Christophe | Kolstø Anne-Brit | Ramarao Nalini | Nielsen-Leroux Christina | Gohar Michel | Dargaignaratz Claire | Michaud Caroline | Susanna Kim | Brillard Julien | Lereclus Didier | Broussolle Véronique
<p>Abstract</p> <p>Background</p> <p>Most extracellular virulence factors produced by <it>Bacillus cereus </it>are regulated by the pleiotropic transcriptional activator PlcR. Among strains belonging to the <it>B. cereus </it>group, the <it>plcR </it>gene is always located in the vicinity of genes encoding the YvfTU two-component system. The putative role of YvfTU in the expression of the PlcR regulon was therefore investigated.</p> <p>Results</p> <p>Expression of the <it>plcR </it>gene was monitored using a transcriptional fusion with a <it>lacZ </it>reporter gene in a <it>yvfTU </it>mutant and in its <it>B. cereus </it>ATCC 14579 parental strain. Two hours after the onset of the stationary phase, a stage at which the PlcR regulon is highly expressed, the <it>plcR </it>expression in the <it>yvfTU </it>mutant was only 50% of that of its parental strain. In addition to the reduced <it>plcR </it>expression in the <it>yvfTU </it>mutant, a few members of the PlcR regulon showed a differential expression, as revealed by transcriptomic and proteomic analyses. The virulence of the <it>yvfTU </it>mutant in a <it>Galleria mellonella </it>insect model was slightly lower than that of the parental strain.</p> <p>Conclusion</p> <p>The YvfTU two-component system is not required for the expression of most of the virulence factors belonging to the PlcR regulon. However, YvfTU is involved in expression of <it>plcR</it>, a major regulator of virulence in <it>B. cereus</it>.</p>
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