Abstract
Regulation of biological functions requires factors (proteins, peptides or chemicals) able to sense and translate environmental conditions or any circumstances in order to modulate the transcription of a gene, the stability of a transcript or the activity of a protein. Quorum sensing is a regulation mechanism connecting cell density to the physiological state of a single cell. In bacteria, quorum sensing coordinates virulence, cell fate and commitment to sporulation and other adaptation properties. The critical role of such regulatory systems was demonstrated in pathogenicity and adaptation of bacteria from the Bacillus cereus group (i.e. B. cereus and Bacillus thuringiensis). Furthermore, using insects as a model of infection, it was shown that sequential activation of several quorum sensing systems allowed bacteria to switch from a virulence state to a necrotrophic lifestyle, allowing their survival in the host cadaver, and ultimately to the commitment into sporulation. The chronological development of these physiological states is directed by quorum sensors forming the RNPP family. Among them, NprR combines two distinct functions connecting sporulation to necrotrophism in B. thuringiensis. In the absence of its cognate signaling peptide (NprX), NprR negatively controls sporulation by acting as a phosphatase. In the presence of NprX, it acts as a transcription factor regulating a set of genes involved in the survival of the bacteria in the insect cadaver.
Highlights
In Gram-positive sporulating Bacilli, triggering of the sporulation process requires a certain threshold concentration of the transcriptional regulator Spo0A-P, whose phosphorylation depends on the activity of a multicomponent phosphorelay controlled by Rap phosphatases
The critical role of such regulatory systems was demonstrated in pathogenicity and adaptation of bacteria from the Bacillus cereus group (i.e. B. cereus and Bacillus thuringiensis)
Using insects as a model of infection, it was shown that sequential activation of several quorum sensing systems allowed bacteria to switch from a virulence state to a necrotrophic lifestyle, allowing their survival in the host cadaver, and to the commitment into sporulation
Summary
In Gram-positive sporulating Bacilli, triggering of the sporulation process requires a certain threshold concentration of the transcriptional regulator Spo0A-P, whose phosphorylation depends on the activity of a multicomponent phosphorelay controlled by Rap phosphatases. Stéphane Perchat1, Antoine Talagas2, Samira Zouhir2, Sandrine Poncet1, Laurent Bouillaut1,¶, Sylvie Nessler2,* and Didier Lereclus1, * +33 1 34 65 21 00; E-mail: Didier.Lereclus@ inra.fr; Sylvie Nessler, Tel: +33 1 69 15 79 66; Email: sylvie.nessler@i2bc.paris-saclay.fr
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